I finally built a mount for my “winter time” antenna setup and have done some testing with it to find out how well it performs.
What I wanted for my winter ops was something that would be pretty simple to deploy as well as worked fairly well, all the while allowing me to stay inside my vehicle where there is a heater. Pretty tall order since all summer I had used a 40m EFHW wire and it had been producing wonderful results for me. Well if you scroll down through the blog you will find a post about the Huntsville Hamfest and at this hamfest, I picked up a 20m HamStick antenna and stuck it in the corner when I got home for a future project… Today I used that antenna.
QSO map showing the region this antenna works with on the 20m band and 5 watts of transmitter power in 2022…
I used it on 20 OCT 2022 to activate Chickamauga National Military Park. The beauty of this setup is that I specifically designed it for use in such parks where you are not allowed to use the trees for antenna supports and in some cases, the park doesn’t even allow spikes/tent stakes to be driven into the ground. I wanted this antenna to be compatible with all those rules should I decide to venture into one of these parks.
The counter poise wires don’t have to be taught, but keeping them pulled out as close to original as possible makes it work really well.
I keep the ends of the counter poise in location with a couple of custom stainless steel weights that I made in my machine shop. They are kept on the wire by a simple 3 hole keeper that the wire is threaded through. This makes everything easy to deploy, I dont currently leave the base in the trailer hitch, but rather store it inside the cab of the truck when not deployed. So assembly goes like this: 1) Insert the yellow mount into the receiver. 2) Screw the hamstick together and then screw it into the mount. 3) unrolled both counter poise wires and put them both under the ground lug on the antenna mount, spread out both counter poise weights to get them taught. 4) install the BNC coax and run it through the window of the truck door and get in the truck. Done. I like this deployment time, especially with the TR-35, as 20meters is a good band for me to get a decent signal out using just 5 watts of power. I have done several other activations with this setup before this day and after and it always performs really well. I am certain that my weights are interacting capacitively with the counter poise wires, but I don’t care because I tuned the system with them in place.
27 OCT trip to K-2169 showing how this setup pulled in almost 40 QSOs in less than 45 minutes at 5 watts!
QSO map for 27 OCT 2022. I like these kinds of days!!!
As evidenced by both QSO maps, this antenna is deaf inside of 500 miles on 20 meters. That one contact in Calhoun GA was most likely ground wave as you can see there is literally no one inside of this circle except for that one QSO. This is why I think a 40m version would be nice, at least I was getting NVIS on my wire antennas on 40 meters, I hope this antenna will too.
The height of the mount it literally just a piece of tube I found in the shop. I didn’t cut it to a certain length, but rather I just wanted it to be above the top of the truck bed…because I liked that idea. I also figured it would help with the ground plane if the antenna was not bedside the metal of the truck body too…
Since I opted to add a counter poise, it required me to tune the antenna. Below you can see the null is on 14040khz and the SWR is fine for me considering the setup. I found that the length of the counter poise is critical to a good SWR null , I settled on 16’ 4 3/4” on one (1/4 wavelength at this frequency) and the other is a little shorter due to a blunder on my part with reading the tape measure wrong… (I saw 164.75” and my mind converted the numbers to be 16’ 4 3/4” and I happily lopped off the wire this long (13’ 8 3/4”) and threw the cut piece over next to the other and noticed it looked MUCH longer… Then I realized what I did. Never to worry much about details like this, I checked and just needed to trim the antenna to get it to frequency. To be honest here, I noticed that the closer that I got the counter poise to 1/2 wavelength the deeper the null got on the SWR plot. When I make the counter poise for the next band I will cut them the same length and see what that does for the plot… Also take a close look at the counter poise wires where I connected them to the base. I have crimped ring tongue connectors on the wires, but then I also added heat shrink tubing as well, this is to reduce the stress on the wire where it meets the crimp connector and prevent the wire from breaking there. These counter poise wires are made from simple speaker wire.
Something I noticed while tuning the antenna, I could move the null up the band by shortening the counter poise wires…for a while. At a certain point though, the SWR null went up drastically and was un-waivered by anything I attempted to do…except adding back the counter poise wires. The length of the counterpoise wires is very important… So once I got that sorted out and the antenna tuned like you see, I was happy to test it with an outing. First test on each outing was to sweep it with the VNA to make sure nothing had changed from tuning it to setting it up in the field. I am happy to report that it worked perfectly. This antenna works so well that I am going to make a counter poise for 40 meters and another one for either 17 or 15 so I can switch bands. For now, I will just add the other counter poise to the mount and see how the SWR null looks on 20 meter to make sure it isnt causing too much trouble. If not, then I will also look into making a plate to hold more than one hamstick at once and we will see if the non-resonant antennas will cause a problem for the one that is matched to the band. I swept this 20m hamstick across the whole HF band and it only has one null…20 meters, there is no harmonics like the EFHW has…at all. So I am thinking this idea will work and will not require an antenna tuner to switch bands.
I am thinking that the 40 meter kit will be just two more 20 meter counter poise wires to add up to 1/2 wavelngth total… these 16’ wires are already LONG…
The upper lot at K-2169 has plenty of room now and I no longer need a tree to hold up my antenna. This is awesome on so many levels. Another wonderful thing is, if it is threatening rain, my radio will stay dry. If it is windy, I can get out of the wind and if it is cold, I can turn on the heater!!! I hope you like and leave a comment on this post and possibly subscribe to the RSS feed as well so you will always know when the next post drops.
Thank you and 72
de WK4DS (David)