On the bending effects of a printed 4x4 antenna array

Abstract

The bending effects of proximity coupled 4x4 patch arrays with printed patch elements operating in the X-band near 10 GHz is presented. The patch arrays have circular patch elements with inclusive slots residing on the top surface of four layers (10mil/layer) of DuPont Pyralux AP. The inclusive slots decrease the axial ratio of the antenna and increase the impedance bandwidth. Each array has a microstrip feed network of quarterwave transformers and T-junction power dividers in the middle of the four layer stackup. The microstrip lines are proximity (or capacitively) coupled to the patch elements. A ground plane on the bottom surface of the four layer stackup provides surface agnostic behavior. The patch elements and microstrip feed network are printed with DuPont CB028 conductive ink using a liquid dispense technique. For the purpose of comparison to PCB processed antennas, 4x4 patch arrays with 1$/_{2}$ oz. electroplated copper for the patch elements and microstrip feed network are also reported. The gain, 3 dB beamwidth, and VSWR bandwidth behavior have been studied for uniaxial bending of the two arrays for radii of curvature down to a 1 inch. The nominal (i.e., no bending) measured far-field gain of the arrays is 14.5 dBi (printed) and 14.7 dBi (copper). The printed and copper arrays behave very similarly with changes in gain of 9.3 dB (printed) and 8.3 dB (copper) for bending down to 1 inch in an axial direction and changes in gain of2.6 dB (printed) and 2.8 dB (copper) for bending down to 1 inch in a circumferential direction.