End-Fed Half-Wave Antennas: The Complete System, Not Just the Wire

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An end-fed half-wave can be wonderfully practical. It can put a multiband wire in the air with one elevated support, keep the feed point near the operator, and pack into a small field kit. Those advantages explain why EFHW systems are popular with portable operators, small-property stations, and anyone who cannot conveniently support the center of a dipole.

But the easy mechanical description—“a half-wave wire fed at the end”—hides most of the engineering. A working installation is not just a radiator. It is a radiator, a high-impedance matching network, a return-current path, a feed line, any common-mode suppression, the station connected to that line, the support geometry, the ground and nearby objects. Change one of those pieces and the analyzer reading, noise pickup, RF in the station, or radiation pattern can change even when the wire itself has not been cut.

That complete-system view is the organizing idea of this handbook. It prevents several common mistakes:

• treating every end-fed wire as an EFHW;
• assuming a nominal transformer ratio proves low loss or high power capability;
• using low SWR as a substitute for efficiency;
• declaring that coax is always, or never, part of the radiating system;
• expecting one radiation pattern on every band and in every deployment;
• transferring generic advice into a specific Chameleon product installation without checking its current guide.

Stop before transmitting

Keep every conductor and support away from overhead utilities. Treat the feed region, matching network, and open ends of the radiator as possible high-RF-voltage areas. Keep people, animals, combustible material, wiring, and uncontrolled conductive objects out of the required clearance area. Lower and de-energize the system before adjustment. For a Chameleon product, use the current product guide—not this general article—as the controlling installation document.

In the United States, RF-exposure evaluation depends on the actual station and accessible environment. Frequency, power delivered to the antenna system, operating mode and duty cycle, antenna characteristics, installation geometry, and controlled versus uncontrolled access all matter. There is no honest universal “EFHW safe distance.” This guide links you to the current rule and a recognized evaluation workflow rather than inventing one number.

What an EFHW actually is

An end-fed half-wave is a half-wave-class radiator fed near one end, where the feed-point impedance is normally much higher than the 50-ohm environment expected by common amateur transceivers and coaxial feed lines. A matching network transforms that high impedance to a range the station can use.

“Half-wave-class” is deliberate language. The familiar free-space half-wave calculation is a starting estimate, not a final cut length. Installed resonance depends on conductor diameter and insulation, bends, slope, height, ground, nearby structures and vegetation, the matching network, and the rest of the feed/return system. A commercial product may also be intentionally designed around a particular multiband response and documented deployment geometry.

The correct acronym is EFHW. Operators often type EHFW, and CKB search should recognize that misspelling without repeating it as the technical term.

“End-fed” describes a location, not a complete design

Many antennas receive power at or near an end. They do not all behave the same way. The useful questions are:

1. What is the radiator's intended electrical length on the operating band?
2. Where is it fed relative to the standing current and voltage distribution?
3. What transforms the feed-point impedance?
4. What completes the return-current path?
5. Is the feed line intended to carry high standing-wave ratio, common-mode current, or neither?
6. Is a tuner part of normal operation?

Without those answers, the label “end-fed” is too vague to predict tuning, loss, pattern, or station behavior.

EFHW versus other wire antennas

These are families, not rigid guarantees. Real installations can combine bending, loading, multiple bands, unusual feed systems, or nearby conductors. The point of the table is to force the right questions before a product or article is treated as interchangeable with another.

The electrical picture: current, voltage, and impedance

On its fundamental half-wave resonance, a thin-wire dipole has current near a maximum around its center and voltage maxima toward its ends. Feeding near an end therefore places the connection in a high-voltage, low-current region. The ratio of voltage to current is high, so the feed-point impedance is high compared with a conventional 50-ohm station interface.

That statement is more useful than memorizing one impedance number. The installed value is not a universal constant. Moving the feed position even slightly, changing wire diameter, bending or sloping the radiator, changing its height, bringing it near soil or a structure, and changing the return-current boundary can all move the resistance and reactance seen at the feed point.

The high-voltage end is also a physical design constraint. It affects insulation, spacing, component stress, weather behavior, and human access. An analyzer sweep performed at milliwatt-level test power does not reproduce the voltage, dielectric stress, core heating, or thermal accumulation that may occur during transmission.

What changes on higher bands

When the same wire is used on harmonically related bands, the current distribution develops additional maxima and minima along the radiator. The radiation pattern therefore develops additional lobes and nulls. The feed-point condition may remain usable through the intended matching system, but practical resonances do not automatically fall in the desired portion of every amateur band. Installation geometry and the matching network still matter.

This is why the correct question is not “What is the EFHW pattern?” It is “What is the pattern for this exact radiator, frequency, geometry, height, ground model, and return-system assumption?”

Calculated length gets you started. The installation finishes the job.

A half-wave formula gives a useful first estimate for a wire in an idealized environment. It does not know what insulation surrounds the conductor, how thick the wire is, whether the radiator will be straight or bent, how close it will pass to the ground or a building, or what matching and return-current system will be connected at the feed end.

Those details change electrical length. A physically unchanged wire can appear electrically longer or shorter after the operator changes its height, slope, end clearance, bend location, feed-line route, transformer, choke, or nearby environment. That is not mysterious behavior and it is not automatically a defective antenna. It means the measured object is the installed system, not an isolated number of feet of wire.

Resonance is not the same as usefulness

At a defined antenna feed point, resonance means the net reactance passes through or near zero. An intervening feed line or matching network can transform what a remote analyzer sees, so the measurement plane must be stated. Resonance does not guarantee a 50-ohm resistance, low feed-system loss, the desired radiation pattern, or acceptable behavior across an entire band. A matching network may transform the impedance seen by the feed line, and a tuner may transform what the radio sees, while the radiator and return system continue to behave according to their actual installation.

The useful field question is therefore not merely, "Where is the lowest SWR?" It is:

In the documented configuration, where are resistance, reactance, and SWR across the frequencies I intend to use, and did I keep the measurement boundary unchanged?

The current product guide may specify a tuning stub, link, extension, trimming procedure, or a configuration that should not be cut. Follow that instruction before applying general wire-antenna advice.

What a 49:1 transformer ratio means—and what it does not

For an ideal transformer, impedance ratio is the square of turns ratio:

\[ \frac{Z_\text{high}}{Z_\text{low}} = \left(\frac{N_\text{high}}{N_\text{low}}\right)^2 \]

A 7:1 turns ratio therefore corresponds ideally to a 49:1 impedance ratio. At an ideal 50-ohm reference, that ratio maps to 2,450 ohms. This is a clean teaching example—not a promise that every EFHW feed point is 2,450 ohms, nor proof that the transformer presents exactly that ratio across every band.

A physical broadband transformer includes leakage inductance, winding capacitance, core loss, conductor loss, imperfect coupling, connectors, compensation components, and enclosure effects. Its behavior changes with frequency. Match, insertion loss, temperature rise, saturation margin, and sustained power capability are separate questions. A good SWR trace answers only part of the first one.

For a product-specific claim, we need a defined device under test, winding and core identity, load or antenna boundary, calibration plane, sweep, power, duty cycle, ambient conditions, and measurement uncertainty. A nominal ratio—or a connector that happens to fit—cannot establish electrical compatibility.

Transformer bandwidth, loss, and heat are separate from ratio

A nominal impedance ratio describes an intended transformation. It does not describe how well the physical device performs that transformation across frequency, power, and time. A broadband transformer behaves as a network containing useful magnetizing and coupling behavior plus leakage inductance, winding capacitance, conductor resistance, core loss, connector effects, and any compensation components. Their relative importance changes across the operating range.

At the low-frequency end, available magnetizing impedance and core excitation can become important. At higher frequencies, leakage inductance, capacitance, winding geometry, and other parasitic effects can limit the useful response. Between those regions, core and conductor losses still convert some accepted power to heat. The exact boundaries depend on the physical transformer and load, not the 49:1 label alone.

