Sometimes builders have not required underhand equipment . This issue every time care of self-builders. Analog Devices manufacturing a lot of IC’s for some homebrew applications. There is example to get some pleasant device with minor budget and not spend a lot of money.
Represented simple power meter, based AD8362 device; in my case from 500 MHz to 2,5 GHz because directional coupler cut some low frequencies range. Also, in use device from first lot, recover up to 2,7 GHz. Today’s TruPwr™ Detector (same device) recover up to 3,8 GHz.
Advantages - data sheets of AD8362 (Analog Devices) is exactly, what declare is what we get. Today with others it is much less.
No LCD and program needed. A small footnote on the scale of output voltages relative to the input power, also does not affect. The level of accuracy (+/-5%) is not in our case, everything is so precise and linear. The maximum input power of +8 dBm is not levels below zero. You can apply a few watts by connecting attenuators to the input (up to 5 watts).
Since the RF-cable from SG to DUT has a loss of 1 dB at a given frequency 2440 MHz, the input signal differs by 1 dBm from the name in the photo.
True schematics and app note part attached. Coupling transformer “RED TC1,6-4-2-3” was in use in 1st mixer of NOKIA 2120 mobile at late 90’s. To expand measurement range may reduce value of 10K resistor. This value adapted to voltage of micro analog port in VNA.
This device AD8362 and PCB have been “waiting” for their moment since 2002, when I built the NWT-7ex VNA (http://www.asobol.ru/moi-konstrukcii/nwt-7-ex UB3TAF). External detector of this equipment’s, PCB makes with Paint Brush and reproduced by thermal method.
See attached pictures of measurements in different levels, diagrams and PCB.