70cm 21 Element Yagi
Elements are through boom (bonded not insulated - the black bits are heat shrink to mark position) then held in place by a grub screw tapped into the boom
Elements are through boom (bonded not insulated - the black bits are heat shrink to mark position) then held in place by a grub screw tapped into the boom
Matching was the hardest part using a 1/4 wave loop (Hairpin match) although I think you could just use a direct feed and 1:1 Balun instead
Matching was the hardest part using a 1/4 wave loop (Hairpin match) although I think you could just use a direct feed and 1:1 Balun instead
Fine tuning of the folded dipole was required to get the correct SWR. Also poisition of the first element which needed folding away from the dipole slightly
Fine tuning of the folded dipole was required to get the correct SWR. Also poisition of the first element which needed folding away from the dipole slightly
Note the folded dipole ends slot into the 13mm tube for adjustment
Note the folded dipole ends slot into the 13mm tube for adjustment
Installed on the mast
Installed on the mast
I used the excellent K7MEM website for calculating this antenna design
Notes: If doing this again, I'd use a larger boom diameter because there is too much flex in mine. I'd suggest 1.25 Inch so that guys aren't required. Element correction would be required which can be done on K7MEM's design page.