2m/440/GMRS Mobile Antennas Needed

[Raybestos]

Talking with a friend the other day, it occurred to me that there is probably a sizable market for a mobile antenna (NMO mount) that would deliver good SWR and radiation/gain on 2m and 440 ham, as well as 462/467 GMRS frequencies.  I know personally of quite a few people who would gladly purchase such an antenna if it were made available.

Yeah, I know you are not supposed to run GMRS on ham radios but the fact of the matter is that a LOT of people do and having one antenna that does it all would be a big thing for those people.  Also, AFAIK, there would be no FCC repercussions for designing and marketing an antenna with that capability.  I wish I had the money to invest in such a venture as it likely would be successful, provided the antenna was efficient and durable.

What sayeth you; Larsen, MelloWave, and others?

[marcspaz]

Just buy a Diamond NR-7900 or 770. They both work perfectly.  My 7900 outperforms every single purpose built gmrs antenna I have ever used in my entire life.

[AdmiralCochrane]

Count me as a 770 fan.

[WRYZ926]

Another good choice is the Comet 2x4SR. The highest SWR across 2m, 70cm, and GMRS is 1.8. And it has good SWR on the 1.25m/220 MHz band even though its not advertises to work on that band.

[WSAM454]

Another vote for the Comet 2x4SR.     Mine works well on my vehicle on the 2 Ham bands and the GMRS band, just as it was designed to.

[NCJeb]

Just to drop in my 5¢ (rounded up since pennies are gone) of opinion:

Whether this would work *well* depends heavily on terrain. In flatter states like Florida, Kansas, or even out east of me here in NC, a multi-band configuration would be not only possible, but perhaps even ideal, as it would provide a generally decent gain value on UHF besides.

 

In more mountainous areas like I live in here in Western NC though…not so much. Through direct experimentation, dual-band antennas and purpose-built moderate gain GMRS work dismally, if at all, in some cases, but lower gain 1/4 Wave GMRS antennas work far better and a lot more consistently.

 

That said too, the dual-band 2m/70cm comet ham antenna I’ve experimented with has reasonable SWR on GMRS, checked before the tests began—so a purpose-built GMRS addition might not even be necessary, as @WRYZ926 and @WSAM454 have pointed out. 

 

I say all of that to say, as with all antenna configurations, something like the OP is suggesting honestly makes a lot of sense across parts of the country, but not necessarily others. A tweak of a standard 2m/70cm antenna might even improve upon the existing SWR levels for GMRS, although someone smarter than me might could say what impacts that would have on the SWR for 2m and 70cm…

[gortex2]

I use standard commerical LMR multi band antennas with no issues. Motorola all band, Larsen and PCTEL all offer wideband all band antennas;. MY work truck has 4 of th MSI all band and I use ham/gmrs/lmr in all my radios. On my personal vehicles I run the Larsen mutiband.

 

Motorola AN000131A02

Larsen NMO150/450/758

Laird All Band

 

[tweiss3]

If you have to have both bands in a single antenna, I'd choose Larsen NMO2/70B, but you have to have the height available as it is 36" in length.

I have used the Larsen NMO150/450/758 as well as the Larsen NMO2/70SH, but I stopped using them for UHF because they are a 1/4 wave 2m antenna which ends up being 3/4 wave for UHF and has way too much up tilt. I now use a dedicated 1/2 wave UHF antenna from PCTel (BMWU4002S) that claims its good for all of UHF, but is good enough for what I need.

[WRYZ926]

The downside to having a single antenna that works on 2m/70cm and GMRS is that it will be tall. Most are around 35-40 inches tall.

While I do run the Comet 2x4SR on my SxS and truck, I run separate antennas on my SUV since I park it in the garage. I run a Comet SBB-1 dual band and a Tram 1174 tuned for GMRS.

[WRUE951]

54 minutes ago, WRYZ926 said:

The downside to having a single antenna that works on 2m/70cm and GMRS is that it will be tall. Most are around 35-40 inches tall.

While I do run the Comet 2x4SR on my SxS and truck, I run separate antennas on my SUV since I park it in the garage. I run a Comet SBB-1 dual band and a Tram 1174 tuned for GMRS.

