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Mounting GMRS antenna

AggieJeep

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No way I'm transmitting UHF 25watts through a gain antenna inside my cab with the antenna placed near my head? Buy a bracket and put it on the fender or use a handheld.
you should research EM radiation and Inverse Square Law fundamentals. 25 watts many inches from your head is baking your noodle less than the cell phone is at your ear.
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prerunner1982

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@mx5red. Thank you, I knew I had seen it but couldn't find it myself. I thought it was the "ghost" antenna but obviously it's not.
 

49Gramps

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On the hardtop, how would putting that little mag mount on one of the hardtop bolts behind the back seat?
 

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Mounting an antenna as in post # 78 or on the inside of the cab behind the back seat will grossly exceed FCC limits for anyone sitting in the back seat when fed 25 watts of power in the VHF or UHF bands. Even a 5 watt VHF or 4 watt UHF radio used normally where the whip sits 2 to 3" away from your head is right at the maximum exposure for informed persons like amateur operators, law enforcement, etc. Hand the same radio to an uninformed user and it will grossly exceed the limits since there are two different limits for the two different groups.

you should research EM radiation and Inverse Square Law fundamentals. 25 watts many inches from your head is baking your noodle less than the cell phone is at your ear.
 

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AggieJeep

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Mounting an antenna as in post # 78 or on the inside of the cab behind the back seat will grossly exceed FCC limits for anyone sitting in the back seat when fed 25 watts of power in the VHF or UHF bands. Even a 5 watt VHF or 4 watt UHF radio used normally where the whip sits 2 to 3" away from your head is right at the maximum exposure for informed persons like amateur operators, law enforcement, etc. Hand the same radio to an uninformed user and it will grossly exceed the limits since there are two different limits for the two different groups.
Not sure why you quoted me to reference a different post than what I replied to. Those were different installs and the ISL affecting exposure levels would differ quite a bit. The details get complicated and even experts donā€™t agree. As an extra class ham and former broadcast engineer I just donā€™t consider typical mobile comma solutions as alarmingly dangerous. RF exposure is not like ingesting poisons that your body canā€™t process or cleanse; it doesnā€™t keep stacking up. Iā€™ve known far too many OLD tower guys that spent their careers climbing around very high power antenna systems and had no health issues. They would usually get a dose in one day than the rest of us are likely get over a lifetime.

Do what you can to mitigate exposure for all RF environments but I do feel we have bigger issues to worry over than GMRS.
 

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Sorry about the different posts referenced. I have a calibrated Narda RF survey meter and make actual measurements on amateur, commercial, GMRS, etc, antennas and the real levels can be quite different than calculated. Most of the time its much lower than calculated but sometimes it goes the other way and can be technically dangerous for long key down periods.

I'm also a hamster and retired satellite broadcast engineer.

Not sure why you quoted me to reference a different post than what I replied to. Those were different installs and the ISL affecting exposure levels would differ quite a bit. The details get complicated and even experts donā€™t agree. As an extra class ham and former broadcast engineer I just donā€™t consider typical mobile comma solutions as alarmingly dangerous. RF exposure is not like ingesting poisons that your body canā€™t process or cleanse; it doesnā€™t keep stacking up. Iā€™ve known far too many OLD tower guys that spent their careers climbing around very high power antenna systems and had no health issues. They would usually get a dose in one day than the rest of us are likely get over a lifetime.

Do what you can to mitigate exposure for all RF environments but I do feel we have bigger issues to worry over than GMRS.
 

AggieJeep

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Sorry about the different posts referenced. I have a calibrated Narda RF survey meter and make actual measurements on amateur, commercial, GMRS, etc, antennas and the real levels can be quite different than calculated. Most of the time its much lower than calculated but sometimes it goes the other way and can be technically dangerous for long key down periods.

I'm also a hamster and retired satellite broadcast engineer.
Agreed. Radiation patterns are affected by so many factors that there is a rather large ā€œartā€ aspect to this ā€œscienceā€. Iā€™m wise enough to know not to lick an antenna but do figure Houston traffic will kill me before I cook my innards. :)
 

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I got the 3db Midland Ghost antenna mounted to a cowl mount from CoolTech LLC

Jeep Gladiator Mounting GMRS antenna 20210404_201753
Jeep Gladiator Mounting GMRS antenna 20210404_201753
How's that stubby antenna do? Do you get decent range with it?
 

