60 GHz Wideband High-Gain Circularly Polarized Antenna Array With Substrate Integrated Cavity Excitation

This letter presents a new wideband high-gain circularly polarized (CP) substrate integrated cavity excited antenna array for the 60 GHz applications. First, a 2 x 2-element CP array is proposed with an aperture-coupled two-arm spiral antenna as its radiating element, which can exhibit good CP radiation performance. Instead of the conventional lossy and complicated feed network, a simple but efficient excitation structure based on higher-order-mode (TE340) cavity resonance is used to feed the array. The higher-order-mode cavity feeds all of the radiating elements in the same phase and magnitude, and the resonant mode is excited by a single slot aperture. Then, the proposed 2 x 2 element CP array is used as subarray to implement a sequential-rotationally fed 4 x 4-element CP array. Measured results show that the array has a wide axial-ratio bandwidth of more than 18.8% (53-64 GHz) with a peak gain reaching 20 dBic occurring at 61 GHz. The radiation patterns of the array are generally symmetrical with its main beam fixed at boresight.