cheap & fast UHF SATCOM antenna system

While dedicated stuff can be seen on eBay from time to time, prices are pretty high.
A number of projects is available on the net, requiring different skill levels and access to materials, however I found that good, fast and cheap results can be obtained in turning TV in our unwitting allied.
In several countries television is in fact still broadcasted in the so-called band III, just a few megahertz below our range if interest.
This means access to cheap antennas and preamplifiers that can be easily adapted for SATCOM reception.

The entire antenna system can be purchased in DIY or electronics stores for less than €50:

band III yagi beam, the longer the better. Should there be different options, go for the higher channels, around 200 MHz;
masthead wideband preamplifier and matching power supply;
75 ohm coaxial cable. The one sold as satellite grade normally has a better quality and is worth the small price difference. Mismatch from 75 to 50 ohms is not as bad. On the other hand UHF performance of television cable is better at least than RG-58.

Than have a look at the measures here (uhf-satcom.com) or here (satellitenwelt.de) and resize the TV yagi accordingly.
This normally means shortening the elements by a few centimeters using a light metal hacksaw and reducing the spacing between elements by drilling new holes for them. On some models I found this wasn't even necessary as measures were already right.

Driven element may require more care, as it's often built as a folded dipole. Needs than to be unfolded but, given the thin walls of the piping, there's a risk to break it. Flattening the tube into a strip with a pair of pliers seems to work fine.

The broadband amplifier will definitely pull some junk into your receiver. As normally TV transmissions are horizontally polarized, setting your newly built antenna in vertical will help reducing interferences, while the circularly polarized satellite signals won't be affected.
Retuning the amplifier will help, but that requires instruments not readily available to the majority of scanner enthusiasts.

Should you want/need more signal, just buy two yagis and combine them into a single, longer antenna. Element size can be maintained in pairs. A piece of boom split in diagonal and fixed with rivets or screws will serve as joining part.

This solutions is much easier than stacking several antennas, as matching and spacing can be quite tricky.
I'm sure helical antennas are a superior choice, but will hardly go unnoticed, while only somebody with a clue will be able to tell the difference between your aerial and a standard television one.

Any comment and contribution will be most welcome at sinager [at] o2.co.uk.

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