Oki Electric Industry Co., Ltd.

Waseda University

National Institute of Information and Communications Technology, Incorporated Administrative Agency

Seiji Nishi

Tetsuya Kawanishi

Takuro Sato

Hiroyo Ogawa

Yozo Shoji

Kiyoshi Hamaguchi

Hok Huor Ou

Tomoji Hamada

Isamu Matsuyama

Kei Takeishi

Kazuhiko Tamesue

The first conductor plate has a groove portion that has a rectangular cross section and is formed in parallel with a first main surface such that the longitudinal direction becomes a first direction, and a first vertical tube portion formed in a direction away from the second conductor plate in a second direction orthogonal to the first direction and the first main surface, with a branch position in the groove as a starting point. The second conductor plate includes a reflection portion that is inserted into the groove portion in a manner protruding from a second main surface, which is a flat surface of the second conductor plate in contact with the first main surface, and has a reflection surface that reflects the radio wave, propagated along the groove portion, toward the first vertical tube portion.

Waveguide, method of manufacturing waveguide and antenna

A low-cost, compact circular waveguide array antenna which improves an antenna reflection loss characteristic and enables an improvement in radiation characteristics, particularly radiation gain. The circular waveguide array antenna includes feeding portions which feed electromagnetic waves to one ends of circular waveguides and radiation apertures which radiate the electromagnetic waves at the opposite ends. Each circular waveguide includes a conical horn, with a diameter of a feeding side aperture at the feeding portion end being a, a diameter of the radiation aperture being d, which is larger than the diameter a of the feeding side aperture, and an opening angle being 2&#x3b1;. If a wavelength of a central frequency of an employed frequency band is &#x3bb;, then a value of &#x3b1;, which is half of the opening angle, is set between 0.8&#xd7;Arcsin(0.1349114/(d/&#x3bb;)) and 1.2&#xd7;Arcsin(0.1349114/(d/&#x3bb;)).

Circular waveguide antenna and circular waveguide array antenna

A flat antenna includes a 2&#xd7;2 array of circular waveguide antenna elements that receive power from a splitting circuit including first to fourth striplines. The second stripline extends in two directions from one end of the first stripline. The third stripline extends in two directions from one end of the second stripline. The fourth stripline extends in two directions from the other end of the second stripline. Four feeder electrodes extend in mutually identical directions from the ends of the third and fourth striplines into the waveguides. The third and fourth striplines are bowed in way that shifts the second stripline closer to the center of the array. This arrangement permits a compact spacing of the waveguide antenna elements.

Antenna with stripline splitter circuit

A metal-semiconductor field effect transistor includes an AlGaAs buffer layer made of Al.sub.x Ga.sub.1-x As, wherein 0&lt;x&lt;0.4, and a channel layer made of an n-type doped In.sub.y Ga.sub.1-y As, wherein 0&lt;y&lt;0.4, having a thickness equal to or less than a critical thickness for lattice-matching with GaAs. Further, a doped AlGaAs layer is interposed between the AlGaAs buffer layer and the channel layer. The doped AlGaAs layer is made of Al.sub.x Ga.sub.1-x As, wherein 0&lt;x&lt;0.4, is doped with Si of a concentration of 5*10.sup.17 cm.sup.-3 or more, and has a thickness which is sufficient to provide a barrier against holes caused by a donor depletion region.

Metal semiconductor FET having doped A1GaAs layer between channel layer

A semiconductor device for a microwave circuit includes a semiconductor substrate with an active element formed in the top surface, surface wirings on the top surface of the semiconductor substrate which are connected to terminals of the active element, and rear electrodes on the rear surface of the semiconductor substrate which are connected to the surface wirings by via holes. A structure includes the microwave semiconductor device, and a dielectric substrate which has surface wirings on a top surface. The semiconductor device is fixed with the dielectric substrate such that the rear electrodes of the semiconductor device are connected with the wirings on the top surface of the dielectric substrate.

Growing community of inventors

Tokyo, Japan

Seiji Nishi