No Ground Plane Antenna

[h00sierdaddy]

I have a Larsen tri band antenna mounted on the front passenger side of my ford f150 with a trunk lip mount. I'm having problems receiving medium range vhf signals and the close range vhf signals aren't as strong as they should. I've obviously determined this is a ground plane issue because my handheld pro-96 receives better than my larsen / 996xt setup. I can't mount to the roof because of clearance issues. I've seen the PCTEL Maxrad 144-174 No Ground Antenna advertised as 'not needing a ground plane'. Has anybody used this? Is this for real? If not, can anybody give me any tips or tricks on placing my antenna to better the ground plane. Thanks!

 

[wyomingmedic]

As somebody who did radio installs professionally and who has used lip mount antennas in my ham career, I don't think it is a ground plane (GP) issue. While it is true that these antennas would work better with a huge sheet of metal under them, the actual noticed difference between a fender and a trunk lid are almost not noticeable.

I would look and rule out a bugger problem. Usually it is a coax fault. Shorted connector is usually the culprit. Also look at the NMO mount itself. If the antenna is cross threaded on or the little metal tab is not making a good connection, it will be very spotty at those frequencies.

Get an ohm meter and check the coax for shorts. Clean all of the contact surfaces as well. Sometimes corrosion can play havoc. To replace the antenna with a no GP model (1/2 wave length) would probably not actually fix the problem.

Good luck,

WM

 

[h00sierdaddy]

Update: So far, the only change I've made was to the metal tab in the base of the antenna that makes contact with the nmo mount. Pulled it out a little bit so it would make better contact...and so far the results have been great! 100% better vhf reception and about 50-60% better uhf reception. I'm happy with that. THanks!

 

[wyomingmedic]

Glad to hear it. Sometimes with the Larsen antennas, they can be used and the tab can get a little weak. Like you did, a quick little bend on the tab can make a world of difference.

What I also like to do is take a Q-tip and some contat cleaner to the tab and mating surface of the NMO mount.

WM

 

[W0JJK]

I have used the PCTEL Maxrad No ground on International Semi, Case and Deere Tractors, with great success.

 

[ridgescan]

I love it when someone discovers an easy fix to a dilemma-great advice wyomingmedic tco glad to see you can really enjoy some clean reception now.