Five questions that must not be merged

1. Match: What impedance or reflection coefficient appears at the declared input reference plane?
2. Transmission: How much power reaches the declared output/load reference plane under the test method?
3. Temperature: How quickly and how far does the device heat under the declared band, power, duty cycle, load, ambient conditions, and time?
4. Common mode: What impedance does the complete device present to current on the feed-line exterior at the relevant frequencies?
5. Survival and repeatability: Does the device return to its baseline after the test without damage, drift, arcing, or changed connections?

A low-power one-port SWR sweep addresses only part of the first question. It cannot validate insertion loss, sustained digital-mode power, internal voltage stress, enclosure temperature, or common-mode suppression. A transformer may show a usable match while dissipating enough power to become unsafe during a longer transmission.

Use only the power and mode limits in the current product guide or an exact documented product test. Do not transfer a rating between LEFS products, bands, transformer sizes or duty cycles. If the exact configuration has not been verified, do not estimate.

Where does the other half of the current go?

Current does not leave a transmitter, flow into one wire, and disappear. A complete circuit requires a return path. In an EFHW installation that path may include an intentional counterpoise, the outside surface of a coax shield, a ground or bonding connection, station equipment and cables, capacitive coupling to the environment, or some combination of them. Where the effective boundary falls depends on the matching network, choke placement, feed-line length and routing, station connections, and the site itself.

That is why two absolute slogans both fail:

• “The coax is the counterpoise.” Sometimes the feed-line exterior carries meaningful common-mode current, but its amount and distribution are not fixed merely because coax is present.
• “The coax is never part of the antenna.” An unbalanced end-fed installation can place current on the shield exterior, allowing it to radiate, receive noise, change the feed-point condition, or couple RF into the station.

The accurate statement is conditional: the coax shield exterior may participate in the installed antenna system unless the current boundary is deliberately established and verified.

Differential current and common-mode current

Inside a coaxial line, the desired differential currents flow on the center conductor and the inside surface of the shield in opposite directions. Their external fields largely cancel. Common-mode current flows on the outside surface of the shield. That exterior current sees the rest of the installation—the cable route, station, ground, nearby objects, and any choke—as part of its RF environment.

Common-mode current is not diagnosed by a single symptom. It may contribute to RF in the station, touch-sensitive tuning, noise pickup, pattern distortion, or SWR that changes when the cable is moved. Those observations are clues, not proof by themselves. The disciplined test is to hold the antenna geometry and analyzer reference plane fixed, change one feed-line or suppression variable, and record both the impedance response and, when possible, shield-current measurements.

Counterpoise decisions

An intentional counterpoise gives return current a designed conductor instead of leaving the entire job to uncontrolled capacitance, station wiring, or feed-line exterior current. But adding one is not a universal improvement with one universal length. It changes the installed circuit and may change feed-point impedance, common-mode current distribution, tuning, and pattern.

The controlling product guide decides whether a counterpoise is included, required, optional, or not part of the documented configuration. If an operator performs a general experiment, the comparison should keep the radiator geometry, height, feed line, choke, frequency, analyzer reference plane, and site fixed. Change only the counterpoise variable, then record the outcome.

What a common-mode choke can—and cannot—do

A common-mode choke is intended to impede current on the feed-line exterior while allowing the desired differential signal inside the coax to pass. A matching transformer and a common-mode choke solve different problems. A device can transform impedance without providing enough common-mode impedance at the frequencies and installation point that matter.

There is no trustworthy universal instruction to “put the choke exactly X feet from every EFHW feed point.” Placement changes the electrical length and current distribution of the exterior path. The correct location depends on the antenna architecture, band, feed-line route, return conductor, station boundary, and the choke's actual impedance versus frequency. Follow the current product guide where it specifies placement. Otherwise, test placement as a controlled variable rather than repeating a slogan.

Why changing the coax can change the result

Inside coax, the desired signal travels as differential current on the center conductor and the inside surface of the shield. If the load differs from the line's characteristic impedance, the line transforms the impedance along its length. The impedance presented at the analyzer or tuner can therefore depend on the electrical length of the line even when the antenna feed-point impedance has not changed.

There is a second mechanism. If common-mode current flows on the outside of the shield, that exterior surface is part of the installed RF structure. Changing cable length, routing, height, contact with the ground, or proximity to metal can change that exterior current path. The antenna itself may not have changed, but the complete antenna system has.

This gives us a useful diagnostic clue:

• A repeatable change after altering only coax length or routing suggests that feed-line transformation, exterior current, or both deserve investigation.
• It does not, by itself, prove the amount of common-mode current or identify the correct choke location.
• It does not authorize changing the product's documented feed-line or choke arrangement.

Make the measurement repeatable

Before comparing two sweeps, record:

1. antenna model and exact configuration;
2. frequency span and analyzer settings;
3. calibration and reference plane;
4. feed-line type, length, route, and position above ground;
5. choke identity and location, if used;
6. radiator endpoints, support heights, bends, and orientation;
7. soil/weather state and nearby objects;
8. what single variable will change.

Do not hold the analyzer in one hand for the first sweep and place it on the ground for the second. Do not reroute ten feet of coax, move the transformer, raise the radiator, and then attribute the entire difference to the choke. One-variable-at-a-time testing may feel slower, but it is far faster than debugging evidence that cannot answer its own question.

"Ground" can mean four different jobs

Operators often receive advice to "add a ground" without being told which problem the ground is supposed to solve. That shortcut is especially dangerous around an end-fed system because four different functions can be hidden behind the same word.

1. RF return path

RF current requires a complete circuit. An intentional counterpoise, feed-line exterior, radial system, station wiring, capacitance to the surrounding environment, or a combination of these can participate in the return path. This is an antenna-system question. It affects current distribution, impedance, radiation, and sometimes tuning.

2. Common-mode suppression

A common-mode choke is intended to impede current on the exterior of a feed line while passing the desired differential signal inside the line. This is a current-boundary and interference-control question. A ground rod is not automatically a substitute for a choke, and an impedance transformer is not automatically an effective common-mode choke. Choke behavior is frequency-dependent.

3. Equipment bonding and electrical safety

Bonding connects equipment and conductive systems according to the applicable safety design so that dangerous potential differences and fault-current paths are controlled. This is not the same job as tuning an antenna or creating a counterpoise. Requirements depend on the installation and jurisdiction.

4. Lightning protection

Lightning protection addresses surge paths, entry points, bonding, conductor routing, disconnect practices, and the structure's grounding-electrode system. A convenient RF wire or portable ground stake is not automatically a lightning-protection system.

Ask the purpose before touching the hardware

When someone recommends "more ground," ask:

• Are we trying to complete an RF return path?
• Reduce feed-line exterior current?
• Correct equipment bonding or an electrical-safety problem?
• Manage lightning and surge energy?

The answer determines the design. Combining these jobs casually can create a system that tunes differently while leaving the actual safety or interference problem unresolved. The handbook can explain the distinction; it cannot replace the current product guide, applicable electrical rules, or a site-specific lightning design.

Why one wire can work on several bands

An EFHW is commonly designed around a half-wave-class fundamental. On selected harmonically related frequencies, the same conductor can support additional standing-wave distributions while still presenting a condition the matching system and station can use. That is the origin of the familiar multiband benefit.

It is tempting to turn this into a simple multiplication rule: if the wire works on its fundamental, every integer multiple should land perfectly inside another amateur band. Real systems refuse to be that tidy.

Amateur bands are not positioned as exact harmonic copies of one another. Conductor and insulation effects, ground, height, bends, end loading, compensation, feed position, matching-network behavior, and the return-current path all influence the installed response. A resonance that is conveniently placed on one band can fall high or low on another. The acceptable bandwidth may also change substantially by band.

Band coverage is a product claim

For a Chameleon product, use the supported bands and configurations stated in its current guide. Do not infer that a LEFS 4010, LEFS 8010, and LEFS FEATHER share the same band set because they belong to the same family. Do not infer that adding a wire extension, substituting a transformer, or connecting a mechanically compatible accessory preserves the documented multiband behavior.

