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Amateur Radio Antennas - For discussion of all amateur band designed antennas and related accoutrements. This includes base, handheld, mobile and repeater usage. For commercial antennas on the amateur bands please use Commercial Radio Antennas below.

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Old 04-24-2017, 6:08 PM
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Default A case in Favor of Mag Mount Antennas

If you are leaning toward getting a magnetic mount antenna, you might find the information in the following article to be valuable when choosing a style and/or brand. There are lots of formulas and detailed information.

This is also a compelling argument that they are not nearly as bad as some would have you believe, and are surprisingly actually pretty good performers.

If you don't want to drill, or for some other reason you cannot, this is a great resource to read before making a mag mount purchase.

Magnetic Mount Antennas are Electrical Performers
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Old 04-24-2017, 8:01 PM
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What many don't like about the mag mount isn't related to the signal quality, but rather the case of scratching the car/vehicle body; hence his statement, "Here is a way to see they are not so bad afterall... at least electrically." The "...at least electrically." is the catch. I've had both NMO and mag mounts and every time I've used the mag, putting on and taking off, I scratched the crap out of the paint. (And my wife had s@#$ fit !!!) Yes, could have left it on the SUV all the time, but the xyl runs this house!!! lol
Now on my S10, it's NMO only.
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Old 04-24-2017, 8:28 PM
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Yep, all good points, but the author ignores some basics:

Magnetic mounts work fine. Usually there is about 0.1dB of difference between identical antennas mounted by magnet versus a permanent NMO.
I'd challenge anyone to "hear" a 0.1dB difference.

Where the issues arise:
Routing coaxial cable from a mag mount requires getting it inside the vehicle. Since a hole hasn't been drilled, you've got to run it in through a window, door, etc. This risks damaging the cable. Either the cable gets pinched, which creates an impedance issue, or the jacket gets damaged and water gets in.
You can always drill a hole hidden somewhere to resolve this, but then you might as well do a proper install.

Magnetic mounts also damage paint. May not be an issue for an older car, but it is a reality.

Magnetic mounts -can- become a projectile in an accident. I've seen it. No, I don't have pictures.

-I don't like mag mounts.- There, I said it.

On the other hand, there are perfectly suitable cases where they make sense. Done correctly, they work fine, but they are in no way superior to a permanent mount antenna.
I have one I use for testing locations where I'm going to drill a mount, or for very temporary installs. Other than that, if it's worth doing, it's worth doing right. I long ago got over the fear of drilling a hole in a vehicle.

What annoys me is when someone (usually an amateur) claims they are the "right" way to do an install. They are not. They are fine if your significant other will not let you drill a hole in her mini-van, but at least come clean.

To be fair, I'd probably use a mag mount for a temporary install before I did the trunk lip or hood bracket mounts. Getting a mag mount in the center of the ground plane is going to work better than an antenna screwed into the very edge of a ground plane. At least you'd be getting true omni directional performance.
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Old 04-24-2017, 9:26 PM
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As more and more vehicles are being made with aluminum........................
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Old 04-24-2017, 9:48 PM
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I drive a '03 Dodge 2500. Fourteen years of multiple mag mounts and two NMO's. The NMO's are now unused. I'm not physically able to even check if the mag's have "scratched" the paint. I have some NRA stickers on the truck, so I get keyed about once a month along the four doors. Worrying about mag mount scratches, lololol.
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Old 04-25-2017, 10:16 AM
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I'm not a big fan of magnet mount antennas for all the reasons previously stated, BUT sometimes they are the best choice. My 4Runner has a sliding moon roof (not my choice of options-that's how it came from the dealer) and there wasn't adequate clearance to allow through the roof mounts.

I've found good quality mag mounts to be quite adequate with my Wilson 1000, VHF 1/4 wave, and NMO 270 antennas. Because I do a fair amount of off-highway driving, I did find the 270 antenna would tend to wander around on the roof when the vehicle rocked from side to side or get whacked by overhead branches. I solved this issue by using cable ties to secure the antenna coil to the luggage rack. The Wilson magnetic mount is very robust and despite the antenna being about 4 feet long, it remains in place.

Cable routing is through the rear door jambs with the cables secured inside the door jambs to keep them in place. I check periodically for signs of physical chaffing or damage and check the SWR a couple of times each year.
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Old 04-25-2017, 10:42 AM
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Mag mounts may scratch, but most scratches can be buffed out... Holes drilled in the body can't.

I've got a 2016 Jeep Wrangler... I installed a mag mount as a temporary measure, but it's worked so well where I put it, that it has kind of become permanent
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Old 04-25-2017, 3:48 PM
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Magmounts are like spouses. Sometimes they're just what you need. Sometimes they do great damage and it just might be their, or your, fault.

Be glad your family didn't also arrange a magmount for you when they were picking your spouse.

No, wait, be very disappointed that they didn't make a match for both.
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Old 04-25-2017, 4:14 PM
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Having a mag mount creates a vulnerability in the vehicle; the place where the cable enters the vehicle.

I had a mag mount on my truck with the cable coming in through the rear cab window. I thought I was good because I have a shell with a locking rear window on on the truck, blocking access to the cab window. Or so I thought...

A pair of crooks were able to get the tailgate open and get inside the bed. They were able to open the window into the cab and get the doors open. I lost a lot of stuff, including the body of an FT-7900R (the idiots left the control head behind,) a Garmin GPS (password protected) a good pair of binoculars and a bunch of random stuff. They even took my vehicle registration and insurance cards and the contents of the trash bag (looking for credit card numbers.) They were eventually caught and prosecuted, but I never got any restitution even though I applied for it.

