 |
 |
 |
|
|
|
|
|
|
||||||||||||||||||
|
|
|||||||||||||||||||
|
|
|||||||||||||||||||
|
|||||
 Previous: It Seems to Us: Growth |  Next: ARRL In Action: What Have We Been Up To Lately? |
By Stan Horzepa, WA1LOU
Contributing Editor
February 01, 2008
This week, visit Web sites where very useful, previously expensive test equipment is now readily available as an addition to your Amateur Radio tool box.
VNA is the initialism for “Vector Network Analyzer” -- a very useful test tool that was previously prohibitively pricey, but today its price tag fits in the budget of most Amateur Radio operators. You can buy a VNA or you can roll your own, but first things first: Why do you need a VNA?
According to the “Roll Your Own” VNA Web page of Paul Kiciak, N2PK, a homebrew VNA capable of both transmission and reflection measurements can measure among other things, gain/loss magnitude, phase, group delay (on the transmission side), complex impedance and admittance, complex reflection coefficient, VSWR and return loss (on the reflection side).
“Unlike other impedance measuring instruments that infer the sign of the reactance (sometimes incorrectly) from impedance trends with frequency, a VNA is able to make this determination from data at a single frequency. This is a direct result of measuring the phase as well as the magnitude of an RF signal at each test frequency.”
According to the “Buy It Assembled” VNA Web page of Ten-Tec, “The VNA is one of the more useful pieces of test equipment for designers and experimenters. It can measure the forward and reverse gain and phase response of a circuit, and the input and output reflection properties (complex impedance). The VNA is used to measure and adjust filters, coaxial cables, amplifiers, antenna input impedance vs. frequency, just to name a few.”
Roll your own or buy it off the shelf, the VNA connects to a computer running software that performs and displays the network analysis from the VNA’s measurements.
Additional information concerning the VNAs is available at W8WWW’s N2PK VNA page and at the TAPR VNA page (the “Buy It Assembled” VNA was a joint effort of TAPR and Ten-Tec.)
Until next time, keep on surfin’!
Editor’s note: Stan Horzepa, WA1LOU, used homebrew beer and ham gear and he recommends not sampling the two simultaneously. To communicate with Stan, send him e-mail or add comments to his blog. By the way, every installment of Surfin’ is indexed here, so go look it up.
| Previous: It Seems to Us: Growth | Next: ARRL In Action: What Have We Been Up To Lately? |
