Ae409 stainless whip vs. elevated feed UHF <span class="highlight">antenna</span>

In general a elevated feed or Ground Plane Independent antenna will give a much more symmetrical radiation pattern than a straight antenna mounted on a bullbar.

UHF transmission depends on a ground plane with the most symmetrical radiation being from an ( non independent) antenna mounted in the middle of the roof.

On a bullbar most of the radiation is backwards because all of the groundplane is to the rear.

So you should notice a much better transmission performance when radioing someone a fair distance in front.
AFAIK there is no difference in Db gain from like antennas , although a rubber duckie I bought a couple of days ago is rated 2Db gain without a Independent ground plane and 3Db with an independent base.
Regards Philip A

Rangiephil above pretty well sums it up IMO.

I had a GME 4018K elevated feed mounted on the top rail of my bullbar. It was ok most of the time but not great for outback touring where the vehicles get some distance between them to minimise dust. Apart from the fact that the grounding of the vehicle pushes the radiation to the rear, I have tinting ( which is metallic) and a cargo barrier which both contribute to blocking rearward signals. In a convoy it was hard to hear the tail end charlie or visa versa reliably over say 10km

Then I bought a AE409K and a 3db rubber duck antenna and mounted it to a cheap aluminium knock down bracket with a SO239 connector on the roof rack. When I hit say a carpark roof with the rubber duck it simply folds back. It performs a lot better than the bull bar mounted antenna ( I could reliably hit repeaters from further away as the test). Then I use the AE409K for touring where there is nothing above the car to hit. It is quite a long antenna and flexes at 100kmph when it's set for 9db but what an antenna! Last time we went away I could hear other distant conversations as clear as a bell, and the other 3 groups could not even hear anything with squelch off at the same time. It was chalk and cheese.

My advice is to find a way to mount the antenna on the roof so it folds down as priorities 1 - 5, then 6th priority is to choose an antenna.

I went off the 409 model years back - mainly because it flops about too much when used in the 2 coil, longer mode. As it was explained to me, the radiation pattern swings about madly while the antenna flops around and is often orientated way up into the sky. Much better to have a semi rigid setup in my view. I now use a GME elevated feed, ground plane independent unit, with a 150mm stumpy wire for 'close order' work. For longer distances I have a 600mm wire seen HERE - it has a phasing 'corkscrew/spring' type coil I'm told, BUT the lower section is encased in a plastic moulding (to absorb vibration and to stop the antenna breaking at the base, like so many of the plain stainless ones do, especially when mounted on the bullbar. Works for me.

Found the 409's have excellent performance, but on sustained corrugations, they eventually snapped off. One extended gain 6dB aerial we found gave good results was a Polar. Haven't seen them for a few years.

Benelec make an extended gain, with 3 & 6dB whips, and notice Jaycar have one on their website too.

Bob.

Thanks to all of you, they're all been super helpful replies. Always good to hear real experience, much appreciated