Bicycle mobile set up help

[m3mfz]

Hi
Im trying to put a set up on my bike. My idea, and what ive done so far is mount a metal plate on my seat rails. Ive got a snail mount attached near the back and a 1/4 wave of 2m goes ontop of that.
Coax then runs to my bars where my handheld will sit.
Ive done all this, but i just cant get the SWR down. For the 4watts that i put out, the SWR is between 2.1 and 3 on the meter.
Ive tried a different mount that goes on the car. This brings it down more. It sits at 1.5 on the SWR meter.

How do i need to bring the SWR down? Ive adjusted the antenna. The coax is 3*1/4 wave on my mount, a set length on the one for the car(was built with the mount) but no mater what i do this SWR isnt coming down.
Can anyone offer any advice?
I do not want to do a big J pole and put that on the bike so that idea is out the window.
My bike is Alu frame with Carbon forks.
Any suggestions? Its driving me nuts!!!!!!!

[m0bov]

Is the mount bonded to the frame, is the SWR high when your seated on the bike? Have you tried a long cable and used the SWR and radio away from the bike? Could be RF pickup or RF getting into the SWR meter. Had this on my old mobile setup, SWR was high on 70cms, it was the SWR meter showing a "fake" reading. It was one of those self calibrating "mini" SWR meters.

[m3mfz]

Is the mount bonded to the frame, is the SWR high when your seated on the bike? Have you tried a long cable and used the SWR and radio away from the bike? Could be RF pickup or RF getting into the SWR meter. Had this on my old mobile setup, SWR was high on 70cms, it was the SWR meter showing a "fake" reading. It was one of those self calibrating "mini" SWR meters.

Hi mate.
Mount is cable tied onto the seat rails. So its not onto the frame at all. If i bolt it to the frame will this help?
The SWR meter is near the front of the bike on a chair. If i put on a longer run of coax might this help?
Not tired checking SWR when im seated on the bike.
The SWR meter is an Avair AV-20.

[m0bov]

HA HA!! The very same SWR meter I had trouble with! Try another meter, put it inline with the Avair and I bet they show differant readings!

[m3mfz]

Damn it.
Right, ill take it to the local radio shop and see if they have one that i can use. The only other one is one which i have on my Yaesu FT-897. So ill either put a longer cable on, and hook it up to the 897, or take it to the shop and see how we get on there.

Thanks for the help

[5B4AJB]

If i bolt it to the frame will this help?

Yes, if you cant get a metal to metal contact, run a thick bradied wire from the antenna mount to a bolt on the bike.

[m0lsx]

A really good antenna for Bicycle mobile is a ladder line folded dipole cable tied to a flexible whip. It's cheap, virtually unbreakable, does not need a ground plane & performs better than many others.