Description
Modern communication systems demand new approaches like cognitive radios, Multiple Input Multiple Output (MIMO) to increase throughput, use of unused high-frequency spectrum (millimeter wave). The high-frequency wideband antenna can increase the throughput of the system and phased arrays enable the increase of Signal to Interference Ratio (SIR). The antenna needs to be conformed to non-planar surfaces for aerodynamic profile and camouflage. The effects of curving an array antenna to cylindrical surface larger than the antenna aperture are unpredictable. The proposed analytical solution using MATLAB provides a good approximation for the antenna on a curved surface. A novel microstrip patch array antenna design is proposed with multi-stage sequential rotation to obtain wideband axial ratio performance. The design is a single layer flexible substrate microstrip patch array to obtain a high gain antenna which can be curved. The three-stage sequential rotation for 8×8 planar array provides wideband operation from 11.0 GHz to 12.86 GHz in the experimental verification with below 3dB axial ratio (11.0 GHz to 14 GHz). The study concluded that with an increase in curvature the degradation of antenna characteristics are dominant as observed in experimental verification. The axial ratio bandwidth reduced from planar scenario (11.5 GHz to 13.5 GHz) also, radiation pattern degradation with higher side lobe and cross-pol levels. A beam steering linear array with aperture coupled microstrip patch for circular polarization with via cavity wall is proposed to preserve axial ratio and obtain wide angle scanning. The scanning angle of +/–30° has axial ratio bandwidth of 12.15 GHz to 12.69 GHz. In addition to HFSS simulated results, Keysight’s SystemVue based beam scan study is included based on the beam forming network (BFN). At millimeter frequency, a horn antenna is designed as feed for the offset reflector for use in the mini-compact range and as a feed source in the anechoic chamber. Based on the initial study, one such feed has been simulated and its performance parameters are discussed. The feed has peak realized gain varying from 14.2dBi to 16.2dBi over the frequency bandwidth 32 GHz to 57 GHz.
