HF antenna positioning

**goingbush** · 18th March 2014, 07:14 PM

Bit of a conundrum, trying to chose the best place to mount my Tapwhip antenna.

I understand the ground plane is critical to best propagation, ideally mounting the antenna near the front of the solar panel is the best place, but the truck is 2.6m high and I'll need a ladder to change the antenna tap.

For convenience of adjusting the antenna frequency mounting on the bull bar would be good (inplace of the NextG Broomstick) , I still need a step ladder, to climb onto the bumper but bearing in mind the shape of the body and the fact that there is no flat bonnet would there be enough ground plane to make propagation reasonable

3rd option would to be to make a bracket to mount the antenna on the rear of the truck, but I'll still need a ladder and the extra length of coax would also provide extra attenuation

thoughts appreciated.

**123rover50** · 18th March 2014, 08:03 PM

I would mount it down the back if an autotune but given its a tap then probably in front.

**Michael2** · 19th March 2014, 08:00 AM

On the Defender I've mounted my autotune on the kaymar wheel carrier with a sleeved tube that can extend up to clear the roofline (mostly).

Why not make a sleeved tube bracket at the back for the autotune, you can undo a grub screw and drop/raise it. Keep it down around town and get maximum height when stationary. Trying to get it to earth through the extendable tube would not be very effective, so this design is limilted by the length of earth strap that you can attach to the base of the aerial.

**goingbush** · 19th March 2014, 09:22 AM

Originally Posted by Michael2

On the Defender I've mounted my autotune on the kaymar wheel carrier with a sleeved tube that can extend up to clear the roofline (mostly).

Why not make a sleeved tube bracket at the back for the autotune, you can undo a grub screw and drop/raise it. Keep it down around town and get maximum height when stationary. Trying to get it to earth through the extendable tube would not be very effective, so this design is limilted by the length of earth strap that you can attach to the base of the aerial.

Something like that could work, mines a tapwhip antenna, not an auto tune, I guess I could make a bracket that allows it to fold down horizontally .

As its a tapwhip I need to be able to physically move the shunt lead, so reaching the deployed antenna to change freq is the problem.

In reality how useful is HF radio whilst driving anyway. Does anyone listen whilst on the move?? It might just be a case of having to set up the antenna as the need arises.
Does the entire antenna need to be above the roof or just the top part of it above the tuning taps ???

Tombie · 19th March 2014, 11:35 AM

Build a pivoting antenna mount so you can swing it out horizontal to re-tap and then return to upright...

lokka · 19th March 2014, 05:13 PM

Tombie is on the money I would make a mount for it to lay back over the canopy
mount it on the front of the canopy between it and the cab and use a 90 deg swing down mount that way when not in use it can lay flat also can give you access to change freq's by standing on the rear tyre or make up a tyre step

That way you get the high mount position and good ground plane of the canopy and I would not like to sit so close to the HF signal more so with 100 watts of HF only a few feet in front of you on the bull bar

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