The reviewed NEC pattern library also has its own narrower meaning. It contains accepted pattern configurations at named frequencies. The absence of a modeled band does not automatically mean the physical product cannot operate there, and the presence of a pattern does not prove acceptable installed SWR or transformer performance. Pattern inventory and product operating coverage are related records, not interchangeable records.

Tune the installation you intend to use

The most common tuning mistake is adjusting one configuration and operating another. A radiator trimmed horizontally at shoulder height may shift after it becomes a sloper. A wire tuned in an open field may shift beside a house. A result measured through one feed-line length may not reproduce through another if line transformation or common-mode current is significant.

Use this sequence unless the current product guide specifies otherwise:

1. Assemble the exact documented product configuration.
2. Put the supports, endpoints, feed line, choke, and nearby equipment where they will be during operation.
3. Inspect the system mechanically and keep people clear.
4. Calibrate or define the analyzer reference plane.
5. Measure at low power and save the complete sweep.
6. Record resistance, reactance, and SWR around the intended operating segment.
7. Change only the guide-authorized tuning variable in a small increment.
8. Restore the complete operating geometry and measure again.
9. Stop if the response behaves inconsistently, a component heats, or the guide does not authorize the proposed change.

Reading direction correctly

For a conventional wire whose physical length is the controlled tuning variable, resonance below the desired frequency normally indicates that the wire is electrically too long; resonance above the desired frequency normally indicates that it is electrically too short. But an EFHW product may include a tuning stub, extension, link, loading element, or matching-network behavior that changes what should be adjusted. The product guide controls the action.

Never make a large cut based on a single sweep. Wire can be shortened again; it cannot be uncut. Fold-back or another reversible method is useful during controlled experimentation when the guide permits it.

What a tuner changes

A tuner can transform the impedance presented to the transmitter. It cannot guarantee that the transformer is cool, the feed line is low-loss, the radiator is efficient, or the pattern suits the desired path. If the tuner finds a match but the results are poor, the next step is system diagnosis, not a declaration that the tuner or antenna "does nothing."

A low SWR is useful. It is not an efficiency meter.

SWR describes impedance mismatch at a declared reference plane. It tells us how the load presented there compares with the line's reference impedance. It does not tell us where accepted power goes after it crosses that plane.

A system can show a comfortable SWR while losing power in a transformer, feed line, lossy conductor, connection, soil-coupled return path, or suppression component. Loss can even broaden or flatten an SWR curve because dissipated energy is no longer returning to the analyzer. Conversely, a low-loss antenna can present an inconvenient impedance until a suitable matching network or tuner transforms it.

An antenna tuner changes the impedance presented to the transmitter. That can let the transmitter deliver power safely into the feed system, but it does not repair a burned connection, restore transformer power lost as heat, remove common-mode current automatically, or guarantee that the radiator is producing the coverage pattern the operator needs.

The practical sequence is:

1. define the measurement plane;
2. verify the documented physical configuration;
3. sweep at low power and record resistance, reactance, and SWR—not only the minimum SWR number;
4. check sensitivity to controlled changes such as cable route or choke placement;
5. evaluate loss or heating with a method designed for that question;
6. compare the observed result with the current product guide and the exact modeled configuration.

The goal is not to distrust SWR. It is to stop asking one measurement to answer five different engineering questions.

The same wire can become a different antenna system

Changing geometry changes current distribution relative to the ground and surrounding objects. It also changes polarization components, lobe direction, null placement, feed-point impedance, and coupling to the feed line. A layout name is useful only when its physical details are known.

Horizontal

Both endpoints are supported at similar heights and the radiator is approximately level. Electrical height in wavelengths strongly influences the elevation pattern. A physically fixed height can be electrically low on 40 meters and much higher on 10 meters, so the same wire should not be expected to preserve one takeoff angle across bands.

Sloper

The endpoints are at different heights. A sloper is not merely a horizontal wire tilted for convenience. The slope, endpoint heights, horizontal span, feed-end location, ground, and direction of the slope all help define the modeled and installed case.

Inverted-L

The radiator has substantial vertical and horizontal portions. The bend position and the lengths of both portions matter. It is not acceptable to show an inverted-L pattern for a straight sloper merely because the total wire length is similar.

Inverted-V

The radiator changes direction at an elevated point. Feed location, apex height, included angle, endpoint heights, and leg symmetry all matter. An inverted-V dipole and an end-fed wire arranged in a V shape are not automatically the same electrical architecture.

Bent or low-profile route

The wire follows available supports, property boundaries, an attic, or another constrained path. Every bend and nearby material can affect the result. A bent installation can be useful, but the honest evidence is its exact geometry - not the nearest straight-wire illustration.

Customer-facing selector rule

Use the CKB pattern selector to choose the product, radiator or extension, geometry, support height and band. It opens a pattern only when that combination matches a reviewed configuration. If no exact model exists, use the closest documented setup instructions and do not substitute another antenna's curve.

Height matters in wavelengths, not only in feet

An operator may raise a support by five feet and expect a dramatic change because five feet feels substantial on the ground. Electrically, that change may be small on 40 meters and more significant on a higher band. The resulting pattern change also depends on the rest of the geometry, ground, and frequency.

A low horizontal component over ground often strengthens high-angle radiation, which can be useful for regional Near Vertical Incidence Skywave coverage when propagation supports it. Greater electrical height can redistribute energy into lower-angle lobes. But "higher always means lower angle" is too crude. At some bands and geometries the principal-lobe change may be small; at others, multiple lobes exchange prominence or the useful azimuth directions change.

Lobes and nulls are the antenna's directional opportunities and blind spots

A lobe is a region where the model shows relatively stronger radiation. A null is a direction where the modeled response falls sharply relative to a lobe. The principal lobe is the strongest lobe in the selected pattern data; secondary lobes can still be operationally important.

On a fundamental half-wave distribution, the broad pattern may look familiar. On higher harmonically related bands, additional current maxima and minima form along the same wire, producing more lobes and nulls. Sloping and bending the radiator, changing its electrical height, or changing the return-current boundary can rotate or distort them.

That has a practical consequence: the direction that worked well on 40 meters may sit closer to a null on 10 meters. Rotating or reorienting a field installation can matter, but the model's X and Y axes are not automatically north, south, east, or west. They describe the reviewed model. A compass bearing can be claimed only when the configuration explicitly defines one.

How to read Chameleon's 2D and 3D NEC patterns

Start with the installation card, not the colorful surface. Confirm the product, radiator, extensions or links, frequency, feed point, endpoint/support heights, geometry, ground model, and return-system boundary. If those do not match your installation, the pattern may still teach general behavior, but it is not your exact case.

Elevation pattern

An elevation plot is a vertical slice through the calculated three-dimensional radiation field at a stated azimuth or model plane. It helps answer: at what angles above the modeled horizon are the important lobes and nulls in that slice?

It is not a side-view drawing of the antenna. A sloping wire shown rising to the right does not mean the elevation curve is a physical trace of that wire.

Azimuth pattern

An azimuth plot is a horizontal slice at a stated elevation angle. It helps answer: at that chosen angle above the horizon, which model-relative horizontal directions are stronger or weaker?

An azimuth plot at one elevation cannot describe every elevation. If the principal lobe is high-angle but the azimuth cut is taken low, the horizontal shape may emphasize a different part of the radiation volume.

Three-dimensional pattern

The 3D surface connects the relative response across many azimuth and elevation samples. Bulges represent stronger modeled directions relative to the displayed maximum; indentations represent weaker directions or null regions. The surface is not a coverage-distance map, and its size is not the physical size of the antenna.

Coordinate system

The Chameleon pattern display uses this convention:

• +Z is up and -Z is down.
• X and Y are model-relative horizontal axes.
• X and Y are not geographic bearings unless the reviewed configuration explicitly says otherwise.
• "Top" means looking from +Z down toward the ground.
• Front and side views must identify the model-axis viewpoint.

