As stated above, you will have to mix the signal down to a frequency where gain is cheap. There is still the problem of gain variations with time and temperature.
Many amplifier modules change their gain by 10% of the dB of gain with temperature.
I want to measure the signal strenght (like as the bargraph in mobile cell phones) in the air around a 5.8GHZ transmitter .I need help on this problem.
it is a software solution x Win and Linux (free!). It display the signal strength using the RSSI ( received signal strength indicator) signal section. you only need a compatible WLAN card. You can try also another protocol analyzer (wireless sniffer).
hi ninhawk
Thanks for your links.But I did not find exactly what I need ,I need board that in one side can be connected to antenna and at other side have a digital or analog output (interface) that I can use it in my product.I want that the board give me the signal strenght as digital or analog data.