The fairy tale of the poor performing end fed vertical
Last Friday I had a bad experience with my tried and trusted end fed vertical on 40m (actually a multi-band end fed for 10-20-40m).
While listing around I stumbled upon Paul MM0ZBH on 40m. He is the one who recommended me the Sirio 4-element CB antenna for use on 10m. I was about to tell him how much I enjoyed the CQWW thanks to that beam. However he did not seem to hear me, even though I copied him with 58. After several attempts he was able to make out my call sign but there was not a chance for a decent QSO (report received: 33).
The multi-band end fed that I use is 12m long and has a coil at 10m from the network to make the wire resonant on 40m. I blamed this shorter wire for the lousy performance on that band. Frustrated I started looking at other possible antenna configurations for /P operations.
From all the available options the inverted v looked the most promising as it requires only one mast (as the end fed does), while you can still operate with a "full size" antenna (1/2L in this case). The inverted v would also be a candidate configuration for an 80m antenna. I do not have an 80m antenna at the moment and although I can get the 40m wire resonant on 80m when I work from my home (using the tuner of my IC-756P3), it is not a performer by any standard, nor does it help me when I am /P.
This weekend I was able to put something together that looked like it could work as an inverted v. I made the legs a bit longer so I could tune it to perfection. Today I was able to set the antenna up. It took me some fiddling to get it up in a way the Spiderbeam mast did not bend too sharply (the coax goes all the way up with this antenna, so you need to find a way that it does not pull the mast down). I decided to not use the last segment of the mast, so the top of the antenna was at about 11m. I roughly measured 11m from the mast to two opposite directions for the anchor points of the legs.
The Spiderbeam mast was fixed to the side of my car. To the other side of the car I fixed my extended Spieth mast (15m) with the multiband end fed on it. A lovely site: a car upgraded with impressive lengths of fibreglass and loads of wires.
Testing with an antenna switch I directly noticed differences in the received signals. I also saw that the inverted v was miraculously resonant on the whole 40m band, dipping around 7.150. How this can be, with the extra wire length I cut, I haven't figured out yet (wrong measurement surely).
The other thing I saw was that the end fed was not resonant by far. The FT-857 warned me for High SWR. This was peculiar... I had this once before when one of the wire ends attached to the coil broke. I took down the end fed to find... that the wire on the other end of the coil had broken (inside the shrink tube, hard to spot). This explains why Paul was unable to copy me: the antenna was 2m short and SWR was sky high.
Would this not have been the case I would not have started with the inverted v. Now however I got both antennas up (I temporarily fixed the end fed on the spot) - so I started testing any way.
19 OMs came to the rescue to provide me with a nice set of signal reports. The reports came in from DL, G, MM, I, HB9 and S5 - roughly from 300km to 1250km.
All OMs agreed on one point: the inverted v resulted in a stronger signal at the receivers end. The difference was not the same though. It varied from 2 s-points to "not a lot". Most of the times it was 6dB or 1 s-point difference. The same difference I saw on rx.
As the inverted v is a little less practical than the vertical end fed, I will test it a bit more before I decide whether to switch antennas for my /P operations. I am especially curious on how the difference in performance is on longer distances - as signal levels within Europe are hardly an issue worth the extra hassle.
Forgot to take pictures of the antenna park I created around my car. Will try to remember to do this next time.
Next project: building the 80m version of the inverted v. With the nice results I got with the 40m version I will definitely add an 80m inverted v to my /P operating set. It will be nice to activate a PAFF or COTA-PA on 80m for the first time (for me).