Aperture coupled microstrip patch antenna array for high gain at millimeter waves

Four-element microstrip patch antenna array is proposed at millimeter wave frequency. The proposed antenna achieves the impedance bandwidth of 4.6% at 28 GHz as well as a flat gain of 13.5 dB over an operating frequency band. It uses the aperture coupling along with air cavities to feed the patch elements. It achieves the side lobe level of -23 dB in the H Plane and -14.5 dB in the E plane. In addition, the proposed structure also achieves the wide beamwidth of 70° in H plane.