Simple design based on Analog Device's AD8313 chip, providing visual display of broadband signal strength and audio level output of demodulated signal.
The circuit detects, demodulates the amplitude and amplifies high frequency electromagnetic emissions (100 MHz to 2.5 GHz approx) for audio frequency output. The main component is the Analog Devices AD8313 IC: RF logarithmic detector and controller, whose output is further amplified by the TL082 op-amp.
Circuit diagram:
Or: http://1010.co.uk/images/rssi_strength.pdf
PCB and all Kicad/GERBER files:
http://1010.co.uk/rssi_strength.tar.gz
References:
http://f6bon.albert.free.fr/Milliwattmetre.html
http://www.analog.com/en/prod/0,,759_847_AD8313,00.html
http://www.turnpoint.net/wireless/cantennahowto.html
http://www.engadget.com/2005/11/15/how-to-build-a-wifi-biquad-dish-antenna/