Plain-language answer: A field-strength meter samples RF energy at a location so relative radiated-field changes can be compared under controlled conditions.
Why it matters at the radio
It can reveal pattern, polarization, or system changes that SWR cannot, but reflections, distance, orientation, overload, and nearby objects can dominate the reading.
What to watch in the field
Keep transmitter power, frequency, antenna geometry, meter position, polarization, and surroundings fixed while changing one variable.
The common misunderstanding
Turning one uncalibrated reading in a reflective yard into an absolute gain claim.
Learning boundary
This lesson explains established radio and antenna practice. Current regulations, electrical and building codes, site conditions, and the exact equipment or antenna guide control legal limits, ratings, compatibility, and safety.
