Glass Mount UHF Antenna

[Fire232]

Can you please tell me who makes a quality glass mount antenna to transmit and receive on UHF?
And the pro's and con's of using a glass mount, I have heard good and bad?

[txshooter]

Larsen....

[Tom in D.C.]

The glass through which the RF must travel acts as a capacitor, so to
compensate for this a small tuning device is provided with an adjustment
circuit inside. In most cases, though probably not all, you can get a
perfect match of near 50 ohms for the antenna's impedance. Setting
up an on-glass antenna can be a real pain but most of the time they
work okay. Follow the setup instructions and get a ground connection
if it's called for, and have a good wattmeter or SWR meter available and
you should be okay.

[High_order1]

Hey -

basically, glass mounts suck. In addition to what Tom says, you gotta be certain that you clean the glass well, that there isn't any tint in between the aerial side and the box side, and that whereever you mount it a little aught to stick up over the roofline.

Seriously, unless you have a specific reason, a NMO mount is generally the best way to go.

-Shawn

[txshooter]

My current ride has a 800MHz Larsen Glass Mount. Works like a champ. I have used them in UHF as well without any issues. Now VHF on the other hand did not work well.

If you can drill a hole, drill it. Otherwise this is not a bad way to go.

If you have the money and can deal with a narrow bandwidth set up, Sti-Co makes some great antennas that replace your OEM antenna. Not a bad way to go other than being expensive.

[whls3]

The higher the freq, the better they work. And when tuning, you are not tuning a match between the radio and antenna, you are tuning between the radio and the box on the inside of the glass. That box is a resistance matching device. With no physical connection to the mast, there can be no actual effect on the signal to the mast. At 800mhz, they work at about 80% efficiency, at VHF you'll be lucky to get 50%.

I read your other thread about the dash lights. My guess is a bad ground, either at the lip mount, or the hood to the truck. I understand the reluctance in drilling holes, In another forum, we are merciless regarding the subject(man up, grow a pair) but I'll be nice here. A solution I have used is an L bracket screwed into the fender, inside the hood. With the bracket over the fender, so it doesn't interfere with the hood. An NMO mount in the L bracket. I think Antenna Specialists makes the bracket. This set up provides a good ground, and the extra height(about 3/4" over a standard hole mount) doesn't have much effect on the ground plane.

[IMBEJames]

I have had a couple glass mounts and no complaints at all. My current setup has an Antenna Specialists glass mount. As far as I can tell, it performs just as well as NMO mounts I have had in other vehicles. Proper tuning is a must, and it seems you get what you pay for.

[FireCpt809]

Ive used the AS one for years. Other than a few broken whips from car washes they have been pretty good.

[whls3]

A field strength meter will prove my point. Or a radio with an S meter and a mag mount antenna. The second would be a better test as the true test of a rig is how well it "hears".

[kb9suy]

I have used nmo mounts for years and believe the only way was the nmo way. That said When I had customers asking for glass mounts I tried the antenna specialist from pctell and Besides people breaking the whips going through carwashes I was really impressed with how they performed. I originally was driving a dodge pickup with a 3db gain uhf antenna a vhf qaurter wave on nmo mounts. When I bought my new car a dodge magnum I installed the antenna specialist glass mount antennas 1 vhf an 1 uhf unity gain. I noticed absolutly no difference on vhf. These antennas provide a ground plane kit that you ground to the inside of the roof then connects to the matching device box. I have done alot of significant field testing and found no difference. Uhf works just like a unity gain antenna noticed no difference in performance. I found out they make a 3db uhf antenna I might switch out to see if it performs better. These were conducted both tx and rx through long distance simplex and repeater operation. These are mount on factory tint windows not after market.

[Firebuff66]

I use a Larson UHF & AS 800Mhz. Both work great. I have roof mounts in my other car and can't tell too much diffrence, Both systems are repeaters in town.