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I've got a new Mojave and found a trunk lip mount works fine on the rear edge of the hood either side of the hinges where there is a reasonably flat spot. Its a much better location than a cowl mount that is below hood level and it gives you the entire hood as a ground plane. I also lined the plastic cowl parts between the hood and windshield with wide aluminum tape which makes contact and grounds to the vehicle body. That extends the ground plane another several inches towards the windshield. I'm also going to bond across each hood hinge with some wide flexible braid to ground the hood which can reduce spark plug noise on CB and HF.

I used trunk lip mounts from Laird in all black which are a very small footprint and look ok on the hood. Long antennas point outward a few degrees from vertical and I will simply put a slight bend in the whips. For a stubby UHF antenna you would never notice the angle. Here are the Laird mounts I found cheap on Ebay. https://www.ebay.com/itm/153412489927?ssPageName=STRK:MEBIDX:IT&_trksid=p2060353.m2749.l2649
 

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How's that stubby antenna do? Do you get decent range with it?
Still not been able to do long range testing. It handily beats the import handhelds that we used, but havenā€™t done range testing yet. Other friends did ham so still havenā€™t had a chance to put it through the paces. Will report more once summer gets into the swing here.
 

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I've got a new Mojave and found a trunk lip mount works fine on the rear edge of the hood either side of the hinges where there is a reasonably flat spot. Its a much better location than a cowl mount that is below hood level and it gives you the entire hood as a ground plane. I also lined the plastic cowl parts between the hood and windshield with wide aluminum tape which makes contact and grounds to the vehicle body. That extends the ground plane another several inches towards the windshield. I'm also going to bond across each hood hinge with some wide flexible braid to ground the hood which can reduce spark plug noise on CB and HF.

I used trunk lip mounts from Laird in all black which are a very small footprint and look ok on the hood. Long antennas point outward a few degrees from vertical and I will simply put a slight bend in the whips. For a stubby UHF antenna you would never notice the angle. Here are the Laird mounts I found cheap on Ebay. https://www.ebay.com/itm/153412489927?ssPageName=STRK:MEBIDX:IT&_trksid=p2060353.m2749.l2649
Do you have a picture of your setup? I'm having trouble picturing where you could do this and have it not prevent you from opening the hood.
 

Mikey_89

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I bought the Midland package, about a month ago, that came with the ghost antenna. Wasnā€™t happy with the ā€œmirror mountā€ bracket they sent, so I only used 1/2 of it and mounted between the hood and the cowl. Ran the cable outside under the front panel, down the driver dash and under to the passenger side. No issues so far!

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Toyfrog

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Agreed. Radiation patterns are affected by so many factors that there is a rather large ā€œartā€ aspect to this ā€œscienceā€. Iā€™m wise enough to know not to lick an antenna but do figure Houston traffic will kill me before I cook my innards. :)
Especially if you are driving anywhere on 610. šŸ˜‚šŸ‘šŸ»
 

Radio Guy

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Here is the NMO trunk lip mount on the hood. I have one on each side although I haven' t run the cables yet. The Larsen dual band 2m/70cm antenna coil pictured is a little larger diameter than the mount and looks a little funny.

The whole point here is the hood is about the only place on the vehicle to get an adequate ground plane for an antenna. Sticking them out the side or up high above any flat sheet metal will seriously reduce the performance and range plus some antennas will never match up right, especially CB antennas.

I've also covered the underside of the plastic cowl parts behind the antenna with a wide aluminum tape that bonds to the vehicle sheet metal below it to extend the ground plane.

Jeep Gladiator Mounting GMRS antenna 1.JPG
Jeep Gladiator Mounting GMRS antenna 2.JPG

Jeep Gladiator Mounting GMRS antenna cowl part.JPG



Do you have a picture of your setup? I'm having trouble picturing where you could do this and have it not prevent you from opening the hood.
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