New to radio: GMRS mobile antenna - ground plane?

[SIO2GA]

Hi Everyone,
I am totally new to radios. I bought a wouxun KG1000-G Plus 50 watt mobile GMRS radio , a midland cable with NMO connector, and a matching 5/8 wave over 5/8 wave "no ground plane" midland antenna. I will be on GMRS channels that are 462 - 467 Mhz.
I bought everything from "buy two wave radios" who wouldn't answer my question about if the antenna should be grounded when I bought the antenna, and when I bought the $400 radio I asked the same question again in the notes section. They ignored the question both times and I didn't get a response.
I took it to a shop that does CB radios only to have the system installed. I think my mounting bracket that the antenna is mounted on is not grounded and that my antenna isn't grounded aside from the coax it is connected to. I wrote "I think" because the bracket is screwed into the a pillar with two painted screws. So it may be grounded but poorly. I'm not sure if the nmo mount, which is attached to the powder-coated bracket is actually electrically connected to the bracket if it happens to be poorly grounded.
My first question is: should I ground the mounting bracket and should I then make sure the NMO mount is grounded to the bracket?
The radio seems to be putting out a decent signal as I was able to be heard by my daughter with a handheld GMRS radio when I was almost 6 miles away. And the signal had to go through acres of woods and across gently rolling hills of middle Georgia. It wasn't flat land but definitely not mountains or huge hills.

My second question is: Should I make a ground plane using a copper plate under the NMO mount? If so, what is the minimum size? While the 5/8 over 5/8 wave antenna is the "no ground plane" type, where it is mounted is a good distance away from any metal underneath. It's probably 5" away from the hood of the Jeep. It's mounted on a "Ditch Light Bracket" via an extension bracket. I'd like to make sure that I am putting the strongest signal possible and I have bought a 8 x 8 copper plate and a 12 x 12 copper plate to fashion a ground plane with. Anything over 7 x 7 will be awkward to fit but I can make it work. If I use a 12 x 12" radius plate I will likely have to remove the antenna to open the hood.
I'm not opposed to going with a different style antenna. While I live in Georgia I go out to Arizona in the Payson area which has mountains, and the area near Blythe California that has mountains. So I'll be on very flat desert plains at times but also in the mountains at times. I got the radio to communicate with my daughter who'll be in the truck while I am out exploring and carrying a hand held radio. I will also have friends out exploring that I'll want to communicate with.
I discovered this forum and thought that I would ask this question here because you all will certainly have the answers. Please remember that I literally know almost nothing about radios. I've read a lot over the last couple of weeks but the antenna thing is beyond me being able to easily figure out. Thanks in advance for any help.
Attached is pictures of the antenna set-up. Supposedly the curved body piece that is immediately under the antenna is plastic - which I didn't know when I came up with this set-up. I figured that I would add a copper plate under the antenna anyways. Most of you will know that the Jeep Gladiator is nearly identical to the Jeep Wrangler and that the roof is plastic sections that come apart in 3 pieces.

 

[ENGINEERCARL1]

5/8 wave antennas do require a ground plane, and with that mount I'd be hard-pressed to find a ground plane on that. I wouldn't even both trying to fashion up a copper plate to put underneath it...that would just look janky.

While the mount may be plastic, the NMO mount is connected to the shield of the coax, which is tied to case of the radio. So it is grounded electrically, but poor RF-wise.

IMHO you'd be better off with a half-wave antenna that requires no ground plane. You already have 50w with a mobile radio, and your coverage considerations between the Jeep and the HT are more limited to the range of your HT than your choice of 5/8 vs 1/2 wave antenna (assuming simplex comms).

