Design and Analysis of a Novel Wide-Angle Scanning Stub-Loaded Cavity Array Element

A novel design methodology is presented to mitigate scan blindness in cavity antenna arrays without the need for any changes on the radiating structure itself. For a first proof-of-concept demonstration, a fully PCB-compliant dual-polarized cavity element is loaded by vertical stubs to manipulate the dispersion characteristics in the aperture plane. In contrast with its conventional cavity antenna counterpart, the proposed stub-loaded unit cell element shows through scattering and eigenmode analysis that the vertical stubs may effectively enhance the antennafs wide-angle scan performance by preventing the onset of surface and leaky wave resonances. Owing to this additional design freedom, an element gain improvement of at least 1 dB is achieved, due to a truly TE and TM mode-free characteristic along the lateral directions. A dual-polarized 11×11 array prototype was implemented. The measurement results are in very good agreement with those obtained by full-wave simulations. The realized stub-loaded cavity element exhibits reflection coefficients lower than -10 dB with a very low inter-port coupling <-40 dB across the frequency range from 26.8 GHz to 32.7 GHz. Moreover, the co-polarized embedded elements are close to the ideal cos(ϑ)-pattern for 60∘ E-and H-plane scans from 28 GHz to 31.5 GHz without oversampling the aperture.