Effects of Steel/Aluminum mast behind GH

[iblackford]

My build plans for an upcoming GH build include bolting a piece of plexiglass to a metal pole that would serve as my mast. The plexiglass would hold all the reflectors, narods, and mounts for the feed element.

The mast would be <1/2" behind the reflector plane, but perpendicular to the reflector elements. Would this adversely affect the antenna? I know most folks here use PVC, but I think steel or aluminum would work well also, and I'd like to try it.

[300ohm]

Which specific model are you building ?

The most important thing is to avoid shorting the colinear reflector rods or the mesh reflector air gap. Also its best to keep the gaps as far away from the mast as practically possible. Inserting some thick plastic or rubber at the u-bolt connection can do that.

[iblackford]

I was going to build a reflector rod DBGH with tophat NAROD's. The mast would run the entire length of the antenna, with some overhang at the bottom to mount in the rotor. The rods would affix to the plexiglass backer, and the backer would then bolt to the mast. I don't plan to use a u-bolt to affix the antenna to a mast, just bolts periodically to affix the plexiglass to the mast. The bolts would be placed so as not to be in line with the reflector rods.

[300ohm]

Sounds kind of fragile to me. Also, the plexi can contract/expand and crack.

[iblackford]

Ok, fragility concerns aside, would the metal mast adversely affect the performance of the antenna?

[300ohm]

The mast would be <1/2" behind the reflector plane

Thats close, and you could lose a little. The antenna would still work fine of course, just not up to full potential. If its overkill for your area, then I wouldnt worry about loss.