Vector network analyzers can measure both amplitude AND phase of both reflected signals and "through" signals (e.g., signal path between two antennas). For NSA, all that is needed is amplitude, and so a scalar network analyzer will do the job. Measuring the transmission characteristics of a filter or attenuator likewise can be done with a scalar network analyzer.
The real power of a vector network analyzer is that is can measure the impedance of a load. But measuring both the magnitude and phase of the reflection, both the resistive and reactive part of the load can be measured in a swept measurement. From a single reflection measurement, a modern network analyzer can give readouts of VSWR, reflection coefficient, S11 (or S22), complex impedance, complex admittance, equivalent series RC or RL, and equivalent parallel RC or RL. The measurements can be made at the end of a cable. This is done by first measuring calibration standards (short, open, and 50 ohm load). Cable imperfections are removed by the calibration, as are imperfections in the network analyzer itself. Since the RF source and receiver are synchronized, swept measurements of high loss paths (say up to 100 dB) can be made in real time. My first job in 1975 was as an RF designer for Hewlett-Packard. I knew about S-parameter measurements, and had made some manually. On my interview trip, my jaw dropped to the floor when I saw a vector network analyzer making swept S-parameter measurements in real time. Don Borowski Schweitzer Engineering Labs Pullman, WA, USA From: [email protected] To: [email protected] List-Post: [email protected] Date: 03/29/2011 04:36 AM Subject: VNA Sent by: [email protected] I am not familiar with vector network analyzers. What practical measurements can be made with them from an EMC standpoint. I know that they can be used to determine site NSA. What other applications are they useful for? Thanks, Bob Heller 3M EMC Laboratory, 76-1-01 St. Paul, MN 55107-1208 Tel: 651-778-6336 Fax: 651-778-6252 - ---------------------------------------------------------------- - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to <[email protected]> All emc-pstc postings are archived and searchable on the web at: http://product-compliance.oc.ieee.org/ Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <[email protected]> Mike Cantwell <[email protected]> For policy questions, send mail to: Jim Bacher: <[email protected]> David Heald: <[email protected]>