The physical installation is explained beside the evidence. It is not drawn through the radiation volume because that can make a model-relative surface look like a literal picture of the antenna.

Normalized decibels

In a normalized pattern, the strongest value in the selected data is displayed as the reference, usually 0 dB. Other directions are shown below that maximum. A -3 dB direction represents about half the modeled power response of the normalized maximum for that plotted quantity. It does not mean that half the transmitter's power was radiated overall.

Normalization is excellent for comparing shape, lobe direction, beamwidth, and null structure. It deliberately removes the absolute scale needed to claim realized gain or total efficiency.

A 60-second reading sequence

1. Name the exact configuration and frequency.
2. Read the geometry, heights, ground, and return boundary.
3. Find the principal elevation lobe and important secondary lobes.
4. Read the azimuth slice at its stated elevation; identify useful directions and nulls.
5. Use the 3D surface to connect the slices, then read the evidence boundary before making an operating decision.

What the reviewed NEC patterns can show

For an accepted configuration, Chameleon's normalized NEC data can support discussion of:

• relative radiation-pattern shape;
• principal and secondary lobe directions;
• operationally important null directions;
• relative azimuth variation at a declared elevation;
• relative elevation behavior in a declared vertical cut;
• changes between controlled models when the differing inputs are explicitly identified.

The current customer-facing LEFS library contains 43 reviewed configurations: eight for CHA LEFS 4010, 28 for CHA LEFS 8010 and seven for CHA LEFS FEATHER. Each pattern belongs to a named geometry and frequency; one configuration must not be used as evidence for another.

What the normalized library does not establish by itself

It does not prove:

• installed SWR or bandwidth;
• transformer insertion loss or heating;
• conductor, connection, ground, or feed-line loss;
• radiation efficiency;
• realized gain;
• power handling;
• communication range;
• on-air field strength;
• correlation with an installation that differs from the modeled geometry;
• behavior of a product or frequency not represented by the selected accepted record.

Those questions require other evidence: calibrated network measurements, thermal testing, controlled field-strength work, current measurements, or another reviewed model with the needed system components and assumptions.

Compare models without fooling yourself

A controlled model comparison holds all irrelevant inputs fixed. If height is the question, do not also change radiator length, ground, conductor, segmentation, feed location, and frequency. If geometry is the question, disclose which endpoints and bends moved. If a model lacks the matching network or feed-line exterior, say so plainly.

Likewise, a field comparison should hold frequency, receiver settings, feed line, power, site, time window, and measurement method as steady as practical. Propagation can change while the operator is moving hardware. A single louder signal report is useful operating feedback, but it is not automatically a controlled antenna-efficiency measurement.

Where transmitter power can go

Power accepted from the transmitter does not have only two destinations, "radiated" or "reflected." In a complete EFHW installation, some accepted power can be radiated and some can be converted to heat in the matching transformer, conductor, connections, feed line, return path, choke, tuner, or nearby lossy materials. Current on unintended conductors can also move energy into parts of the installation where it causes interference or heating instead of contributing usefully to the intended pattern.

An SWR measurement cannot allocate those destinations. It describes the impedance relationship at a defined reference plane. A system can show a comfortable SWR while concealing loss, and a low-loss system can show a higher SWR that the transmitter does not like. That is why "the radio is happy" and "the antenna system is efficient" are separate findings.

Separate the questions

Ask each question with its own evidence:

1. Will the transmitter accept the load? Measure impedance or SWR at a stated reference plane.
2. What is lost in the feed system? Use declared feed-line data and, where required, calibrated transmission measurements.
3. What is lost in the matching network? Use a documented fixture, load, calibration, frequency sweep, and thermal method. Do not infer it from turns ratio.
4. Where does return current flow? Use current measurements and controlled routing or choke tests.
5. What pattern does the exact installation produce? Use the reviewed model for that exact configuration, then validate important conclusions in the field.
6. What survives the intended operating cycle? Use product-specific power and temperature evidence.

No one number answers all six. In particular, the ideal impedance relationship of a nominal 49:1 transformer says nothing by itself about real insertion loss, heating, saturation margin, bandwidth, or sustained power.

A useful diagnostic sequence

If a station has a good match but disappointing results, begin by preserving the exact configuration. Record the band, frequency, mode, transmitter power, tuner state, feed-line type and length, support heights, geometry, weather, and nearby objects. Inspect and test connections at low power. Compare receive and transmit behavior using repeatable methods. Check for component heating only under the product's documented limits and with the station de-energized before touching anything.

Do not "improve" several variables before recording the baseline. A new coax route, different support height, different tuner state, and different time of day create a new system and erase the evidence needed to identify the cause.

Power rating is a test condition, not a universal EFHW property

"One hundred watts" can mean a short voice peak, an average over a transmission, a continuous carrier, or a marketing label with unstated conditions. Those are not thermally equivalent. Transformer and connection temperature responds mainly to average dissipated power over time, while voltage and current peaks can impose different electrical stresses.

Peak and average power

Voice modes normally contain pauses and changing envelope amplitude. A sustained carrier, long digital transmission, or key-down test can hold average power much closer to the indicated output. Two operators can therefore use the same peak-power setting and impose very different heating on the matching network.

Duty cycle also exists on more than one time scale. The percentage of each transmission occupied by RF matters, and so does the percentage of the operating period spent transmitting. A short test may not reveal the temperature reached during a long session.

What changes thermal margin

The operating band, actual load impedance, mismatch, transformer loss, core material and geometry, winding parasitics, enclosure, ventilation, ambient temperature, solar heating, feed-line loss, mode, transmission duration, and recovery time can all matter. A system that remains cool during a short, low-duty-cycle test on one band is not thereby cleared for sustained operation on another band.

Product-specific rule

Only the exact current product guide and controlled Chameleon test record may define a Chameleon product's power boundary. The general handbook must not average ratings across the LEFS family, transfer a rating from one transformer to another, or turn a connector's rating into an antenna-system rating. When the intended mode or duty cycle is not covered, reduce power and ask Chameleon Support before proceeding.

A low-power analyzer sweep verifies neither sustained power handling nor safe touch temperature. If a transformer, connector, feed line, choke, or tuner becomes unexpectedly warm, stop transmitting, de-energize the station, allow it to cool, and investigate. Do not touch or open an energized matching unit.

Why feed-line routing can change received noise

An antenna receives the electromagnetic environment around the complete system. If common-mode current is present on the outside of the coax shield, that exterior surface and anything coupled to it can participate in reception. The feed line may pass near power supplies, network wiring, displays, chargers, inverters, building wiring, or other noise sources before it reaches the receiver.

Changing the route or adding effective common-mode suppression may therefore change the received noise. That observation is useful, but it does not prove that one antenna type is universally quieter. It may show only that one installation couples differently to a local noise source.

Do not compare the S-meter casually

Receiver bandwidth, preamplifier or attenuator state, RF gain, AGC behavior, display averaging, noise blanker, time of day, propagation, and the selected frequency can all change the apparent noise level. Even an S-meter scale may not be calibrated in uniform power increments.

For a useful comparison:

1. choose an unoccupied frequency and record it;
2. fix bandwidth, mode, RF gain, preamp/attenuator, AGC, and display settings;
3. switch rapidly between the two controlled states where practical;
4. preserve antenna geometry and every other station variable;
5. record several measurements over time;
6. compare both noise and a stable reference signal when available.

If rerouting only the coax changes the result, investigate feed-line exterior current and nearby coupling. If shutting down one household circuit removes the noise, investigate equipment on that circuit safely. Never bypass protective grounding or open energized electrical equipment as an RF-noise experiment.

A comparison must be able to answer its own question

An A/B test is useful only when A and B differ in the variable named by the question. If the antennas are tested at different sites, times, frequencies, powers, feed-line losses, receiver settings, or propagation conditions, the result cannot isolate antenna performance.

