Vertical Dipole Array (VDA) Test

7 February 2025

Not too long ago someone contacted me and recommended I try out a “VDA”. I have heard of a lot of different kind of antennas but this I had not heard of. I didn’t look too far into it as I assumed it might be a little more time consuming to dial in. Then, Greg (KP4PK) sent me an email recently, also highly recommending the VDA for use by the ocean. He also included a link to F4BKV’s website that lays out the plans for this relatively easy to build antenna.

Basically, it is a vertical dipole that has a driven and reflector in the shape of a diamond. All that is needed is a non-metallic vertical pole, and something to provide a boom at the midpoint to create the correct distances between the wires. Time to get to work.

After work last night I pieced together what I could find to make this antenna. Since my DX Commander vertical is still in production I reused the telescopic mast to give me the height I needed. The first thing that I found to act as the center boom was a neglected fishing pole. With the wires pre-cut (a little long) I headed to the beach to put it together. My first attempt was a bit of a nightmare consisting of entirely too much electrical tape holding all the temporary pieces together. I over-thought the spacing for the wire ends and my solution worked but it was definitely a temporary solution.

Once hoisted and in the air the SWR indicated 1.2:1 at a center frequency of 26.5 give or take. What I immediately noticed was the wide bandwidth potential this antenna would provide when I finished tuning it. With the initial test complete and the sun quickly setting I headed home with thoughts of how better to set it up bouncing around in my head. I think this will actually work.

Insider information about me. I despise tangled wires, ropes, extension cords, and fishing lines. I was not born with the patience to deal with those types of messes and do what I can to prevent them from happening in the first place. So I was a little apprehensive taking this project on as it will require a lot of things going on and three guys at the bottom to keep the antenna in play.

Fast forward to today and I had thoroughly stewed over possible upgrades to my initial design attempt. The first realization that came to me was that I could use the upper, unused, portion of my telescopic mast as the boom crossmember. It would be much more balanced than my fishing pole that is much heavier on one end. The other solution that came to me was how to secure the ends. I must have just over-thought that part. The ends need to be specific distances away from the mast, so I just used some rope tied to the end of the antenna wire and tapped it further down (or up) in the same line the wire was going, using a tape measure to ensure the wire end was in the relative correct position.

So, “what about the results,” you must be thinking by now. Well, after my first cut (ensuring to cut the driven and reflector an equal amount) the new center frequency was just below 28MHz, but with the wide bandwidth it was still <1.5:1 at 28.400. Time to get this antenna on the air. I just plopped my radio, and myself down on the most comfortable coral rock I could find and did a few test calls. With the antenna pointed WNW I was slightly surprised to hear Steve, VK3KTT answer my call for a signal check on my new antenna. At least it was radiating. After a quick chat the word got out and a pile up ensued. I did not expect 10m to be open to EU but there it was, and many stations were booming in a true S9 and some +10.

I truly was just looking for some test samples but I felt implored to dish out a bunch of QSOs. At least as long as I could take sitting on the rocks by the ocean With one page full, I contemplated turning off the radio but decided to do another test and swing the antenna around 180 degrees (ESE). Many stations faded away but I could still hear many EU stations. I don’t think they were coming in longpath. While JA stations nearly dropped out I worked several stations in China. So I’m not sure what to make of the directivity for this antenna (without a field strength meter handy), but the gain I felt it provided was a big step up from the usual horizontal dipoles I have been using here. Tomorrow I will make a final adjustment cut to try to get it centered around 28.300 and have it ready for my next 10m activity. I can’t wait. 73, Allen