Choosing an HF vertical

Last week, an online amateur radio retailer contacted me about writing some blog posts for his website. One of the topics he suggested was “Choosing an HF vertical.” Here’s what I wrote this morning:

Choosing an HF vertical

For many amateur radio operators, a vertical antenna may be the only option they have to put up an HF antenna. They may, perhaps, live on a small lot, or they may not have suitable trees or other antenna supports from which they can hang dipoles.

Fortunately, there are many good products on the market. Unfortunately, there is some confusion about the different types of verticals out there. This short article will attempt to give you some guidance on how to choose the right vertical for you.

Trap verticals
Trap verticals have been around for a very long time. My very first HF antenna back in 1971 was a hy-gain 14AVQ. These verticals use “traps” that are parallel resonant circuits to electrically isolate portions of the antenna when transmitting on various bands. The traps make the antenna act as if it were a resonant quarter-wave vertical. For example, when the 14AVQ is being used on the 10m band only the lower portion of the antenna is active. When operating 40m, the entire length of the antenna is active.

Trap verticals need radials to operate effectively, and the more the merrier. Take this into consideration, when deciding whether or not to purchase a trap vertical.

No-radial verticals
In recent years, several manufacturers have introduced vertical antennas that do not need radials. GAP Antennas is one manufacturer that offers these kinds of antennas.

The manufacturers claim that these antennas are more efficient than trap verticals, and  many amateurs use them with good results. There are some drawbacks, however. They can be difficult to tune, and they do require mounting at some distance above ground. The reason for this is that they are, in effect, vertical dipoles and if the end of the antenna is too close to ground, capacitive coupling will detune the antenna.

Non-resonant vertical antennas
A third class of vertical antenna that is becoming popular is the non-resonant vertical antenna. An example of this type of antenna is the LDG S9v43 Vertical Antenna, although several other manufacturers also make this type of antenna.

One reason that this type of vertical antenna is becoming popular is that it can be used across a wide frequency range. The resonant frequency of this antenna is actually about 5.4 MHz. With an antenna tuner, however, you can use the antenna on all bands from 80m to 6m.

This tuner can be located in your shack, but for the lowest loss, you will want to locate the tuner near the base of your antenna. Don’t try using it with the internal tuner in your rig. On some frequencies, the antenna impedance will be quite high, and most internal rig auto tuners do not have adequate range to provide a 50-ohm match.

These antennas require radials. There is no formula to calculating the length of the   radials, but they should be at least 0.2 wavelength at the lowest frequency that you wish to operate.

We carry the entire line of LDG vertical antennas. The LDG S9v43 antenna is 43 ft. high and covers 80m – 6m, the LDG S9v31 antenna is 31 ft. high and covers 40m – 6m, and the LDG S9v18 antenna is 18 ft. high and covers 20m – 6m. All of these antennas use heavy-duty, telescoping fiberglass sections. The antenna is self-supporting, and because it’s very light weight, easy to install.

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I know it’s not a comprehensive guide to how to choose an antenna, but that’s not the intent. I also know that it’s a bit slanted towards the non-resonant vertical, but that’s the kind of antenna that the company carries.  Having said that, I’d love to hear your comments.

Comments

  1. Good article on vertical antennas. If one will install radials, the Hustler and Butternut antennas are real popular here in Tampa Florida area,
    One Ham has the 43 ft vertical on a boat dock in Tampa Bay with NO radials under it.
    LOL, being right on salt water over Tampa Bay, he cracks pileups on 40 meters easily with this antenna!

  2. Ned WB4BKO says:

    I have been using an S9V31 for a couple of years. I have forty 28 ft long radials under it. It works well using an indoor auto tuner. For a while I used my Icom 746 built in tuner until I decided to add two feet of wire at the base an feed the vertical as a 40/15 meter vertical. It works well that way too.

    I was not that impressed with its performance on 15 and 10 meters primarily because I’m using 100 feet of buried coax between the Icom and the antenna. I don’t recommend that long a feed line with an indoor tuner. The losses are just too high. Oh yes, be sure to use a 4:1 unun at the antenna feed point. It works so much better.

    The S9V series are very good portable verticals. They telescope down to a yard long package that weighs almost nothing. I close mine and take it back to Michigan with me in the spring. One must ensure the antenna is periodically wiped down with WD-40 since the antenna’s plastic mast will oxidize. Also, ensure the segments are lubed at their overlaps, or they will freeze in place and twisting them to unlock the segments, or one will have a devil of a time trying to unlock each segment to collapse it.

