Many thanks to Rich (KQ9L) for sharing the following field report:
Field Report: Testing a horizontally-polarized antenna at a high QRM POTA site
by Rich (KQ9L)
I wanted to give a quick follow up report from Santa Fe Prairie State Park (K-7839).
As you may recall I wrote up my POTA activation from this park on Oct 23, 2022. I made 15 Q’s that day but deep down felt I could do better. The setting of the park is quite industrial and consequently the man made noise is bad. Reflecting back on this activation, I feel that the limited the number of QSO’s I made that day was due to this QRM.
I resolved to try again but this time my objective was to figure out a solution to mitigate the effects of the QRM on my QSO count. Thinking about the problem, I recalled than manmade noise typically is vertically polarized and therefore for my second attempt, I decided to test this and use a horizontal antenna.
As luck may have it, here in Chicago we continue to experiencing unseasonably warm weather and my work schedule wasn’t too busy on Thursday, November 3, 2022, so it seemed like a great chance to put my theory to the test.
For the antenna, I decided to use one which I have owned for awhile, but have never used. I had purchased a RadioWaves Double bazooka from an online retailer some time back when they were on sale and planned to set up it a flattop dipole.
If you recall from my description of the Santa Fe Prairie State Park, there is a scenic overlook which has a tree mounted pulley system perfectly spaced to mount a 20m dipole. Although this would be the first time I used the system, it turned out to be a well designed and intuitive hoisting solution to use.
The “pulley” is actually an eyelet with paracord running through the eyelet. The paracord is in a continuous loop just like rope on a flag pole. By employing a simple overhand knot I secured the end of the antenna to the paracord and hoisted the antenna up into the tree about 20ft. It literally took a few minutes and I was ready to go.
Antenna was fed with my RG-316 feedline with built in common mode choke. Since a dipole is a balanced antenna system, it really doesn’t need the choke, but it was the coax that I had packed with me and I figured it wouldn’t cause any harm or negatively affect my test. I was QRV by 3:20pm, and anxious to get on the air.
The station was my Elecraft KX2 at 5 watts, CW Morse single lever paddle, and iPad. I like to use an external keyboard since I find data entry from utilizing the iPad touch keyboard to be a pain. I also use a small notebook to write calls down— yes I log both electronically and on paper, I’m paranoid about losing my data. Learning from my Torrey Pines activation, I even brought a small stool to sit on.
With slight apprehension, I connected the coax to the KX2, turned on the rig and initiated a tune cycle. A 1:1.1 match, yaas!
Early impression on first listening to the 20m band was that there was a noticeably lower noise floor. Previously the noise floor on the vertical was at least an S5-6 noise floor and now I was an S3 max. Tuning around the band signals came in loud and clear and some stations were S9 plus. I also clearly observed that weaker signals were much easier to copy. At this point I was pretty confident that I would be able to easily log more Q’s than the last activation.
I called CQ POTA, was spotted on the RBN and in no time I had a little pile up! Copying stations was much easier with less QRM and I made far fewer errors with call signs. I began to believe that my theory was right. The activation went far better than I had hoped for.
I completed 43 QSO’s, almost 3x the number from my prior activation and all in 50 minutes of non-frenzied operation. I didn’t struggle to hear even the faintest signals, some of which were not even moving the S meter beyond the base line noise.
The highlight of the activation was when Paul W4KLY came back to me from GA and gave me a 599 plus 20db over S9, that made my day.
I really learned a valuable lesson that day. In high noise environments, a horizontal antenna is probably a better choice than a vertical and if you have less QRM, you are more likely to be able to copy more stations and consequently complete more contact.
I hope that by sharing my experiences with you and your readers that some insight may be gained that will help folks interested in operating in the field to do so with less difficulty and trial and error. Below is the QSO map from the activation, thanks for reading!
Take care and keep up the great work!
4 thoughts on “Rich re-activates Santa Fe Prairie State Park with QRM-busting in mind”
Thanks for the update, and comparison. I wonder how a small (magnetic) loop would fare in a noisy environment like that? It would be great to have the time to do a side-by-side, real-time comparison.
Mike, thanks for commenting. That is next on the list to try! I’ll post after I get it done.
The noise level seems to be a little high at my QTH but not as bad as it was back home in Florida. The reminder of how noisy a vertical can be is a good one.
Like Mike in Knoxville, I am wondering how a magnetic loop would do in that park. A friend is loaning me his Alexloop to try out at my QTH which is HOA governed. I am forced to keep my antennas inside so I’m hoping the mag loop is the solution to the noise and works well inside.
I have never really experienced a high noise level when I activate that park. At least until a train passes by in the rail yard a bit further back. Then I get noise some its injectors or something (it sounds like how the actual train engine sounds so I know they are related.)
I am actually being out there tomorrow. (11/12/22) With a 100ft random wire and my IC-718 and tuner to do some “high” (50w) power FT8 compared to my normal 10w QRP (with my Ubitx v6).
As for antenna I have used horizontal EFHW and Random Wires, and also Vertical Hamsticks / a 1/4 Wave 20m with a loading coil. Just depends on what I am feeling or if I need to test out a modification.