Hidenori Yukawa

Millimeter-wave plastic waveguide phased array antenna

Low cost and high performance millimeter-wave phased array antennas have been demanded in recent years due to increasing millimeter-wave applications in highspeed mobile communications, broadband wireless LAN/PAN (WLAN/WPAN), automotive collision avoidance radars, and so on. Several types of millimeter-wave antennas and components have been proposed for these systems. For example, plastic waveguide structures, which are composed of hollow liquid crystal polymer (LCP) and plated copper [1], [2], have been reported in order to reduce the cost for mass-production scheme. However, the phased array antennas are difficult to form their complex configurations and difficult to obtain low-loss characteristics as well. This paper presents millimeter-wave waveguide-type phased array antennas using low-loss engineering plastics not only to reduce cost but also to obtain high performances with complex configurations. That is a Cyclo-Olefin Polymer (COP) waveguide horn array antenna which is fabricated by injection molding process [3].

Design of iris‐coupled broadband waveguide filter using modified reflection‐zero frequencies

In spite of its low loss and superior power handling capability, the waveguide filter cannot have broad bandwidth due to the strong frequency dependence of the reactance values for coupling of the cavity resonators and the guide wavelength. To achieve a broadband design of the iris-coupled waveguide bandpass filter with the Chebyshev function as the transfer function, the susceptance value of the inductive iris is optimized by specifying the ideal zero frequency of the reflection. Based on this method, a diplexer is trial fabricated and a broadband diplexing characteristic is realized. In addition, agreement with numerical results is demonstrated, confirming the effectiveness and validity of the method. The tested diplexer has a VSWR of less than 1.24 and an isolation of more than 53 dB at passband bandwidths of 32 and 7% relative to the wavelength.

A compact Ku-band power combining network using rectangular coaxial line technology

A compact Ku-band power combining network with a combining loss less than 0.45 dB has been developed using rectangular coaxial line technology. Novel hybrid couplers using impedance-transforming nonuniform coupled transmission-lines are employed as power combiners to reduce the degradation in the combining network performance due to manufacturing inaccuracy.

A Q-band low-profile waveguide BRF with built-in open-ended λ/2 microstrip resonators

A new and low profile waveguide band-rejection filter (BRF) is proposed. In the waveguide BRF, two dielectric substrates with open-ended λ/2 mictostrip resonators are employed without via holes, and they are inserted in a hollow waveguide. For this simple configuration, this waveguide BRF is low-profile and easy to be fabricated compared with a conventional waveguide BRF, which employs resonant waveguide cavities outside the waveguide and needs costly machining processes. Q-band prototype waveguide BRFs were fabricated using alumina substrates, and the measured results showed high attenuation more than 50 dB at 47 GHz in 2 % fractional bandwidth with less variability.

Modern plastic millimeter-wave array antennas

Two types of millimeter-wave waveguide-type array antennas were presented using low-loss engineering plastics. The mass production and cost reduction of millimeter-wave antennas are enabled to realize by using these technologies. The fabricated array antennas have shown the technologies suits for low-cost millimeter-wave applications. This research is results of “Research and Development of the Millimeter-wave Antennas for a Broadband Communication System in 60GHz band” and “Research and Development on the Millimeter-wavelength High Speed Mobile Communication System”, which are sponsored by the Japanese Ministry of Internal Affairs and Communications.

A Broadband Directional Coupler using Nonuniform-Coupled Transmission Lines with Uniform-Coupled end Sections

A compact broadband directional coupler has been developed using novel nonuniform-coupled transmission lines with uniform end sections. By using these coupled lines, both the coupled line spacing and the coupled line length can be reduced. A 50% size reduction and a broadband performance are achieved in the fabricated coupler.