The VP2E – A Strange (But Proven) Antenna

As an avid POTA activator I was quite excited to come across a new-to-me wire antenna that is rapidly field deployable, fairly stealthy, directional and which has some gain. I would like to thank Germany-based SOTA operator Ed Durrant DD5LP, G8GLM, VK2JI for introducing me to the VP2E.

As is my custom, I read Ed’s description of the VP2E and wanted to learn more – by building one, tinkering with it, then putting it on the air to see how it performs. Before wading into the details I can disclose up front that this is a remarkably good antenna. I took it to the field for a QRP POTA activation and it did fine business, demonstrating both its directional properties and gain.

Being an ever curious experimenter I also came up with a variation that will make the VP2E even more directional and improve its gain. More on that later.

As Ed writes in his blog post, the VP2E was designed by HB9SL (SK). Note that VP2E is also the callsign of a ham on the Caribbean island of Anguilla who might be flattered to learn that he had been mistakenly credited with its design (by me, at first). But no, VP2E is an abbreviation for Vertically Polarized 2 Element.

My initial take on the VP2E was that it is an Off-Center Fed Full Wave. What was most intriguing was the fact that it is intentionally erected quite close to the ground. I modeled the VP2E using EZNEC and injected some of my own ideas to gauge the impact of several variables on the original design.

Ed’s diagram shows the 20m version of the VP2E. It comprises a full-wave element supported at its center by a short pole. The feedpoint is at a 50-ohm point of the element on one side and the maximum radiation is from the other side of the wire (NB: important update on that later in this post). Note that no tuner, unun, balun or radials are required.

Here are my EZNEC far-field propagation charts (NB: using MININEC ground and with my local ground conductivity figures):

Ed DD5LP used MMANA for modeling the VP2E and came up with lower elevation angles for the signal. I don’t have MMANA and I can’t comment on which modeling software is more accurate.

First Trial Results

I set up the VP2E in my backyard for testing. It was oriented N-S and, after a little trimming, an SWR of 1.3:1 was obtained in the CW portion of 20m. I called a POTA activator in Colorado (2000km away from my QTH in Ontario) and was given a 579 report using just 5 watts. That was encouraging; I was excited already.

The Big Test – a POTA Activation

It was one of those very rare days in Ontario – a warm day in February! After recent days that had given us minus twenty degrees Celsius, plus five degrees with bright sunshine was a welcome change. The VA3KOT POTA station was set up on a park bench overlooking the beautiful Colpoys Bay and with towering bluffs behind me to the south. I erected the VP2E in a West-East orientation theoretically with propagation favoring the west.

I spotted myself at pota.app and hit the big red button that sends out my CW CQ. My power was just five watts. I recently returned to QRP operating after becoming a QRO operator during the solar minimum. QRP is working for me again and I received a response on the very first CQ. Then the hunter express train hit me with the usual intense pile-up. After just nine minutes the requisite minimum 10 contacts were in the log and the VP2E had proved itself!

But who stops at ten contacts? I plowed through the pile-ups until there was a hiatus after 31 QSOs were in the log when I called QRT. My wife was in the truck patiently reading another of her Stephen King novels while I played radio outside. It suddenly dawned on that it was Valentine’s Day. Her patience and understanding cost me a big bunch of red roses on the way home.

Oh! That’s Unexpected!

I log using pencil and paper and transfer the log to HAMRS when I get home. When I looked at the QSO map of my activation log something very curious was apparent. I should have been getting most of the QSOs from the west. Instead, most – including European DX stations – were to the east. Was this long path propagation or is there another explanation?

Wednesday Morning 1:00 AM

Still buzzing with the excitement of my new antenna, I lay tossing and turning in my bed wondering why I got such unexpected propagation. I projected the picture of that afternoon’s setup onto the back of my eyelids and a cunning theory began to emerge.

Out in the field, practical limitations often dictate how we set up our antennas. And so it was on Valentine’s Day. Post-activation I realized my antenna was not set up symmetrically about the truck hitch-mounted 14ft pole. The feedpoint side of the wire was a little shorter. As I lay in bed I wondered if this would impact the propagation. I had to know; I really had to know and waiting until morning was not an option if I wanted to get any sleep.

So, at 1:00am, I climbed out of bed, crept down to my shack in the basement and fired up EZNEC on my laptop. Voila! Editing the previous model I found that displacing the support pole toward the feedpoint end of the wire switched the maximum propagation from west to east.

Now, if the feedpoint were positioned directly at the top of the pole, then the pole could also support the weight of the dangling coax cable. How would that work?

EZNEC says both the directionality and gain would be improved. It still isn’t as good as a beam antenna by a country mile, but we’re dealing with just a simple rapidly deployable field antenna.

Will real world results match computer modeling? That’s for my next activation to discover. Meanwhile the VP2E has earned a place of honor in my antenna box and will be making the trip every time, every park this year.