U-Slotted Isolated Cavity-Backed Ku-Band MSA with the Analysis of Bandwidth Enhancement Methods

The paper examines various options for isolated cavity-backed microstrip (patch) antennas (exciters) operating in linear polarization in the Ku frequency band (from 13.5 to 17 GHz). Cavities are used to improve the directivity of exciters. Isolators based on lines surrounding the exciter and shorted to the ground plane are designed to reduce the E-field spread over the surface of the antenna to enable the use of elements in antenna arrays. Methods for expanding the operating frequency bandwidths of the exciter are considered based on the use of a U-shaped slot of various dimensions cut in the patch, the use of a quarter-wave transformer at the antenna input and changing the shape of the patch. The analysis of the applied methods is performed by simulation in the ANSYS EM Suite (HFSS Design). The results show the possibility of expanding the operating bandwidths of a linearly polarized antenna up to <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$18.2 \%(13850-16614 \text{GHz})$</tex> with cross-polar discrimination of more than 40 dB while maintaining the shape and orientation of the field (main lobe) with a directivity (gain) of 8 to 9 dBi. The proposed isolated wideband linearly polarized exciter can operate as an independent antenna, an element of an antenna array, and a feed for various designs of parabolic reflector antennas, owing to its highly stable phase center.