New coplanar waveguide/stripline feed network for seven patch hexagonal CP subarray

A novel CPW-to-stripline post coupler is demonstrated. This device couples the output power from a coax-to-CPW inphase seven-way radial power divider to a balanced stripline line stretcher and together forms a multilayer probe-type feed network. The feed network excites a seven patch hexagonal circularly polarised (CP) subarray. The measured return loss and insertion loss of the coupler are better than 17 dB and 0.25 dB at the design frequency of 2.875 GHz. The measured on-axis axial ratio for the left hand circular polarisation (LHCP) is 1.5 dB and the 3 dB beam widths are 36 degrees in the principal planes of the subarray. The gain of the subarray is 13 dB. The input return loss of the subarray is better than 10 dB.