The 8491B attenuator, in a coaxial design, has fixed attenuator values such as 3 dB, 6 dB, 10 dB, 20 dB, 30 dB, 40 dB, 50 dB and 60 dB. It offers precise attenuation and a very low standing wave ratio. It is equipped with N connections and the bandwidth extends up to 18 GHz. The attenuation has been tested by the manufacturer for the complete frequency response to ensure a slight mismatch. The individual calibration points are listed in tabular form for each measuring head and fixed on the head.