Design of displaced and circular polarized Waveguide Slot Array antenna with dielectric for K-band radar application

In this paper we design an effective Waveguide Slotted Array (WSA) antennas for K-band radar application. First of all, WSA parameters such as waveguide dimensions, slot length, slot width, slot displacement and other parameters of the antenna are calculated by using analytic techniques for 25 GHz. After, in order to suppress side lobe level Taylor and Chebyshev coefficients are determined in detailed and then we calculate slot displacements for each slot. The antennas are simulated according to Taylor and Chebyshev coefficient to obtain low side lobes and also reach effective result, which have high efficiency, high gain and small size, for 25 GHz. Sixteen and thirty-six slots are used to obtain desired results like high gain and narrow beam width at the H-plane. According to simulation results, the antennas which have sixteen and thirty-six slots presents 15.9 and 19.3 dBi realized gains, −17.2 and −16.1 dB side lobe levels (SLL), 9.6 and 4.1 deg. half power beam widths at 25 GHz, respectively. The most significant part of this paper is that change of antenna polarization. Normally longitudinal slots have linear polarization and to obtain circular polarization inclined or cross slot are used. However, these slot structure require complex analytic approach and optimization of the structure takes a lot of time. So, effective approach to change antenna polarization are presented.