A surprising hack to a vertical antenna

HF9V vertical in snowy yard
The HF9V vertical at WA0TDA

Out in the back yard, far from the house and all the neighboring houses, is my Butternut HF9V vertical HF antenna. It’s ground-mounted and fed with underground 50 ohm coaxial hard line. There’s a three foot high wooden fence surrounding the base to keep dogs and critters at bay. Three UV-resistant Dacron rope guys run down to the ground for guying, an extra insurance policy for high wind days, but not strictly necessary and easily moved for mowing.

The HF9V is a workhorse of an antenna. It covers 80 through 6 meters, and at 26 feet (7.92 meters), it is relatively low profile and is hidden from view to passersby on the street unless they are really looking for it between the houses. The ground beneath the vertical hides insulated copper wire radials fanning out like the spokes of a wheel from the base of the grounded antenna support tubing.

It has always been a good antenna, and really shines during periods of solar maxima when there high numbers of sunspots and great ionospheric conditions on 20 through 10 meters. It still works quite well on 30 and 40 meters, but 80 meters can be challenging, especially if I want to use it for regional nets. The low angle of radiation may be great for DX, but is definitely a disadvantage on a statewide SSB net on 75 meters.

In 2019 we are nearing solar minimum, the worst time for communications on 20 through 10 meters, and that means I am turning to the longer wavelength bands for daily on the air activity. Most modern HF transceivers cover 160 through 6 meters. A multiband antenna like the HF9V is a good choice for getting the most flexibility out of these radios, but it doesn’t cover 160 meters, at least not without an expensive add-on. And in any case, I would really prefer sending some RF into the air at higher angles on these longer wavelength bands to make local and regional contacts easier.

Of course I could put up separate wire antennas and feedlines for the 75 meter and 160 meter bands, but space can be an issue. Depending on the configuration, a half-wave dipole on 75 meters will be around 125 feet (38 meters) long. A dipole for 160 meter operation would be twice that.

Reasoning that I could treat the HF9V as I would a quarter-wave ground-mounted vertical, I decided that it would be possible to feed multiple other quarter-wave “verticals” in parallel with the “real” vertical without radically detuning the existing system. The existing ground radial system would suffice to serve the additional radiators as-is.

I got busy and found some lighter weight (but still strong) stranded copper wire with black insulation. Measuring off approximately 67 feet (20.42 meters) for a 75 meter band quarter-wave and 125 feet (38.1 meters) for a 160 meter band quarter-wave, I laid out each length on the lawn in turn.

Next, I surveyed the yard for antenna supports (trees!) and planned the routing for each new radiator. Each would be connected to the HF9V at the base where the center of the coaxial feedline was connected. A stainless steel hose clamp would hold both new wires to the base of the vertical. The ends of both wires were stripped of insulation, tinned with solder, and ultimately they would be clamped to the HF9V’s base tubing with the hose clamp.

First, though, they needed to be routed over a couple of trees to bring them up and away from the feedpoint. They don’t really need to be terrible high, but higher is better if you can manage it. Luckily I had an aspen tree within about 10 meters of the antenna base, so I routed the first wire through the top of that tree’s branches, then off at an angle to the branches of a pine and off to an apple tree. The second wire, the longer one for the 160 meter band, went up at a slightly different angle to the aspen tree, changed direction to the pine tree’s higher branches, then turned back again to another apple tree in the far back corner of the lot.

With the wires in the trees and a bit of final dressing to keep them separated enough to avoid close electrical coupling (and potential detuning), both were secured to the base of the antenna with the hose clamp and at the far ends with the Dacron rope. No particular care was taken to keep the insulated wire away from the trees’ foliage. The end result is two more or less independent quarter-wave radiators with some vertical components near the feedpoint but also with significant horizontal components that would allow for better regional communication at higher radiation angles on 160 and 75 meter SSB.

So does it work?

Yes, it does – and surprisingly well. In contacts with my “local” 160 meter group of stations during our informal evening get-togethers on 1.966 MHz, I have gotten excellent reports while running an Icom IC-706M2G at 100 watts. On the multistate 75 meter PICONET (3.925 MHz) I have also done quite well, making nearly every contact I attempt. And best of all, the HF9V still performs well on the other bands.

I do have two other HF antenna systems on the property; a 270 foot (82.3 meters) dipole fed with 450 ohm ladder line and a current balun, and an inverted vee maypole covering 80 through 6 meters and fed with underground 50 ohm coaxial cable. Both of these antennas feed IC-7200 radios that are on the internet via Remotehams.com. Although I can use them both, I wanted a “private” radio that would also have an effective antenna system, so that I why I upgraded the IC-706M2G station and the Butternut vertical. In comparisons, the vertical holds its own with both other antenna systems, so I am pleased with the results.

I didn’t specify how to get the wire for the additional radiators up into the trees. Some of you probably prefer slingshots of some sort. I used a drone, to with I taped a length of lightweight mason line on a spool. I flew the drone trailing the line over the trees in the desired spots and landed on the opposite side, detached the mason line from the drone and used it to pull the heavier antenna wire up into and over each tree. If you’ve ever put up temporary ARRL Field Day antennas, you’ll have some ideas about how to get that part of the job done. Since you want the installation to be up for a long time, allow some slack in the wires so that windy days will not cause the tree branches to stretch and break your wires. Even with light wire, my installation easily stood up to a challenging Minnesota snowy and icy winter and winds in excess of 50 mph (80 kph).

Finally, in order to take maximum advantage of your transceiver’s capabilities, you will probably want to use an antenna tuner. Most antennas cannot cover all the frequencies you might want to use. An automatic antenna tuner will provide the right match, allowing the radio’s transmitter section to operate at full power out with a low standing wave ratio presented to the radio, even though the actual radiator out in the yard might not be exactly tuned to your operating frequency. A characteristic of shorted vertical antennas (as is the case with the HF9V on a band like 80 meters) is that the tuning range of the antenna is very limited if you want to stay under 2:1 VSWR, which is recommended. By adding a longer wire element, you have now greatly broadened the tuning range, making it easy to use the entire band – as long as you have a good automation (or manual) antenna tuner.

I hope this has given you some ideas about how to think about vertical antennas a bit differently. Have fun trying new antenna configurations and make the most of your radio’s capabilities!

73 & DX,

Pat, wa0tda@arrl.net