Their are two adjusments on the Antenna to match the coax Imp. Adjust the Gamma Match Tube for Lowest SWR, then the tuneable stubs move in or out for lower swr. Do not use Stainless Steel Screws, Soldering them to the end caps is almost impossible. The 2 meter square loop is a folded Dipole around itself. Solder the antenna parts together using 90 degree elbows at the corner open ends and mind the gap.
All measurements are critical.
When using the RG8 discard the outer shield and use only the Dielectric. Secure with stainless steel screws right before the 90 degree elbow. Either side doesn't matter. Adjustments to the gap in or out can be made with the modification of installing the brass screws on the end caps. The Antenna is more or less Omni Directional and horizonatally polarized.