Mobile antenna location

[NWI_Scanner_Guy]

Well, I got so much information when I last posted an antenna topic here I thought I'd tap into y'alls wisdom once again.

I still haven't decided on what type of mobile antenna to get for my Yaesu FT2800M, but I am definitely going to get one within the next couple of weeks. I've been wanting to put it in my car, and I figure with the advent of Spring, this would be a good time to do it.

Anyway, I really enjoy looking at the pictures of the mobile installs down in the "Picture Of Your Shack/Mobile Setup" forum, but something has puzzled me. I've noticed in some of the pictures, the antenna is mounted either in the center of the trunk lid, or off to either side on the lip of the trunk lid. Some antennas are mounted on the roof of the vehicle and still some are mounted on the front of the vehicle, usually to either side of the hood.

I guess my question(s) would be does it really matter where the antenna is placed? I can kind of understand on the roof of the vehicle, since it's the highest point available, and even I know that higher is better LOL. Is there any advantage to having it trunk mounted, on either side or the middle or hood mounted versus roof mounting?

Thanks for your patience with an antenna noob. Once again, I appreciate all information/suggestions/tips provided. Many thanks in advance.

SSSG

 

[n5ims]

Here's a graphic by Larsen on this topic that shows the various placements and the effect on signal strength. http://www.repeater-builder.com/antenna/pdf/larsen-mobile-antenna-mounting-and-designations.pdf

Basically the more of the car's metal available to act as a ground plane is best and drops off as you move away from the center. Remember that the signal strength isn't always the most critical thing to an installation. It may be that there are several antennas that have to work well so they must compromize the location to make them all work well. Other times the "best" mounting location will cause issues due to clearance height so another location may be needed. Still other times folks can't bring themselves to drill large 3/4" holes into their car, but are OK with some small screw holes into the trunk lip.

 

[LtDoc]

Typically, it's mounting place is what's most convenient for the user. There can be some differences in performance but not as much as a lot of people assume.
- 'Doc

 

[NWI_Scanner_Guy]

Thanks for the link and the information. Definitely appreciate it.

 

[tmnkwd]

I’m in the same boat. Spending a lot of time searching for the right place to put an Austin Spectra Multiband antenna for scanner. Confused over the ground plane issues I read about. Does it really make much difference if I lip mount it on the hood, 3” off the back of the roof (SUV) or center of the roof?

In any of those three places, I have easy access to route coax but not too excited in punching a hole in the roof of a brand new SUV but would do it if performance was much better.

 

[roadranger]

Scanning Antenna on the mobile

Antennas usually receive best at the highest point possible. Top center. I used to use the available mag-mount antennas, and could remove them when necessary. Yet, I would eventually replace them because of the crimping of the coax in the door. I've even used glass-mount antennas. Drill some holes and permanently mount it.

 

[joehawth]

A lot of antenna placement is personal preference, but often placement is out of necessity. If you only have to place one antenna (assuming in addition to your car’s stereo radio antenna), it is not too hard and you have choices. I have 7 antennas and not much realty available for more…
You mentioned some people put an antenna in the middle of their hood, DON’T do that, it can obstruct your vision, distract you, and cause you to look like a UNICORN, especially if you drive a white vehicle.
Other than that the best is, in my opinion, to drill a ¾” hole in the center of your roof, and mount an NMO antenna. Pull down the headliner inside and run the wire. Looks sharp, lasts forever, great Rf ground plane etc etc.
If clearance or appearance is an issue with that, I suggest the same on your trunk. (assuming you have a trunk) One word of caution, be sure you have an actual metal trunk first, a fiberglass trunk will not serve as a good Rf ground plane, and you will lose range. A lip mount is ok too but some don’t last forever. When choosing a mount, be sure it will accommodate any angles, if your trunk curves toward the edges, either get a mount that can adjust or put the antenna in the center, you want your antenna as vertical as possible.

As far as cables go, don’t be afraid to get creative, you can usually avoid going through a door jam- which causes unnecessary wear. If you open your door and go through the hole where your door’s wires go inside your car, follow that trough and your in, you can run wires above the firewall and under the hood, follow stock wiring, or drill  You can also send wires into the vehicle behind taillamps.
Good luck and remember it’s all up to you and how you like it. You can drive around and talk on your radio however you rig it up, even if you decide to hold it out your window when you talk….
Good luck and be sure to throw pics up on the forum!

KB1RRG