third brake light antenna mounts / ground plane

[E5911]

I'm getting ready for a antenna project on my GMC AT4 and it was suggested to me to go with the Third brake light mounts. The concern I had was about a proper ground plane. I really did not see any real comments about it when I researched previous posts. Am I going to suffer alot of performance loss vs a roof mounted NMO?
I don't have a issue drilling, but this seems a bit less intrusive.

The radios are going to be xtl2500s, one UHF and one VHF, any chance the proximity of the antennas with de-sense the receivers on Tx?

Also Any suggestions for antennas, going to buy new...

 

[mmckenna]

I'm getting ready for a antenna project on my GMC AT4 and it was suggested to me to go with the Third brake light mounts. The concern I had was about a proper ground plane. I really did not see any real comments about it when I researched previous posts. Am I going to suffer alot of performance loss vs a roof mounted NMO?

Lopsided ground plane, will make the radiation pattern wonky. Even if you use "ground independent antennas", the existing ground plane will toss a lot of your signal to the stern.

I don't have a issue drilling, but this seems a bit less intrusive.

I've never used one, but I've read of people complaining that they have leaked on them. Water inside an expensive new truck would be way more intrusive that just drilling the holes.

Plus, if your 3rd brake light is LED, you'll have the antennas right up close to that.

The radios are going to be xtl2500s, one UHF and one VHF, any chance the proximity of the antennas with de-sense the receivers on Tx?

Yes. And the two antennas that close will wonkify your radiation pattern even more on UHF.

Also Any suggestions for antennas, going to buy new...

Larsen or EM Wave, accept no substitutes, and don't put Cheap Chinese Antennas on a nice truck like that. Same for the NMO mounts. Don't use Chinese crap to save a few bucks.


I'll probably get flamed for this, but here it goes:
These third brake light mounts are designed for people that are concerned that doing a permanent NMO mount is going to "reduce the resale value of their truck", which has been proven not to be the case. The off road crowd loves them since it requires minimal effort to install and they are usually looking for the "cool" factor rather than actual performance. I think I'd rather use a (gasp!) magnetic mount (gasp!) than use one of those third brake light mounts. At least with a mag mount, you could stick it in the middle of the ground plane.

It's a nice truck, and you want the radios to work well. Go all the way and do the permanent install. I'd do a VHF 1/4 wave and a UHF 1/4 wave. On a good ground plane, they'll have a nice radiation pattern, and they'll be nice and wide band, so you can use the full capability of the radio. Larsen NMOQ or the EMWave 1/4 wave antennas would be my choice.

 

[mmckenna]

I've never used one, but I've read of people complaining that they have leaked on them. Water inside an expensive new truck would be way more intrusive that just drilling the holes.

I'll add:
I've never had a properly installed NMO mount leak. Not once.

 

[E5911]

Kinda what I thought, i'll drill 'em, best way, thanks for confirming.

 

[8K10F1E]

The resale value thing really strikes a nerve with me. Blows my mind that people think they have equity and re-sale value in a deprecating asset that serve a function like a tool, which is nothing more than a mode of transportation. Think of all the people who said the same **** back in the 90 and early 2000's, with their Tahoe's, Cherokees, and F150's, which today are all rust buckets that they wouldn't think twice to drill into. What makes new vehicles today any different? They all end up rusty pieces of **** and nobody is paying attention to your NMO mount when you are selling a vehicle

 

[mmckenna]

and nobody is paying attention to your NMO mount when you are selling a vehicle

Yeah,

Issue usually isn't about the trade in value. It's more common that the individual doesn't want to put the effort in, doesn't know how, wife won't let them, or they just don't like the idea. That's cool, but it's not a trade in issue. It's just a handy excuse.

 

[tunnelmot]

I've never had a properly installed NMO mount leak. Not once.

Neither have I. 15 plus vehicles, about half had multiple mounts.