One impressive contact proves that communication occurred. It does not establish efficiency. One distant station's signal report includes propagation, its antenna, its receiver, interference, fading, operator judgment, and the path at that moment. Treat it as an operating observation, not a laboratory measurement.

Minimum field comparison record

Record the following before the first transmission:

• the exact question and the one variable allowed to change;
• product, configuration, radiator, matching network, and tuner state;
• geometry, endpoint heights, orientation, and site;
• feed-line type, length, route, and connectors;
• frequency, mode, occupied bandwidth, and power at a declared point;
• receiver settings or remote-report method;
• date, time, weather, and propagation observations;
• switching time between A and B;
• number of repeated pairs;
• known uncertainty and anything that changed unintentionally.

Rapid switching reduces, but does not eliminate, propagation variation. Repeating the sequence A-B-B-A can expose drift that a single A-B pass hides. A calibrated field-strength, current, power, or network measurement can answer some questions more directly than signal reports, but its fixture and reference plane must still be documented.

Report what the test supports

If A repeatedly produces a stronger received reference signal at the same noise level under the controlled conditions, report that observation and its uncertainty. Do not automatically translate it into a universal efficiency percentage. If a choke reduces measured feed-line exterior current, report the current change at the measured point and frequency. Do not claim that every unintended current path has been removed.

Treat the feed end and voltage maxima as live RF hazards

An EFHW has a high-impedance region near the end feed. High RF voltage can exist around the radiator end, matching network, and other voltage maxima. Conductive objects, wet vegetation, damaged insulation, loose connections, and people near those regions can change the system and create contact, burn, arcing, or fire hazards.

Before transmitting, create and protect an exclusion area around the entire antenna, not only around the radio. Keep the wire, matching unit, supports, feed line, and guys away from people, animals, traffic, structures, and conductive objects according to the current product guide and the station's RF-exposure evaluation.

Never adjust, reconnect, trim, coil, uncoil, raise, lower, or inspect the antenna while transmitting. Stop transmission, disable the transmitter against accidental keying, disconnect power where appropriate, and verify that the system is de-energized before touching it. A tuner showing a match does not make a reachable radiator safe.

Stop immediately if you see arcing, smell hot insulation, hear unusual snapping, observe intermittent SWR, or find a hot component. Do not resume at full power after merely tightening a connector. Inspect the complete path, repeat low-power measurements, and follow the product guide or contact Support.

RF exposure depends on the station that actually exists

For US amateur stations, 47 CFR 97.13(c) requires action before transmissions are caused or allowed where RF exposure could exceed the applicable limits. The controlled and uncontrolled categories depend on who may be exposed and whether those people are informed and able to exercise control. Accessible areas matter. This is why a generic "safe distance for an EFHW" is not an honest answer.

An evaluation uses actual station variables, including frequency, power delivered to the antenna, operating mode and duty cycle, antenna gain or an appropriate conservative assumption, exposure category, accessible geometry, and sometimes ground-reflection assumptions. Directional lobes and multiple operating configurations may require more than one calculation. The ARRL calculator is a useful screening tool within its stated limits; unusual geometry or near-field conditions require a more appropriate analysis.

Practical workflow

1. Identify every band, mode, power level, antenna configuration, and occupied area that may be used.
2. Determine the correct controlled or uncontrolled exposure category for each accessible group.
3. Use current rules and an appropriate evaluation method with conservative, documented inputs.
4. Evaluate the relevant antenna directions and accessible locations, not merely the distance from the feed point.
5. If an accessible area could exceed the applicable limit, change power, duty cycle, antenna location, exclusion controls, or another documented variable before transmitting.
6. Save the inputs, method, date, result, and operating restrictions with the station record.

This handbook cannot issue a legal conclusion for a particular property. Regulations and guidance can change, and other countries use different requirements. Recheck the current rule and applicable local requirements when the station changes or before relying on an older evaluation.

A successful deployment must also come down safely

Site selection begins with overhead conductors. Do not erect an antenna, mast, support, or lead-in where it could contact a power conductor during assembly, operation, failure, or lowering. If the antenna or support could fall into a line, choose another site. Do not attempt to move or retrieve antenna material from an energized conductor.

Inspect supports, attachment points, guys, knots, strain relief, connectors, wire, and abrasion points before raising the system. Account for the tension needed to hold the shape, the direction a failed support will fall, and the path people will use around it. Mark low wires and guys. Keep them away from roads, paths, doors, livestock, and public access. Do not use a tree, fence, railing, vehicle, or structure merely because it is convenient; confirm that it is permitted and can safely carry the load.

Weather is a stop condition, not a tuning variable

Check the forecast before deployment and continue monitoring it. If thunder is heard, stop the activity and move to a substantial building or hard-topped vehicle. Do not remain outside to lower, disconnect, or protect the antenna. The National Weather Service advises waiting at least 30 minutes after the last thunder before resuming outdoor activity.

Wind, heat, cold, precipitation, ice, and wet soil can affect both people and hardware. Wet vegetation or contaminated insulators can change electrical behavior. A changing SWR during rain is diagnostic information, not permission to touch the system. Lower and dry the system only when weather conditions make that action safe.

Portable deployment does not replace permanent-installation requirements. Electrical bonding, lightning protection, building entry, and structural work require the applicable code, the equipment instructions, and qualified help where needed. The four meanings of ground remain separate even when one conductor appears to serve several physical connections.

Symptom: resonance is not where expected

Safety check: Do not trim or move an energized wire. Confirm power-line clearance, weather, and a controlled work area before lowering it.

First controlled test: Restore the exact documented configuration and record a low-power sweep at a declared reference plane. Record resistance, reactance, SWR, geometry, heights, feed-line route, tuner state, and nearby objects.

Interpretation limit: A frequency shift does not identify its cause. Wire length, geometry, ground, coupling, transformer, feed line, choke, and measurement boundary can all contribute.

Next test: Change only the guide-authorized tuning variable in a small reversible increment, restore the operating geometry, and sweep again. If the movement is not repeatable or does not follow the expected direction, stop cutting and inspect the system.

Escalate: Use the exact current product guide. Contact Chameleon Support with both sweeps and the complete configuration record when the guide does not authorize the needed change.

Symptom: SWR changes when the coax moves or changes length

Safety check: De-energize before rerouting. Keep the cable and operator clear of the radiator, power lines, traffic, and trip paths.

First controlled test: Return to the original cable and geometry. Save a sweep. Change only one routing segment or one declared cable length, without changing support height or analyzer position, and repeat.

Interpretation limit: The result may reflect feed-line impedance transformation, common-mode exterior current, changed coupling, or more than one mechanism. It does not prove the coax is defective.

Next test: Restore the baseline and use an appropriate current measurement or a documented choke A/B test while preserving all other variables.

Escalate: Do not invent a universal choke distance. Follow the product's documented feed-line and choke arrangement or send the records to Support.

Symptom: RF affects audio, controls, computers, or other equipment

Safety check: Reduce power and stop if RF burns, arcing, loss of control, or unsafe equipment behavior occurs. Do not defeat protective earth or bonding conductors.

First controlled test: At low power, reproduce the symptom on one frequency with a fixed station configuration. Record the power threshold, affected device, cable states, antenna geometry, feed-line route, and tuner state.

Interpretation limit: RF in the station can involve feed-line exterior current, equipment susceptibility, bonding, cable routing, or direct field coupling. A single ferrite added at random does not identify the path.

Next test: Change one cable route, suppression point, power level, or affected-device connection at a time, using components suitable for the frequency and conductor mode being treated. Log what changed.

Escalate: Restore protective connections after every test. Use the exact product guidance and qualified electrical or EMC help when the symptom involves mains-powered equipment or building wiring.

Symptom: the matching unit becomes unexpectedly warm or hot

Safety check: Stop transmitting, disable accidental keying, and allow the unit to cool before touching or inspecting it.

First controlled test: Verify the exact product, band, mode, power, duty cycle, tuner state, SWR at the stated reference plane, ambient conditions, and transmission duration. Repeat only at reduced power within the guide's limits if inspection finds no damage.

