I'd like to see how you mounted your comms
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2022 RMAX4 XTR, Freedom UTV Glass windshield, Trail Armor UHMW Skids and A Arm Guards
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Drilled holes In the channel above the rear view mirror in the factory top (just the tunnel on the inside not all the way through) and initially used self tappers but it still had some wiggle to it so I used rivets instead for the bracket. Fits nice. The antenna bracket if from RB3 off-road. It’s a bit pricey but honestly for 2” vertical bar mount with an NMO antenna mount there aren’t many options and all are about the same price. This one is very high quality and has a ton of adjustability. I’m likely sacrificing some range for antenna longevity by keeping it below the roof. I Routed the coax above my overhead bags and power down the A post through the firewall. Turned out really clean. Just have to add some switches to finish the deal, hopefully this evening. Mic holder is a gear keeper. Here’s a few pics.Hey folks, I have good idea of how I want to mount all my comms and such... but I'd like to see how you mounted yours. I know there's some pretty talented heads & hands out there
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Mounted my Midland MXT275 GMRS vertically behind the passenger seat headrest and ran mic cord down ROPS to driver right shoulder harness and then down the strap with mic at front of my right shoulder. The radio controls are in the mic so convenient to change any settings. On the radio mount I used a couple of cage bar mounts with a small plate ran vertically. I covered the radio on the top and outside with a piece of black EPDM roofing that gives it weather protection and minimal visibility. The antenna is above bed on the cage, basically behind passenger's head. I can post pictures later if anyone interested.
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I am an amateur radio operator. I run a 2 meter radio in my vehicle. I can't help with radio placement, but if you guys have questions about antennas or antenna placement, I am able to help. I have built my own antennas, and I am knowledgeable of various equipment.
I also am a HAM
KJ7RUK
I have a Yaesu FT-2980R w/cable and ant, and a Midland MXT400VP3, cable/ant... arriving this week.
I'm strongly considering mounting the radios off the front/top rops bar, and the antennas off the rear rops cross bar - opposite sides ... but I wanted to consider what others have done with physical placement also.
I run a FTM300-DR both in my truck (w/Pulse/Larsen ant) and as a base. (Comet GP-6)
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W6RNJ, nice to meet you. You have to get above the roof if you want to clear the ground plane. But an offroad vehicle tends to clip the antennas off. It hurts when you loose an expensive one. Mounting the antenna down will produce a non-omnidirectional pattern. I mount just down from the top so that the spring is lower than the roof. It's a compromise, but it saves the antenna.
Just don't mount the radio where you can hit your head on it.
Just don't mount the radio where you can hit your head on it.
The antenna is 1/4 wave, so yes... I'll have to give it some ground plane.. it's a dual/band, (Comet B-10NMO) but it's only 12" long, which I think will work reasonable well although it's 0db gain for 2m. Playing around with the idea of carrying a 1/2wave whip that I can swap out in the base, if needed... if I need to get out much further. I like the radiation pattern of 1/4 & 1/2 wave as I live in mountainous area.
Actually I misspoke earlier about the Midland GMRS radio.. its a MXT400VP3 with the 3.5" long 'ghost' antenna... intending to mount the antenna just below roof line.
Actually I misspoke earlier about the Midland GMRS radio.. its a MXT400VP3 with the 3.5" long 'ghost' antenna... intending to mount the antenna just below roof line.
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I mounted my Browning 3db 5/8 wave (IIRC) 14" spring whip below roof line on a cage bracket with NMO thru a 10" saw blade (tips ground off & painted). Midland told me the blade is a big enough for ground plane, what do you guys think? is it big enough or should I use a bigger one or a lateral like Papaskeeta mentioned in another thread?
2022 RMAX4 XTR, Freedom UTV Glass windshield, Trail Armor UHMW Skids and A Arm Guards
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According to what I found doing research GMRS antennas needs about 3.5” radius (7” circle) for a ground plane.
