Understanding SWR by Example
Take the mystery and mystique out of standing wave ratio.
Darrin Walraven, K5DVW
“It sometimes seems that one of the most mysterious creatures in the world of Amateur Radio is standing wave ratio (SWR). I often hear on-air discussion of guys bragging about and comparing their SWR numbers as if it were a contest. There seems to be a relentless drive to achieve the most coveted 1:1 SWR at any cost. But why?
This article is written to help explain what SWR actually is, what makes it bad and when to worry about it. What is SWR? SWR is sometimes called VSWR, for voltage standing wave ratio, by the technical folks. Okay, but what does it really mean? The best way to easily understand SWR is by example. In the typical ham station setup, a transmitter is connected to a feed line, which is then connected to the antenna.
When you key the transmitter, it develops a radio frequency (RF) voltage on the transmission line input. The voltage travels down the feed line to the antenna at the other end and is called the forward wave. In some cases, part of the voltage is reflected at the antenna and propagates back down the line in the reverse direction toward the transmitter, much like a voice echoing off a distant cliff. SWR is a measure of what is happening to the forward and reverse voltage waveforms and how they compare in size. “
Read Full Article:
“Testing a kite antenna for HF during the Oceania DX Phone Contest on Oct 3, 2010 at Tania Park, Balgowlah Heights, Sydney. The Rokkaku kite eas... Read more
2 Meter Quad This is a different way of using PVC pipe to build a 2 meter cubical quad antenna. Instead of an “X” style spreader this ante... Read more
“Space communication has forced the use of Circular polarization. The fundamental advantage of circular polarization is that all reflections cha... Read more
Introduction: Acquired in 2014 by Alpha Antenna, the S9 Antennas have been completely improved and resigned. Years of perfecting the manufacturing pro... Read more
by David Spero Some things in life you can never have too much of. But for this article, we’ll concentrate just on radio range/efficiency! There are... Read more
Announcing the BTECH GMRS-V1 We are excited to announce the most flexible GMRS radio, the BTECH GMRS-V1. The GMRS-V1 includes 23 modifiable channels f... Read more
The new version of the IARU Region 1 VHF Handbook 7.50 covering VHF, UHF and Microwaves is now available for download. The handbook has chapters on Ba... Read more
“The Baofeng UV5R. Some have called them the savior to ham radio and others say they are nothing but a scourge to the hobby. But one is for sure... Read more
To commemorate our 3rd anniversary, special event stations will be on air during the FT8DMC Activity Days from 1. to 31. July 2020. All stations will... Read more
In a post to the WSJT-X email group today, Joe Taylor K1JT hinted at some ongoing experimentation of a new digital mode with sub-modes. His post was a... Read more
WWSA GACW I – Dates Second weekend of June of every year. From Saturday 15.00 UTC until Sunday 15.00 UTC. 24 hours period. II – Goal To co... Read more
CATSync allows you to syncronize public WebSDR receivers with your real rig connected via CAT control to your computer. It supports the classical WebS... Read more
SDR has never been easier! SmartSDR is now available for your Mac. It has never been easier to operate your FlexRadio 6xxx Radio. SmartSDR for Mac is... Read more
LATEST STABLE VERSION OF SDRUNO IS 1.4 (12th August 2020) Release Notes: Release notes for all versions of SDRuno can be found by clicking here Known... Read more
This release contains several important customer requests. The Yaesu FTDX101D/MP is added. The last QSL comment is gathered into callsign lookup. The... Read more