Skip to main content

Simple Ham Radio Antennas--HF Antennas 101. Post #696.

HF Antennas 101
(http://www.sgcworld.com/Publications/Downloads/antennas.pdf.
Accessed on 23 February 2016, 03:07 hrs, UTC.
Author:  Van Field (W2OQI).
Special thanks to Dean (KH6B) for running off a copy of this outstanding article.
Please click title link or URL address to read the full article.

I'm always searching for interesting antenna articles to add to my reference library.  Sometimes, the greatest antenna articles can be found in the "QST" archives.  Such is the case here.

"HF Antennas 101" by Van Field (W2OQI) appeared in the September 2004 issue of "QST" published by the ARRL.

Van's concise, accurate article lists "10 tips and truisms that every ham should know."

Here's the list for easy reference:

An antenna doesn't have to be resonant to work.  According to Van, a non-resonant dipole fed with television twin lead, 450-ohm ladder line, or homemade open-wire and an antenna transmatch (i.e. "tuner") "is a great multiband antenna.

Antenna "gain" is derived by shaping and aiming RF where you want it to go. Beam antennas get their name because they concentrate RF energy in one direction.

The function of an antenna "tuner" is to effect a match between the output of a transceiver and the input of the antenna system.  Antenna tuners "are variable-impedance transformers that allow you to transform the antenna system impedance...to  50 ohms for the transceiver."

A wire antenna doesn't always have to be center fed.  Such antennas as the end-fed Zepp or the classic Windom remain popular today.  You'll need an antenna tuner because the typical impedance for these antennas is around 600 ohms.

A dipole antenna doesn't have to be perfectly horizontal.  Your dipole can be sloped, bent, zig-zagged, or used as an inverted V.

Vertical antennas shorter than a half wavelength need a ground radial or counterpoise system.  This "missing half" of a vertical antenna usually takes the form of  a buried or elevated configuration of evenly spaced wires below the vertical element.

With vertical antennas, there is no such thing as too many radials.  Van says, "The more radials you install, the more efficient your antenna system becomes. Of course, you'll reach a point of diminishing returns, "but that number is somewhere around 100."  Commercial AM broadcast stations often use 120 or more buried wires beneath their vertical antennas to establish a decent ground radial system.

Having a 1:1 SWR does not mean you have a good antenna.  All that 1:1 SWR means is that you have an impedance match between your transceiver and your antenna system. Val adds that a 1:1 SWR "says nothing about how well your antenna is working."  For example, a vertical antenna without a ground radial system may show a 1:1 SWR, but most of the antenna's signal is being used to heat the ground.  A vertical without a good ground radial system is a fancy dummy load.

Always use the best feed line you can afford.  Val says "Better (less lossy) coax will cost more, but this is the cable that is carrying your precious RF signal to and from your antenna."

Hopefully, this list of basic antenna "truths" will help you design, build, and use better antennas.

For the latest Amateur Radio news and events, please check out the blog sidebars. These news feeds are updated daily. Thanks for joining us today!

Aloha es 73 de Russ (KH6JRM).



Comments

Popular posts from this blog

G5RV Multi Band HF Dipole Antenna. Post #1555.

If you can't see the video, please insert this title URL into your browser search box: https://www.youtube.com/watch?v=aeNHIQ_j4Dk

This well-produced and richly illustrated tutorial on the classic G5RV HF Dipole Antenna was presented to the Brandon Amateur Radio Society in Brandon, Florida in 2017 by Bernie Huth (W4BGH).  Bernie does an excellent job of  explaining the pros and cons of this popular HF antenna from the late Louis Varney (G5RV).  Although Varney envisioned his design primarily as a 3/2 wavelength antenna for the 20 meter Amateur Radio band, radio amateurs have used the antenna for multiband use.  The G5RV is an excellent choice for the 20 meter band.  Performance on other HF Amateur Radio bands is good enough to qualify as stand alone HF antenna if you can only erect one HF antenna.

For the latest Amateur/Ham Radio news and information, please visit these websites:

http://www.HawaiiARRL.info.
http://www.arrl.org.
http://www.arrl.org/arrl-audio-news (a weekly podca…

Amateur Radio Bicycle Mobile Setup. Post #1554.

If you can't see the video, please insert this title URL into your browser search box: https://www.youtube.com/watch?v=2zWb-KnkGdY.

Here's a way to use Amatuer/Ham Radio while you work on shedding a few pounds in useful exercise.  Why not equip your bicycle for 2 meter/70 cm mobile operation?

In this short, well-made video, "taverned" shows us how he used a mag mount antenna, a simple C clamp, and a basic ground system to convert his mountain bike into a mobile station.  The project is straight forward, simple, and gives you emergency communications while you peddle down the road.

For the latest Amateur/Ham Radio news and information, please visit these websites:

http://www.HawaiiARRL.info.
http://www.arrl.org.
http://www.arrl.org/arrl-audio-news (a weekly podcast which is updated each Friday afternoon).
https://hamradiohawaii.wordpress.com.
https://bigislandarrlnews.com.
https://amateurradionewsinformation.com (Amateur Radio News & Information).
https://www.eha…

An 80-Meter Vertical Helix

Like many amateur radio operators, I live on a small lot surrounded by neighbors, utility lines, and civic-minded citizens concerned about the "attractiveness" of my community.  Whether by design or outright fear, I've adopted the "stealth" approach to ham radio antennas.  It's the old "out of sight, out of mind" idea applied to amateur radio antennas.

The amateur radio press is full of articles describing the struggle of amateur radio operators to pursue their hobby under the burdensome regulations of CC & Rs, HOAs, and other civic minded citizens who object to antenna farms.  So far, my modest verticals, loops, and inverted vees have blended well with the vegetation and trees bordering my small backyard.  Vertical antennas have always been a problem because of the limited space for a radial system.  There are times, however, where a shortened vertical for the lower HF bands (such as 80/75 meters) is necessary where horizontal space is lacki…