Now I have an NMO mount in the roof of the cab and a lock on the tailgate. The vehicle is lot more secure. If I have to use a mag mount (the wife's car) it is removed and the window rolled all the way up if I have to park for any length of time.
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Old 04-25-2017, 4:41 PM
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I can't claim this idea as my own; I read it on here a good while back. I have tried it and it does work.

If you just have to use a mag mount, get some rocker panel protection material. This is a semi-clear tough plastic with an adhesive backing. Cut a piece a bit larger than the base of the mag mount and apply it to the roof/trunk lid/wherever you intend to stick the antenna. It will keep the base from scratching the paint and can be removed with a heat gun or a hair dryer when the time comes to turn the vehicle in, leaving no trace that it was ever there (except maybe a little circle that isn't UV faded, LOL).

Again, not my brainstorm, and I don't care for mag mounts either...but if you just gotta, this will help keep your paint from getting molested.
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Old 04-25-2017, 5:01 PM
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Quote:
Originally Posted by k6cpo View Post
Having a mag mount creates a vulnerability in the vehicle; the place where the cable enters the vehicle.

I had a mag mount on my truck with the cable coming in through the rear cab window. I thought I was good because I have a shell with a locking rear window on on the truck, blocking access to the cab window. Or so I thought...
It is only a vulnerability IF you go through the window.

I have driven F-350 trucks for the last 6+ years. IF I need to put a mag mount on an F-350, I usually go through the door I don't use (passenger rear door) and slip the coax between the body and the door seal. Never had an issue with it and it does not get pinched. Chevy on the other hand, well, I pooched the coax on a couple of magmounts because of how the door fits to the body.

I will always drill. It looks cleaner. Plus I do not like magmounts either. I see the rust and scratch marks EVERY day in my new job of looking after my companies fleet trucks(Ford F-350 Stupid Duty and Chevy/GM 3500). I would rather hard mount a radio in every truck, and do fender mounts, but my manager would rather have the mobiles on headrest mounts(Not everybody needs a radio all the time) and use mag mounts.
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Old 04-25-2017, 5:15 PM
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Dunno how to tell anyone, but for many years now the AAA and other raod service guys who offer "lock out protection" if you lock you keys in the car? They get in by shimming open the top of a door, any door, just enough to slip in a flat rubber bladder. Then they blow the bladder up. The window/frame always flexes out an inch, then they can manipulate the door latch or lock and they're in. Fast.
So the "bulge" a cable may cause? Doesn't mean anything, they don't need that. Heck on some cars you can bend the opening back by hand.
For that matter, if it is parked overnight, the "STEAL ME< GOOD STUFF IN HERE!" antennas are easy enough to take off the roof.

I always try to be gentle to the cable by just NOT taking it directly across the weatherseal. I'll come down the side of the door frame, crossing at a gentle angle, or come down the rear hatch, again at a long gentle angle. More flex, less damage, years of intermittent use and nothing has ever complained. And I don't exactly use the thinnest cable I can find.
Use a 1/4" or thinner cable, and you're in like Flynn.
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Old 04-25-2017, 5:22 PM
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Quote:
Originally Posted by Rred View Post
Dunno how to tell anyone, but for many years now the AAA and other raod service guys who offer "lock out protection" if you lock you keys in the car? They get in by shimming open the top of a door, any door, just enough to slip in a flat rubber bladder. Then they blow the bladder up. The window/frame always flexes out an inch, then they can manipulate the door latch or lock and they're in. Fast.
So the "bulge" a cable may cause? Doesn't mean anything, they don't need that. Heck on some cars you can bend the opening back by hand.
For that matter, if it is parked overnight, the "STEAL ME< GOOD STUFF IN HERE!" antennas are easy enough to take off the roof.
Cable or not, it makes little difference to getting in the vehicle with a slimjim, real or improvised(like 1/4" stainless steel instrument tubing for example BTDT)
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Old 04-25-2017, 7:11 PM
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I'm not saying this is anwhere near correct however, I get pretty good performance with a low profile mag mount. I have for several vehicles used this set-up on the rear dash. I place a piece of metal with 2-sided tape down and stick it to that. I have never noticed any real lack in performance in reception. I have also used this set up for transmitting on UHF. I have never had it come loose and it has never scratched my paint. YMMV.

ok let all the theory folks chime in...lol


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Old 04-25-2017, 7:16 PM
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It works because your vehicle is not a faraday cage at UHF. How ever if you tried it on VHF your results would be quite different.
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Old 04-25-2017, 7:31 PM
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Interesting... I imagine this is all the result of resonance?


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Old 04-25-2017, 8:00 PM
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No it is a function of the size of the openings in the body(windows) being much larger than the wave length of the frequency you were using. I have sucessfully used a UHF repeater, while mobile with a MTS2000 portable, with its wideband UHF antenna, from 50km away. Having said that, any bit of vegetation that got in the way completely wiped out the repeater, but I was able to hold a brief conversation.
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Old 04-25-2017, 8:09 PM
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Understood, I thank you.


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Old 04-25-2017, 9:34 PM
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Quote:
Originally Posted by jwt873 View Post
I've got a 2016 Jeep Wrangler... I installed a mag mount as a temporary measure, but it's worked so well where I put it, that it has kind of become permanent
Where did you put it? The hardtop is entirely plastic (I know I have a 2016 Wrangler Unlimited)
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Old 04-25-2017, 11:55 PM
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Quote:
Originally Posted by jwt873 View Post
Mag mounts may scratch, but most scratches can be buffed out... Holes drilled in the body can't.
Use an NMO plug if you have to uninstall the system. Doesn't look TOO weird.
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