The Mainsail - Your Antenna

Since the basis of this site is to is to encourage hams, new and old, to explore and/or rediscover the HF bands, and to empower them to do so in the easiest, most cost efficient way possible, nothing more than very basic antenna theory will be discussed. Rather I'll attempt to focus on a few of the most popular, easiest antennas to erect - antennas that with a modicum of effort and adjustment should permit excellent results for a minimum financial outlay.

Despite any thought you may have about simply purchasing say, a multi-band vertical, I'd encourage you to consider working through the process of building and erecting an antenna from scratch. The reasoning here is simple - nothing will make a larger difference on your ability to receive weak signals and increase actual radiated power than the construction, placement and intelligent adjustment of your antenna system.

Over the years our research has found the most accurate, easy to understand explanation of both simple complex antennas to be provided by the late L.B. Cebik W4RNL. For that reason, included in the discussion are numerous links to the webpages that continue to host the information he provided. For that reason, as we go through 3 different antenna types, you are encouraged to explore the Cebik site as well as others for all the wonderful information they provide on antenna theory and propagation alike.

The Dipole Antenna

At the top of everyone's list of favorites is often the simple, effective half wave dipole. Fundamentally, it is simply a length of wire one half wave length long for the intended frequency. Insulated at the ends, it is split at the center, and fed from the transmitter with 75 ohm coaxial cable with the braid or outside conductor connected to one side and the center conductor connected to the other. The standard formula is 468/frequency in MHZ.

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Once cut, and a space determined for its installation, consideration should be given to the height of its placement. While the dipole is effective when placed at less than ¼ wavelength above ground, its true performance characteristics don't really become apparent at those heights. However, even at 20 feet above ground, the dipole will provide effective regional communication, keeping in mind that its advantages become evident only at heights above ¼ wavelength. Additionally, the dipole has directional characteristics that run broadside or perpendicular to its length, particularly when its placement is above ¼ wavelength.

With that very basic description in mind take a look at W4RNL's excellent discussion on the technical aspects of this legendary bulwark of most ham radio stations.CLICK HERE

The Vertical

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The second, and perhaps most popular simple antenna for use on HF is the quarter wavelength vertical. Properly installed either at ground level or some height above ground, its performance is outstanding. The reason lies in the angle of radiation it is capable of providing. Unlike the dipole at height, which radiates a portion of its power vertically, toward the ground and straight up, a vertical radiates the largest majority of its power horizontally. This advantage however relies almost entirely on a properly installed set of ground radials.

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The number of ground radials (also cut at a quarter wavelength) for a surface mounted vertical should in every event exceed eight, with performance dramatically improved by the addition of many more.

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While a goodly number of radials is critical to the efficency of a vertical, it is able to function with something less than that.

A case in point, after experimenting with a dipole at limited heights (15-20 ft) when I first got on the air, I went with a surface mounted quarter wavelength vertical constructed of steel tubing and resting on a pop bottle, the bulk of which had been buried in the ground. I was shocked, when with only two radials, I worked a station in France on CW, running 50 watts as a Novice. This is not to say, by any measure, that the contact was typical of a poorly constructed vertical, but rather that the angle of radiation combined with an 0 dark 40 contact with good propagation made me seriously consider the value of vertical antennas on 40 meters.

To learn a whole bunch more about the performance of verticals as opposed to dipoles and acquire important specifics regarding this antenna, check out W4RNL's write up on them at:

CLICK HERE

Vertically Oriented Full Wave Loop

For those interested in DX, particularly on 80 and 40 meters you may wish to consider my personal favorite, the vertically oriented vertically polarized full wave loop (VOVPL). From personal experience, it's likely the most bang you'll get for your buck.

After a hiatus from ham radio for several years and primarily focused on working 40 meters, I first erected a vertical. That worked fine for stateside contacts but was unusable for DX and very noisy. After some on-air research I discovered that the strongest signals that emanated from wire antennas at heights of less than 35 feet, were from full wave loops - both deltas and squares.

Visiting W4RNL's writeups and a number of others, and taking into consideration what I had available on my small lot, I settled on erecting a vertically oriented rectangle spanning approximately 49 ft wide by 21 ft high at 3 feet above the ground and fed in the middle of one side with a 1:1 current balun.

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The performance has been nothing short of amazing. The main radiation lobes are low and perpendicular to its orientation. With it orientated north and south, from central South Dakota, I receive signal reports into Europe of 57 and 58, running 100 watts and typically 59+ to both coasts - all during a sunspot minimum.

An additional advantage of the V0VPL is that it is capable of operating on other bands as well depending upon the primary band its designed to service. I've listed a number of sites for reference if this sound like something you'd like to explore further.

References

The references listed below will be tremendously helpful it you are considering a VOVPL antenna.

In print, consider "Low-Band DXing" Fifth Edition, by John Devoldere ON4UN, ARRL.CLICK HERE

The W4RNL reference is very practical in nature and also provides a significant amount of detail about the its radiation characteristics in various configurations: CLICK HERE

KN9B provides an outlay of the practical aspects including its use for multi-band operation - a must read for those with space limitations/covenants:CLICK HERE

For a more conventional delta configuration, Ron, DJ0IP, provides a layout for a simple, effective loop requiring only one tall vertical support: CLICK HERE

As a final note to those venturing into antenna work - explore a portable fully featured antenna analyzer such as that shown below, that are not only inexpensive, but that can provide a ton of useful information on the antenna under test.

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A Recommendation

Two key features of an antenna analyzer should be portability, or the ability to take the instrument to the feedpoint of the antenna, and second a sweep function that will allow you to monitor the changes as you adjust the antenna. There are a number of manufactures, but perhaps one of the best packages for the money that we've found may reside in the RigExpert series, available at virtually any ham supply outlet, as well as Amazon. Please keep in mind that we do not get paid for doing this but reference you to their site for further information on this rugged, inexpensive, amazing instrument for simplifying not only antenna work but for any work you may do on resonant circuitry.

CLICK HERE TO CHECK OUT THE FULL LINE OF RIGEXPERT ANTENNA ANALYZERS