Interpretation limit: Temperature rise can result from loss, mismatch, saturation, connection resistance, sustained average power, or environmental heating. A good low-power SWR does not clear sustained operation.

Next test: Compare temperature rise under a shorter, lower-power, documented cycle on the same band without altering the antenna. Do not open the matching unit or substitute a transformer unless the guide authorizes service.

Escalate: Stop use if heating is rapid, repeatable, accompanied by odor or discoloration, or outside the documented boundary. Send the operating log to Support.

Symptom: readings jump, especially with movement or moisture

Safety check: Stop transmitting. Do not handle wet antenna hardware during unsafe weather, and do not continue outdoor work after thunder.

First controlled test: When conditions are safe and the system is dry, visually inspect and gently test each connector, strain-relief point, wire termination, and abrasion point while de-energized. Then save a low-power baseline sweep.

Interpretation limit: Moisture can expose an existing seal, contamination, or insulation problem, while movement can expose a loose or fractured connection. A dry result does not prove long-term weather integrity.

Next test: Reassemble only as the guide specifies, change one suspect connection at a time, and compare the sweep. Never use a transmitting test to locate an intermittent contact by touch.

Escalate: Replace damaged parts with exact approved parts or contact Support. Do not make an improvised high-voltage repair at the feed end.

Symptom: received noise is high or changes with the installation

Safety check: Do not open mains equipment, remove protective grounding, or work near energized wiring to chase noise.

First controlled test: Fix the receiver frequency, bandwidth, AGC, gain, preamp/attenuator, and display averaging. Record the level over several intervals, then change only the feed-line route or one documented common-mode treatment.

Interpretation limit: A changed noise floor may indicate local coupling, common-mode pickup, receiver behavior, or propagation. It does not prove a universal antenna-noise ranking.

Next test: Restore the baseline. Compare a stable signal as well as noise, or safely isolate suspected household sources one circuit at a time if qualified to do so.

Escalate: If noise follows the product configuration and controlled routing tests do not isolate it, send the complete station and test record to Support.

Symptom: the tuner finds a match but operating results are poor

Safety check: Confirm that the product configuration and frequency are authorized and that the RF-exposure evaluation covers the actual mode, power, and accessible area.

First controlled test: Bypass the tuner only if the radio and guide permit it, measure the antenna system at a defined reference plane, and record R, X, SWR, band, configuration, feed line, and power.

Interpretation limit: A tuner changes the impedance presented to the transmitter. It does not prove low loss, proper current distribution, the desired pattern, or safe component temperature. Propagation may also be poor.

Next test: Verify each loss and configuration boundary separately. Compare a known reference signal, inspect connection and feed-line condition, check for abnormal heating at reduced power, and confirm that the exact geometry suits the intended path.

Escalate: Do not increase power to overcome an unexplained result. Provide the guide revision, configuration, analyzer sweep, tuner state, feed-line record, and operating observations to Support.

Symptom: the same antenna behaves differently at a new site

Safety check: Treat every site as a new deployment. Recheck overhead conductors, public access, weather, supports, RF exposure, and safe lowering space.

First controlled test: Recreate the previous documented geometry as closely as possible and record the differences that cannot be held fixed: ground, slope, vegetation, structures, support positions, cable route, and weather.

Interpretation limit: "Same product" does not mean "same electromagnetic environment." A changed result does not automatically indicate damage. Nearby materials, ground, geometry, and common-mode paths can change tuning, noise, and pattern.

Next test: Select one practical site variable, change it in a reversible way, and repeat the same low-power measurement. Preserve both records instead of tuning immediately to the new site and losing the comparison.

Escalate: If the system cannot reproduce stable measurements, inspect for transport damage and intermittent connections. Use the product guide or contact Support before trimming or modifying a component.

Portable deployment: choose repeatability before novelty

A portable EFHW earns its place by solving the operator's actual field problem: fit the site, reach the intended bands and paths, deploy within the available time, stay within the power boundary, and come down safely. The shortest packed antenna, the highest support, or the greatest number of advertised bands is not automatically the best choice.

Decide before leaving

Record the operating objective, bands, mode and power, expected contacts, site rules, available footprint, support options, feed-line length, weather plan, public-access controls, and deployment time. Then select the exact product configuration whose current guide covers those requirements.

Carry every required-but-not-supplied item. Depending on the product and site, that can include coax, nonconductive support line, an anchor, a throwing line and weight, additional paracord, or a suitable support. A product page showing the antenna assembly does not mean the complete field station is in the pouch.

Use a known baseline

The first field deployment should not be the first full assembly. Rehearse the documented configuration, label its parts, save a reference analyzer sweep, and record the normal feed-line route, support heights, and tuner state. At the operating site, reproduce that baseline before experimenting.

A compact field record should include:

• product and guide revision;
• radiator and extension state;
• geometry, endpoint heights, span, and orientation;
• feed-line type, length, route, and choke location;
• band, frequency, SWR, resistance, and reactance at a stated reference plane;
• mode, power, and operating duty cycle;
• site, ground/weather condition, nearby objects, and support method;
• received noise, reference signals, and contact observations;
• changes made and the result of each one-variable test.

The record turns the second deployment into a repeatable operation instead of another first attempt. It also gives Support evidence that can be diagnosed.

HOA and low-profile deployment: concealment changes the antenna

A constrained site often forces lower supports, bends, shorter visible spans, temporary operating windows, proximity to structures, or a feed-line route chosen for discretion. Those changes are not merely cosmetic. They can alter electrical length, current distribution, common-mode coupling, received noise, impedance, and pattern.

Begin with the property and operating limits:

1. What space is legally and practically available?
2. Which supports and anchor points are permitted and structurally safe?
3. When may the antenna be present?
4. Which bands and communication paths matter most?
5. Where can people, animals, vehicles, and neighboring property be kept outside the controlled area?
6. How will feed line enter or reach the station without creating a trip, pinch, abrasion, or common-mode problem?
7. Can the complete system be lowered and recovered without approaching a power line?

Use the current guide's documented geometry whenever the site permits it. If the wire must bend or run lower, treat that as an unmodeled installation unless an exact reviewed Chameleon pattern exists. Measure the installed system at low power, keep changes reversible, and do not present a neighboring straight-sloper curve as the constrained site's pattern.

Concealment is not permission to hide risk. The radiator and feed end can carry high RF voltage even when visually unobtrusive. An attic, eave, fence line, balcony, or tree route may place the system closer to wiring, gutters, flashing, people, combustible materials, or wet vegetation. The RF-exposure and mechanical-site evaluation still applies.

Emergency deployment: readiness is a rehearsed system

An antenna in storage is inventory. An emergency antenna capability includes the complete configuration, compatible radio and feed line, supports and anchors, power plan, frequency plan, exposure controls, weather stop rule, trained operators, deployment record, and recovery procedure.

Build the operating package

Keep the current guide with the kit, offline as well as online. Mark the selected configuration and pack the exact included and required-not-supplied items. Avoid unrecorded substitutions. A connector that fits does not prove that a feed line, choke, transformer, radiator, or accessory preserves the documented electrical behavior.

Prepare at least two safe geometry plans where the guide supports them: one for a single useful support and one for a two-support or horizontal situation. Each plan should state footprint, endpoint heights, anchor method, feed-line route, supported bands, tuner requirement, power/mode limit, public-exclusion control, and the time a trained operator needs to deploy and recover it.

Rehearse failure, not only success

Practice in daylight before depending on the system at night or under pressure. Include a missing support, insufficient line, a wet connector, changed SWR, a noise source, and a weather shutdown. The correct emergency response to thunder is still to stop and reach safe shelter, not to finish lowering the antenna.

After each exercise or activation, inspect the wire, terminations, strain relief, transformer, connectors, line winder, support line, and anchors. Save any changed analyzer baseline and replace damaged components through a controlled product or Support path. Do not improvise a replacement radiator from approximate length alone.

