Keysight Technologies N9330B User Manual

Contents

Keysight Technologies N9330B User Manual Manual pdf 35 page image

Making MeasurementsMeasuring Return Loss/SWR/Cable Loss29Measuring Return Loss/SWR/Cable LossReturn loss is the measurement of the signal reflectioncharacteristics of a cable and antenna system. A returnloss measurement is useful in detecting problems in theantenna feedline system and the antenna itself. Aportion of the incident power is reflected back to thesource from transmission line faults as well as from theantenna itself. The ratio of the reflected voltage to theincident voltage is called the reflection coefficient. Thereflection coefficient is a complex number, meaning ithas both magnitude and phase information. InS-parameter terms, return loss is referred to as an S11measurement.SWR and cable loss measurement derive from returnloss measurement.Perform a basic return loss measurementWhen measuring return loss, SWR, or cable loss withyour N9330B, follow the same operation procedure asshown below.To make a return loss (versus. frequency) measurementover a frequency range of 50 to 400 MHz, perform thefollowing steps:1 Press the [MODE] hardkey to call up a measurementmode menu. Rotate the front-panel knob to select ameasurement mode (for this example, Return Loss).Press the [ENTER] hardkey to confirm your selection.For more detailed information, refer to "Selecting aMeasurement Mode" on page 24.2 Press the {Start} softkey to call up the start frequencymenu. Press {50} > [ENTER] to set the start frequencyto 50 MHz.NO TE Test signals can cause interference. When testing cables attachedto an antenna, the test signal is radiated from the antenna. Verifythat the signal used for the test CANNOT cause interference toother antennas.