Hello Jim I built a 910mhz coax antenna using 6 - 1/2 wave elements,
1/4 wave on bottom and the top. I used 3/8" copper hardline
instead of coax i had to tried to adjust for a faster .88 VP but found
using the same length as required for RG58 worked just as well.
Initally i did not put the antenna up because at ground level it did
not work very well on recieve, i was going to throw it out but desided
to put it up anyway. It really made a big difference once it was in
the air @ 25', it works much better than a Sinclair commercial omni i
had been using,