88 Keysight N9923-90001 User’s GuideCAT (Cable and Antenna Test) Mode2-Port Insertion Loss Measurements14.Use Averaging to remove random noise from high-loss measurements.Press BW 2 then Average.The displayed trace shows the Cable Loss values in one direction through thecable. A Return Loss measurement would show the loss for both down thecable and back. Therefore, a Cable Loss measurement is the same as a ReturnLoss measurement divided by 2.The average Cable Loss across the specified frequency range is shown on thescreen below the graticules.2-Port Insertion Loss MeasurementsA 2-port Insertion Loss measurement is used to measure the loss through aDUT (device under test) – or cable – over a specified frequency range. TheFieldFox signal source is transmitted out the RF OUT connector, through theDUT, and into the RF IN connector. Both ends of the DUT must be connectedto the FieldFox, either directly or indirectly using the cable used in thenormalization cal.‘Insertion’ loss simply means loss through a device, usually expressed in dB. Itis exactly the same measurement as “S21 Transmission” in NA Mode.2-port Insertion Loss measurements are generally more accurate than 1-portCable Loss measurements.How to make a 2-port Insertion Loss Measurement— Press Mode then CAT.— Then More then Insertion Loss (2-Port).— Press Freq/Dist and enter Start and Stop frequency values of themeasurement.— Press Sweep 3, then select a Resolution setting.— Press Cal 5, then perform a calibration. Learn more on “How to Perform aCalibration” on page 104.— Connect the DUT and view the insertion loss measurement results.When measuring very long lengths of cable, it may be necessary to increasethe sweep time. Learn how in “Sweep Time” on page 82. Learn why in theSupplemental Online Help:http://na.support.keysight.com/fieldfox/help/SupHelp/FieldFox.htm
