a repeater station having circularly polarized antennas . a diamond panel antenna and a panel antenna are positioned in a back - to - back relationship . each antenna is circularly polarized . the antennas use &# 34 ; tunnel technology &# 34 ; for isolating the antennas . a chassis forming a recessed portion is provided . a dielectric board is inserted into the recess . patch elements mounted on a board are inserted into the recess and connected to the dielectric board . the width of the boards are such that a &# 34 ; tunnel &# 34 ; is formed about the periphery thereof . absorber material is then inserted into the tunnel around the boards . a radome is placed over the recess enclosing the boards and elements .