EC

 

[SIO2GA]

I'm really interested in setting up a ground plane, looks aside. I probably will only have it mounted for when I make my trip out West. I probably should have mentioned that one concern is if I get stuck or break down that I want to be able to get my signal out as far as possible. I go exploring on BLM and National Forest land where often there is no cell phone signal at all. Reaching someone for help will likely save 10 to 20 miles of walking. The areas near Quartzsite and Blythe (Wiley Wells Road) is teeming with folks in Jeeps and side by sides and most have GMRS radios now. I've seen the argument before that a CB or GMRS radio is a poor plan compared to a satellite radio, but in the areas I go to there are lots of helpful Jeeps and off-roaders that are close by and equipped and usually willing to help. So I want to be able to be able to put out a signal as far reaching as possible. I've read in several places that the "no ground plane" radios do benefit from having a ground plane but I don't know if that's really true. I'm also willing to change antennas and make a ground plane to get the most range.
I posted a picture of my new set-up on a Jeep forum and people were commenting about how due to it being over a curved plastic piece and a long ways from any metal to form a ground plane. So that got me to wondering what I should do to improve it.
I'll eventually add a camper shell/top to the back, where a copper plate won't look bad or even be visible. But decent ones are around $4000 and aren't an option for the next year or so.

 

[mmckenna]

I agree with Carl above.

Hi Everyone,
I am totally new to radios. I bought a wouxun KG1000-G Plus 50 watt mobile GMRS radio , a midland cable with NMO connector, and a matching 5/8 wave over 5/8 wave "no ground plane" midland antenna.

A link to the webpage of the actual antenna you purchased would be helpful, just to confirm. 5/8th's over 5/8th's isn't usually a "no ground plane" antenna design.

I bought everything from "buy two wave radios" who wouldn't answer my question about if the antenna should be grounded when I bought the antenna, and when I bought the $400 radio I asked the same question again in the notes section. They ignored the question both times and I didn't get a response.

That's a bad sign. But likely they didn't know the answer. Wouldn't be surprising.

My first question is: should I ground the mounting bracket and should I then make sure the NMO mount is grounded to the bracket?

Yes. A multimeter or basic continuity tester is your friend.

Do keep in mind that DC ground is different than an RF ground plane. A DC ground is good, but you want to make sure you have an RF ground plane.

While the "no ground plane" type antennas do not -require- a ground plane, they will work better with one.

The radio seems to be putting out a decent signal as I was able to be heard by my daughter with a handheld GMRS radio when I was almost 6 miles away.

That's a good sign. Limitations on the distance was likely due to the hand held radio and its antenna.

My second question is: Should I make a ground plane using a copper plate under the NMO mount? If so, what is the minimum size?

I think it would look pretty dorky. My opinion and that should not have any impact on the decision you make. Yes, it would work.

A proper ground plane for these frequencies would be 12 inches in diameter with the antenna mounted in the center. That's going to look pretty awful. Jeeps are difficult vehicles to mount antennas on. Looks like a nice Jeep and I wouldn't go mounting a ground plane on the bracket like that.

Send us a link to the actual antenna and we can probably provide more info.

Don't get too hung up on this. Your distance limitations are going to be from the hand held radio and it's poor antenna. Remember, it's TWO way radio. Both radios/antennas matter in the equation.

 

[ENGINEERCARL1]

If you're concerned about safety and self-rescue where cellphones aren't reliable, go get an inReach and throw it in the glove compartment. Depending on ANY radio for rescue unless you KNOW there's someone on the other end is unwise.

 

[SIO2GA]

I agree with Carl above.



A link to the webpage of the actual antenna you purchased would be helpful, just to confirm. 5/8th's over 5/8th's isn't usually a "no ground plane" antenna design.



That's a bad sign. But likely they didn't know the answer. Wouldn't be surprising.



Yes. A multimeter or basic continuity tester is your friend.

Do keep in mind that DC ground is different than an RF ground plane. A DC ground is good, but you want to make sure you have an RF ground plane.

While the "no ground plane" type antennas do not -require- a ground plane, they will work better with one.



That's a good sign. Limitations on the distance was likely due to the hand held radio and its antenna.



I think it would look pretty dorky. My opinion and that should not have any impact on the decision you make. Yes, it would work.

A proper ground plane for these frequencies would be 12 inches in diameter with the antenna mounted in the center. That's going to look pretty awful. Jeeps are difficult vehicles to mount antennas on. Looks like a nice Jeep and I wouldn't go mounting a ground plane on the bracket like that.

