Cross-Polarization Suppressed and Linearly Polarized Patch Array Antenna With Cavity-Backed Slot Feed for Vehicle Applications

摘要

A compact linearly polarized patch array antenna with super-low cross polarization is proposed in this letter using multilayer printed circuit board (PCB) process. The radiation unit with stacked structure consists of four partly overlapped and 45 tilted patches and one cavity-backed slot antenna fed by the microstrip line. The proposed patch array antenna inherits not only a compact size, but also an excellent suppression of the cross-polarized radiation. The overlapped scheme introduces the perfect magnetic wall and electric wall by physical connection through current other than by virtual connection through electric field, which suppresses the cross-polarized radiation around the corners. A prototype array antenna with 8 radiation units for vehicle radar applications is designed and fabricated to validate the proposed design. Experimental results of reflection coefficient, gain, cross polarization, and radiation patterns are consistent well with simulation predictions. The prototype array antenna can operate from 23.2 to 24.8 GHz (6.67%) with its reflection coefficient under 15 dB and its gain varied from 16 to 19 dBi. The main beam is stable at broadside with a maximum gain of 18.99 dBi at 24.5 GHz, and the cross-polarization level is better than 55 dB under the maximum gain across the entire operating bandwidth and the main 3-dB beamwidth.