Agilent 5991-0419EN English 2014-01-22 PDF 1.35 MB c20140725 [18] free download

File name 5991-0419EN English _ 2014-01-22 _ PDF 1.35 MB c20140725 [18].pdf

Keysight Technologies Techniques for Precise Cable and Antenna Measurements in the Field Using FieldFox Handheld Analyzers Application Note This application note introduces the practical aspects of cable and antenna testing, interpreting measurement results and instrument operation including calibration options such as CalReady and QuickCal using a Keysight Technologies, Inc. FieldFox handheld analyzer conigured as a cable and antenna analyzer. Measurement examples are provided showing techniques for measuring insertion loss, return loss, and locating faults in a transmission system. Carry precision with you. Introduction Cable and antenna measurements are often required to verify and troubleshoot the electrical performance of RF and microwave transmission systems and antennas. In RF and microwave communications industries, measurements are often made along the coaxial cable connecting a transmitter to its antenna and/or between an antenna and its receiver. This process is sometimes referred to as Line Sweeping and results in the measurement of the signal attenuation and return loss as a function of frequency. Line sweeping may also be used to estimate the physical location of a fault or damage along the transmission line using the Distance-to-Fault (DTF) measurement available on many RF and microwave signal analyzers such as FieldFox. Testing the performance of transmission lines is not limited to only coaxial cable types but systems using waveguide and twisted pair cables may also be characterized once the appropriate adapter is installed between the transmission line and the coaxial interface on the analyzer. In addition, antenna measurements, in the form of signal relection, or namely return loss and VSWR, may be used to verify the performance of an antenna at the installation site. When multiple antennas are required at an installation site, whether the antennas are associated with the same system or different systems, the antenna-to-antenna isolation may also be veriied using FieldFox. Figure 1 shows a typical return loss measurement (upper trace) and DTF measurement (lower trace) for an X-band antenna connected to a 3-meter length of coaxial cable. The antenna was mounted on a vertical mast at a roof-top installation and measured using FieldFox conigured with a preset calibration called CalReady. The return loss measurement includes two frequency markers placed across the speciied operating band at 8 GHz and 12.4 GHz. The DTF measurement includes a distance marker placed at the location of the antenna at 3.23 meters. This application note will introduce the practical aspects of cable and antenna testing, interpreting measurement results and instrument operation including calibration options