Can I use a roof rack with my antenna?

If you've got plenty of room in front of your rack, maybe it's not full length. On the Troopy the full length rack is 2200, which is pretty massive. If you know the troopy, the roof is higher than normal and slopes from the windscreen to just behind the driver, at which point it then becomes flat. The full length extends even over the slopy part, so it's quite radically long. My antenna right now is on part of the roof where it just starts becoming flat.

The 3/4 length racks are about 1800 which might possibly fit right behind the antenna. My measurements say it would be close. The 1/2 length are 1100 which seems too short. Iron man make a 1400 model which is an option.

The question becomes, ok if it's going to affect the radiating pattern to the rear, how badly, and should I go for the 3/4 length, or hold back for 1400 length.

I just measured ours, it's 1800mm long. The distance from the rack to the top of the windscreen is 450mm. Yes in my case it would be better in front of the rack but then that would mean another hole in the car for small gain. And even better still with a ground independant antenna which would lift the base of the active antenna element close to the height of the top of the roof rack.

Then you put a metal gizmo (read any metal based load) on the roof rack and stuff it up.

Personally, I wouldn't bother. On the angled bracket using existing bolts on the RH mudguard has been quite effective for many years.

Phil

If you've got a ground plane dependant antenna you definitely need a ground plane. Of course I could switch to a ground plane independant antenna, but then they tend to be taller, and bigger (height in car parks is already touch and go with the troopy, and the stubby 12cm one works a treat), and also tend to perform worse. But maybe that is the direction I should go with a roof rack, I'm just not sure.

Seems to me mounting on the snorkel means switching from a ground plane dependant to an independant antenna. Which is fine if that's the best option. But I'm concerned how much that would add to the height of the already tall troopy compared to the little 12cm ground plane dependant stubby I use around town, and also the relative performance. I've heard of fold down ones etc, I guess that's also an option. The question is if I get the 3/4 rack, and it affects the pattern to the rear, just how badly.

We didn't mount the aerials ON the snorkel, but on a metal bracket that used the upper snorkel mount's captive nuts. So in fact this bracket became part of the roof, or ground plane, of the vehicle.

You can buy aerial bases pretty cheap, and set up a 2nd 150mm stubby off the snorkel bracket, if you found the roof rack fouled the centre roof mount.

As for signal to the rear, might depend on length of aerial, and the amount of gear you've stacked on the rack.

Bob

Yes but to work a ground plane needs to extend in all directions. If you mount it near the snorkel it will only extend towards the back / left of the car, so you'll have directional issues

You may be right, Chris.

However the aerials we used were a Polar extended gain unit, ground independent, similar to the one below, 2nd from the left. Excellent performance from a 900mm aerial.



Bob