Compact Dual-Polarized Low Sidelobe Monopulse Slot Antenna Array Based on Gap Waveguide Technology

A new approach for integrating unequal power dividers into a series-fed resonant slot antenna subarray is proposed, to reduce the sidelobe level (SLL) while avoiding bandwidth degradation in an extended linear slot antenna array. Subsequently, a compact dual-polarization (DP) antenna array is designed to utilize gap waveguide (GWG) technology, which features high gain, low sidelobe, and high efficiency. By coordinating power-weighted feeding networks (FNs), a 2-D low SLL array is accomplished. Furthermore, monopulse comparator networks are incorporated to expand the potential application scenarios. A prototype array antenna was fabricated and measured to validate the design performance. The measured and simulated results are compared, indicating −10 dB impedance matching of 10% and 12% for vertical and horizontal polarization, respectively, while maintaining consistent performance across both sum and difference ports. For both polarizations, the measured peak gains of sum ports exceed 30.6 dBi over the operating frequency band, with antenna efficiency generally exceeding 50%. At 23.5–24.5 GHz, the first SLLs in azimuth and elevation planes are lower than −19 and −22 dB, respectively. Meanwhile, the difference patterns exhibit a null depth of approximately −37 dB relative to the sum pattern peak within the operating band. The proposed antenna array can provide individual amplitude for each element, demonstrating exceptional performance.