Full Band VHF Aviation Antenna

[TROOPER]

Are any of you blokes able to recommend a VHF antenna which reliably and clearly covers the entire aviation bandwidth of 118.00MHz to 136.95MHz?

I've looked at the Commant, however I don't have enough room to mount them underneath as they are intended to be.

Ideally, an antenna with an independent ground plane would be better.

The TAG gyros are using a neat little antenna which apparently covers the entire range, however I haven't been able to establish comms with them with a view to purchasing one.

Any suggestions would be greatly appreciated.

[chook]

Whatever you get Trooper DON'T mount the thing inside your cockpit like Xenon and MTO have done!
If you think placing a mobile phone which transmits about 400 milliwatts maximum in your pocket is dangerous try placing 5 watts between your legs!

Commant have a reasonable bandwidth coverage but need the groundplane as you mention. Rojone have taken over the Mobile One antenna which has a poor bandwidth but have no issue in charging greater than $165 for em!

Ok so here are 2 plots I have taken from a couple of aircraft. the top one is a fixed wing Commant antenna and the lower one is a Rojone unit. Both have been optimised and tuned by me. The optimum is to get the plotted line below the 3 (that is a measure of the reflected power back into the radio - lower is better) 1:3 SWR and as flat as possible.
These plots show that the Commant is MUCH better than the Rojone.










Regards....Chook.

[TROOPER]

Whatever you get Trooper DON'T mount the thing inside your cockpit like Xenon and MTO have done!
If you think placing a mobile phone which transmits about 400 milliwatts maximum in your pocket is dangerous try placing 5 watts between your legs!

Thanks Chook. You've definitely got my attention.

My bird is much like yours, fully exposed cockpit with the instrument pod on the front. The current Rojone antenna is mounted up the front and is an independent ground plane. I looked at purchasing the Comant C-122 however it would only clear the ground by 60-70mm which means that it would often be dragging in the grass during take off and landings. I just didn't want to spend that money on something that would get damaged. That's why I like the look of those little ones on the TAG.

Regards,

Trooper

[RossM]

Here is a photo of a TAG antenna.
click on the image to view full size

[chook]

The TAG antenna is very similar to the ELA VHF antennas and Neil from TAG went to a lot of trouble to source them. Be aware that the ELA antennas had an aluminium ground plane about 450mm square placed under their antennas within the cockpit. This is as safe as it gets although there will still be some radiation back towards the pilot.

Dave (Trooper) I am using the Rojone antenna on mine and improved the efficiency by about 40% with careful placement of the mounting. In fact it was as little as moving it 30mm forward (away from the instrument support leg) and 10mm to the right of its original mounting which gave the improvement. But you need some specialized radio test kit to get it correct.

One of the guys over here is experimenting with a horizontal V shaped antenna and the original test results are fantastic. When we get some more time to complete it he will probably make it available as a kit. And the good news is that it doesn't require a ground plane as in a large piece of flat metal.

Regards...........Chook.

[TROOPER]

One of the guys over here is experimenting with a horizontal V shaped antenna and the original test results are fantastic. When we get some more time to complete it he will probably make it available as a kit. And the good news is that it doesn't require a ground plane as in a large piece of flat metal.

Regards...........Chook.

I'll definitely be interested in the outcome of this one.