GMRS antenna mounting

Bocephus

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For a GMRS or 2m/70cm ham antenna it shouldn't be a problem. I run both on a roof rack without issue. I wouldn't run a CB antenna on the rack though and that appears to be what that antenna mount is for. You can get coax with a NMO end that has a 3/8" center so that it will fit the CB antenna mount hole and the mount looks to be just wide enough for an NMO antenna base though it would be nice if they provided some measurements on the product to know for sure.
Beyond being a suitable place to mount it,
Does the rack feature as a real benefit for ground plane, and were I to mount there should I consider an antenna that requires ground plane or not ? Thanks !





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prerunner1982

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Beyond being a suitable place to mount it,
Does the rack feature as a real benefit for ground plane, and were I to mount there should I consider an antenna that requires ground plane or not ? Thanks !
Sorry I wasn't more specific, it is a suitable place to mount because it does provide sufficient ground plane for GMRS and/or VHF-UHF ham.
Whether you get an antenna that requires a ground plane or not it up to you. A no ground plane antenna will work better if it has a ground plane so really it's about what length antenna you want or can get by with on the roof...ghost, 1/4 wave, 1/2 wave, 5/8 wave,
 

Bocephus

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Sorry I wasn't more specific, it is a suitable place to mount because it does provide sufficient ground plane for GMRS and/or VHF-UHF ham.
Whether you get an antenna that requires a ground plane or not it up to you. A no ground plane antenna will work better if it has a ground plane so really it's about what length antenna you want or can get by with on the roof...ghost, 1/4 wave, 1/2 wave, 5/8 wave,
Thank you so much, greatly appreciated !
 

prerunner1982

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Thank you so much, greatly appreciated !
Upon further thought regarding that mount specifically I would probably use a no ground plane antenna due to the coating, the fold over joint and the mounting points it likely won't make a good enough connection to the roof rack. If it was a different solid type mount then any antenna would work. Sorry for any confusion.
 

Bocephus

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Upon further thought regarding that mount specifically I would probably use a no ground plane antenna due to the coating, the fold over joint and the mounting points it likely won't make a good enough connection to the roof rack. If it was a different solid type mount then any antenna would work. Sorry for any confusion.
I’m super appreciative, thank you. Given those thoughts..,would the following mount (pictured) do as well? I have this carrier (JL version) and mount point, currently use it for CB but could repurpose for GMRS. If the roof rack does little to improve performance, then this mount point would at least have the benefit of being a more protected location (won’t whack trees with it etc.)


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JocoRubicon

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Tons of great information in this thread. Question I would ask is if someone wanted to run a gmrs antenna and cb antenna on the back end of the JL, separating the mounting locations to either side of the spare perhaps. Can both coax cables be run together or is that a horrible plan? Thanks!
 

prerunner1982

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I’m super appreciative, thank you. Given those thoughts..,would the following mount (pictured) do as well? I have this carrier (JL version) and mount point, currently use it for CB but could repurpose for GMRS. If the roof rack does little to improve performance, then this mount point would at least have the benefit of being a more protected location (won’t whack trees with it etc.)
The higher the antenna the further your signal can go, but many Wrangler owners mount their GMRS antenna on ditch light mounts, fenders, hoods, etc and it seems to work fine for them for trail comms. Mounting it lower than the roof the signal will be blocked some by the body/roof/occupants so your signal will be weaker in that direction. Maybe not as big of an issue in close quarters on the trail. Also where it's mounted on the vehicle will determine where the signal is greater, the signal is pulled towards the greatest metal mass.
antenna-placement2.jpg


Something else to consider when looking at antenna is gain. Most people think higher gain is better and in some environments that is correct. In flat terrain higher gain (longer antenna) directs more signal towards the horizon, less gain (shorter antenna) is more like a donut a thick signal but not as strong and this is better in mountainous terrain. Hopefully the image will demonstrate it better.
propagation.jpg


Another concern with your rear mount is that it looks like it may not be wide enough for a NMO antenna as the base is 1.25" diameter.
Mobile communication set ups can be about compromises.
Try it one way and if that doesn't work you have options to try something else.
 

prerunner1982

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Tons of great information in this thread. Question I would ask is if someone wanted to run a gmrs antenna and cb antenna on the back end of the JL, separating the mounting locations to either side of the spare perhaps. Can both coax cables be run together or is that a horrible plan? Thanks!
No issues, coax is shielded with the signal travelling on the center conductor. It can't tell if another run of coax is next to it or not. I run 5 radios in my Jeep so I have coax travelling near each other and across each other with no issues.
 

