Hi! Good post. Please let me add a line or two about my experiences.
Some authors say you should slope the wire down to the ground at each end, others say to keep it at a constant height, then use a vertical piece of wire at each end.
Often in literature they recycle old plans without a bit of thinking. With luck the author who is writing about antennas has never even tried them. I have got an impression that the setup where there is a vertical piece of wire in the end to the resistor and grounding is more like an illustration of principle than a real schema. In practical situations I have often simply pulled the wire to the ground in an angle of 45 degrees or something close to that after the last branch of last available tree and I haven't even given a thought for that. In fact often I have even turned the end of wire around the tree two or three turns to make sure I am not losing the end of wire from my fingers. Of course this is strictly against all the principles, because now we have a coil in the end of wire, but in -20 C conditions some compromises might be allowed.
Half say that the wire should be something lossy like electric fence wire, the others say to use coper wire.
Warning: You don't want to use regular plastic coated wire in -30 C. The plastic frozes and peels away as soon as you are going to roll it. I have ruined some potentially pretty good wires this way. Thick flexible plastic coating or enamel is ok. (Dad, what they mean by extreme conditions?)
Fill a soda bottle with water. Push the ground rod into the ground. Then drizzle water down the rod so it goes into the ground. Push the rod some more. Lather, rinse, repeat. Guess what? It works!
Fantastic!
They also say that if conductivity of soil is low, one could apply a kilo or so salt into the hole. On the coast a metal wire fish trap in sea should do the same. My personal ultimate solution, that worked great for a while while listening to Indonesians on 90 metres was to hammer a copper nail into a big tree. After some time it stopped working well. I guess I should have pulled nail away and hammer it in a new fresher place. Copper nail doesn't harm trees too much.
Suspecting the problem was the transformer, I looked around some more, and found a balun, either 4:1 or 9:1. (While it was marked, the number had long since worn off) I substituted that for the matching transformer, and voila! success.
I never had matching problems while using trad comm receivers. MW band is so wide that one can't really seriously match an antenna there anyway. The problems began, surprise surprise, immediately with Perseus. Even a portable Grundig brought better signal from Radio Merkurs than Perseus with 500 metres wire. Raw wire into plug didn't work at all and Perseus doesn't have any hi-Z input.
It was unexpectable to me. For the first time in my life I was using a receiver that absolutely requires matching. 9:1 turns over ferrite core with least loss on MW (I have the comparison chart here somewhere) did the thing.
One can also ponder, whether a termination and grounding is necessary. Case study: 50 degrees 600 m long wire to Japan. Excellent tool to listen to 1413 JOIF almost daily during winter time. I might ground it if I like, but then I would lose back beam, and the back beam of 50 degrees points almost exactly towards Netherlands and offers many MW dutches after dark. Back beam towards powerful Europeans does not matter while listening to Japanese, because at Japan listening time it is afternoon here, and most euros are in sunlight. Even in late evening, if conditions allow, dominant Far East stations like HLAZ and JOIF can boom at S9+dB over the weak euros on their frequencies.
NA beverage on the other hand, is a real terminated beverage. I don't want strong Russians to block weak American signals in morning. Terminated beverage doesn't magically wipe away the interference from opposite direction, but it helps, sometimes more, sometimes less.
Show Posts
