Differentially Fed Planar Aperture Antenna With High Gain and Wide Bandwidth for Millimeter-Wave Application

This paper presents a novel planar aperture antenna with differential feeding. Compared with conventional high-gain aperture antennas, such as horn and reflector antennas, it maintains a high gain and wide bandwidth, but has a much lower profile with only one quarter-wavelength height. Since the height (λ_g/4) at millimeter-wave (mmWave) band is as low as the most of the commercially available laminates, planar aperture antennas with high gain and wide bandwidth can be realized at mmWave band using the proposed structure. A prototype working at 60 GHz band was designed and fabricated on a single layer laminate using standard printed circuit board (PCB) technology. A differential feeding network based on E-plane tee was also designed to feed the prototype for the measurement purposes. Experiment results show that the prototype achieves a -15-dB impedance bandwidth from 56.2 to 69.7 GHz (21.5%). The peak gain at broadside is 15.3 dBi at 60 GHz. The 3-dB gain bandwidth is from 54.0 to 67.5 GHz (22.2%). Within the operating bandwidth, the radiation pattern is stable with a low cross-polarization level below -24 dB, and is symmetrical about both the E- and H-planes.