Antenna Location

[Vandit]

I want to put an antenna (2M or GMRS) on the drivers A pillar, next to a ditch light. Two questions for the hams:

1. Will the A pillar interfere substantially with propagation, such that I should consider another location?

2. Should I be concerned about 50 watts of angry pixies leaping out so close to my face?

Thanks,

Michael

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[Lej512]

I got the NMO mount from Rugged Radio that goes on the driver's side mirror mount. Radio works fine considering it isn't the optimum mounting location for a two-way antenna. I can't speak to the effects of RF from that mounting location.

 

[Bschurr]

I want to put an antenna (2M or GMRS) on the drivers A pillar, next to a ditch light. Two questions for the hams:

1. Will the A pillar interfere substantially with propagation, such that I should consider another location?

2. Should I be concerned about 50 watts of angry pixies leaping out so close to my face?

Thanks,

Michael

Mountains2Metal makes the mount you are looking for (I installed one) and just put it on the passenger side if you are concerned about a sunburn…

 

[EasternSierra]

For really good propagation with a vertical antenna you really want a counterpoise (flat metal surface or metal radials) that's 1/4 wavelength in all directions from the vertical. For 2-meter ham that means 1 meter across, and for GMRS or 70cm that means more like 35cm across.

On a vehicle that means putting the antenna more towards the middle of a flat metal surface. I'll be getting the aluminum Armadillo Designs top which will allow that on the roof of my future Bronco.

Putting the antenna in your proposed location or as shown in the photo is common and still works, just not as well. Yes, the two A-pillars and the roll bars will interfere to some extent, but again many, perhaps most people have done it that way or at the back of the vehicle.

As for radiation dose, there's a calculator from the American Radio Relay League (ARRL) here. The instructions are here. A vertical will send out most of its energy to the side in all directions rather than up or down which is where the gain comes in.

I ran through some assumed numbers to get an idea of the situation. With 50 watts of FM transmission and an antenna with assumed 5db gain, the safe distance in an uncontrolled environment would be 1.17m or 46".

That doesn't mean that if someone out there did exactly this and nothing was noticed, there is no hazard to doing it over and over. However, your passengers should be informed if you subject them to a risk.

An advantage of putting the antenna on the roof with a good counterpoise is that instead of beaming the radio waves into the vehicle cabin they will largely be above the cabin, with the counterpoise shielding people in the vehicle.

 

[PhtmBronc63]

I want to put an antenna (2M or GMRS) on the drivers A pillar, next to a ditch light. Two questions for the hams:

1. Will the A pillar interfere substantially with propagation, such that I should consider another location?

2. Should I be concerned about 50 watts of angry pixies leaping out so close to my face?

Thanks,

Michael

I have run a driver’s side quarter panel mount for my 30 years of ham life. I can count only a handful of times that I required 50 watts.

transmission wise it’s not optimal, but on a soft or composite top, it’s the best you can do.

I am looking at doing the same to put 2m / 70cm, DMR rig in my Bronco. Just need to figure out where to mount the radio.

 

[Diller]

Will it cause issues to the radiated pattern yes, but substantially? Maybe to the rear. As to 50 watts VHF that close, not likely to be a big issue, but as someone else suggested check the ARRL web site.

73 Russ W2FSL

 

[Arokcrwlr]

I have my 2m/70cm antenna mounted on the driver side I have had no issues hitting any repeater within a reasonable distance and reports have been good.

 

[KD4RHO]

Here's my setup - highly recommend the CA-2X4SR - no ground plane needed and fold over to get in the garage - works well. Other is my GMRS - added a steel plate to the aluminum bracket for mag mount. 73, KD4RHO

 

[Diller]

This is how I've got my 2M/440 antenna mounted on the taolgate.

 

[murphtron]

This is how I've got my 2M/440 antenna mounted on the taolgate.

@Diller what's that mount?

 

[Squirrel13]

Murphtron - looks like swarfworkshttps://swarfworks.com/bronco-cb/vhf/uhf-antenna-mount/

 

[Diller]

@Diller what's that mount?

It's the Swarfworks.

 

[MorganF]

I originally mounted my 1/4 wave dual band VHF/UHF antenna at the a-pillar driver side but I couldn’t get SWR below 3 so I moved to a rear mount and SWR dropped to 1.5. I switched to a 5/8 wave VHF antenna and SWR was 1 at the rear.

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