variable vertical antenna

If you haven’t seen my kite-portable page, check it out.

Here is the blog page of my first kite antenna expedition. I had forgotten the pulley for the the bottom of the line in Wolverhampton, but the dog stake was thick and smooth enough to use without it.

I wanted to be able to change the antenna length without lowering the kite. I could have used a steel wire as both antenna and flying line, but, if the wind blew hard and for some reason the cord between the wire and the kite were stronger than some weak point in the wire, the kite could fly off with a hazardous piece of wire dangling from it (and “have someone’s eye out” or something). Anyway, I didn’t fancy the strain of winding a heavy kite up and down. And so I decided to use 1mm bare aluminium wire (lighter and cheaper than copper) and a loop of flying line to use as a halyard. I got the idea from the halyard in the old 27 foot mast kit (back in my cadet force days). This would allow the kite to fly constantly near the 60m limit, where the wind would be more stable.

A 20cm line winder was too small for all that line, but i coped. A 15cm spool was just about big enough to accommodate the 60m of wire, and more than big enough for my 8 3m radials. I drilled two small opposite holes in the antenna spool, so that a stiff wire could be fed through and used as a brake (but not so taut that the wire would come under excess strain when the flying line stretched in a gust of wind). I also improvised a plastic brake for where the line met the dog stake, but the antenna rarely sagged without it. I bought 2 15mm fixed pulley blocks, one for each end of the flying line.

This kite would not pull quite vertically, even in a stiff breeze, so radiation patterns and take-off angles might not be as expected.