Mobile High swr !!!. Need a 27mhz ground independent antenna

[cralt]

I've been there! And it is good stuff - I've been wanting to put a mobile rig in my Corvette (10/11m) but the complexity of trying to understand a way to make it work has kept me from doing anything serious.

They make kits for the corvette, they are all based around the firestik system.


I had this kit on my C4 and it was "Meh". But to be fair I didn't put much effort in to tuning it. I just wanted something to listen to 19 on a trip.

 

[TheRATT]

They make kits for the corvette, they are all based around the firestik system.
View attachment 42120 View attachment 42121

I had this kit on my C4 and it was "Meh". But to be fair I didn't put much effort in to tuning it. I just wanted something to listen to 19 on a trip.

The No Ground Plane antenna kit. Yeah, I keep checking those out. I really wanna put a 102 on there.. and figure out a way to try to RF ground it to the frame of my car but I just can't find anyone who will say that will do it!

 

[cralt]

The No Ground Plane antenna kit. Yeah, I keep checking those out. I really wanna put a 102 on there.. and figure out a way to try to RF ground it to the frame of my car but I just can't find anyone who will say that will do it!

If the body is all 'glass then why not just mount the 102 TO the frame and run the whip up through the body?

 

[TheRATT]

If the body is all 'glass then why not just mount the 102 TO the frame and run the whip up through the body?

I'd like to do this but I've been told the thing that matters is the metal body. I've been trying to find out why the body needs to be metal if you can just use the frame and it works OK.

 

[Slowmover]

MFJ-2820 License Plate Mount. (It’s a start)

 

[ljh505]

I can't get enough good metal ground plane on my ute and getting bad swr.

Not familiar with the current Australian vernacular. What type of "ute" vehicle do you have? A 4x4 pickup truck like a Toyota Hilux, or a car body utility vehicle like a Chevrolet El Camino?

Rago Fabrication here in the U.S. makes bolt-on 27 MHz CB antenna brackets for various off-road 4x4 vehicles. Since they bolt to existing hard points on the vehicle, there is usually a path to ground. The hole in the Rago bracket for the "stud" or antenna mount is 1/2 inch. The antenna mounting hardware is all imperial units, the antenna bases are 3/8 inch diameter with 24 threads per inch.

 

[Marconi]

I'd like to do this but I've been told the thing that matters is the metal body. I've been trying to find out why the body needs to be metal if you can just use the frame and it works OK.

RATT, here is my Eznec model of a long bed Chev P/U with a whip on the all metal bumper to the right side. In order to simulate a Fiber Glass body I removed all the metal parts except for the frame.

At just 20" inches above the ground the model is not bad, and if we consider the take off angle important...the FG body model has a lower angle at 10* degrees compared to the Regular body PU truck at 23* degrees above the horizon.

 

[cralt]

Ya I think it will work fine. As long as you get a good solid RF connection to the frame. Like a mirror mount bolted right to the side of the frame-rail. The 'glass body is going to be mostly invisible to the antenna.

I am not an export but I have found 108" whips to be every forgiving to less then ideal mounting positions. My bother has one on the back of his work van. In the rear corner bolted to the rear bumper of a fullsize panel ramvan. Half the whip is inches for sheetmetal but the SWR is OK on his barefoot radio and he does talk out fine. I also ran one for years on the back 1/4 of my XJ Jeep Cherokee Folded over the top and attached to the luggage rack with an insulator tank style. Worked great and was flat SWR. Ya the patterns will be totally wack but still better performance then a small fiberglass antenna with no ground plane. Just my non-scientific anecdotal experiences...

Only way to know for sure is to try it and let us know!

 

[Marconi]

Only way to know for sure is to try it and let us know!

Real testing is the only way...that's for sure.