Bocephus

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The higher the antenna the further your signal can go, but many Wrangler owners mount their GMRS antenna on ditch light mounts, fenders, hoods, etc and it seems to work fine for them for trail comms. Mounting it lower than the roof the signal will be blocked some by the body/roof/occupants so your signal will be weaker in that direction. Maybe not as big of an issue in close quarters on the trail. Also where it's mounted on the vehicle will determine where the signal is greater, the signal is pulled towards the greatest metal mass.
antenna-placement2.jpg


Something else to consider when looking at antenna is gain. Most people think higher gain is better and in some environments that is correct. In flat terrain higher gain (longer antenna) directs more signal towards the horizon, less gain (shorter antenna) is more like a donut a thick signal but not as strong and this is better in mountainous terrain. Hopefully the image will demonstrate it better.
propagation.jpg


Another concern with your rear mount is that it looks like it may not be wide enough for a NMO antenna as the base is 1.25" diameter.
Mobile communication set ups can be about compromises.
Try it one way and if that doesn't work you have options to try something else.
Exceptionally helpful, super appreciative, if you ever find yourself in Virginia give a holler ...beers are on me.
 

JocoRubicon

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No issues, coax is shielded with the signal travelling on the center conductor. It can't tell if another run of coax is next to it or not. I run 5 radios in my Jeep so I have coax travelling near each other and across each other with no issues.
Thanks!! I'm planning to run two coax lines from the rear up to the front, with this information I'll wait to do them at the same time since it's a little effort to do it cleanly up the right side. Appreciate the info greatly!
 

Jlrut

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I put mine on top of the sport bar:

IMG_20200323_232313.jpg
Now that you’ve had it for a while, can you update the reception? Highway and trail? Thanks
 

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That’s nice do you know if it will work for a hardtop when it’s on?

Now that you’ve had it for a while, can you update the reception? Highway and trail? Thanks
 

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I've now had mine out on a trail for testing. We didn't have any great distance but it worked well, nice and clear.
 
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Let me say right off, I am not a radio engineer nor do I mean to be patronizing, but my years in the two-way radio business has given me some insight. Before you look specifically at the particular radio bands, I think you first have to look at the Jeep Wrangler itself. No matter the band, all two-way radios need good antennas and generally good ground planes; that is, a reflective metal surface that the signal from an antenna bounces off of to improve the antenna’s intended design purpose. Wranglers, unfortunately, do not provide them. Fiberglass tops, soft tops, or no tops. In addition, Wranglers supposedly utilize a mix of steel, plastic, aluminum, and, reportedly, magnesium. They each have varying degrees of “reflection,” and you can presume things like plastic have little to none for our purposes. A paint can lid could be more of a ground plane than what you might find on a Jeep.

There are essentially two types of antennas that we use: ground plane dependent (“GPD”) and ground plane independent (“GPI”). These are somewhat self-explanatory definitions, but without an adequate ground plane, GPD antennas become effectively useless. GPI, also referred to as “no ground plane” (“NGP”), antennas are able to reflect and direct the radio signal without an external ground plane, although having one will still help. Some radio techs suggest first buying the best antenna you can get, along with a good ‘low loss’ coax, and then buying a radio to match it. The antenna is that important.

My remarks are prefaced with this discussion because in everything from Jeeps to trucks to emergency vehicles, people often “mis-match” equipment and then wonder why their radios don’t work or work poorly. Can’t tell you the number of radio installs I have seen on public-safety vehicles with $5,000 radios and techs reusing a $10 coax that is seven years old and bent and twisted or $50 antennas that are shot. Any radio install I was responsible for ALWAYS got a new antenna and new coax.

So good equipment and proper use of it is important. As I mentioned before, the best place to mount an antenna on a Jeep may be the center of the front bumper (or that area), for both ground plane purposes and direction. Because that is an awkward location, I generally prefer to use NGP antennas and mount them elsewhere around the vehicle (and with some separation from each other). Enough about that, I think you get my point. As to the different radio bands, each serves its own purpose.

Citizens Band (“CB”) radio (or as my good buddy Gil calls it, the “Children’s Band”), is short range, cheap to own, easy to install, and simple to use without a license. Although fading in popularity, even the truckers aren’t yakking on Channel 19 as much as they use to, I understand many Jeep groups still use it and some even require it. The Federal Communications Commission (FCC) allows a maximum of 4 watts of output power for CB radios to avoid signal interference with other devices, so expect that even with a properly mounted and operating antenna, range is going to likely be limited to less than five miles, but at times it could go further. If you are on top of the Red Rocks in Sedona, your range will be considerably better than downtown San Diego. In the typical Jeep group outing, where Jeeps stay somewhat together, a CB radio should reach all of the vehicles in the group. Signal quality is adequate, but you are sharing the radio band with numerous other users, so signal interference is always a possibility and it operates on “AM” which is more prone to issues. CB antennas are generally bulky and need SWR tuning, and the best antenna, the 102” whip, is banned (as a hazard) by some Jeep groups. We’re also at the end of a solar cycle and CB radio signals are problematic at the moment.

