Friday, May 18, 2012

The magic of an inverted V dipole and 100 watts



This screenshot tells a story. That story is the signal strengths at which I am being received around the world using just 100 watts of RF into my home made inverted V for 30 metres. Granted, conditions do help. Sometimes the figures aren't as good as this. However, it shows what a home made wire antenna can do in limited space. I have two inverted v dipoles, one for 30m and one for 40m, nested off the same feeder. There is no balun or twin line running to the antenna.

It consists of two wire dipoles made from 1.5mm wire bought for less than 40 euro for 100m, plus a dipole centre, a length of coax and some PL259s. There is a 20ft pole with another smaller 10ft pole bracketed on to give about 9-10m total height at the apex. They are cheap dipoles. I reckon the total cost, including pole, stand-off brackets and the other items listed above was less than 100 euro. Having made my own dipoles (with the help of my ham friends!) I can firmly say that anyone who shells out good money on buying commercially-made dipoles needs to see a psychiatrist! Either that or they have money to burn . . .

The first one to come back to my call, incidentally, was FM5BH in Martinique in the Caribbean. I also worked UN7LZ, Valery in Kazakhstan. Nice contacts with a small station. And I'm in the middle of a densely crowded housing estate! So you have no excuse !!

The signals above are from skimmer station on the Reverse Beacon Network.

7 comments:

  1. Good evening Anthony, that is a very impressive list for sure!! The cost of making the antenna and the results are both fantastic. Just goes to show you the cost of the antenna do not reflect the results. Great decision on making the antenna.

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    1. Mike, I find that this is one of the most rewarding aspects of amateur radio, ie home brew. I have made several things now, including some morse paddles, at least one of which I use regularly. I also made an attic dipole. This needed to be short due to space restrictions, so I could only fit a dipole that resonated on 10 metres. However, it works well on 12m, 15m and even 17m as well, and I have worked Africa and South America on it on CW with 50 watts. I would encourage anyone thinking of buying a commercial dipole to make one instead!

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  3. Nice stuff again, Anthony! I used my 80m vertical delta loop for 30m and it works well as a dx antenna there.

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    1. Sauli, that's pretty nice - using an 80m delta loop for 30m. I imagine that works very well for you.

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  4. For HF I only use homemade antennas. The horizontal loop I use in winter costst about 100 euro as well. I use normal electricity copper wire not any special stuff. Actually I made my directional antennas as well years ago. And I will design a new one as soon as the antennamast is up again. So, I absolutely agree with you about constructing a simple dipole yourself instead of buying a commercial one. 73, Bas

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    1. Bas, yes, very rewarding indeed. I would like to make something more adventurous, like a beam!

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