Asymmetric Iris Structures for Dual-Polarization Waveguide Slot Arrays for E-Band Wireless Backhaul Systems

This article proposes a design of waveguide slot arrays with asymmetric iris to achieve broadband properties with high polarization isolation for E-band wireless backhaul systems. The proposed subarray of 2 x 2 radiating slots is excited by two-layered feeding networks carrying two orthogonal waves, and the asymmetric iris is inserted at the intersection where the waves merge. For verification, a prototype with 16 x 16 radiating slots is fabricated, and its antenna characteristics are measured in an anechoic chamber. The fabricated antenna has a bandwidth of 13 GHz at Port 1 and 10.5 GHz at Port 2 for voltage standing wave ratio (VSWR) <= 2.6, and the isolation between two ports is greater than 30 till within the target frequency bands. The average bore-sight gains of the two ports are 30.85 and 31.67 dBi, and the half-power beamwidths are 3.5 degrees and 3.25 degrees. We also fabricate another prototype with 64 x 64 radiating slots for a field test. The proposed prototype is capable of maintaining the received power to he greater than 15 dB for an effective isotropic radiated power of 40.7 dBm at 25 m, which demonstrates that the proposed antenna is suitable to replace current parabolic dish antennas with a reduced profile.