I live in the middle of the Philippines. As soon as possible, financially, I want to put up the best antennas I can build. This includes, mostly, beams for all amateur bands, including, at least, antennas from 70cm to 160m, although for 80m and 160 meters a compromise such as a full sized vertical might be the best solution. It would still require a tower (preferably nonconductive) to support a full sized vertical on these bands. I would, of course, need towers to get the antennas up high enough to be more effective, especially for the lower bands. In accordance with local rules, the towers can only be a maximum of 50 meters high, due to the airport we have here. I have thought that I will probably lose little if I self-impose a limit of 40 meters +/-. Most bands require less than 40 meters for a dipole and even at 160m, a 1/4 wave vertical is only 40 meters long.
I also want to avoid, if possible, rotators. They are expensive and I think I can build an extra tower (or 2, or 3) cheaper than buying the rotator. I also wouldn't need wires that flex and break with age/use. I would rather have several fixed antennas that cover all directions than needing to rotate antennas. I also would consider it a benefit to just switch antennas, without a need to rotate, and virtually no delay to chose any direction, on any band, that I want
There are plenty of sugarcane fields that I rent, or could get access to, where I can put the antennas. There is also a mountain nearby and some these fields have significant slopes to take advantage of, so maybe the towers for most bands can be lower and still very effective.
The biggest question in my mind is WHAT materials I can use to make the tower, and how to preserve them in this harsh environment, all while making it as affordable as possible?
Special materials that need to be ordered and shipped from another country will probably be too expensive. I know that smaller cross-sections will make the load, and required strength lower, and I might get away with cheaper materials if they can be strong enough for the load required and still be small. I also know that smaller cross-sections will probably require materials with greater strength.
I am NOT rich and on a smaller budget, but sometimes can get a temporary increase in income (and I HOPE I can increase my usual income in the future), so it is not unreasonable to believe that if I wait patiently I will have enough money to build towers at some point. I have software to help design the towers safely. I want to use my time, which I have plenty of right now, to be prepared for this so that when the time comes I am ready and can proceed immediately.
Bamboo is plentiful and cheap, but harder to preserve (it is the prefered material if I can overcome the preservation doubts I now have). I also prefer bamboo so that the antennas will perform without any nearby conductive materials if possible, especially if I build fullsize verticals for 80m and 160m.
Steel (unless I use the more expensive and rust resistant varieties) will rust easily here and is expensive, and would need a lot of maintenance. Aluminum is also expensive here.
I have also thought about cement, plastic pipe (large diameter, filled with cement, etc.), pultrusions, using a mix of different kinds materials, etc. Using SOME steel would be acceptable, if it is limited (for cost reasons and also due to detuning the antennas and distorting patterns).
For the higher frequencies it would not need great strength due to the slopes I can take advantage of. I believe that there is little need for towers higher than about .5 to .6 wavelengths for any band except VHF/UHF.
What solutions (especially correct or cheaper materials and/or preservation techniques) does anyone have for this situation?
Sorry for the long post, but I wanted to give all the relevant information that I could.