Like a lot of hams, I find myself with limited resources. I could pour a lot of money into a tower and beams, but I'd feel guilty doing so. My gut feeling (reinforced by being raised as a Bohunk) is that you should spend substantially less on ham radio than you would on a good used car.
One of the more limiting ramifications of this philosophy is the lack of antenna support structures. If I had four or so towers, I could put up all kinds of gain antennas; W8JK arrays, bobtail curtains, wire yagis, etc. However, towers would not only cost money, they would take time, which I don't have much of these days (here's why):
As for trees, well, there are ten or twelve trees on the property that are all of about twenty-five feet tall. They are all down by the creek, some 1500 feet from the house. (My grandfather told my father once that when he was a boy there were no trees at all in this part of Texas, except for the creek bottoms.)
Shortly after we moved to my current QTH, I put up a 45 ft. push-up pole to run some sloping long-wire antennas, as well as some "fan dipoles" (several dipoles fed with one feedline). The "fan dipoles" were too low to work really well for DX, with the exception of 20 and 10 meters. The long wires worked well, giving about 3 dB gain on 40 meters, where they were four waves long. However, they were too heavy to run several for each band, as I had planned on doing. I didn't guy the top section of the mast at the very top, so that the longwires would clear the guys. Instead I guyed it about five feet down. This proved to be a fatal error, and on September 14, 2000, a small convective-cell thunderstorm, which formed right on top of us, generated seventy-mile an hour straight-line winds, and took the shingles off the north face of our roof, as well as bending double the top section of the mast. After cleaning up the water damage from the leaking roof, I sawed off the irreparable mast section, re-guyed it (at the top, this time), and hung the longwires again. They were somewhat lower now, but that did not seem to affect their performance much.
I now had one 36 foot antenna support. I racked my brains trying to decide what kind of antenna I could put up that would offer good low-angle performance for DX. At that height, horizontal antennas would only come into their own on 20 meters, and 40 is my favorite band. In addition, I have gleaned many new countries on 30, and was reluctant to make do with a low dipole on that band.
Early on I thought of a delta loop, but I wanted an antenna for 40m, and each side of a delta loop for 40m is 47 feet long. I knew you could distort the shape a little, but I didn't think the antenna could possibly work if I only had a 36 ft. support. My options were to make one side some twelve or fifteen feet short, or make it "only" ten feet short and have the bottom edge of the loop very low to the ground.
I simply couldn't come up with any other ideas, though, and after a conversation with Matt, KK5DR, I decided to just grit my teeth, throw up an experimental delta loop for 40m, and not worry about all the things I was doing wrong.
It wasn't easy. With the antenna so close to the ground, it was difficult to prune to resonance. I kept at it, though, and finally I got the antenna tuned satisfactorily. The next day the wind began to blow. It can really blow here in the blackland prairie of Central Texas, even when there is no storm system within hundreds of miles. During the gale-force gusts, The swr on the antenna went from basically flat to almost 1.7:1, and the 2:1 bandwidth dropped from 325 kHz to about 260 kHz. It took me a while to figure out what was going on; the wind was blowing the leg of the loop that was vertical just a few inches closer the mast! There wasn't that much movement, but it very effectively detuned the antenna. I sloped the horizontal leg away from the mast, but this resulted in the feedpoint of the antenna now being about two feet above ground, whereas it had been five feet or so. It didn't matter! The loop still held its own against my longwires in a DX trial.
Now, obviously the antenna would work even better if it was higher off the ground, but here's the point of this whole essay: it still works very, very well. It works so well, in fact, that I'm going to build another just like it, at a ninety degree angle, to get what few stations might be in the null of the first loop. I am also going to build duplicate loops, at ninety degree angles to each other, for my other favorite DX bands: 30, 20 and 15 meters.
The only problems I have encountered are, I believe, due to the loop being so low to the ground. The wind still changes the resonant frequency and swr of the antenna a little, although not nearly as much as before. I think this is because the wind distorts the shape of the loop, causing the lower leg to droop even closer to the ground. It is also very sensitive to changes in geometry, and it took quite a bit of tying and retying to get the loop to load up the way I wanted it to. Again, I think this must be due to the proximity of the lower leg to the ground.
Even with these minor annoyances, it is nice to have an antenna that I can use on both the CW and SSB portions of the band without using an antenna tuner, and that gives me good results for both regional and DX communication. Other hams who have a similar problem with lack of available antenna supports may wish to try the experiment for themselves.