Orthogonally-Arranged Center-Feed Single-Layer Slotted Waveguide Array Antennas for Polarization Division Duplex

Fixed wireless access (FWA) systems in the 26 GHz band have been commercialized in Japan for high-speed Internet connections between subscribers and base stations. Compact and low-cost user terminals are realized by adopting alternating-phase fed, single-layer waveguide slot arrays. This unique antenna consists of two parts: a slot plate and a base plate with corrugations. The two plates are screwed to each other, which dispenses with electrical contact in the strict sense. To double the frequency efficiency, we propose a system that utilizes orthogonal polarization. This system is called Polarization Division Duplex (PDD). The challenge is for full frequency reuses based upon high isolation between the Tx and Rx antennas, which is inherent to planar slotted waveguide arrays. Orthogonal arrangement of two arrays has almost 70 to 80 dB of inherent isolation. The communication test uses QPSK modulation and with a 20 MHz bandwidth in the 26 GHz band. For measurements, the two wireless station's distance is almost 300 m. The results of the field test show same time transmission available using same frequency band.