Electrically Reconfigurable Antenna Array with Cross-Polarization Suppression Technique in the Ka-Band Using PIN Diodes

In this article, an electrically reconfigurable antenna array in the Ka-band that performs linear polarization conversion while also having low cross-polarization levels is proposed. The single antenna element features two PIN diodes positioned orthogonally to generate two linear polarization modes. In the initial simulation results, a bandwidth of 1.2 GHz is achieved for the single antenna in both polarization states, with the cross-polarization discrimination (XPD) being 14 dB. To increase the XPD, various strategies are proposed and investigated, considering 2×2 subarrays by mirroring the antenna elements. Based on the best performing subarray, a 4×4 antenna array is constructed and studied by setting the error magnitudes and phases of the antenna elements. Furthermore, a prototype of the 4×4 antenna array is fabricated to verify the XPD results at different steering angles. The radiation pattern measurement exhibits an XPD greater than 25 dB at a broadside beam that stays above 18 dB within the scan range of ±30o. These results confirm that the proposed antenna achieves high polarization purity and stable beam-scanning performance, making it suitable for reconfigurable Ka-band array applications.