Yup,  why I keep two antennas in my Truck.   Most of the time I have the MXT26  on the roof, lately I've been running only GMRS. When I run dual band I like the Comet 2X45 that I switched to from a Tram. 

[Raybestos]

22 hours ago, marcspaz said:

Just buy a Diamond NR-7900 or 770. They both work perfectly.  My 7900 outperforms every single purpose built gmrs antenna I have ever used in my entire life.

Interesting!  The friend I had that conversation with had purchased a 7900 about a year ago on the advice of another friend who likewise had great praise for the 7900 antenna.  He said it worked well on 462 MHz GMRS, but had high SWR (I believe 3.0 or higher) on the 467 MHz inputs.

[marcspaz]

1 hour ago, Raybestos said:

Interesting!  The friend I had that conversation with had purchased a 7900 about a year ago on the advice of another friend who likewise had great praise for the 7900 antenna.  He said it worked well on 462 MHz GMRS, but had high SWR (I believe 3.0 or higher) on the 467 MHz inputs.

 

It was likely the install.  It would have to re-test since it's been awhile, but on two of my vehicles, the antenna is below 1.5:1 on every band I use it on.  I am running a 300w VHF radio and a 115w commercial UHF radio. I need the SWR to be below 2:1 on both radios to preserve the PA's, rather than cooking them in heat.

 

I can always run and SWR sweap if you are interested in the exact numbers.

[WRTC928]

On 11/20/2025 at 3:35 PM, marcspaz said:

My 7900 outperforms every single purpose built gmrs antenna I have ever used in my entire life.

I have the Diamond SG7900 on my truck. It's very similar to the NR7900 but it's 5" taller and has more gain. It has perfect SWRs on GMRS, 70 centimeters, 2 meters, and even acceptable SWR (right at 2.0:1) on MURS with essentially no ground plane. It's the best mobile antenna I've ever tried for GMRS, either GMRS-specific or multi-band. 

[dosw]

I trust that the several recommendations made here already are good choices.

 

I have a Comet CA2x4SR NMO that works very well when it has a good ground plane below it. Without a good ground plane its SWR can be all over the place.

 

I also have a Larson NMO 2/70. It's designed to work without a great ground plane. The gain is slightly less than the Comet, but I get very good signal reports from it, and that includes in the GMRS band. It works well mounted on the fender of my F150, which can be a challenging location.

 

[WRYZ926]

12 hours ago, dosw said:

I have a Comet CA2x4SR NMO that works very well when it has a good ground plane below it. Without a good ground plane its SWR can be all over the place.

 

And the ground plane does not have to be solid metal. I have one of those hitch receiver cargo shelves made from expanded metal mounted to the rack on my SxS. And that is where I normally run the 2x4SR on a magnet mount. It works just fine and the highest SWR is 1.8 on GMRS.

 

[WSAM454]

On 11/21/2025 at 8:35 AM, WRYZ926 said:

The downside to having a single antenna that works on 2m/70cm and GMRS is that it will be tall. Most are around 35-40 inches tall.

While I do run the Comet 2x4SR on my SxS and truck, I run separate antennas on my SUV since I park it in the garage. I run a Comet SBB-1 dual band and a Tram 1174 tuned for GMRS.

Yes, the 7900 is a bit over 5' tall, and the maker does not suggest using a mag mount for it.

[nokones]

On 11/21/2025 at 3:52 AM, gortex2 said:

I use standard commerical LMR multi band antennas with no issues. Motorola all band, Larsen and PCTEL all offer wideband all band antennas;. MY work truck has 4 of th MSI all band and I use ham/gmrs/lmr in all my radios. On my personal vehicles I run the Larsen mutiband.

 

Motorola AN000131A02

Larsen NMO150/450/758

Laird All Band

 

Is it necessary to use the Motorola Antenna multiplexer with the multi-band antenna?

[marcspaz]

If you have multiple radios sharing an antenna, you either need to swap cables between radios, add an antenna selection switch, or add a multiplexer/diplexer. The multiplexer/diplexer route offers the best solution as far as needing the least amount of effort. But depending on brand and model, they can be a little pricey and have observable insertion losses.

