Just finished my handheld 2,4GHz powermeter.
Build with a AD8313, Arduino Nano and small 16*2 LCD display.
Works good from -55 to -5dBm with a error <0,2dB from -55 to -5dBm.
Next week i give it to a friend who checks it against a fresh calibrated R&S signal generator.
73s DB8TF