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For those of you following this thread who might not understand what we are talking about, I will try to explain the details. Think of the signal coming off the antenna as a gigantic doughnut. The volume of the doughnut can't change unless you increase the power to the antenna. The only thing we can do to the doughnut is manipulate it's shape.
Smaller antennas like 1/4 wave or shorter form the doughnut into more of a ball shape (see image, purple shape), like squishing the doughnut inwards. This is better in mountains and canyons, because you will be radiating power upwards and downwards, but at the expense of range. Longer, larger antennas like 1/2-green, 5/8- red or even full wave, tend to flatten the doughnut, like smashing it thinner, but this makes the circumference larger, giving you longer range at the expense of signal at higher or lower angles. These are great for open areas, like desert or corn fields.
A ground plane is a horizontal conductive surface that reflects radio waves, basically launching them outward. The higher the frequency, the smaller the ground plane needs to be. You need about ¼ wavelength in ground plane, any larger will not increase your performance. For example, GMRS is 462 Mhz I think, so a ¼ wave is about 6” in diameter. I operate on the 2m band (146Hhz), which is a lot lower frequency, so my ¼ wave is like 19”. I am not going to drive around with a pizza dish, luckily my roof is metal.
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Smaller antennas like 1/4 wave or shorter form the doughnut into more of a ball shape (see image, purple shape), like squishing the doughnut inwards. This is better in mountains and canyons, because you will be radiating power upwards and downwards, but at the expense of range. Longer, larger antennas like 1/2-green, 5/8- red or even full wave, tend to flatten the doughnut, like smashing it thinner, but this makes the circumference larger, giving you longer range at the expense of signal at higher or lower angles. These are great for open areas, like desert or corn fields.
A ground plane is a horizontal conductive surface that reflects radio waves, basically launching them outward. The higher the frequency, the smaller the ground plane needs to be. You need about ¼ wavelength in ground plane, any larger will not increase your performance. For example, GMRS is 462 Mhz I think, so a ¼ wave is about 6” in diameter. I operate on the 2m band (146Hhz), which is a lot lower frequency, so my ¼ wave is like 19”. I am not going to drive around with a pizza dish, luckily my roof is metal.
2022 RMAX4 XTR, Freedom UTV Glass windshield, Trail Armor UHMW Skids and A Arm Guards
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Great info! I’ve been in Fire and EMS long enough to pick up most of the information you posted above but I’m in the dark on NGP antennas. So what about a base loaded NGP (no ground plane) antenna for things such as boats and ATV’s without any substantial metal surfaces for mounting? What’s the science behind them? It’s exactly what I have but I’m clueless how it works. Mine is a 1/2 wave base loaded NGP antenna.
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No ground plane / dipole antennas do not need, nor should have a ground plane. They require a special coax to simulate a ground plane. These are usually used on boats which use the ocean as the ground plane. The performance is less than a ground plane antenna. What frequency do you use?
2022 RMAX4 XTR, Freedom UTV Glass windshield, Trail Armor UHMW Skids and A Arm Guards
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GMRS so 460’s
I believe in practice your ground radials should be 1/4 wl. 1/4 wave at 460mhz is 6.4"... and the standard is looking at 6" extended from vertical mount.. so a ground plane that is 12x12 would be ideal.
Did you tune the install with a SWR/PWR meter?
VA3CGT Ontario, Canada. No radios in my machine yet.
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You are correct, it is 6" radius, not diameter.
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I think I understand the idea and your explanation, however, and here is were I am probably off track ha..... if I have a 5/8 wave does that mean then that my GP should be 2.5 times as big as a 1/4 wave since it appears you are using some basic math logic? 6.4" x 2.5 = 16" R = 32" dia or sq GP. ??? Or does the ground radial stay the same at the whatever frequency regardless of the vertical?
No sir did not tune it. I had a friend's SWR CB meter but understood it would not work on GMRS frequency. And over the months have forgotten to get that done. I do recall that that money for a proper meter is probably the best transmit money you can spend. Correct?
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