 

[K7CT_JH]

Larsen or EM Wave, accept no substitutes, and don't put Cheap Chinese Antennas on a nice truck like that. Same for the NMO mounts. Don't use Chinese crap to save a few bucks.


I'll probably get flamed for this, but here it goes:
These third brake light mounts are designed for people that are concerned that doing a permanent NMO mount is going to "reduce the resale value of their truck", which has been proven not to be the case. The off road crowd loves them since it requires minimal effort to install and they are usually looking for the "cool" factor rather than actual performance. I think I'd rather use a (gasp!) magnetic mount (gasp!) than use one of those third brake light mounts. At least with a mag mount, you could stick it in the middle of the ground plane.

I am new to this and appreciate your comments.

Sadly a magnetic mount is not an option on my aluminum body truck. That said I read and respect the consensis in this thread regarding "drilling the damn hole" 1) results in a much improved radation pattern, 2) Less likely to leak and 3) would likely not affect the value.

My other issue would be placement due to the sun roof which again screws up the ground plan.

Jim H

 

[mmckenna]

I am new to this and appreciate your comments.

Sadly a magnetic mount is not an option on my aluminum body truck.

I'm running a 2018 Ford F350, it is aluminum body and the permanent NMO was my only real option. I'd never use a mag mount, anyway, at least not for anything other than testing.

My other issue would be placement due to the sun roof which again screws up the ground plan.

One of a few reasons I don't purchase vehicles with a sun roof.
If you have a sun roof, then you have to make a compromise of one sort or the other. Either the third brake light, or make use of whatever body metal you have. Getting some ground plane under the antenna is better than none.

 

[madrabbitt]

OP didnt mention the year or the specific model of the truck unless i missed it.

If its a current body style full size truck, they do not and probably will not make those mounts, the design of the third brake light and spoiler panel are completely different then previous body styles. if its the redesigned current body style canyon, they also do not make them,

That being said, one of my mounts is a 3rd brake light mount, and it was originally going to be for the cell booster, but plans changed, and its currently being used on a low power GMRS or ham (mostly 70cm) mobile when needed.

The radiation pattern is weird, but i havent had any issues with it, primarily monitoring with some repeater work. I wouldnt use it for a higher power radio, and i definitely wouldnt use it on a VHF mobile because of ground plane issues... and i know its mostly sold for the off road community and their higher power VHF mobiles, which always made me shake my head.

 

[K7CT_JH]

MadRabbit,

Thank you for your input.

"OP didnt mention the year or the specific model of the truck unless i missed it."

The truck is a 2019 Ford F150 platinum trim level. I would rather not have a sunroof on any vehicle. Sadly, you rarely if ever see this trim without a sunroof.

"That being said, one of my mounts is a 3rd brake light mount, and it was originally going to be for the cell booster, but plans changed, and its currently being used on a low power GMRS or ham (mostly 70cm) mobile when needed."

Re "I wouldnt use it for a higher power radio" - by that do you mean something higher than a 25 watt radio? Or less even?

Thank you!

Jim H

 

[madrabbitt]

MadRabbit,

Thank you for your input.

"OP didnt mention the year or the specific model of the truck unless i missed it."

The truck is a 2019 Ford F150 platinum trim level. I would rather not have a sunroof on any vehicle. Sadly, you rarely if ever see this trim without a sunroof.

"That being said, one of my mounts is a 3rd brake light mount, and it was originally going to be for the cell booster, but plans changed, and its currently being used on a low power GMRS or ham (mostly 70cm) mobile when needed."

Re "I wouldnt use it for a higher power radio" - by that do you mean something higher than a 25 watt radio? Or less even?

Thank you!

Jim H

I only use it on a 20 watt mobile. Originally it was going to be for a cell booster as said. I got it so that it would be as far from center of the roof as possible and still be roof mounted, because originally the truck was going to get a high wattage VHF mobile, and that antenna would be center of the roof.