Bill Grimwood wrote:
How high does a 20 meter yaga need to be. will 50 feet be enough or do I
need 70?

Depends upon what areas you want to cover. I prefer 30 ft because
I get a large "localized" beamwidth. Here's what EZNEC sez about
the 5 element 20m Yagi that is included in the EZNEC package.

Height Gain Take-off-angle Vertical Beamwidth
30' 13 dBi 25 deg 30 deg
50' 14.5 dBi 18 deg 20 deg
70' 15 dBi 13 deg 14 deg

Decide who you want to talk to and take your pick.
--
73, Cecil, W5DXP