GMRS antenna placements - which option is better?

[ElGuano]

I've been noodling a mobile radio setup for the truck, and while there is a ton I don't have settled yet, a few of the big considerations are how to route cables for power, microphone, and antenna. I'm starting to think about the antenna first, because it's the one thing that has to be outside of the truck.

My main considerations are to try and be as non-destructive as possible, and as streamlined as I can make it.

One of the main options I'm considering is using the cargo crossbar mounting points, for which I got a mounting/tie-down adapter. The thinking there is I can more easily move it if needed, and it's a way to avoid drilling larger holes into bodywork (maybe). I mocked up a couple of possibilities on the 3D printer, with the idea that I could get a final product CNC cut out of steel.

Option 1: On the bed cap (the floppy disk): I could have a plate the width of the cap serving as a smallish ground plane:

Main problem is routing the cable would have to be along the top of the bed cap, or drilling into it and having to replace the cap entirely since it seems to be a one-time-removal piece.

Option 2: On the roof: No ground plane, but it'll be at the highest point of the truck and maybe best reception. Cable routing would have to go down along the back glass, and enter the body somewhere around the shelf above the powered tonneau cassette.

Besides the obvious height advantage, I think it's also much less likely that I'll ever use my crossbars on the roof, so It'll be a more permanent solution.

Any major downsides, or things I'm not thinking about?

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[Dasoss]

I've been noodling a mobile radio setup for the truck, and while there is a ton I don't have settled yet, a few of the big considerations are how to route cables for power, microphone, and antenna. I'm starting to think about the antenna first, because it's the one thing that has to be outside of the truck.

My main considerations are to try and be as non-destructive as possible, and as streamlined as I can make it.

One of the main options I'm considering is using the cargo crossbar mounting points, for which I got a mounting/tie-down adapter. The thinking there is I can more easily move it if needed, and it's a way to avoid drilling larger holes into bodywork (maybe). I mocked up a couple of possibilities on the 3D printer, with the idea that I could get a final product CNC cut out of steel.

Option 1: On the bed cap (the floppy disk): I could have a plate the width of the cap serving as a smallish ground plane:

Main problem is routing the cable would have to be along the top of the bed cap, or drilling into it and having to replace the cap entirely since it seems to be a one-time-removal piece.

Option 2: On the roof: No ground plane, but it'll be at the highest point of the truck and maybe best reception. Cable routing would have to go down along the back glass, and enter the body somewhere around the shelf above the powered tonneau cassette.

Besides the obvious height advantage, I think it's also much less likely that I'll ever use my crossbars on the roof, so It'll be a more permanent solution.

Any major downsides, or things I'm not thinking about?

You can get a longer antenna eg 5/8 or 1/2 wave, that is designed to work without a ground plane. It will be about 16 in long rather than the 7 inches for the 1/4 wave antenna. That could cause a clearance problem for the rooftop. You could alse use a ditch light bracket. Note that there is really no such thing as a mini ground plane. Also, any mount that is not flush with the sheet metal like a bracket is sub optimal. Be sure to put an appropriate ferrite bead on the feedline near the antenna. People have reported that electrical noise makes reception from antennas at the front of the truck difficult up to 150 M hz. I don't know about GMRS at 450 MHz.
That said, you can probably live with whatever you can work out.
You might consider the Btech GMRS50-PRO tranceiver. It has Bluetooth connectivity. There is an available Bluetooth speaker-microphones that has a color display. It can control most functions of the radio. There is also an app that allows complete control from your phone. The app also updates the firmware in the tranceiver and the microphone. The microphone has a GPS receiver.for position reporting. You can mount the tranceiver in the tunnel, bed, or frunk and use the microphone wherever you please. The mic charges from a USB C connector.

 

[ElGuano]

You can get a longer antenna eg 5/8 or 1/2 wave, that is designed to work without a ground plane. It will be about 16 in long rather than the 7 inches for the 1/4 wave antenna. That could cause a clearance problem for the rooftop.

Thanks, 16" wouldn't be a huge problem, but I was thinking the longer 32" ones would be hard to keep on the roof.

You might consider the Btech GMRS50-PRO tranceiver. It has Bluetooth connectivity. There is an available Bluetooth speaker-microphones that has a color display. It can control most functions of the radio. There is also an app that allows complete control from your phone. The app also updates the firmware in the tranceiver and the microphone. The microphone has a GPS receiver.for position reporting. You can mount the tranceiver in the tunnel, bed, or frunk and use the microphone wherever you please. The mic charges from a USB C connector.

The more I think about the wiring requirements (3 routes for each of mic, power, antenna), the more I think that might be a reasonable course of action. I'm not a fan of BT because I've noticed most GMRS radios already have a built-in "activation" delay, especially with CTCSS/DCS activated, and adding BT latency on top of that would be even more annoying. But not having to route wiring from the head unit up into the cab and driver seat would be a huge plus.

