Wideband circularly-polarized 3-bit transmitarray antenna in Ka-band

This paper describes the design of a 3-bit circularly-polarized transmitarray antenna operating in Ka-band. The array is based on a unit-cell composed of two U-shaped slot loaded patch antennas, which are connected by a metallized via hole and printed on two identical dielectric substrates. The latter are separated by a ground plane and bonded by a CuClad 6700 film. A 400-element transmitarray is simulated and demonstrates a maximum gain of 27.5 dBi, an aperture efficiency of 47.8% at 29 GHz. The 1-dB gain-bandwidth (LHCP) is equal to 14.8% at 29 GHz. The 1-dB axial ratio bandwidth covers the frequency band between 27-32 GHz. A good agreement is obtained between the full-wave simulation results performed with Ansys HFSS and the ones obtained using our hybrid in-house simulation tool. The impact of phase quantization on the performance of a 40×40-element array is also presented. The corresponding radiation patterns (co- and cross-polarization components) are compared to the masks defined by the European International Standardization Institutions (ETSI) in the case of point-to-point applications.