[G0HZU_JMR]

I made a similar power detector module when the AD8307 was first released many years ago. I still have it here and It looks quite similar to yours. We used the AD8307 in volumes of tens of thousands at work. Usually as a basic RF level sensor.

However, you do have to be careful if using it as a power meter. It is a log detector so can't measure average power correctly. This means you ideally have to use it with a clean sine wave. It won't cope well with modulated signals and it suffers high uncertainty in the presence of odd order harmonics. Best to keep these at -30dBc or better or the uncertainty creeps up rapidly.

I sacrificed some sensitivity with my version because I wanted a low VSWR input and mine has an input VSWR < 1.04:1 across LF through 500MHz. I also incorporated some frequency compensation into mine. The aim was to get it flat to 150MHz to about +/- 0.2dB at 0dBm and then allow it to roll off towards 500MHz by a few dB.

This way I didn't have to mess with correction factors vs frequency when using it up to 100MHz or so. At the time I also had an HP431C/HP478A thermistor power meter but this only works well down to 50MHz and has a limited range. So the A8307 sensor was used mainly below 100MHz.