Emergency use does not suspend licensing, frequency coordination, RF-exposure, electrical, property, or safety obligations. The purpose of rehearsal is to make compliance and safe operation easier when time is limited.

Fixed-station deployment: design the permanent system, not a permanent field setup

A portable guide can explain the antenna's documented RF configuration. It does not automatically design a permanent building entry, structural support, grounding-electrode system, bonding network, lightning protection system, surge path, or code-compliant installation.

Before leaving an EFHW installed, document:

• the structural rating and weather exposure of every support and attachment;
• clearances from power conductors and the complete failure/fall envelope;
• strain relief, abrasion protection, drip loops, connector weather protection, and inspection access;
• feed-line entry, bonding, surge protection, and lightning-disconnection plan;
• RF return and common-mode strategy as functions separate from safety bonding;
• accessible areas and the RF-exposure evaluation for every operating condition;
• vegetation growth, seasonal movement, ice, wind, heat, and water paths;
• inspection interval and the conditions that require immediate shutdown.

A convenient ground rod cannot casually be assigned four jobs. RF return, common-mode suppression, equipment bonding, and lightning protection must remain separately understood and properly coordinated. Use the applicable electrical and building requirements, the equipment instructions, and qualified help where the installation demands it.

Recheck the baseline after storms, support movement, feed-line replacement, tree growth, building work, or unexplained tuning changes. A fixed station is not a configuration that stopped changing; it is a configuration whose changes are inspected and controlled.

CHA LEFS 4010: a 65 ft field system with separate EFHW and dipole paths

The CHA LEFS 4010 is the route for an operator who wants the current 65 ft, 20-gauge supplied EFHW radiator and the option to use separately documented linked or single-band dipole wire sets through the end assembly's dipole connections. Those are distinct electrical configurations, not accessories attached indiscriminately to the EFHW port.

At a glance

• Current guide: CHA LEFS 4010 Operator's Manual, revision 6/9/2025.
• Supplied EFHW radiator: 65 ft, 20-gauge wire, terminal lug, and far-end insulator loop.
• Documented EFHW geometries: sloper and horizontal NVIS.
• Documented no-tuner EFHW bands: 40, 20, 15, and 10 meters within the guide's stated ranges.
• Guide power boundary: 100 W SSB, 50 W CW, and 25 W digital and all other modes.
• Current coax choice: no coax or the storefront-selected 25 ft RG-316 feed line with integrated RFI choke.
• Available normalized pattern set: eight cases covering the 65 ft sloper and horizontal/NVIS configurations on 40, 20, 15, and 10 meters.

The current guide raises the End Assembly, which is the feed point, to approximately 15-20 ft in the sloper and anchors the far radiator end near ground. It documents sloper, horizontal NVIS, and separate dipole configurations. Use those documented EFHW layouts unless a later controlled guide adds another geometry.

What is included, selected, or supplied by the operator

The LEFS end assembly, 65 ft radiator, carabiner/strain relief, and current storefront storage pouch are included. Coax is selected as a storefront variant. Nonconductive support line, suitable supports, and a safe far-end anchor are site equipment. The guide's approximate line examples are planning guidance, not a promise that every site needs the same quantity.

CHA LINK-D, CHA LINK-D15, and the applicable CHA WARC-D pairs are optional dipole paths using the dipole terminals and dipole BNC port. They are not extensions of the 65 ft EFHW radiator. No exact replacement radiator or end-assembly SKU is named in the current guide; replacement requests go to the current catalog or Support record.

Product, guide and patterns

• Product: CHA LEFS 4010
• Guide: CHA LEFS 4010 Operator's Manual
• Pattern: open eight reviewed CHA LEFS 4010 configurations.
• Compatibility: handbook relationship table and current product compatibility guide.
• Support: current Chameleon Support page with product, guide revision, configuration, and measurement record.

The current radiator length is 65 ft.

CHA LEFS 8010 standard: a loaded approximately 63 ft multiband configuration

The standard CHA LEFS 8010 path uses the included approximately 63 ft, 20-gauge copper-clad Kevlar PTFE radiator with its loading coil in the documented order. It is appropriate when the operator needs the guide-defined standard sloper or horizontal/NVIS configurations without adding the included 67 ft extension.

At a glance

• Current guide: CHA LEFS 8010 Operator's Manual, updated 5/11/2022.
• Standard radiator: approximately 63 ft with loading coil.
• Documented standard bands: 40, 20, 17, 15, 12, and 10 meters.
• Documented standard geometries: sloper and horizontal NVIS.
• Guide power boundary: 500 W SSB, 250 W CW, and 150 W digital.
• Feed line: required but not supplied; the guide recommends RG-58 with an integrated RFI choke and identifies the CHA 50 ft coax as an available accessory.
• Tuner boundary: the guide separately mentions 60-meter operation with a tuner; a tuner does not authorize an undocumented configuration or raise the power limit.

The line-winder assembly is both the matching/feed unit and a mechanical suspension point. The optional UHF male-female right-angle elbow is recommended to reduce cable bend stress at the SO-239. That is a mechanical relationship, not proof that every UHF-connected feed system has been electrically validated.

The approximately 50 ft Micro 90 paracord is included. A safe anchor, suitable support, and sometimes additional line or a throwing system remain site equipment. Allow the guide-specified sag and do not over-tension the lightweight wire.

Product, guide and patterns

• Product: CHA LEFS 8010
• Guide: CHA LEFS 8010 Operator's Manual
• Pattern: open the reviewed CHA LEFS 8010 pattern library and choose the standard radiator, geometry and band.
• Compatibility: handbook relationship table and current product compatibility guide.
• Support: current Chameleon Support page with the exact standard configuration and measurement record.

Keep the standard and extended configurations distinct even when they share the line-winder assembly.

CHA LEFS 8010 extended: the documented approximately 130 ft path

The extended path connects the included approximately 67 ft extension to the approximately 63 ft standard radiator as the current guide specifies, producing an approximately 130 ft combined radiator. It is not a generic invitation to add any wire of similar length. The loading coil, conductor sections, extension connection, and strain relief remain in the documented order.

At a glance

• Extended radiator: approximately 130 ft combined.
• Documented added bands: 80 and 30 meters require the extension according to the current guide.
• Documented extended geometries: 80-meter extended sloper and extended horizontal NVIS, with additional guide-controlled band use.
• Power, feed-line, tuner, and safety limits: remain those of the exact current guide; extension length does not create a new general rating.
• Pattern inventory: use only the extended cases inside the reviewed 28-case CHA LEFS 8010 pattern library. Do not show a standard-radiator pattern for an extended installation.

The longer footprint changes site selection. Confirm support capacity, anchor placement, public access, wire tension, lowering space, and overhead-conductor clearance for the entire approximately 130 ft radiator and its failure envelope. Carry additional line when the site requires it.

Product, guide and patterns

• Product and included extension: CHA LEFS 8010
• Guide: CHA LEFS 8010 Operator's Manual, using the exact extended-configuration section.
• Pattern: open the reviewed CHA LEFS 8010 pattern library and choose an extended configuration.
• Support: use the current Support route if an extension, loading coil, connector, or replacement section is damaged or uncertain.

No exact replacement primary radiator, extension, or line-winder SKU is named in the guide. Do not substitute another LEFS-family wire by length or connector.

CHA LEFS FEATHER: the lightweight, guide-defined QRP sloper

The CHA LEFS FEATHER is the route for an operator prioritizing a lightweight QRP EFHW system in the exact documented sloper geometry. Its included End Transformer Unit, confirmed 66.5 ft AWG 26 PTFE braided Kevlar radiator, tuning stub, line winder/end insulator, S-Biner, isolation ring, and strain-relief connection form one complete assembly.

