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cb antenna mounting???

knucklehead 61

knucklehead 61

NAXJA Forum User
Location
Cottage Grove, Oregon
are there any issues with mounting a cb antenna (firestick) horizontally next to my roof rack, running front to back above the gutter line, below the rack mounts?
 
As others have responded.... ENSURE the antenna is grounded very well and your RX/TX will be severly reduced...
You will probably also find that your SWR readings will be higher than normal since when you transmit you are reflecting off the roof...
A better idea would be to purchase a Wilson 1000 magnetic mount antenna and centrally locate it on the roof. Your RX/TX will be increased dramatically over the Firestik and the SWR should be a 1:1.
 
CharlesS said:
As others have responded.... ENSURE the antenna is grounded very well and your RX/TX will be severly reduced...
You will probably also find that your SWR readings will be higher than normal since when you transmit you are reflecting off the roof...
A better idea would be to purchase a Wilson 1000 magnetic mount antenna and centrally locate it on the roof. Your RX/TX will be increased dramatically over the Firestik and the SWR should be a 1:1.
Click to expand...

i just picked up the "little wil" wilson, it is only a 3 foot whip magnetic mount. a little better than the ~5 foot whip from the wilson 1000
 
Really what makes the Little Wil better then the 5' whip? Nice thing about a whip is you can wrap it around to a mounting point for the tip so you can have a long whip but have it "bent" around so your not hitting every thing when you don't need it.
 
Going to lay some antenna basics on you so you understand the how and why of it all. I apologize if its too basic.

The antenna radiates in a pattern that looks like a upright cylinder when the antenna is vertical. If you lay it on its sides you will be sensitive to the sides, above and below but very little will get out or get in from anywhere else. You will be down at least 6dB (75%) on gain front and rear and its probably more like 12dB (94%). Its a bad deal. That loss applies to both the transmit power and receive sensitivity.

It gets even worse. CB's are V-V polariation, they transmit and receive with the Electric field oscillating vertically. If the antenna is vertical then all is well. If its laid on its side then it will be aligned with the magnetic field of a properly oriented antenna and you will loose at least 3dB MORE or half of the signal when the tranmitting antenna is off to the sides, above or below you. When you transmit you will be sending out signal that is horizontally polarized so who ever "receives" it will automatically loose half of the signal because it came in with the wrong polarization.

So by laying the antenna on its side the best case is 50% of your gain lost and it just keeps getting worse, a lot worse from there.

You have an XJ. CB performance really rocks on an XJ compared to our soft topped brethren. Put a mag mount in the center of the roof. You get a great ground plane out of the roof which will make yoiur antenna perform really well. I have cheap Radio shack antenna and radio set up and it blows the doors off of some high dollar stuff that the soft tops carry. Mainly because of the good ground plane, no blockage and good (low loss ) RF cables.

Mag mounts are a hassle in the trees, you will have to get out and stand it up again from time to time. I have roof rack and that really helps. I have had to replace my antenna once in 5 years of wheeling, most of it in the east, but I broke it in a parking garage, not on the trail.

Get a mag mount and stand it up.
 
Last edited:
thanks for schoolin' me. i should have asked before i ran the wires. at least i didn't fab up the trick hidden mounts i was planning on yet. i'll switch gears & vertical mount it. thanks again! :cheers:
nosigma said:
Going to lay some antenna basics on you so you understand the how and why of it all. I apologize if its too basic.

The antenna radiates in a pattern that looks like a upright cylinder when the antenna is vertical. If you lay it on its sides you will be sensitive to the sides, above and below but very little will get out or get in from anywhere else. You will be down at least 6dB (75%) on gain front and rear and its probably more like 12dB (94%). Its a bad deal. That loss applies to both the transmit power and receive sensitivity.

It gets even worse. CB's are V-V polariation, they transmit and receive with the Electric field oscillating vertically. If the antenna is vertical then all is well. If its laid on its side then it will be aligned with the magnetic field of a properly oriented antenna and you will loose at least 3dB MORE or half of the signal when the tranmitting antenna is off to the sides, above or below you. When you transmit you will be sending out signal that is horizontally polarized so who ever "receives" it will automatically loose half of the signal because it came in with the wrong polarization.

So by laying the antenna on its side the best case is 50% of your gain lost and it just keeps getting worse, a lot worse from there.

You have an XJ. CB performance really rocks on an XJ compared to our soft topped brethren. Put a mag mount in the center of the roof. You get a great ground plane out of the roof which will make yoiur antenna perform really well. I have cheap Radio shack antenna and radio set up and it blows the doors off of some high dollar stuff that the soft tops carry. Mainly because of the good ground plane, no blockage and good (low loss ) RF cables.

Mag mounts are a hassle in the trees, you will have to get out and stand it up again from time to time. I have roof rack and that really helps. I have had to replace my antenna once in 5 years of wheeling, most of it in the east, but I broke it in a parking garage, not on the trail.

Get a mag mount and stand it up.
Click to expand...
 
here is my set up, works great

it's off to the side in the pic but I have it centered now
IMG_42841.jpg


ziptied the wire to rack rail
IMG_42851.jpg


ran wire into cab using a factory plug next to the tail light
IMG_42861.jpg
 
Here are some pics of mine setup with a 3ft Francis and a firestik door jamb mount. Only had to drill two holes for it and reuse one existing brakelight housing bolt. It has gone through several car washes, bent it back 90* by hitting a tree and the mount just bent right back didn't break, i'm very very happy with it and with the 3ft antenna, it allows 1/3 of the antenna above the roof giving a good ground plane for the signal to bounce off.





 
ridgerunner97 said:
Here are some pics of mine setup with a 3ft Francis and a firestik door jamb mount. Only had to drill two holes for it and reuse one existing brakelight housing bolt. It has gone through several car washes, bent it back 90* by hitting a tree and the mount just bent right back didn't break, i'm very very happy with it and with the 3ft antenna, it allows 1/3 of the antenna above the roof giving a good ground plane for the signal to bounce off.





Click to expand...



Looks good, but around here that thing would get taken off first trail. Under the hood is the way to go!
 
ert01 said:
How do you mount a cb antenna under your hood and maintain any half decent SWR reading? You'd be better off using a FRS/GMRS radio...
Click to expand...
And for that matter, any radiated signal at all...

This is EXACTLY what first came to mind when I saw that post. He's talking about where the end of the bracket goes (so the hatch location would be "under the hatch") if I understand properly though.
 
why couldn't you mount it like RenegadeStang? the hood acts as a beautiful ground plane and you should tune your antenna period, make for a good talker don't matter where you mount it as long as you have a good ground plane and the antenna is tuned to the radio
 
ridgerunner97 said:
why couldn't you mount it like RenegadeStang? the hood acts as a beautiful ground plane and you should tune your antenna period, make for a good talker don't matter where you mount it as long as you have a good ground plane and the antenna is tuned to the radio
Click to expand...
Wrong! It totally effects the wave pattern,thats why its supposed to be mounted a central as possible.Truckers run "twin" sticks because it pushes the pattern to the front and rear!
 
I wasn't commenting on teh directional transmit and receive of an antenna setup. If you put it at the right rear of the vehicle, it projects teh signal back, but mostly forward and to the left. There is a diagram online somewhere. All i was commenting on was the ground plane and general reception, I regularly talk 3-5mi in dense woods and steep hills and valleys with my antenna where it is. No biggie to me, and on the highway lookout i can talk up the road quite a long ways. The average wheeler doesn't need to be able to talk uber distances, they just need clear good communication and a proper ground plane and tuned antenna are key to that communication.
 
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