Weather was good enough again this morning although rain was forecasted. So, I carried out some more tests on the deltaloop. First of all I thought the problem could be the place were I fed the deltaloop. Although I carefully measured 1/4 wave from the top it looks too high. So I lowered it by another 40cm down to the corner. Surprisingly after attaching my MFJ259 analyser nothing did change at all. So I finished the idea of feeding the deltaloop like this and decided to go for the next experiment. Feed it in the corner through a 75Ohm 1/4 wave matching stub. Now, things change. SWR was much better, almost 1:1. It also confirmed 21,5m was the right length as best SWR was on 14,2MHz again. I was quite happy with the result. But wasn't so happy when I tried it on the receiver. I still had significant noise (S3) were the vertical produces only S0-1 noise. And again the deltaloop performed less good as the vertical on top of the mast. It received equal or less and the noise was annoying. You probabely think now that the vertical receives much better at low angle signals, but I tried for a half hour listening to various stations far away and close by. Only in 2 occasions receiving a station from Spain and England the deltaloop performed better for a few seconds.Time to abandon the deltaloop project. It is not a miracle antenna or my vertical is better as I think?
I probabely know what the real problem is. It is the same problem that is affecting my earlier vertical antenna experiments. Buildings around do have to much effect on the performance and the antenna is too low. On the picture you see a glass house, it has a iron/alu frame, the green hedge you see is not really a hedge, it is a iron frame with climbing plant. In front of the deltaloop is the house and then there is a garage with a lot of iron in it.....oh my not a good environment for a antenna close to the ground...
It started to rain when I dismantled the deltaloop. But I wanted to quickly install the PE1BVQ endfed. It is a 3 band 40m/20m/10m. Excellent as a back-up antenna. I ad some radials to increase some efficiency this time. I did a test on 20m after I placed it, it is not as good as the vertical on top of the mast but equal to the deltaloop including the S3 noise. The advantage however is that it includes 10m and 40m as well.
Well, no miracle antenna or secret weapon for the PACC contest next weekend. But I learned and tried something at least. It is fun experimenting with antennas although it doesn't always work as good as you hope for. I have to think of something else to improve my signal and possebilities on the 20m band. I guess the only thing that would really work is a directional beam...
2 comments:
Some years ago when I still lived in Drieborg the rural area I had a same experience with such a antenne on 30 meter. Everyhting I tried it never worked well. Build also Deltaloops for 40-20-10-11-6 meter and always they worked well, only the 30 meter antenne was not performing well at all. Never found out what it could be. Johan de PE9DX.
Tnx for the comment Johan, I'm shure the antenna worked well. But not good enough for me. I wanted to have a advantage over the multiband vertical on top of the tower. I thought a monoband deltaloop performance would be a lot better but this was not the case. I think it has to do with the height and the surroundings. But it was worth the experiment. You can't tell f it is better or not if you don't try. 73, Bas
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