rear mounting of hf aerial on prado off spare tyre mount

Have a look at the link on this EO website,

HF Radio

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Hi
I have my Codan NGT aerial mounter to my Kaymar swing away wheel carrier, just about the whole (fat part) aerial is below the roof line. Just how i wanted it so i couldn't catch it on tree's, obviously the whip is quite long so this pokes up about 6ft.
Mine works well.
Cheers Lyndon

Codan did some tests a while ago that showed how much the signal dropped from a rear-mounted aerial compared with Bullbar mounted.

The loss varied quite a bit with the direction of the other station.

With the current regulations we don't any choice about mounting autotune antennas.

Moonraker claim their autotune is less affected by metal near the lower part of the antenna.

Yep, I made a bracket on my 90series tailgate. Its a bit tricky to get it right - you have the option of buying one - from memory between $125 and $150 (Electric Bug in Adelaide were selling them).

If you want to make your own, the following advice was offered to me by someone with a vast amount of HF experience.

To mount a Codan autotune on the Prado you'll need a bracket that comes out to the LHS of the spare - thats because the Codan aerial is so tall. Barrets can be mounted on the RHS, because the autotune is shorter.

For optimal transmission, the base of the autotune needs to be at least 160mm away from the metalwork. The signal radiates 45degrees upwards from near the bottom of the autotune, so the aerial needs a lot more clearance at the top of the autotune. This extra clearance can be obtained by tilting the aerial backwards a bit. If you skimp on clearance, your transmissions will not be as good.

The bracket itself can be attached to 3 of the 4 holes that hold the spare wheel bracket to the tailgate. Ideally, the backet should lean against the spare tyre as it comes out sideways - this offers additional stability for the bracket, so it doesn't have to be overengineered. Don't mount the autotune too close to the sparetyre because they have steel belts and will affect the signal too.

Also use a big fat earth wire from the autotune to the body of the Prado. The best place to pick up the earth is one of those big bolts for the tailgate hinge that go into the body, not the tailgate. I also made mine, so you had to remove the spare to undo the aerial - just some additional theftproofing.

When you transmit, have the vehicle point towards the base being transmitted to. You'll throw the signal better in a forward direction, with a rear mounted autotune.

If you do all that, you'll transmit as signal thats as good as any front mounted aerial.

There's a thread on this subject over on the 120 LCOOL site with some good info on the bracket.

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