Antenna position question

[KD8GRM]

I am new to ham radio, got my tech license in July.  I'm trying to figure out the best way to mount an antenna on my '02 F150 4x4.  

From reading here and talking to local hams, center of the roof is best.  However, I still want my truck to go in the garage without having to stop and remove/fold-over the antenna.

My garage door opening is 96" tall, and the top of the truck is 75".  That only leaves 21" for the mount and antenna.  The top of the bed rail is 54".

My question is:  Would a short 2m/70cm antenna on the roof be better than an longer antenna on the back corner of the bed rail?

I'm leaning towards the Larsen NMO2/70SH if I mount on the roof.  If I go the bed rail route, I'm leaning towards a tri-band antenna like the Maldol EX-510BNMO or Diamond SG-M911.  Both will keep the total height under 96".

What about other positions?  I have seen antennas mounted on the back door of the crew cab.  With that style, a portion of the antenna is blocked by the cab.  Will that cause high RF exposure inside the cab or will the sheet metal block the RF?

Thanks for any and all suggestions and comments.

Steve - KD8GRM

[K0BG]

ANY shortened antenna is a compromise, no matter the frequency.

If it were mine, and the bed didn't have a shell on it, I'd go to www.geotool.com, and purchase an NMO stake pocket mount, and stick an Larsen NMO2/70B on it.

If you don't want to use a stake pocket mount, a Larsen angle bracket will work very well screwed to the bed rail.

Almost with out exception, the import antennas are not rugged enough, they don't have the gain they say they do, and although their NMO mounts are similar, they are not fully compatible with the Motorola ones.

Alan, KØBG
www.k0bg.com

[KD8GRM]

Thanks for your advice Alan.  I appreciate your wisdom.

I think I'll follow your suggestion on the antenna and GeoTool mount.  I already had their information printed out.  It looks hard to beat.

Is their any noticable difference mounting on the front corner of the bed rather than the back corner?  I originally thought about using the back corner to keep the RF farther away from the cab.

BTW, You've got a great website.  

Steve - KD8GRM

[K0BG]

Personally, I'd use the back corner. If you look at my web site's Photo Gallery, you'll see lots of examples.

Alan, KØBG
www.k0bg.com

[K4QXX]

The GeoTool mount is well worth the money.  I installed one recently on my 2005 Dodge Ram with the Larsen NMO2/70B and it works great.

Burch
K4QXX

[W0FM]

Steve,

Another option would be to install BOTH a 2 meter quarter wave whip (~19") and a 70cm quarter wave whip (~5.5") in the center of the roof, but spaced a bit from each other.  Your stated 21" of clearance would allow this with a couple inches to spare.  Although you would not have the gain of the Larsen, you are sometimes better off with a 0db gain mobile whip for urban repeater work.

If you're sold on the Larsen dual band, then I'd second the stake mount idea.

73,

Terry, WØFM

[KD8GRM]

Thanks everyone.  

The GeoTool is on order, should be here in a couple of days.  The Larsen dual-band should be here tomorrow.

Weather forcast is calling for rain for the next couple of days.  I should be able to get the truck in the garage and get it installed.

Steve - KD8GRM

[KD0AFK]

I may be late chiming in on this, but Diamond makes a 1/4λ dual band antenna. It is only about 20" long and it is on an NMO mount.