 

[zefram47]

Will be curious to see which way you go. I've stuck with handhelds because I didn't feel like figuring out a solution for my mobile amateur radio yet. I tried to go with a glass-mount antenna, but the rear spoiler made that impossible

 

[ElGuano]

Will be curious to see which way you go. I've stuck with handhelds because I didn't feel like figuring out a solution for my mobile amateur radio yet. I tried to go with a glass-mount antenna, but the rear spoiler made that impossible

In my thread trawling, I found at least one glass-mount:
https://www.rivianforums.com/forum/threads/antenna-mounts.51523/#post-883186

Doesn't look all that bad, but it certainly has a 90s cell phone vibe that I completely forgot existed! No way to stand it up in the rear due that vector on the truck.

 

[Dasoss]

Thanks, 16" wouldn't be a huge problem, but I was thinking the longer 32" ones would be hard to keep on the roof.



The more I think about the wiring requirements (3 routes for each of mic, power, antenna), the more I think that might be a reasonable course of action. I'm not a fan of BT because I've noticed most GMRS radios already have a built-in "activation" delay, especially with CTCSS/DCS activated, and adding BT latency on top of that would be even more annoying. But not having to route wiring from the head unit up into the cab and driver seat would be a huge plus.

I have a UV-PRO HT, the ham radio HT version of the GMRS-50PRO (got the model wrong before.) I haven't noticed any activation delay with the BS-52 Bluetooth speaker/microphone. The delay you noticed might be due to the radio sending a squirt of data when you push tht PTT. You can turn it off in the app for the BTECH radios. The BS-52 lacks a display but it can change memory channels and adjust the speaker volume. It pairs and connects instantly, too. The newer version with display and 6 extra buttons is BS-50.
I would recommend the Nagoya mobile antenna but its 84 inches long. Diamond Antenna sells a remote controled motorized fold-over antenna mount for a cargo rack that could be adapted.
Yes, I'm a ham, extra class, actually; and a retired electrical engineer too. I'm still thinking about a tri-band in my R1S. There are fewer options for than for the truck. Well, I have accumulated lots of HTs. That happens to old hams. I'd be interested in what you work out.

 

[Dasoss]

Will be curious to see which way you go. I've stuck with handhelds because I didn't feel like figuring out a solution for my mobile amateur radio yet. I tried to go with a glass-mount antenna, but the rear spoiler made that impossible

Anybody consider a through glass mounted antennan on the roof glass?

 

[UnsungZero_OldTimeAdMan]

Anybody consider a through glass mounted antennan on the roof glass?

Generally works, with compromised performance.

 

[ElGuano]

I'd be interested in what you work out.

It's great to have Elmers around, I'm probably way too much of a newbie to understand a lot of the advice though

I eventually went the EZ route, mainly cause I just happened to run into a crazy craigslist deal on an unused Midland mobile radio with all the necessary extras I'd have to get. I posted my install here:

https://www.rivianforums.com/forum/...-midland-mxt575-full-build.56527/#post-959456

 

[SLVRon]

I have a 15W Midland MXT275 in my R1S. I have the main unit vertically mounted on double-sided velcro forward of the 12V outlet in the trunk. I ran the cable under the seats to the front to the handheld part. When I'm using the radio I run the antenna cable through the gap in the tailgate and it attaches with the magnetic mount to the roof. The antenna has held securely over 50-60 miles of rough roads at speed, and I can get at least 2 miles of clear reception when moving.

I haven't mounted a speaker though, so since the receiver is effectively acting as my speaker I do need to run with the third row seats folded so they're not muffling the audio.

No drilling or any vehicle modifications needed, and works perfectly.

 

[ElGuano]

I have a 15W Midland MXT275 in my R1S. I have the main unit vertically mounted on double-sided velcro forward of the 12V outlet in the trunk. I ran the cable under the seats to the front to the handheld part. When I'm using the radio I run the antenna cable through the gap in the tailgate and it attaches with the magnetic mount to the roof. The antenna has held securely over 50-60 miles of rough roads at speed, and I can get at least 2 miles of clear reception when moving.

I haven't mounted a speaker though, so since the receiver is effectively acting as my speaker I do need to run with the third row seats folded so they're not muffling the audio.

No drilling or any vehicle modifications needed, and works perfectly.

Having a 12v in the cab, + a radio rated for the 12v load, plus a smaller housing, makes it a great solution for the MXT275 and R1S!

Do you not use the speaker/mic for the speaker output? Is it because of the clicking/popping from the extension cord?

 

[SLVRon]

Having a 12v in the cab, + a radio rated for the 12v load, plus a smaller housing, makes it a great solution for the MXT275 and R1S!

Do you not use the speaker/mic for the speaker output? Is it because of the clicking/popping from the extension cord?

I didn't want to find homes up front for all of the pieces, so I did an initial trial without the speaker. Turns out that if the 3rd-row is folded down I can hear it fine.

 

[loqueid]

What about this?

from: youtube.com/watch?v=I6lMz6pyiUY

 

[ElGuano]

What about this?

the front corner is actually a great option, especially for easy cable routing and having a ground plane. In addition to the ditch light option there are also hood clips NMO mounts that provide a lower profile install.

I wanted to see if there was something even more out of the way (nearly invisible), and went with this, which is actually pretty similar (did the install last week).

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