Takashi Tomura

A 45

A 45° linearly polarized hollow-waveguide slot array antenna has been proposed to achieve low sidelobes in the E- and H-planes by a diamond-shaped array arrangement. A layer for radiating slots was added into the conventional plate-laminated antenna. The 2 × 2-element sub-array was designed to suppress grating lobes and low cross-polarization. The 16 × 16-element array in the 60-GHz band was fabricated by diffusion bonding of the laminated thin metal plates. The first sidelobe levels in the E- and H-planes were -25.5 and -26.1 dB, respectively, and the cross-polarization was - 31.5 dB in the boresight. High antenna efficiency of 70% with greater than 32 dBi gain over 5 GHz was maintained by the corporate-feed hollow waveguide structure. Quantitative amount of fabrication error due to etching and alignment was revealed by simulations.

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A 16×16-element plate-laminated-waveguide slot array antenna is fabricated by diffusion bonding of thin copper plates with inclusion of equivalent over-etching amount. The measured reflection characteristic has good agreement with the design one by considering the equivalent over-etching amount. At the design frequency, 32.6-dBi gain, 76.5% antenna efficiency and 19.2% bandwidth for gain more than 31.5 dBi have been achieved.

Linearly Polarized Hollow-Waveguide Corporate-Feed Slot Array Antenna in the 60-GHz Band

We apply hybrid MoM/FEM to an X-shaped cavity-backed slot 2×2-element array. One entire-domain sinusoidal basis function is assumed for the magnetic current in each slot aperture. The eigenmodes of a waveguide with the cross section of the X-shaped cavity are numerically derived by FEM to calculate the reactions of the basis functions of the magnetic currents. The frequency characteristic of the reflection is shown with HFSS result and has good agreement with each other.Application of the method of moments (MoM) with eigenmode expansion to a waveguide slot array enables fast analysis even though the number of the slots is large because of small analysis scale, that is, the unknowns are sources placed only in the slot apertures. However, the method is applicable typically to slot shapes whose eigenmodes are analytically derivable. The hybrid MoM/FEM was proposed for analysis of an array of slots with arbitrary shapes. The eigenmodes of a waveguide with the cross section of the slot shape are numerically derived by the finite element method (FEM) for the basis functions of the magnetic currents in the slot in MoM. In this paper, we apply the hybrid MoM/FEM to an X-shaped cavity-backed wide slot 2×2-element sub-array in the corporate-feed double-layer hollow-waveguide slot array antenna. The 2×2-element sub-array is the radiation unit and fed in equal amplitude and phase by a coupling slot placed at each end of the feed waveguide in the antenna.

A 16×16-element plate-laminated-waveguide slot array with 19.2% bandwidth in the 60-GHz Band

In order to achieve a wide bandwidth characteristic of high gain, high efficiency and low side lobe level, a plate-laminated-waveguide corporate-feed 45-degree linearly-polarized aperture array antenna is proposed. A 4-element sub-array is designed for a 256-element array. The 256-element array is fabricated by diffusion bonding of etched thin copper plates in the 60 GHz-band. About 70 % antenna efficiency with more than 32 dBi is achieved over 5 GHz.

Analysis of an X-shaped cavity-backed wide slot 2×2-element sub-array by hybrid MoM/FEM with numerical eigenmode basis functions

This paper presents plate-laminated waveguide slot array antennas for wideband and high-gain operations. Fig.1 shows the structure. A corporate feed circuit is placed on the bottom layer. A coupling slot at each end in the corporate feed circuit excites 2×2 exciting slots in an x-shaped cavity. Each of the exciting slots excites a radiating slot pair in a radiating cavity. All the radiating slot pairs are basically excited in equal amplitude and phase at any frequency. The radiating slot pair consists of two narrow slots to suppress the cross polarization. The antenna will be installed by rotating by 45 degrees as shown in Fig.1 to suppress sidelobes in the horizontal (E) and vertical (H) planes in fixed wireless access system.

Plate-laminated-waveguide corporate-feed 45-degree linearly-polarized aperture array antenna in the 60 GHz-band

This paper presents conversion to circular or tilted linear polarization by adding a layer of apertures over the plate-laminated-waveguide corporate-feed slot array antenna. A circularly polarized 16×16-element array antenna achieves high antenna efficiency of 91.6% including losses at 61.5GHz by diffusion bonding of laminated metal thin plates. In a tilted linearly polarized 16×16-element array antenna, the measured cross polarization is −31.5dB in the boresite at the designed frequency of 61.5GHz.