Explanation
Overview Reactance is the portion of an antenna's impedance that stores electrical energy instead of dissipating or radiating it. Reactance varies with frequency and is responsible for much of the behavior observed in resonant antenna systems. Types of Reactance Inductive reactance. Capacitive reactance. Every practical antenna contains both inductive and capacitive properties. Resonance At resonance, inductive and capacitive reactance cancel each other, leaving primarily resistive impedance at the feed point. This generally allows more efficient power transfer. Frequency Dependence Reactance changes with operating frequency. This is why antenna impedance changes as operators move from one amateur band to another. Matching Networks Antenna tuners and matching transformers often compensate for reactance by adding controlled inductance and capacitance to the system. Applied to Chameleon Products Products such as the CHA URT1 automatically compensate for changing antenna reactance by selecting appropriate matching components during the tuning process. Related Articles What Is Feed-Point Impedance? What Is Resonance? What Is an Antenna Tuner? What Is SWR? Related Products CHA URT1 CHA
The exact result depends on the complete station: frequency, geometry, feed line, matching network, return-current path, environment, operating power, and the reference plane of any measurement. A low SWR establishes an impedance relationship at that point; it does not by itself prove efficiency, radiation pattern, compatibility, or safety.
What to Verify
- Use the newest official product guide or primary service documentation.
- Confirm the exact model, revision, components, configuration, and operating conditions.
- Begin tests at low power and change one variable at a time.
- Do not infer compatibility from connector or thread fit.
Learn Next
- Antenna Selection: A Mission-First Decision Guide
- Engineering Design Tradeoffs in Portable HF Antennas
- Antenna Measurement Reference Planes
- Understanding Common-Mode Current
Source note: Independently synthesized with reference to The ARRL Handbook for Radio Communications, 99th edition (2022), and The ARRL Antenna Book for Radio Communications, 24th edition (2019). Verify changing regulations, services, software, specifications, availability, and safety requirements against current primary sources.
