Currently, I’m working on an RF sniffer that also can be used as a mW meter. It’s based on an AD8307 logarithmic D/A converter.
The idea started because we still used 6W TL-tubes for checking transmissionlines for voltage maximums. I used an AD8307 integrated circuit that drives a LM3914 Bar Display driver. It produced a scale ranging from -75dBm, in 10dB steps, to +18dBm (The last step is 13dB in stead of 10dB, probably due to the 2 anti-series 2.4V zener diodes, added to the input for protection). Currently, we’re building prototypes. If all works satisfactory, the design will be published in the PI4RAZ club magazine.