Batboard

Are there any really compact, non ground plane antennas that work for a fiberglass bus application on high band? In the past we had taken to installing ground radials out of sticky foil tape but it would be nice to not have to do that in the future. A long whip gets taken out by trees though so that part is also a pain.

Birken

Basically you need a groundplane-independent antenna. Theoretically a 1/2 wave antenna does not need a counterpoise.

According to their catalogue, Larsen makes a cellular look-alike that's glass mounted and is 20" tall (model KGFFREQUDPL). If you have a window you could mount it to that would work. They also make a 1/2 wave glass mount but it's quite a bit longer (model KG144UD or KG160UD).

For years Antenna Specialists made UHF and VHF bus antennas that
were roof mounted, low profile, long with a plastic radome (cover) on them.
The specs said these were vertically polarized, though to look at them
you'd think they were horizontal. They MAY have been half-wave units but
I'm not aware of the actual design specs so you'd have to check this out but
they looked pretty bulletproof and were made for rough duty. I've seen these
used on many buses in different cities, as well on RR passenger cars.
It might be worth checking out.

so your looking for an antenna you can mount to fiberglass but have the antenna reasonable short, 2 feet?

Short as possible I guess without being a dummy load...we have had excellent results with the no ground plane Antenex units but they are 1/2 wave long overall and these buses are pretty tall already and around here we have lots of low hanging trees.

Birken

The problem with the ASP, Sinclair and other low profile "transit" antennas is they need a ground plane.

Where clearance is a problem on a fiberglass roof bus, I side mount the 1/2 wave antenna with an L bracket or use a side mirror mount.

That's what we had been doing and most likely will continue. Just trying to put some feelers out there in case there are any other good ideas that might exist. With ambulances the manufacturers embed a mesh screen in the roof and that makes it easy. I wish they would do that with buses too.

Birken

We work on well over 100 buses with our local transit provider. Alot of them are now fiberglass. A solution we had, was we take a piece of sheetmetal and mount that in between the bus and the ASP transit antenna. normally 4 screws in the outer edge nad it works great. We now have the transit authority putting these plates on before we even get the bus, and it matches the paint.

Just our way....

JAS

I think what Tom is talking about is what is commonly known as a 'blade' antenna. I'm not sure, but I think they are 1/4 wave. As Tom said, they are almost indestructable. Once again, I'm not sure, but I don't think they require a ground-plane.

All require a ground-plane that I'm aware of including the railroad models.

is it a Bus with a Van/Truck Cab

Yeah, plan "B" is to install them on the front fenders like the broadcast radio antenna is now, and we have done it with good success. Every bus is different though. And it will definitely save time and hassle if I can install antennas in their original location. We are replacing 800 MHz ones, and most or all of them already have NMO mounts on them so you can see the advantage.

Birken