Send us a link to the actual antenna and we can probably provide more info.

Don't get too hung up on this. Your distance limitations are going to be from the hand held radio and it's poor antenna. Remember, it's TWO way radio. Both radios/antennas matter in the equation.

Hi Mmckenna, the antenna is a Midland MicroMobile MXTA26 that is a 5/8 over 5/8 wave no ground plane. There was lots of people that had good things to say about it, especially when coupled with the matching connecting cable mount. The link to the Midland website has photos of this antenna in places where it is far from the metal of the jeep, which gave me confidence that it would work at least okay. Midland MicroMobile MXTA26 6DB Gain Whip Antenna

I think that Laird or Larsen also makes this same style antenna but found that out after I'd already bought the Midland model. I've read that the stacked 5/8 wave antennas are not good for if someone is higher or lower in elevation (mountain of valley). At times I'll be leaving the truck and hiking and will have a significant difference in elevation from my daughter in the truck , so I'm thinking it might be better to go with something else . ENGINEERCARL1 mentioned going with a 1/2 wave and I'm guessing that was related to avoiding the problems the stacked 5/8 wave antennas have with communicating with folks at a different elevation.

I should have mentioned in the original post that I want the strongest signal going out as possible for reasons beyond communicating with my daughter in the truck by using a hand held. Two of the main areas that I go to are a long way from houses or cell reception. But there are usually lots of people in Jeeps and side by sides that have GMRS radios. The place at Wiley Wells road not far from Blythe, California, has a campground in the middle of nowhere. No electricity, water, or cell reception but usually at least 4 or 5 camp sites that are occupied that are about 20 miles from a paved road or a regularly maintained dirt road. The locals collectively bought an old motor grader and scrape the roads twice a year.
The problem with a sat phone or an inreach is that it might save me walking 20 miles, but I still will have a stuck or broke down vehicle in the middle of nowhere. Getting in touch with local Jeep folks is what will get me pulled to pavement or out of a (deep!) ditch. I've not gotten stuck in Western states but I've found out that in Georgia that if someone is stuck that it does no good to call wrecker companies because they all refuse to take the wreckers off-road due to lack of insurance coverage. There's Matt's offroad recovery that has some entertaining rescue videos, but he or a similar outfit are mighty expensive! The Jeep community is very helpful and contacting someone in the area will be the ticket to getting help within hours compared to perhaps days if I am only able to contact someone that could post my predicament on an online forum and ask for help. So I really do want to have the strongest signal possible to be able to contact people that are in the area.
I'll only mount the copper plate when I'm heading out west and for that 2 weeks I won't care how it looks. But a smaller plate, say 8" radius would be easier to deal with than a 12 inch radius. Would a 1/2 wave antenna with a 12 inch ground plane be a huge improvement over the 1/4 wave with 8" radius? I've already bought both a 8 x 8 and a 12 x 12 copper sheet to make them with.

 

[mmckenna]

The link to the Midland website has photos of this antenna in places where it is far from the metal of the jeep, which gave me confidence that it would work at least okay. Midland MicroMobile MXTA26 6DB Gain Whip Antenna

Thanks for the link.
No where in the specs does it claim to be a ground independent antenna, and 5/8th's wave designs are not.

Midland isn't always very accurate with their information. They are trying to sell radios/antennas to people that are not radio/antenna people. Consumer oriented marketing is often lacking in accuracy.

I think that Laird or Larsen also makes this same style antenna but found that out after I'd already bought the Midland model. I've read that the stacked 5/8 wave antennas are not good for if someone is higher or lower in elevation (mountain of valley).

Right, it compresses the radiation pattern into a more flat plane and directs the RF energy towards the horizon. Not the best application if you are trying to hit a repeater high above you, or if you are on a mountain top and trying to reach someone way below you.
Yes, it'll probably work fine for most, but there is no one antenna that works best for all applications. The nice thing is that the NMO mount makes it super easy to swap out antennas based on your needs.

