The Cat's Studio

I decided to set up a mast on the highest point of our property. I did not want any guy wires to keep our yard free of obstacles. For maintenance reasons the mast should be able to be tilted. Round tube is pretty whippy when it is 6 or more metres long. My material of choice was square hollow profile made from stainless steel. I wanted a mast with minimal maintenance.

Solutions I found on the Internet which gave me ideas for my mast:

• WV7U tilt over mast
• Vertical antenna with no concrete

I know about the advantages of using square hollow profile stainless steel. It’s very resistant to twisting and bending and still has a certain flexibility to withstand strong winds. My plan was to use a 6m length of 50x50x1.6mm RHS (rectangular hollow section) for the main mast and the top section would be constructed of 38mm round tube. I went for round tube to make the use of an antenna rotator possible. When you use square material it would be very difficult to mount any of the popular rotator or antenna systems because their brackets are all made to deal with tubular masts.

I was fascinated by the idea of using an antenna rotator to be able to tune into different transmitters just in case one was affected by some sort of problems. The bottom part of the mast would consist of two length of 50x50x1.6mm RHS with the main mast clamped in between the two posts and resting on a long bolt acting as the pivot point when tilting the mast. For the foundation I planned to use a concrete base.

After reviewing several solutions I found on the Internet, I decided against the concrete block and used compacted gravel instead. The advantage of this is the ability to easily dig the mast out and move it to another location if necessary. When you use a concrete base you are stuck because the bottom part of the mast is fixed into the massive block.

One internet source pointed out that using a concrete foundation can cause problems when the soil around changes properties caused by climate conditions such as drying out. This can result in an irreversible permanent tilt of the system. A base filled with gravel is dynamic and can be easily topped up or corrected if conditions in the surrounding soil should change. The gravel in fact is sort of self-compacting when the mast is being worked by winds. Gravity causes the gravel bits to fill in any gaps.

So far, I have not had to top-up my foundation and we have plenty of strong winds. It is looking a bit scary when the mast is swaying in the storms. These movements do not cause any degradation of the signal. The only pixel errors or the occasional dropout of the sound signal I noticed seemed to be caused by electrical storms moving through between transmitter and the antenna system.

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