How well are your low profile CB/GMRS antennas so close to windshield working

[chorky]

Seems the best place to mount CB/GMRS antenna is right on the front of the windshield since many companies, including Mopar, make mounts for them or lights or both. Of course the optimum location would be drilling a hole and mounting on the roof, but that would also require a alum or steel sub plate for proper ground pane, and might not work with the Alu-Cab or some other type of roof mount rack with stuff.

So I am curious what sort of range and signal quality folks are getting with their radios and mounting on the front cowl or near about... I am also curious if anyone has measured the distance from that to the driver or passenger to see if it is too close for radiation exposure (probably is just fine).

Taller antennas probably work better, but are those with short stubby ones happy with their performance? Has anyone tested to see if you can get the max advertised range of the radio you chose with the stubby's and having the big radio wave block (windshield)?

Looking forward to hearing how folks like or dislike their chosen mount location

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[ArmyMP]

I get out about 60 miles on my GMRS. CB is meh... not enough people on for a radio check.


WRPK996

 

[Trout Safari]

I am looking at possibly putting mine on the front bumper. I like the looks of these.
https://www.gme.net.au/au/antennas/

 

[wv_gladiator]

What did you say?

 

[chorky]

I get out about 60 miles on my GMRS. CB is meh... not enough people on for a radio check.


WRPK996

CB is still the primary option around here for most groups but I like having both.

60 miles? What's your set-up? Can't say I have known anyone, even on other forms, to get that kid of range unless your running a true wave antenna on the top of the rig with a solid ground pane.

 

[ArmyMP]

CB is still the primary option around here for most groups but I like having both.

60 miles? What's your set-up? Can't say I have known anyone, even on other forms, to get that kid of range unless your running a true wave antenna on the top of the rig with a solid ground pane.

I'm running a 40w midland mxt400 on high power through RG8X and a 5/8th wave Larsen antenna.

 

[chorky]

I'm running a 40w midland mxt400 on high power through RG8X and a 5/8th wave Larsen antenna.

Got it that makes more sense. I'm looking at running a 275 and mounting under the dash. it would be great to have the 400 power living in the mountains but I would like to have it not exposed and cluttered.

Is your antenna mounted on the cowl in front of the windshield like most? Have you tested performance to the rear of the JT to see how that placement affects it?

 

[ArmyMP]

Got it that makes more sense. I'm looking at running a 275 and mounting under the dash. it would be great to have the 400 power living in the mountains but I would like to have it not exposed and cluttered.

Is your antenna mounted on the cowl in front of the windshield like most? Have you tested performance to the rear of the JT to see how that placement affects it?

I'm on a driver's side nmo cowl mount. With 400w at the back and a 5/8 antenna where I put it on the jeep didn't really make a difference.

 

[Josh00333]

Have to clarify this for googling people later.

Need much more info Army.

Gmrs is a very short wave, UHF and VHF are similar, it will not wrap bounce or do much more than line of site. HF 2m HAM can do cool things.

If you got 60 miles there is a geographical reason for it, high peak to high peak, bouncing off a repeater set high etc.

no mater the wattage, antenna radio etc gmrs will not normally go past the horizon of line of site.

6’ tall line of sight is apx 6miles due to the curveature of the earth. That is all that should be expected on flat territory (big lake be best). Mountains canyon etc will all effect actual range. You may get 60 miles off one side of a mountain broadcasting out over a valley and not be able to take to some one 1m away with a peak of granite between you.

that said you can easily talk to the ISS when it’s over head, due to line of sight.

to the OP question, jeeps fiberglass/soft top does not infer much and the window frame roll bar has little to no practical impact.

I get out about 60 miles on my GMRS. CB is meh... not enough people on for a radio check.


WRPK996

 

[chorky]

Have to clarify this for googling people later.

Need much more info Army.

Gmrs is a very short wave, UHF and VHF are similar, it will not wrap bounce or do much more than line of site. HF 2m HAM can do cool things.

If you got 60 miles there is a geographical reason for it, high peak to high peak, bouncing off a repeater set high etc.

no mater the wattage, antenna radio etc gmrs will not normally go past the horizon of line of site.

6’ tall line of sight is apx 6miles due to the curveature of the earth. That is all that should be expected on flat territory (big lake be best). Mountains canyon etc will all effect actual range. You may get 60 miles off one side of a mountain broadcasting out over a valley and not be able to take to some one 1m away with a peak of granite between you.

that said you can easily talk to the ISS when it’s over head, due to line of sight.

to the OP question, jeeps fiberglass/soft top does not infer much and the window frame roll bar has little to no practical impact.

Which is why in my area a lot still use CB with a longer wavelength that 'can' bounce up and over hills.

