A Wideband High-Gain Planar Integrated Antenna Array for $E$ -Band Backhaul Applications

A novel wideband high-gain planar antenna array for E-band backhaul applications is presented in this article. The antenna element is composed of a substrate integrated waveguide (SIW) cavity-backed patch and a stepped waveguide horn. The SIW cavity-backed patch is worked as wideband waveform and impedance transformer to excite the stepped waveguide horn on the upper layer. The stepped waveguide horn is employed to enhance the gain of the antenna element by increasing the radiation aperture. Based on the proposed antenna element, a 2 x 2 subarray with element spacing larger than a wavelength is designed. A groove, which works as secondary radiation source, is etched between the elements to improve the gain and suppress the high sidelobes of the 2 x 2 subarray. By taking the advantage of the groove, the 2x2 subarray achieves a maximum boresight gain of 17 dBi and an -10 dB impedance bandwidth of 21.8% from 70 to 87 GHz. For further enhancing the gain, a prototype including 16 x 16 elements is manufactured and measured. The experimental results confirm that the proposed antenna achieves the -10 dB impedance bandwidth of 22.4% from 71 to 88.5 GHz and a peak gain of 28.8-30.9 dBi. With the merits of a wider operating bandwidth, high gain, low profile, and low cross-polarization, the proposed antenna array is suitable for application in the E-band wireless backhaul systems.