Sunday, June 01, 2008

VHF antenna (144Mhz), another one!

After building at least 4 different VHF and VHF/UHF antennas I found this design on the net and decided to build one to replace my trusty old one (little piece of TV antenna tubing and an support making an 1/4 wave vertical dipole).
The idea is to make an acceptable antenna at very low cost and weather/waterprof.

I started buying two plastic conduit tube of 3m each, so it will give me the opportunity to make two 1.5m antennas. Total cost was 2.5 Eur ( 1.25 Eur each antenna )

The aluminum foil I had in the kitchen and the electric tape and cable was in the spares box. So total cost by antenna could be around 4.25 Eur (and you still stay with lots of aluminum foil). 1 Euro to the PL plug, 1 Euro to the electric tape, 1 Euro to the cable and 1.25 for the plastic tube.
The tubes were VD12 for the foil suport and VD32 for the outside protection.
Now on to the images, it's self explanatory.

The aluminum foi was trimmed at the end to get the least SWR ( almost), I didn't care about getting to low because I would have to cut a litle more on the elements and since the antenna it's gonna be used to receive around 120 Mhz it's nice to be a little bigger.

Be prepared to do some trimming on the elements, put a little bit bigger and then cut with and knife in increments of 5mm till you get the resonance you want, my top element is around 56cm and the lower element is 39 cm.

The top cap will be placed latter, probably will use some plastic bottle inverted.
The idea is not to have an high gain but an simple and cheap construction that can last long in the roof.

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