At a glance

• Current guide: CHA LEFS FEATHER Operator's Manual, revision 3/30/2026.
• Radiator: 66.5 ft, the final production length.
• Matching unit: integrated nominal 49:1 transformer with BNC female connector. The ratio does not state real loss or thermal performance.
• Final tested geometry: sloper with the transformer/feed end about 3 ft above ground and the far end about 25 ft high. The confirmed product specification is approximately 25 ft.
• No-tuner bands: 40, 20, 15, and the lower portion of 10 meters through 28.5 MHz.
• Guide tuner path: 30, 17, 12, and the 10-meter FM segment.
• Guide power boundary: 25 W SSB and 10 W CW/digital.
• Available normalized pattern set: seven 25 ft cases across 40, 30, 20, 17, 15, 12, and 10 meters.

A suitable BNC feed line and nonconductive support line are required but not supplied. The guide recommends CHA RG-316 in 15 ft or 25 ft lengths with the integrated RFI choke at the transceiver end. Do not transfer the 4010 or 8010 feed-line arrangement to FEATHER merely because the connectors or product family appear related.

The CHA CFM-16 is a documented lightweight support option when trees are unavailable. It is a mechanical companion; it does not create a new electrically modeled geometry unless the exact support heights and configuration match a reviewed case.

Product, guide and patterns

• Product: CHA LEFS FEATHER
• Guide: CHA LEFS FEATHER Operator's Manual
• Quick start: CHA LEFS FEATHER Quick Start
• Pattern: open the seven reviewed CHA LEFS FEATHER configurations.
• Support: current Chameleon Support page with guide revision, 66.5 ft configuration, feed-line/choke placement, and measurement record.

The current radiator length is 66.5 ft.

Glossary

Reviewed configuration - A product, geometry, frequency, and model record that passed the Chameleon evidence and integrity process. Review does not convert normalized simulation into measured field performance.

Common-mode current - Current on the exterior of a feed line or other conductors that does not form the intended equal-and-opposite transmission-line pair. It may alter tuning, radiation, reception, or station interference.

Controlled comparison - A test designed so that the named variable changes while material alternatives are fixed or recorded.

Counterpoise - An intentional conductor or conductor system used as part of an RF return path. It is not automatically an electrical-safety ground or lightning-protection system.

Current guide - The exact product document designated by Chameleon as controlling at the recorded revision. An older quick start, flysheet, cached page, or copied description cannot silently override it.

Differential current - The desired transmission-line current pair, equal and opposite on the center conductor and the inside surface of the coax shield in the ideal case.

Electrical height - Physical height expressed as a fraction of wavelength at a stated frequency. The same support height represents a different electrical height on each band.

Electrical length - The phase-related length of a conductor or line at a frequency. It is affected by construction and environment and is not always equal to physical length divided by free-space wavelength.

EFHW - End-Fed Half-Wave: a half-wave-class radiator fed near one end through a high-impedance matching system. EHFW is retained as a search alias, not the preferred acronym.

Evidence boundary - The limit beyond which a source or test no longer supports the proposed conclusion.

Feed point - The defined location where the feed system connects to the antenna system.

Impedance - The complex ratio of voltage to current, written as resistance plus reactance and measured in ohms.

Insertion loss - The reduction in transmitted power attributable to inserting a device or network under a declared test method and reference plane.

Matching network - A network that transforms impedance. A match does not by itself prove low loss, current balance, efficiency, or safe power handling.

Normalized pattern - A radiation pattern scaled so its strongest displayed response is the reference, commonly 0 dB. It shows relative shape, not realized gain or total efficiency.

NVIS - Near Vertical Incidence Skywave: regional HF communication using energy launched at relatively high elevation angles when ionospheric conditions support return to Earth.

Reference plane - The point in the antenna system where an analyzer reading applies, such as the end of a calibrated feed line.

Return path - The complete RF-current path back through the antenna system. It may include intended and unintended conductors and coupling to the environment.

Resonance - A condition at a defined point and frequency where net reactance is zero or near zero. It does not guarantee 50 ohms, low loss, or a desired pattern.

SWR - Standing-wave ratio on a transmission line. It describes mismatch magnitude at a reference plane, not antenna efficiency.

Tuner - An impedance-transforming network that changes what the transmitter sees. It does not physically retune a distant radiator or erase feed-system loss.

Unmodeled configuration - A combination or geometry without an exact reviewed pattern. It may be useful experimentally, but do not borrow performance claims or curves from another configuration.

Equations and bounded examples

Wavelength and approximate half-wave length

lambda = c / f

where:

• lambda is free-space wavelength in meters;
• c is the speed of light, approximately 299,792,458 meters per second;
• f is frequency in hertz.

An ideal free-space half wavelength is lambda / 2. At 14.2 MHz, the free-space wavelength is approximately 21.11 m and half of it is approximately 10.56 m. This is a starting scale, not a final cut length. Conductor construction, insulation, geometry, ground, nearby objects, loading, matching, and the return boundary alter the installed result.

Electrical height

h_lambda = h / lambda

where:

• h_lambda is height in wavelengths;
• h is physical height in meters;
• lambda is wavelength in meters at the stated frequency.

Using the 14.2 MHz wavelength above, a 6.1 m support height is approximately 6.1 / 21.11 = 0.289 wavelength. The calculation describes scale only. It does not determine one universal takeoff angle because geometry, ground, and current distribution remain part of the model.

Ideal turns and impedance ratio

Z_ratio = n^2

where:

• Z_ratio is the ideal impedance ratio;
• n is the winding turns ratio, secondary turns divided by primary turns under the declared convention.

An ideal 7:1 turns ratio gives 7^2 = 49, or a nominal 49:1 impedance ratio. Applying that ideal ratio to 50 ohms gives 2,450 ohms as a mathematical example. It does not prove that a practical EFHW feed point is fixed at 2,450 ohms or that the transformer is efficient, broadband, cool, or suitable for a Chameleon product.

Reflection coefficient and SWR

For a lossless line with reflection-coefficient magnitude |Gamma|:

SWR = (1 + |Gamma|) / (1 - |Gamma|)

and therefore:

|Gamma| = (SWR - 1) / (SWR + 1)

At an SWR of 2:1, |Gamma| = 1/3. The corresponding reflected-to-forward power ratio at that reference plane is |Gamma|^2, or about 11.1 percent under the stated assumptions. This is not an antenna-efficiency calculation, and real line loss changes the measurements observed at a remote plane.

Time-average power for a rectangular on/off cycle

For an ideal constant carrier that is either fully on or off:

P_average = P_on x D

where:

• P_average is the time-average power at the same defined point in watts;
• P_on is carrier power while transmitting in watts;
• D is the transmit fraction from 0 to 1 over the stated interval.

A 100 W constant carrier present for exactly 30 percent of the interval has a 30 W time average at that point. Real voice and digital waveforms need their actual envelope, transmit pattern, losses, and time interval; this simplified example does not assign a safe product rating.

Sources and evidence

Different sources answer different questions. A current Chameleon manual controls product assembly and operating limits. A reviewed NEC model explains the normalized pattern for its exact geometry. A documented measurement describes only the equipment, reference plane and conditions actually tested. General engineering references explain mechanisms, while current government sources control regulatory and safety requirements.

Operator observations are valuable clues, but they should lead to a repeatable test rather than an unsupported performance promise. When evidence for an exact configuration is unavailable, this guide says so.

Technical and product references

• CHA LEFS 4010 Operator's Manual
• CHA LEFS 8010 Operator's Manual
• CHA LEFS FEATHER Operator's Manual
• CHA LEFS FEATHER Quick Start
• 47 CFR 97.13(c): station location and RF exposure
• ARRL RF Exposure Calculator and instructions
• 29 CFR 1926.408: antenna conductors and electric power conductors
• National Weather Service lightning safety
• NEC-2 radiation-pattern and ground-model documentation
• Roy Lewallen, W7EL, “What Baluns Do”

Keeping this guide current

Always use the latest product manual for assembly, configuration and operating limits. When a product guide, antenna configuration, pattern library or safety requirement changes, the affected guidance is reviewed before it is treated as current.

If something on this page conflicts with a current Chameleon product manual, stop and follow the product manual. Please report the conflict through Chameleon Support so the handbook can be corrected.