Snorkeldepth

I've done a bit of searching and haven't seen a definitive answer to this question. I bought a Cobra 18 WX ST II mostly because of all the endorsements on YT. The fiberglass shell (aka cap) on the truck has aluminum framed glass windows in the sides and the back (SnugTop brand). Fiberglass is invisible to the antenna . . . I'm not sure about the effect of the window frames.

I've seen the mounting option using a bracket at about bed rail height that mounts to the inside of the tail gate opening . .. . nice option. Apparently mounting the antenna to the shell wouldn't work well without putting a metal plate under the antenna and grounding it all to the chassis. I don't have much space on the cab roof due to the factory sunroof. But, there's space for a hole if necessary I guess. There's also the hood mount, fender mount, bumper mount options.

It seems from what I've read that a roof mount is the best. Next "best" seems to be the rear corner mount (when factoring in offroad practicality).

Has anyone determined what their performance is using any of these mounting options by measuring SWR or otherwise including "the seat of your pants"?

Snorkeldepth

A couple issues that got me thinking about a truck mount, as opposed to a 4rnr mount, are that there's not a solid metal roof in back (so the ground plane is the rim of the bed?) and that there are possible reflection issues to deal with from the back of the cab.

deathrunner

My 4runner basically has a fiberglass cap. I have my antenna mounted on my rear swingout gate, but it was in a similar position before on a mount in the tailgate crack. I just mounted it high enough so that the antenna was not in line with the metal bedisdes, it is slightly above that and the antenna is in the fiberglass area or above.

From what I understand, vertical metal planes are bad to be in the way of the antenna. A hrizontal plane of metal is ideal. The best spot for the antenna would be perpendicular to the hood or roof and in the center. But this is not really functional or structurally feasible. So as long as it is not parallel to any vertical surfaces you should be ok. That is my understanding at least.

Snorkeldepth

Thanks! On the 4Runner you avoid the vertical plane by not having a bed front or cab back (particularly the upper cab back because the antenna is mounted just above the bed rail). I'm wondering how much that will affect performance in my application. I'm pretty new to this radio stuff and have read just enough to make myself dangerous.

deathrunner

I know a couple of guys that run it there and not too many problems. Most guys that I know with 2nd gens run a shorter antenna on the roof or roofrack. Seems to be an effective place.

fourwd1

The "ideal place" is dead center on the roof.
Anything else is less than "ideal", but possible. Bumper mounts, gutter mounts, etc. are compromises.
An antenna needs to be mounted on the largest area of horizontal sheetmetal possible. That acts as a groundplane, which is the second half of the antenna.


There is a way to create a groundplane on a FG top if you really want the "ideal" and are willing to drill a hole in the top.

snap-on

I know a couple of guys that use an offset bracket in the hood seam. (ie it mounts up front and uses the hood as a ground plane.

I mounted my 2m ham antena on the back corner of my cab.


but i suppose that would still be in the way of the topper.

Lots of guys that have the ARB mount one on the front bumper (youve had to have seen the classic ARB posters with it front and center)

Snorkeldepth

The cab roof is occupied by my factory sunroof. So, there's no place for the antenna mount in the center. I suppose I'd rather put a hole in fiberglass than metal. I have a whole lot more experience doing fiberglass repair than fixing holes in metal if necessary. The only way I read about creating a ground plane for a shell was installing a large metal plate in the ceiling of the shell.

It seems like most guys get enough range with all of the compromise mounting positions to keep in touch with their trail buddies. ???

fourwd1

True. If you're just looking to talk with people on the trail, range is not really an issue, so most anything will work.

rngrchad

Ideal place: in the middle of the top of the cab. Slap a Wilson 1000 MAG MOUNT and your swr's will be good, and your radio will talk great. I've tried everything, my tacoma with a cap talks best with the antenna mag mounted to the cab. Remember it's all about groundplane. If you center your antenna around a good groundplane you will have a good talking raidio in all directions. If you put it on the bumper the radio will only talk forward, if you put it on the side of the hood it will talk back and to the left.
just a little info........good luck.

Snorkeldepth

I can't put the antenna in the center of the cab roof due to the factory sunroof. How will it work to put it behind the sunroof? It won't be centered on the groundplane (cab roof). Is this the best place I have available?

Thanks everyone!

fourwd1

Probably. I've done the same thing on my 4Runner with good results.