At times I'll be leaving the truck and hiking and will have a significant difference in elevation from my daughter in the truck , so I'm thinking it might be better to go with something else . ENGINEERCARL1 mentioned going with a 1/2 wave and I'm guessing that was related to avoiding the problems the stacked 5/8 wave antennas have with communicating with folks at a different elevation.

I think his recommendation for a 1/2 wave antenna was based off the fact that a 1/2 wave antenna does not require a ground plane. For your application, that may work better.

A half wave will also not focus the radiation pattern into a flat plane like the higher gain antennas, and MAY work better in some applications.

For what you are doing, unless you are thousands of vertical feet above or below your Jeep, you are unlikely to run into any major challenges with this. If you do, you probably need a better hand held radio with a more efficient antenna. Or, practice with your hand held radio skills to find what works better.

I should have mentioned in the original post that I want the strongest signal going out as possible for reasons beyond communicating with my daughter in the truck by using a hand held. Two of the main areas that I go to are a long way from houses or cell reception. But there are usually lots of people in Jeeps and side by sides that have GMRS radios.

The higher gain antenna can help with that, in some applications. Not every application. Like I mentioned above, there is no one antenna that is right for every application.

Antenna gain will help give you a bit more range in SOME applications. It isn't necessarily going to get you through to someone where a lower gain antenna won't. Usually it comes down to a tiny bit more range, or a slightly clearer signal when out on the very fringes. Based on your use case, being on the "very fringes" sounds like where you are sometimes, so maybe having two antennas might be a good choice.

As for range, when I was more active on GMRS, I had a 1/4 wave UHF antenna (about 6 inches tall) mounted dead center on the roof of a full sized truck. My brother was in a full size SUV with a 1/4 wave UHF antenna mounted dead center on the roof. We were at about 17 miles between us before we lost contact, and that was only because a mountain got in the way.
High gain doesn't solve everything, but it can help a little bit. If that little bit is worth carrying two antennas, then go for it.

The other big issue with GMRS, or really any radio service:
Most people have no clue how they work, how to program them, or how all the features interact. That is a -very- common issue in the off road/UTV crowd. People buy these radios based on feed back from others, but rarely take the time to understand how they work.
Making random contacts on GMRS can be difficult:
22 possible channels they could be on.
There's something like 65 total CTCSS tones if you add in the "non standard" ones. There's also something like 224 DCS tones (including normal and inverted codes).
That works out to 6358 or so possible combinations of channels/squelch codes that you'd have to contend with to cover all possibilities.
6358 possibilities, plus:
Is their radio turned on?
Is the volume turned up?
Are they paying attention?
Is their power/antenna setup sufficient to hear you?
Are they willing to help/answer you? (Don't assume they will, I've had issues with this….)

So, don't put all your reliance on GMRS/Hobby radio services for -any- type of emergency. The correct tool for an emergency in the back country is a satellite phone, a PLB, or a device like the Garmin InReach.
When in the back country working, I've got a lot of radios in my work truck on radio systems I'm allowed to use, plus GMRS, plus MURS, plus amateur radio, plus my work satellite phone, plus the possibility of hiking to a place where the cell phone will work. I still carry a Garmin InReach with me. And I've used it when getting a truck stuck in the middle of nowhere Nevada.
I won't ever go out on the fringes without it.

The problem with a sat phone or an inreach is that it might save me walking 20 miles, but I still will have a stuck or broke down vehicle in the middle of nowhere. Getting in touch with local Jeep folks is what will get me pulled to pavement or out of a (deep!) ditch

See above, 1 ton truck buried to the frame in mud. Garmin InReach dispatcher contacted an off road towing service for me and had me out and on the road. $8/month for the Garmin service.

There's Matt's offroad recovery that has some entertaining rescue videos, but he or a similar outfit are mighty expensive!

Mine experience with another company was just under $3K, but cheaper than a new truck. Considering the crew, distance they drove and the equipment they showed up with, it was a bargain.

The Jeep community is very helpful and contacting someone in the area will be the ticket to getting help within hours compared to perhaps days if I am only able to contact someone that could post my predicament on an online forum and ask for help. So I really do want to have the strongest signal possible to be able to contact people that are in the area.

