Definition
A test instrument used to measure the strength of a radio-frequency electromagnetic field at a given location. In aviation maintenance and avionics work, it is used to check the output and radiation pattern of transmitting antennas, such as those on communication and navigation radios, to confirm they are radiating properly.
Plain English
A handheld tool that measures how strong a radio signal is at a particular spot. Technicians use it to check that an antenna is actually putting out a signal and that the signal is strong enough.
Context Anchor
Seen in avionics maintenance, radio checks, antenna testing, and troubleshooting communication or navigation equipment.
Derivation
The 'field' here refers to the electromagnetic field surrounding a transmitting antenna — the invisible region of radio energy radiating outward. The meter measures the strength of that field at the point where the meter is held.
Why Pilots Care
An antenna can look perfectly fine but radiate a weak or distorted signal. A field strength meter confirms the radio is actually transmitting at full power, which matters for reliable communication and for verifying ELT operation during required inspections.
Analogy
It is like the signal-strength bars on a phone, but as a separate measuring tool used to check radio equipment more deliberately.
Intuition Check
Do not read “field” as a runway or airport area here. In this term, “field” means the invisible radio energy present in the air around an antenna.
Example Sentence 1
After replacing the COM antenna, the avionics technician used a field strength meter to confirm the radio was radiating at full power.
Example Sentence 2
Maintenance crews rely on a field strength meter to confirm that approach signals reach far enough for safe instrument approaches.