Covert Aerials

Some people seem to object to the sight of an odd collection of bits of wire and strange metal poles with bits sticking out in other peoples gardens, can’t understand why but there’s none so queer as folk. A way round this is to hide your aerials in plain sight.

As I understand it it is OK to have a TV antenna, on a pole, fixed to your house. If a 10 ft pole with a small TV aerial is fixed on the side of the house with stand-off brackets, it ought to be about a quarter wave on 15 metres. Insulate the pole from the U bolts with plastic tube you have an aerial. A counterpoise wire about 11ft can be put in and you have a vertical, half wave dipole. The counterpoise can be pulled away from the house at about 45 degrees to reduce losses.

If RG58 feeder is used a balun can be made by winding the feeder through a ferrite ring, four turns one way then four turns the other way, a Fair-Rite 43 mix is often used. This is a common mode choke but in this applicalion it is also acting as a balun. If an ATU is used the aerial can be tuned to 15, 12 and 10, it may even work on 17.

Thats the dx bands sorted, what about 40 and 20 metres. If there is a shed or other building at the end of your garden you may require power to be fed to it. If it is fed by overhead mains cable it must be at a minimum height of 3.5 metres, by a happy chance 4 metres is 0.1 of a wavelength on 40 metres, an ideal height for a high angle (NVIS), 7 Meg horizontal aerial.

An aerial pretending to be a power feed should work quite well, the length of the garden determines the aerial type, an inverted L fits into 7 metres and a half wave would need at least 20 metres.

End feeding is the order of the day, a feeder hanging down from the centre would rather give the game away. Ladder line and an ATU at the rig end would be good for the half wave, a un-un impedance transformer can also be used. The inverted L would be fed with 50 ohm coax, RJ58 etc.

I will confess that all of this is theoretical, I haven’t tried it but I have used a 12ft tank whip, with a counterpoise at 45 degrees, on the gable end of a house. It was a very good dx antenna on 15 metres and would tune to 10 metres with an ATU.

Secret Squirrel