Understood, and that's a good reason to have a properly working radio. But don't rely on GMRS. Or CB. Or amateur radio. Relying on hobbyists in an emergency is not a good idea. Too many variables for me to be comfortable with, and I do this radio stuff for a living. A $9,000 Harris multiband public safety grade radio in my F350 did absolutely nothing to get me help when I was stuck.

I'll only mount the copper plate when I'm heading out west and for that 2 weeks I won't care how it looks. But a smaller plate, say 8" radius would be easier to deal with than a 12 inch radius.

Smaller ground plane is going to reduce effectiveness. You may also run into trouble getting your antenna to tune up correctly. I know Midland claims their antennas are "pretuned at the factory", but that's a load of BS. Proper antenna tuning depends on exact mounting location. There is no such thing as "pretuned". They've ball parked it close enough for many, and then they rely on most users not having an antenna analyzer or SWR meter. Yours might be right on, or it could be off. Probably not enough to make a huge difference, but if you are looking for every last inch of coverage, Chinese radios, "pretuned" antennas, less than ideal mounting locations, wrong antenna, that all adds up.
Not trying to tell you that you need to toss all this gear and start fresh, just saying don't get too hung up on all these variables unless you are going to tackle the entire system. Really, you should have more than a GMRS license/radio if you want to do this right. Not every off roader is using GMRS. Some still use CB. Plus, if you are not accessing GMRS repeaters or amateur radio repeaters, there's still a lot you could be doing.

And don't overlook improving your hand held radio situation. That'll help your range, and in the event you need to abandon your Jeep, having something you can take with you would be wise. That could be a better GMRS hand held, or the above mentioned satellite devices.

Also, don't overlook that many newer IPhone or Android devices now have satellite messaging capability built in. That can be a much more useful tool that you may already have (or may soon upgrade to).

Would a 1/2 wave antenna with a 12 inch ground plane be a huge improvement over the 1/4 wave with 8" radius? I've already bought both a 8 x 8 and a 12 x 12 copper sheet to make them with.

1/2 wave with a 12 inch diameter ground plane should out perform a 1/4 wave antenna on a less than ideal ground plane.

But, having the antenna mounted up close to the windshield on your jeep is going to impact performance. That metal in close proximity to the antenna can detune it, and/or cause it to be directional away from it. But with a jeep, you don't have a whole lot of options so do what you can with what you have.

 

[prcguy]

A trunk lip mount on the hood near a hinge will provide adequate ground plane for most antennas. No ground plane type antennas will radiate better when mounted on a ground plane. A 5/8 over 5/8 definitely has a compressed pattern at the horizon with less signal up in the air and may not work as well as a 1/4 whip when talking from the base of a tall mountain to the top, but its usually just a degradation and not a failure to communicate to the mountain top.

If you lived, worked and played at the base of a 5,000ft mountain and needed to talk to the top all the time then a 1/4 wave whip might be a better choice. If you live, work and play mostly in the flatlands and occasionally have the base to mountain top comms then I would stick with the higher gain at the horizon 5/8 over 5/8. Or do what I do, have one of each and swap when needed.

 

[ENGINEERCARL1]

mmckenna makes some excellent points in his reply. I wish more GMRS users would read (and heed) what he had to say.

He was right: I specified the 1/2 wave antenna because of the option of forgoing the ground plane. That at least would make your mount look tidy. And it would be valuable to have perhaps more than one antenna.

Were it me in that situation, I’d perhaps stow a 5 foot piece of mast, a 4 element UHF beam, coax and bungee cords. If I was so unfortunate to have stuck myself in a place where the vertical didn’t work, I’d plug in the beam and point it where I thought there would be people. But I’d be doing that to kill time while I awaited whomever I had summoned via other means.

Always have a backup plan, even if it’s the satellite capability of my iPhone.

Either way, you’re 90% of the way there. I’d be interested in hearing an after-action of how it did work for you out in the dirt.

EC