How does the window frame not impact the signal going rewards of the Jeep? Its taller than most antennas and should prevent the signal even going that way very far.. Thats why it's always best to use a roof mount. I get the fiberglass not being an issue due to being 'invisible' to UVH but the windshield frame I would think would be a big obstruction.

 

[Josh00333]

From what I read at mygmrs.com there just isn't enough metal there to mess with it. 95% of it is a window.

Stand at your ant, and look, if your top was off how much can you see through, almost all of it.

 

[ArmyMP]

Have to clarify this for googling people later.

Need much more info Army.

Gmrs is a very short wave, UHF and VHF are similar, it will not wrap bounce or do much more than line of site. HF 2m HAM can do cool things.

If you got 60 miles there is a geographical reason for it, high peak to high peak, bouncing off a repeater set high etc.

no mater the wattage, antenna radio etc gmrs will not normally go past the horizon of line of site.

6’ tall line of sight is apx 6miles due to the curveature of the earth. That is all that should be expected on flat territory (big lake be best). Mountains canyon etc will all effect actual range. You may get 60 miles off one side of a mountain broadcasting out over a valley and not be able to take to some one 1m away with a peak of granite between you.

that said you can easily talk to the ISS when it’s over head, due to line of sight.

to the OP question, jeeps fiberglass/soft top does not infer much and the window frame roll bar has little to no practical impact.

I live in Indiana, so pretty flat. I can occasionally pick up the Indy 600 repeater in Richmond and can transmit on the repeater from Spiceland. So I get up to 60 miles as the crow flies. But I'm also not running bubble pack gmrs junk.

 

[chorky]

Have to clarify this for googling people later.

Need much more info Army.

Gmrs is a very short wave, UHF and VHF are similar, it will not wrap bounce or do much more than line of site. HF 2m HAM can do cool things.

If you got 60 miles there is a geographical reason for it, high peak to high peak, bouncing off a repeater set high etc.

no mater the wattage, antenna radio etc gmrs will not normally go past the horizon of line of site.

6’ tall line of sight is apx 6miles due to the curveature of the earth. That is all that should be expected on flat territory (big lake be best). Mountains canyon etc will all effect actual range. You may get 60 miles off one side of a mountain broadcasting out over a valley and not be able to take to some one 1m away with a peak of granite between you.

that said you can easily talk to the ISS when it’s over head, due to line of sight.

to the OP question, jeeps fiberglass/soft top does not infer much and the window frame roll bar has little to no practical impact.

Having a high DB gain also decreases the height variability of the wavelength too. Most antennas seem to be at least 3db gain... I live in very hilly mountainous terrain, so would much prefer no gain - also the reason for my concern of the only 'easy' mounting location of along the cowl or hood.

I had thought a few years ago about going 2m/70cm - but I have too many other hobbies at the moment to do that right now. Maybe in the future... I do like the APARS options of some of the radios though!

As for fiberglass not interfering - well that's cool and all, but to add another level of complication I am putting a Alu-Cab on. So, that certainly would cause impact. I am considering the idea of installing antennas on top of the alu-cab but that has other complications then of wire routing and whether or not to drill holes.

Also under consideration is having a steel or alum plate fabricated to go under the front seats top area to act as a good ground pane, and drilling and mounting antennas right above the center console essentially. Only concern for that is then the proximity of antenna and radiation to my head when transmitting.

 

[Radio Guy]

I don't usually do low profile antennas except for a few models of the COMPACtenna, which can work better than a full 1/4 wave whip in some cases. I have two NMO trunk lip mounts on the hood near the hinges and do a lot of 2m and 440 amateur with some occasional GMRS.

My main antenna is a large Larsen dual band 2m/440 amateur version and it works very well with great range, similar to when I had it roof mounted on another truck. My other mount sees various antennas from a 6" whip for GMRS to a 9.5" tall multiband COMPACtenna and several others and they all work well on the hood. I briefly tested an NMO mount CB antenna on the hood mount and it tuned up fine but I haven't used it enough to rate it for range.

In my opinion the NMO trunk lip mount on a hood is probably the best place for an antenna on a JT, you don't have many other good choices. I would avoid the small plastic low profile "pud" antennas for GMRS, there is simply no reason for them on a JT when a very thin flexible 6" long 1/4 wave whip will outperform it and survive much better on the trails. If something smacks or grabs your pud antenna it can rip the mount right off the truck. A 6" NMO whip will simply bend over flat and return to its original shape with no damage under the same circumstances.

Once you have an NMO mount on the truck you can collect different antennas for different purposes like a 6" 1/4 wave spike for GMRS on the trails when everyone is close range and you don't need maximum distance. Then swap it out for a 2-3ft tall 5/8 over 5/8 wave colinear for maximum distance down the highway simplex or to a very distant repeater.

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