A 1/2wl antenna theoretically does not need one because of current
distribution...a 5/8wl on the other hand, does...
(personally, I use a gp on a 1/2wl anyway
On a 5/8wl antenna, use a ground plane...at least (4) 1/4wl radials in
length at 90deg to each other. For max performance, the antenna should be in
the center of a solid metal ground plane at least [1.5*(1/4wl of freq)] x
[the same amount]...on 2m, that would be 28 x 28 inches

Chris
WB5ITT


"bbnn" wrote in message ...
I know that a 1/4 antenna needs one to work but do 1/2 and 5/8 ant. need a
metal gnd plane.
Or will they work on a wooden building?