GMRS SWR issues

[avere3]

I originally got a bracket to mount a stubby Midland GMRS antenna on the front edge of my '24 Gladiator's bed. I recently bought an SWR meter to check my setup in both the Gladiator and my old Wrangler. In both vehicles, my SWR was over 3.0. I bought a 1/2 wave NGP antenna and tried it on both Jeeps. The Wrangler was measuring around 2.0, which is probably as good as it gets when mounting a short antenna on the back of a Wrangler, but the Gladiator was still too high. I could hear weather stations pretty well, but there isn't really anyone to talk to here with it.

I bought a bracket that bolts to the side of the Gladiator's cowl, rerouted the cable up through the left side of the dash, between the windshield and roll cage, and out under the cowl. I put everything back together and checked the SWR again. It's still showing around 3.5. I plan to check the SWR again with the longer antenna from the Wrangler.

I see a lot of stubby antennas mounted with the same cowl bracket. I know the stubby antennas aren't great, but do most owners with this setup not check their SWR? If you have this setup and have checked SWR, what type of reading did you get?

I don't know if it matters, but I'm powering the radio from the Aux 4 switch. I did try swapping radios between the Jeeps and using the 12V power adapter, and that didn't make a difference before.

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[Vetterestorer]

It should not matter where you power your radio from as far as SWR is concerned. If you measure your SWR higher and lower in frequency you can determine if your antenna is too long or short. If a friend has a antenna analyzer that you could borrow, you can find out where your antenna is resonant (if it is anywhere). At 3.5 to 1, your radio's fold-back circuit will likely limit your transmit power severely.

 

[avere3]

That's what I thought, especially after trying two different radios with two different power sources. I was going to try the other antenna, but we just had a downpour start.

I'll have to see about an antenna analyzer. Thank you!

 

[sarguy1941]

IT would help if you had some pictures or could tell us what model antenna's you are using. I run the Laird UF pepper shaker on my JK and a Laird TriBando n my Gladiator. Both are on cowl mounts and both are well within specs

 

[avere3]

I swapped out the Midland ghost antenna for an HYS 17.7" antenna, and the SWR dropped to 1.3. I had previously tried that antenna mounted to the front of the bed, and there was no difference between the Midland and HYS in that location. The combination of the cowl bracket and the different antenna seems to make a huge difference. I should be all set now.

 

[Vetterestorer]

Super, that should work very well. Also, a longer antenna should work much better.

 

[kb5zcr]

When I mounted my antenna to the front driver cowl it wasn't grounded to the body, I had to remove some paint under the screws to get a good ground. Use multimeter from mount to inside engine bay to test.

 

[David G]

Your SWR CAN VARY GREATLY also depending on the coax, mount and fittings that you’re using. My Midland works just fine with SWR’S below 1.4. The Diamond hood mounts have given me the best results. I typically place a mount in place and attach the coax to the radio before routing cable to test SWR and antennas, as my radios also do 2m and 70CM. You may want to try different components too. Good lick.

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