Measures Relative Field Strength with your wattmeter.
Similar to the obsoleted Bird 4030 FS element.
This sensor does not have an amplifier, it is a passive device for relatively larger signals.
Use your Bird Model 43 as a relative field strength meter for sniffing out transmitters, antenna tuning, etc. 1 to 1000 MHz.
Compatible with 30uA meter instruments - Bird Model 43, CDI 81000A, etc.
No active components, no batteries required.