On May 24, 10:48*pm, artie wrote:
I'm going to be putting an NMO-mount dual band (144 and 440 MHz)
antenna in a plastic vehicle roof.

I plan on making a counterpoise using 3 inch wide (or so)
adhesive-backed metal (hvac) tape. *I can do an overlapping run of
close to 6 inches wide.

Question for the crowd -- any benefit/detriment for making this
counterpoise as long as possible, or should I stick to odd multiples of
a quarter length (at 2 meters)?

There's more room "behind" the mount point than in front of it, so I
could have a quarter wave section in front of the NMO, and a 3/4 wave
section behind.

I can also do a cross member, but that would be pretty much limited to
a quarter wavelength per side.

Opinions?

Good luck trying to get a good electrical connection to that stuff..
I'd probably just stick to odd multiples..
You could use wires also.. In fact, just two wires 180 degrees
apart will give you a fairly omnidirectional pattern with minimal
fuss. Easier to solder too also..
You could probably use the longer radials for 70cm, but you
could also add shorter radials for that band if needed.
BTW, another thing about that tape.. After a few months of
summer heat pounding the roof, the glue will become useless and
it will fall down on you. :/