General Mobile Radio Service (“GMRS”) has been around for a while, and is becoming more popular with overlanders and off-roaders (Jeepers!). Sort of the evolution of CB radio. However, the FCC requires that you purchase a license to use GMRS; the license is good for 10-years, and it allows both you and your family members to use it. The fee for a l0-year license is currently $70. One of the nice things about GMRS is that you can buy mobiles or small portable radios making it easy to communicate with your spotter when you are on the trail, or with others who wonder away from your vehicle or campsite. GMRS operates in the 460 MHz range and the FCC allows a maximum of 50-watts of output power for these radios. They will likely double the cost (or more) of owning a CB, but IMHO offer more versatility and better range. Antennas are considerably more compact and will be easier to mount. The radios operate “FM” so also less static compared to CB and less effect from solar cycles.

According to the website ‘TheRangerStation.com,’ “Midland says that their 15-watt [GMRS] radio has a range of 5-10 miles obstructed, 10-15 miles partially obstructed, and 50 miles with no sight obstruction. Their 40-watt radio has a range of up to 65 miles with no sight obstruction.” Take any of these numbers with a big grain of salt. GMRS also has repeater channels available, which receive signals and retransmit them. Keep in mind though, where one might venture with a Jeep, repeaters may not be available so you are operating “Jeep to Jeep.”

Family Radio Service (“FRS”). Think of FRS radios as a subset of GMRS, although as my friend Gil would say, the “children’s division.” While they share the 460 MHz operating range, GMRS radios have designated channels within those frequencies that aren’t available to FRS radios. The number of frequency channels of GMRS sums to a total of 30 channels, and among these 30 channels, 22 channels are shared with FRS, which allows the users of the two radio services to communicate with each other. Because of FRS’ low power (max of 2 watts), no license is required, but you can obviously see the immediate limitations of such a low power radio. According to MidlandUSA.com, “for those who plan to use two way radios only infrequently, in close range, or in outdoor scenarios that aren’t particularly technical, an FRS radio is just fine. FRS two way radios are powerful enough to have a range of a mile or two (depending on the terrain) and will keep you in touch with your party in case of emergency.” By FCC rules, FRS radios are generally limited to handhelds. Lots of people modify mobiles to access FRS, but that is generally illegal.

Ham Radio (or Amateur Radio). Ham operates in a completely different stratosphere (literally and figuratively). First, Ham radio operation requires a (10 year) license of each individual user. There are three classes of Ham radio licenses and users must pass an exam for each class, which corresponds to an increasing degree of technical knowledge and corresponding radio band privileges. Only FCC licensed Ham radio operators may use the Ham radio assigned frequencies and, unlike GMRS, family members are not permitted to talk on these radios unless licensed themselves. Ham radio can be used over very long distances due to the use of repeaters and satellites, and you can communicate with it via your voice, messages, and even images. Ham radios are also as expensive or more expensive than GMRS. It is truly a “hobbyist” radio service, although it certainly has a large element of public service. Ham radios are used all over the world for emergency services, weather spotting, disaster services, and other public purposes.

So, what would I recommend? Like anything else, what are you going to use it for? I just packed up my MOAB and drove from Wisconsin to Florida. CB radio was the most helpful and GMRS/FRS was not even a factor and the Ham was my background noise. However, if I were on a Jeep outing, particularly with a group, I would recommend whatever radio they are using. If you are a member of a group and your comm needs have not yet been established, I would highly recommend GMRS, which covers a broader area, works better in areas with competition for radio signals, has more flexibility, and multiple power options. I would also recommend that Jeep clubs consider investing in a GMRS repeater, either fixed or portable. If your budget doesn’t allow for GMRS, then CB. Frankly, while FRS is fine for spotting and such, it is not a good mobile-to-mobile solution. And as much discussion as there is on the Forum about Ham radios, the long and short of it (pun intended) is that Ham radio is in a class all by itself. Every user has to be individually licensed and Ham radio has specific rules of use that may seem onerous to Jeep users.

For the road: CB. For the trail: GMRS. For the hobby: HAM.

Steve
As a fellow HAM I knew you were a HAM after the first paragraph of your write up. Good advice for all I can confirm this information is spot on.

For Jeeping.... short range handy talkies are generally fine. Lots of options of varying legal status are available (depends on your country ... Canada is a bit more relaxed than USA). A 4 watt GMRS handy talkie would get you a 1-2 miles fairly reliably without the need for any install.... throw repeaters in to the mix and even more.
 

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