    • Dan KB6NU says:

      Great advice on using the S9v43. Also glad to see that you persevered with the Captcha on my website. :)

  3. Dave, N8SBE says:

    As far as the Captcha goes, I found out a long time ago to copy (CTL-c) my text before hitting ‘Post Comment’, so I can paste it back (CTL-v) when the Captcha fails for me. Keeps my blood pressure a lot lower 8-).

    I believe that a number of folks that use the ubiquitous 43-ft. non-resonant verticals are mistaking poor pattern performance on the higher bands for increased loss in the coax. There have been several recent articles (including a couple in QST) where it is shown that the antenna pattern breaks up and starts to have major lobes that are not optimal for typical HF work. As you go up in frequency, it usually becomes easier to match to the 43 ft. pole, and the actual coax loss doesn’t really increase all the much, at least up to 30 MHz.

    So, this is where the trap or non-trap tuned verticals tend to shine, when compared to the non-resonant 43 footers. I believe there was a recent article on how to ‘fix’ the typical 43 footer so it behaves better on the higher HF bands, but I forget what the technique was, other than to make the antenna appear electrically shorter, as appropriate.

    I guess what I’m trying to say is that even though the 43-foot vertical looks like a simple, easy to implement do-all antenna, it tends to work effectively really only on 80 and 40 meters, and it tends to fall off pretty drastically on 20 and above. Seems counterintutive, but that’s the case,

    On the other hand, I have direct experience with a GAP Titan DX, which nominally covers 80-10m. As a vertical dipole that is “only” 35 feet high, it is definitely a compromise on 80, and only somewhat less so on 40. It tends to be best on 20-10, but I have a two-element spider-boom quad up 40 feet that beats the GAP all hollow on those bands.

    So, I’m still looking for a solution for 80-40, and quite likely will go back to my 50-foot pushup mast and 80-40 inverted vees (in an “X” pattern, when viewed from above). Maybe not the best “DX” antenna for those bands, but in a suburban lot, I can get it to ‘fit’, and it has been a very effective antenna for me, particularly stateside. Just don’t make the mistake I made the last time I put it up, where I put a 1:1 voltage balun on the center, and taped it to the metal mast (essentially shorting out the balun).

  4. It amazes me at how much false advertising the different manufacturers get away with to sell antenna’s in this day and age. Most of the no-radial antennas actually work very poorly until you add ground radials or a counterpoise of some sort. I always try to go by the reviews first before buying an antenna. The same with radios.

    • Bruce VK3WL says:

      Unless the groundless vertical is a 1/2 wave, don’t believe what the manufacturers of these antennas tell you. Analysis will tell you they are trying to rewrite the laws of physics. Take a look at the Butternut web site. It has a number of excellent articles about vertical antennas and ground systems in particular.

      I’m after a motorized retractable vertical that is 3m tall when retracted, and about 6~8 m tall when extended. I don’t really want a StepIR vertical, preferring to use an auto ATU at the antenna base. Anyone have any ideas?

  5. An additional type to consider is the asymmetrical hatted vertical dipole. My prototype works adequately. N6BT makes one type and I have the plans for another on my site. Google KX4O-000049.pdf to find mine.

  6. This makes things a little tough for us noobs when it comes to selecting an antenna. If you can’t trust the manufacturer to give you the straight scoop. I’m new to this… just got my technician license last week. I have a nice DX radio.. a Yaesu FT DX 1200 and for an antenna I chose a GAP Challenger DX, which is supposed to be a pretty highly rated antenna. I guess it is essentially a vertical dipole… It says you have to run 3 radials, 25 ft. long at 120 degree locations around the base of the antenna and that running more than that has very little additional purpose. i.e. it don’t do much.

    Since I have it I guess I will make the best of it. I do however have one question and that is with installing it. I have a 4″ dia aluminum pole in my back yard that is about 25 feet tall. I’m not even sure why its there. It was here when we bought the place. Would there be any advantage to mounting my GAP Challenger DX to the top of this pole to get it much higher off the ground? Or would this screw up all of its characteristics… would it work if I isolated the antenna from my aluminum pole, so its not electrically connected to the antenna or doesn’t it matter. Would raising it somehow negate the influence of the ground radials? I’m dying to put this thing up so I can get on the air. Anyone have any words of wisdom… besides “buy a different antenna”.

  7. I think that lots of hams have had good success with the Gap vertical antennas, so I’m not sure that “buy another antenna” would be my advice.

    One of the general rules of thumb regarding antennas is that the higher up you can mount it, the better. So, I’d say do it. make sure that you get the radiating portion of the antenna above that pole, though.

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