38 GHz high-directivity planar leaky-mode antenna array

This paper presents a high-directivity planar microstrip antenna array operating at microwave frequency. The antenna array consists of 48 sub-arrays, and each sub-array comprises 4 elements. The radiation mechanism of the single element, by exciting the first higher order mode (EH ₁ mode), can be estimated by the full-wave analysis. Through appropriately arranging and feeding these 192 single elements, the radiated characteristic of the antenna performs narrow radiation beamwidth both in azimuth (AZ) and elevation (EL), thus achieving high directivity. The planar microstrip antenna array prototype is built and tested at 38GHz by traditional printed circuit board (PCB) fabricating process. The measurement result indicates the high directivity of 22.3dB and the 3-dB beamwidth of 8°/12° (AZ/EL) at the elevated angle 30.2° away from the broadside direction.