Naofumi Yoneda

A design of novel grooved circular waveguide polarizers

This paper presents a novel type of polarizer that is composed of grooved circular waveguides, The presented polarizer is suitable for realizing high performance and low fabrication cost in Ka-band and above because of simple structure. An accurate design of the polarizer is performed using mode-matching techniques. A Ka-band polarizer fabricated with the aid of the design technique has realized excellent performances.

Ultra-thin broadband OMT with turnstile junction

This paper presents an ultra-thin broadband waveguide orthomode transducer (OMT) for low profile reflector antenna feed systems. The presented OMT is composed of a turnstile junction with a metallic pyramid, a circular-to-square waveguide step, and thin combiners/dividers. A broadband design of the OMT is performed by applying a circular-to-square waveguide step to obtain good match. An ultra-thin Ku-band OMT fabricated with the aid of the design techniques has realized wideband excellent performance with very low height, that is, VSWR less than 1.18 over 30% bandwidth and reducing the height to 20.2 mm.

A Compact Forward Coupler Using Coupled Composite Right/Left-Handed Transmission Lines

A novel forward coupler using coupled composite right/left-handed (CRLH) transmission lines (TLs) is presented. Forward coupling is enhanced by the CRLH TLs, which have a considerable difference between the effective phase constants in the even and odd modes. A 10-dB forward coupler using the coupled CRLH TLs is simulated and experimentally demonstrated in the S-band. Its coupled-line length is reduced to half that of the conventional right-handed forward coupler with the same coupling.

A 90 GHz-band monoblock type waveguide orthomode transducer

This paper presents a 90 GHz-band waveguide orthomode transducer (OMT) which is composed of a short circuited circular common waveguide and two branching rectangular waveguides dug through a metal block. An analysis and design of the OMT are performed using full wave mode-matching techniques. A 90 GHz-band OMT fabricated with the aid of the analysis and design technique has realized excellent performances.

Metal-plated plastic waveguide filter using injection molding process

A metal-plated plastic waveguide filter for Ka-band wireless Internet access systems is presented. As the filter is made using a plastic injection-molding process, the influence of indispensable draft angle on the waveguide walls was precisely considered in the design. By merging this design technique with the high-accuracy molding technique, no electrical tuning was necessary. It also realized the mass-productivity and cost reduction of Ka-band waveguide components.

Ku-band power combiner composed of metal-plated plastic waveguide hybrid

This paper describes the feasibility study of a metal-plated plastic waveguide power combiner for Ku-band solid state amplifier, aiming at the reduction in cost for high volume production and/or in weight. The relation between the draft angle for molding process and the combining loss characteristics is theoretically clarified. Furthermore, the experimental result of the 40 W four-way power combiner using plastic waveguide hybrid parts demonstrates validity of this investigation.

Mono-grooved circular waveguide polarizers

This paper presents a unique type of polarizer that is composed of a circular waveguide with an only groove. The presented polarizer is suitable for realizing compact size and reducing degradation in performance due to manufacturing inaccuracy. An accurate design of the polarizer is performed using mode-matching techniques. A W-band polarizer has, been designed, and the results of error analysis have verified the high efficiency of the presented polarizer.

A Q-band Low-profile Waveguide BRF with Built-in Cavity-Embedded Dielectric Substrates

A new low profile waveguide band-rejection filter (BRF) is proposed. In the waveguide BRF, substrate integrated waveguide (SIW) cavities are employed as resonators, and they are simply inserted in a hollow waveguide. For this simple configuration, this waveguide BRF is low-profile and easy to fabricate compared with a conventional waveguide BRF, which employs resonant waveguide cavities outside the waveguide and needs costly machining processes to fabricate. A Q-band prototype waveguide BRF is fabricated using alumina substrates and the measured results showed high attenuation more than 50 dB at 47 GHz in 2% fractional bandwidth.

Analysis and design of grooved circular waveguide dual-mode filters

This paper presents a novel type of circular waveguide dual-mode filter with grooves for coupling orthogonal resonant modes and correcting resonant frequency. The presented dual-mode filter is suitable for realizing high performance without tuning elements in Ka-band and above because of the simple structure. A Ka-band elliptic function type dual-mode filter has been designed by accurate and fast full-wave analysis performed using mode-matching techniques.

An Elliptic-Function Bandpass Filter Employing Left-Handed Operations of an Inter-Digital Coupled Line

A new elliptic-function bandpass filter (BPF) is proposed, which utilizes an inter-digital coupled line (IDCPL) as a left-handed transmission line. The IDCPL is employed in order to realize a negative coupling between non-adjacent resonators in a wideband BPF. As the authors knowledge, the left-handed operations of the IDCPL has rarely utilized before, although the IDCPL itself has been widely used in many microwave circuits without being paid attention to the left-handed operations. Measured results of a 3-5GHz BPF for ultra wideband communication systems (UWB) are also presented in this paper.