Expat

I have a 4ft Firestick currently mounted on the drivers side front fender.

I have trouble with sending and recieving from anyone on the left of my truck as the ground plane is towards the right (across the bonnet).

So I have been playing with the idea of relocating the antenna to the roof rack.

1st question - can anyone confirm whether the 4th gen roof racks have a metal contact to the roof? I assume that as it bolts into the roof somewhere along the rail system it must have some metal contact.

2nd question - if the roof rack has a metal contact to the roof, will the roof act as a ground plane or does the antenna have to actually contact the roof directly to make use of the possible ground plane the roof would have?

3rd question - I have made a stainless steel plate "sandwich" that bolts over and under both the cross beams of the roof rack system. The antenna bolts onto this stainless plate sandwich. Do you think that if the roof has indeed got metal contact to the racks and the racks are in contact with my metal sandwich, that the roof will indeed become a ground plane as part of the whole system?

4th question - how does an antenna mounted to a bullbar provide a good ground plane? Is it because the bonnet is close to the antenna to provide the ground plane? In which case wouldn't it suck trying to recieve and send forwards? (5th question!)

I am not interested in drilling holes into the centre of my roof, nor mounting in an inferior location such as the front or rear bumper. I also am not so keen on magnetic base antennas.

Thanks for your input.

Cheers
Mark

Bob_98SR5

mark, i know this doesnt answer your question, but have you considered a magnetic base antenna? dealmaker has one (i think its a wilson k40) and i recall on our death valley trip this year, his transmitted signal was imoh, the cleanest and the clearest of all the people in the group. made me think about getting the same thing too

edit: oops, i sorta glossed over your last sentence

bob

midiwall

Ummm, even though I've read your last sentence , I agree with Bob... I've been running a mag base for 2+ years now and have never had a complaint. Don't rule them out 'cause they're "temporary" or "seemingly inferior".. They is (temp) & ain't (inferior).

They give you a nice ground plane, right up the middle of your rig, and on top of it, are low-profile in the sense that they're _are_ temporary!

Expat

Thanks for the replies guys. This is one of those "project" ideas I want to play around with. The magnetic base seems pretty good (maybe even ideal) for the temp fix but I am looking at a more permanent solution just for the sake of the project more than anything else. I guess I have this bee in my bonnet about ground planes and want to play around with possible alternatives.

Hope someone can answer my questions about the ground plane issues.

Cheers
Mark

Expat

Hmmm...always find good info on the Firestick site.

Looks like the roof rack may not be good due to the coating.

"anodizing (on aluminum), powder coating and paint are all insulators. If your rack has an insulating finish (even if it is chassis grounded) you will still need to check that the antenna mount has contact with the grounded rack. Relying on a ground through the coax, as previously mentioned, is an SWR problem waiting to happen."

Ok...I'll start comparing the K40 with the Wilson 1000 and 5000 which I briefly saw mentioned elsewhere had much higher power capacity than the K40.

Intrepid

Make sure your CB is tuned correctly and that there are no opens or shorts, mine is on my fender in a hood channel mount and I have no problem with it now. When I first installed it I could only transmit/receive a few feet away and not if I was moving. Make sure everything is hooked up correctly and if you are using the "fire-ring" coax make sure that where you bolted it on isn't too tight.

jacksonpt

another option - the Firestick No Ground Plane antenna - I run one on my roof rack with very good results.

Expat

Is this the one you are referring to?

http://www.firestik.com/CatalogFrame.htm Then click on Roof Mount in left sidebar.

Expat

I know the connections are good and the SWR readings were around 1.3.

Problem has been that it can transmit and recieve over a few miles then get nothing based on direction of other users and the orientation of my truck to them. As an example when travelling on hwy I can lose reception from someone in the convoy only a mile way to my left yet get crystal clear from the same distance but to my right. (Disregarding any land features that might obstruct wavelength.)

jacksonpt

yep - I've got the 2' NGP kit - works great for me. I've had it mounted to my aluminum roof rack and to my thule bars... works very well on trail runs. Not sure how it would work on the highway if you were miles apart...but that's not why I got it. I use it for trail runs only.

If you get it, just be careful with the wire... if you cut it, you're sunk. There's something about it that it has to be kept in stock lengths or your reception will suck (at best).

fourwd1

Use an ohmmeter to see if the rack is grounded.
A quality mag mount (K40 or Wilson brands) is your best bet as mentioned.
The shorter an antenna is, the less efficient it is.

ldivinag

i had a cheapie $20 mag mount one from wally world.

but i had a friend with an SWR meter tune it.

on a trip with people, i could transmit and recieve with them.

it's all about the tuning...

rngrchad

Wilson 2000 Mag mount. Tune it. And it'll talk. I've talked all over the country with mine. Even Nova Scotia.

VSS589

I'm new to the site, but not to CB. Having an ill adjusted antenna system is what can potentially cause serious damage to the CB, your transmision range, and receive capability. I believe one of the earlier replies misconstrued your directional pattern with an overall problem. I have installed many CB systems and have always been able to get SWRs below 1.3. All of but one of my installations have used magnet mounts. Clean and wax the location where you intend to put the mount. Clean the bottom of the magnet very well also. Place, tune and do not move. There are a lot of concerns about magnets scratching the paint, or other damage issues (fading, staining from rust). I believe this is why they are sometimes called inferior. With proper precautions these can be alleviated. I had a magnet on one of my rides for about 18 months with no discernable degradation of vehicle finish.

I currently have a Wilson 5000 mag mount in the center of the roof with a 1.2 SWR on my '05 Tacoma Sport. It's omnidirectional, has great receive capability, and I've talked 25 miles line of sight on quiet nights and 15 during the day without problem. Let me know how that roof rack plate works if you get it up and running. I had a friend back in high school that had a magnet mount on a large metal desk in his room and was able to achieve a 1.4 SWR. That may be a similar size to your plate. Good luck with it and let us know if it works.