Antennas By N6LF

QEX letter to the editor

I recently sent the attached letter to the editor of QEX.  It may answer some questions and correct some incorrect figure captions: Download QEX letter to the editor 1 

Series of QEX articles on ground system experiments

Last year I posted results from a series of experiments on ground systems for vertical antennas.  That series of reports was converted with some modifications into a series of seven articles in QEX magazine.  The ARRL has kindly given me permission to post .pdf files of these seven articles for those who do not have access to QEX.  Here they are:

Download QEX ground systems part 1

Download QEX ground systems part 2

Download QEX ground systems part 3

Download QEX ground systems part 4

Download QEX ground systems part 5

Download QEX ground systems part 6

Download QEX ground systems part 7

A summary of these articles was published in QST for March 2010, pp. 30-33. 

In QEX for May/June 2010 letters to the editor I made the following comments.  "I think too many people are taking the QST article as gospel when it should be viewed only as an interesting set of expriments which shed some light on a few questions.  Even the QEX series, which is much more detailed, raises far more questons than it answers.  I was really hoping to encourage others to expand on my work (as I expanded on Sevick's) by showing how it might be done.  73, Rudy N6LF"

Broadband antennas

In terms of percentage of frequency the 80m band is quite wide.  Few antennas will provide a low SWR to a random length of transmission line over the entire band.  Here are two antennas which will do just that and one of them will even provide 3 dB of gain over a dipole.  Broadband 80m dipole, 747 kb, QST July 1995 and Improved double zepp , 2,581 kb, Antenna Compendium 4

Half-square antennas

The half-square antenna is a simple 2-element wire phased array.  It has modest gain and can be particulary useful on 80 and 160m.  Even though the half-square has been with us for a long time, there are still a lot of practical details that are not widely known.  These two articles on the half-square antenna give practical details and ways to broadband operation on 80m.  half-square antennas for the low bands, 585 kb, Antenna Compendium 5 and broadband half-square for 80 m, 88 kb, Antenna Compendium 5.

Bruce arrays

The Bruce array is a simple wire antenna capable of considerable gain.  It has been around since the late 1920s but amateurs seem have forgotten about it.  That's a shame because it can be just the ticket for some applications.  The article on the Bruce array, Bruce arrays for 80 and 160m , 142 kb, NCJ Sept/Oct 2000, goes into many details which have been lost over the years.

Single support low-band antennas

Antennas with gain and good F/B can be a challenge on the low-bands.  This is especially true if only one support, such as a tower, is available.  It turns out there are a lot of relatively simple ways to build a vertically polarized array with very good performance.  Half wave sloper arrays have many possibilities as shown in High performance half-sloper arrays , 1,104 kb, QEX Jan/Feb 2004.  There are also a variety of other ways to go, as discussed in single support gain antennas, 415 kb, NCJ Mar/Apr 2003.

Low band quad antennas

On the lower amateur bands (40-160 m) quad antennas can become very large but they are not impossible to build!  The great performance obtainable from these antennas may make them a worthwhile project when seeking contest level performance.  The following article discusses this class of antenna and makes practical suggestions for their implementation monster quads , 168 kb, Antenna Compedium 6.

Elevated radial verticals

Ground-plane verticals are widely used by amateurs but frequently it is not possible to install the classical 1/4-wave vertical with 1/4-wave radials.  There are many variations that work around common problems.  You can for example use shorter radials as shown in short radials in GP antennas , 88 kb, Antenna Compendium 6. You can also combine fewer and shorter radials with top loading as discussed in The lazy H vertical , 3,243 kb (a biggie!), Communications Quarterly Spring 1997.  It also can be  helpful to see the relationship between elevated and buried radial systems.  This is discussed in another way to look at verticals , 145 kb, QEX Mar/Apr 1999.

Ground system design

The ground system is a fundamental part of HF vertical antennas.  because of this the design of ground systems have been a hot topic for the last 80 years or more.  Unfortunately despite the intense interest a lot of very useful information has not found its way into amateur literature.  The articles attached to this post are intended to help.  The first article gives a good overview of the basics and reflects the accepted wisdom from BC antenna work, Ground system basics , 275 kb, QST July 2000.  More posts on ground system design will be added shortly.

Conductors for HF antennas

Wire antennas can be simple and economical but many times conductor losses can lead to less than optimum performance.  This is particularly a problem in gain antennas where the radiation resistance may be low.  With some care, these losses can usually be minimized.  The following two articles discuss round wire and foil conductors,  HF wire conductors , 220 kb, QEX Nov/Dec 2000, HF foil conductors , 311 kb, QEX May/June 2002.