Measurement Journal Issue 6

Analyzing the CAT’s role The handheld cable and antenna tester plays a vital role in guaranteeing the quality of transmitted signals in the ﬁeld to support wireless communications trafﬁc. Working together with the handheld signal analyzer, it completes the full set of tools required to provide optimized hardware installation of cables and parts of the antennas (Figure 5). One basic requirement for the ideal CAT is the ability to measure return loss in the ﬁeld. Return loss is a measure of the signal reﬂection characteristics of the cable and antenna system. In S-parameter terms, it is referred to as an S11 measurement. To make the measurement, the handheld CAT (e.g., the Agilent N9330B) uses a signal generator to generate a swept RF signal which is sent to the cable and antenna system under test. A portion of the incident power is reﬂected back to the source from each transmission fault and the antenna. The ratio of the reﬂected voltage to the incident voltage is called the reﬂection coefﬁcient — a complex number containing both magnitude and phase information. By measuring the signal reﬂection, the handheld CAT can identify the parameters of the cable and antenna system. Another key requirement of the ideal CAT is to provide the returnloss measurement in both the frequency and time domains. In the frequency domain, the CAT uses an inverse Fourier transformation of the time domain signal to identify the fault point location. It also supports standing wave ratio (SWR), return loss and cable loss tests. SWR and cable loss are two measurements which can be derived from the return-loss measurement. In the time domain, the CAT supports return-loss and cable-loss tests. These frequency- and time-domain test functions have today become the standard in test for the cable and antenna system. Processing the data All I&M wireless network procedures require the utilization of a fast and agile post-processing and reporting tool (Figure 6). The Agilent N9330 PC software offers powerful post-analysis of test data. In addition to providing a good user interface, the PC-based post-analysis tool can provide Smith chart displays and analysis functions. It also supports powerful printing functions that make report writing convenient. A database function even provides an organized ﬁle management feature. Conclusion The successful implementation of I&M routines is critical to ensuring around-the-clock service continuity and network stability over an extended period of time and under stress conditions. Use of proper test equipment such as the handheld signal analyzer and CAT, coupled with a suitable post-processing tool, can aid in this process by greatly simplifying the engineer’s performance of these typically complex and cumbersome test routines. The author would like to thank Marco Kong, HH Product Manager, Agilent Technologies, ChengDu Division, People’s Republic of China, for his support given during the preparation of this article. Figure 5. Example measurement screen from a cable and antenna tester system Figure 6. The Agilent Technologies N9330A post-analysis tool Agilent Measurement Journal 46

Table of Contents Feed for the Digital Edition of Measurement Journal Issue 6

Measurement Journal Issue 6 Using a Few Words to Convey a Deeply-Held Spirit Charting a Unique Path to Technology Innovation Contents Announcing First Commercial GC/MS Metabolites Library Assessing Nonlinear Behavior Testing Combines Form and Function Testing Multiplay Networks Higher Sensitivity LC/MS Easing Military Radio Test Stepping Up Calibration Accuracy Increasing Spectrum Analyzer Bandwidth 3GPP Tool Supports TS 36 Standards The Olympic Story Spotlights Agilent's Continuing Contribution to Technology Innovation Ensuring a Level Playing Field in Competitive Sports GPS: Coming of Age Resolving Design Issues in HSPA Mobile Devices Achieving Accurate Results with Oscilloscope-Based Jitter-Analysis Software RF Handheld Testers Guarantee Traffic Stability Under Olympic-Sized Stress Conditions Utilizing LAN-Based Instrumentation to Measure Total Harmonic Distortion in Remote Facilities IMT-Advanced: 4G Wireless Takes Shape in an Olympic Year EPO Doping: A Speed Engine, Turbo-Charged by Chemistry

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