High-Gain Electrically Large Air-Cavity-Backed Patch Antenna Element and Array

In this paper, single high-gain patch antenna element with electrical large property (ELP) based on TM
₃₀
mode is presented. Stable field distribution of the TM
₃₀
-mode is maintained by using one TE
₂₀
-mode substrate integrated waveguide (SIW) slot-coupling feed structure. Furthermore, air-cavitybacked structure and metal pins are introduced to expand the antenna bandwidth. The ELP element resonates at 22 GHz with simulated -10-dB impedance bandwidth of 6.9% and maximum gain of 14.2 dBi. Then, in order to correct the asymmetrical field distribution in TE
₂₀
-mode SIW, differential feed technology is introduced in the array design. The feeding network consists of two TE
₁₀
-TE
₂₀
mode planar transducers and one anti-phase power divider. The working principle and design procedure of the ELP array are given in detail accordingly. Finally, a 2 × 2 ELP array is optimized and fabricated for verification. The measured results show that the array antenna has -10-dB impedance bandwidth of 9% and maximum gain of 18.9 dBi. Furthermore, it owns merit of excellent radiation performance with high aperture efficiency of about 90%.