What to use to build a tower here in the Philippines?

Question

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.

Answer 1

Have you thought about how you would get the signal from the towers (that seem to be placed rather at a large distance) to your shack? How will you compensate for the transmission losses? As for your idea of building strong, lasting, 40m high towers with bamboo, I'd think the only people that can advise you on that matter are around you, rather than the average radio amateur.

I've been in the Philippines a couple of times and seem to remember quite some construction being done with bamboo, and bamboo most often used to build temporary working constructions during building. Maybe ask the people who build these for their input?

Or wait, and shop around for used, steel, towers?

Answer 2

I have modeled steel, as a standard for comparison, and a couple of bamboo configurations. I also wrote some simple spreadsheet tools to help me know how strong/ thick any material needs to be if I know, or can easily get, the correct yield strength information. I also considered using steel, in a limited way, to stiffen the legs of the towers. Leg stiffness and strength is the key to making it work in this application. I think almost anything is possible if I spend a lot of money, OR if I am smart enough (or someone here helps) to figure out how to do it with less money. It boils down to cost versus life of materials and degradation of signals. It would be great if I can do it with nonconductive and inexpensive materials, since in the fields there is little to nothing to foul up a good antenna design. Even the soil "wants" to help. It is probably very good to excellent, even when dry, although it is often wet.

Answer 3

Keith, I am all planning my relocation back to the PI - we will be in Central Luzon, So I also have been thinking of which tower to build.

I believe that the best tower for the PI would be a crank up tower. For the following reasons

1. U-Beams are readily available
2. Local workforce is good in steel work
3. It would be relatively cheap.

However it will require

1. Solid foundation (rebar & concrete)
2. A "tilt-plate" assuming you are going to fit a Yagi/Steppir etc
3. A Maximum mast height of 12-15m

I do not mind using a rotator - as the directivity (in my opinion) is a necessity (especially in contests). There are some OLX shops selling some ham gear, mainly based in Cebu rather than Manila it seems.

I would be most interested on hearing your thoughts/development on this.

73s de Tim. A45WG