Single-layer waveguide power divider with chokes for dispensing with close electric contacts and its applications to planar antennas

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A compact receiver with a high gain planar array has been developed for 26GHz band fixed wireless access systems (FWA). This is the user wireless terminal (WT) in wireless IP access systems (WIPAS) and a drastic cost reduction as well as high efficiency is realized by using an alternating phase fed single layer waveguide array as well as MMIC. This terminal is 180×180×98 mm3 in volume which accommodates a 30 dBi antenna with radome, all the RF, IF and base band components as well as the Ethernet interface. This paper presents the design of WTs with the focus upon the unique antenna array as well as the installation of components that contribute to drastic reduction of the cost and the size.The alternating-phase fed single-layer slotted waveguide arrays are applied to 76GHz and two types of contact between the slotted plate and the feed structure are tested. 34.3dBi gain with 50% efficiency is obtained by thermo compression bonding at 76.0GHz, while 31.9dBi gain with 30% efficiency by the contact with screws.We have proposed a novel planar cross-junction as the unit for the center feed of radiating waveguides in single-layer slotted waveguide arrays in order to reduce the long line effect. The junction is analyzed by Galerkin's method of moments. By using four posts, the divided ratio is controlled both in amplitude and phase and the reflection is suppressed. The cross-junctions are designed and manufactured for two different coupling ratios of 10% and 25%. The calculated and measured results agree well with each other except the 10 deg. phase error in S21. The placement of the feed waveguide at the center would cause the blocking of the aperture and then the increasing sidelobe levels. Slot excitation over the antenna aperture should be synthesized to reduce these sidelobes ; this is one of the future studies. We showed the feasibility of this center feeds as applied for an alternating phase fed single-layer waveguide array.