Antenna Systems & Technology - Spring 2014 - (Page 18)

GUEST COLUMN Don't Let Your Choice of Tool Hinder Your Cable and Antenna Testing By Rolland Zhang - Agilent Technologies If you are an engineer or technician verifying or maintaining a cellular base station these days, you face an increasingly difficult task, especially given that wireless technology continues to evolve and as it does, grows more complex. Also, there are just more components to have to worry about and therein lies the crux of your problem. By some accounts, upwards of 60 percent of all cellular base station problems are caused by components, faulty cables, connectors and antennas. And it's not just one type of fault you have to worry about. On the contrary, a whole litany of issues can go wrong. Components may become damaged during installation, operation and maintenance. They may show reduced performance over time. They may even be damaged by extreme weather conditions. Whatever the cause, the end result is the same: degraded cellular coverage and unnecessary handovers in the cellular system. Figure 1. An example of a modern microwave analyzer is Agilent's FieldFox. This combination microwave analyzers' base function is a cable and antenna analyzer, but it can also be configured to include spectrum and network analysis. It offers amplitude accuracy of ± 0.5 dB at power-up with no warm-up required, a frequency range up to 26.5 GHz, built-in calibration capabilities, and ruggedized operation, making it suitable for a range of applications. Figure 1. An example of a modern microwave analyzer is Agilent's FieldFox. This combination microwave analyzers' base function is a cable and antenna analyzer, but it can also be configured to include spectrum and network analysis. It offers amplitude accuracy of ± 0.5 dB at power-up with no warm-up required, a frequency range up to 26.5 GHz, built-in calibration capabilities, and ruggedized operation, making it suitable for a range of applications. Now that you know the root of the problem, the real question is what can you do about it? Cable and antenna testing is the obvious answer, although the type of tests you choose to conduct and tools you use to conduct those tests with might not be quite so obvious. With regard to the tests, you'll need to tackle cable insertion loss, measure antenna Return Loss (RL) and Voltage Standing Wave Ratio (VSWR), verify the antenna-to-antenna isolation (when the site has multiple antennas), and locate any faults or damage along the transmission line. But what instrument should you use to perform these measurements? You might naturally assume that a dedicated cable and antenna test (CAT) analyzer would be the optimal choice and granted, it wouldn't be a bad choice. However, for all of the measurements previously mentioned, a modern handheld microwave analyzer configured for cable and antenna testing proves especially effective (Figure 1). Its performance, flexibility and functionality-it can also be configured to include spectrum and network analysis, make it a useful tool for quickly and accurately characterizing the entire transmission system, as well as the performance of individual components in the system. Most modern microwave analyzers are configured with 50-ohm test port impedances to accurately measure insertion loss due to the transmission line (coaxial cable), source (transmitter) and load (antenna). They also feature two-port, one-port and power-meter techniques that allow you to measure cable insertion loss from one end of the cable when it's too difficult or too costly to remove the installed transmission line cable to verify its operation or troubleshoot failures. Antenna RL and VSWR can also be easily measured with a modern microwave analyzer in the field or lab. Once the antenna is actually installed in a system, only its reflection properties are measured to determine 18 Antenna Systems & Technology Spring 2014 www.AntennasOnline.com http://www.AntennasOnline.com

Table of Contents for the Digital Edition of Antenna Systems & Technology - Spring 2014

Editor’s Choice
What's So Exciting About the Future of M2M? Everything
Antenna Design for LTE Enabled Tablets
Recent Progress on Plasma Antennas
Guest Column: Don't Let Your Choice of Tool Hinder Your Cable and Antenna Testing
Antennas
Components/Subsystems
Short-Range Wireless
Software / System Design
Test & Measurement
Industry News
Marketplace

Antenna Systems & Technology - Spring 2014