By putting two SO-239 socket on each end of the conduit and have them connected inside the pipe, a female to female adapter is formed. The upper socket is for mounting of the antenna, the lower one is for connection of feed line. It provides a flat platform where the ground-plane elements can be mounted. Holes at 60 degree separation are drilled on the vertical edge of this round-pan. Length of ground-plane elements control their resonance frequencies.
Different materials needs different lengths to achieve resonance.
Our earlier mentioned value 135mm at UHF and 500mm at VHF are only good for copper conductor. For steel, the length will be different. Practicle test indicated that UHF ground elements in this design is best at length 70mm while VHF elements at 350mm. This length refers to rod's length between their tips and mounting point at round-pan. Since these rods are mounted with two nuts, their effective length can be adjusted.