[Whistlepig]

On 11/20/2025 at 4:35 PM, marcspaz said:

Just buy a Diamond NR-7900 or 770. They both work perfectly.  My 7900 outperforms every single purpose built gmrs antenna I have ever used in my entire life.

How durable is the 7900? Will it handle getting smacked by branches and the like?

[WRYZ926]

On 11/24/2025 at 10:30 PM, WSAM454 said:

Yes, the 7900 is a bit over 5' tall, and the maker does not suggest using a mag mount for it.

My brother has a 7900 and a triple magnet mount would not hold it to the roof of his truck at 60-70 MPH. A permanent mount is needed. He went with the Comet 2x4SR instead.

[WRTC928]

2 hours ago, Whistlepig said:

How durable is the 7900? Will it handle getting smacked by branches and the like?

It's pretty solidly built. I haven't taken it through dense woods, but for the ordinary occasional low-hanging branch, I haven't had any problem.

[marcspaz]

2 hours ago, Whistlepig said:

How durable is the 7900? Will it handle getting smacked by branches and the like?

 

I would say it's pretty solid. I take it off and use an SSB1 when im offroading in the woods, but on wooded roads where it came into contact with tree branches at speed, it's been perfect. I've had to straighten the elements a few times, but the capacitive components and loading coils have never failed. I had one hit that was so hard, the lip of the bed of the truck bent more than the antenna did. But, again, just straightened everything out by hand and started using it again no issues. 

[Whistlepig]

54 minutes ago, marcspaz said:

 

I would say it's pretty solid. I take it off and use an SSB1 when im offroading in the woods, but on wooded roads where it came into contact with tree branches at speed, it's been perfect. I've had to straighten the elements a few times, but the capacitive components and loading coils have never failed. I had one hit that was so hard, the lip of the bed of the truck bent more than the antenna did. But, again, just straightened everything out by hand and started using it again no issues. 

Thanks for the reply.

 

One more question. DO you think mounting a 7900 on a bed rail close to the cab or doing something like a SSB1 on a third brake light mount would end being much different in TX/RX?

[WRYZ926]

Bed rails and at the edge of the roof (3rd brake light) is not ideal for any antenna. While antennas will work without a proper ground plane, you will see better performance with a proper ground plane.

Another thing is that a good portion of a 7900 will be blocked by the cab if placed on the bed rail close to the cab. In this instant you might find that the short SBB1 on top of the cab might actually work better.

I would try to get either one in the center of the cab if all possible. I know the 7900 will require a permanent mount where you can get by with a magnet mount with the SBB-1.

The SBB-1 mounted in the center of the roof on my Ford Escape performs well in most circumstances. Of course a taller and higher gain antenna will work even better in the center of the roof. I run a Comet 2x4SR placed in the center of the cab on my F-150.  The 2x4SR is 38 inches long, so parking garages and even covered drive throughs are out of the question.

[Whistlepig]

3 minutes ago, WRYZ926 said:

Bed rails and at the edge of the roof (3rd brake light) is not ideal for any antenna. While antennas will work without a proper ground plane, you will see better performance with a proper ground plane.

Another thing is that a good portion of a 7900 will be blocked by the cab if placed on the bed rail close to the cab. In this instant you might find that the short SBB1 on top of the cab might actually work better.

I would try to get either one in the center of the cab if all possible. I know the 7900 will require a permanent mount where you can get by with a magnet mount with the SBB-1.

The SBB-1 mounted in the center of the roof on my Ford Escape performs well in most circumstances. Of course a taller and higher gain antenna will work even better in the center of the roof. I run a Comet 2x4SR placed in the center of the cab on my F-150.  The 2x4SR is 38 inches long, so parking garages and even covered drive throughs are out of the question.

I understand the ground plane issues I am dealing with but do not have much of a choice, drilling a hole in the center of the cab is not going to happen and a magnet mount will not work out good for me.

If it goes on the third break light it is going to have to be a shorter antenna, my truck is 7'2" tall so a 5 footer will be way top much up there. This is the issue I am in trying to figure out, a taller antenna on the bed rail or a shorted on third break light....in my mind the shorter on the break light mount would do better but not totally sure and hate the make a $400 gamble on it.