The Boonton 4220 is a microprocessor-based, single channel, solid state RF power meter. It is capable of measuring RF power levels from -60dBm to +20dBm. With the 51013 sensor included in this package, the frequency range is from 100KHz to 18GHz. With different sensors, the frequency range can be increased up to 110GHz. Diode sensors measure the voltage across a precision resistor, using specially selected diodes. Digital display can show reading in W, mW, ?W, nW, dBm, and dBr. Display resolution is 0.01dB or 4½ digits. Accuracy is ±0.7% (23ºC) for 90 days.