HP Precision variable waveguide WR28 attenuator 0 - 100 dB, tested with two Flann 22093-KF20 waveguide-to-coax transitions between 23 and 52 GHz. Working well at 24 GHz ham-radio band. At 47 GHz ham-radio band the test was limited to 0 - 30 dB attenuation due to too low power of 47 GHz source, dynamic range of network analyzer, and ripple of the Flann transitions above 45 GHz.