Cavity-Backed Angled-Dipole Antennas for Millimeter-Wave Wireless Applications

A cavity-backed angled-dipole antenna is proposed for millimeter-wave wireless applications. The angled-dipole radiator is built on both sides of an RT/Duroid 5880 substrate (epsilon(r) = 2.2) and fed by a parallel-plate transmission line. The cavity-backed reflector is utilized to improve the radiation characteristics of the angled dipole, such as gain, back-radiation, symmetric pattern, and similar 3 dB beamwidth in the E- and H-planes. The design, with a cavity aperture of 0.5 lambda(28-GHz) x 0.5 lambda(28-GHz), results in a vertical bar S-11 vertical bar < -10dB bandwidth of 26.7-30.6 GHz, a gain of 6.6-8.0 dB, and a similar 3 dB beamwidth of approximately 70 degrees for both the E- and H-planes. Eight-element linear arrays with the proposed antenna having a center-to-center spacing of 5.6 mm(0.52 lambda(28-GHz)) are characterized, fabricated, and measured. By applying nonuniform power distribution across excitations, the array achieves a scan angle up to 40 degrees and a sidelobe level below -15 dB.