Shintarou Urasaki

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The authors propose a low sidelobe dual-polarized planar array antenna for Ku-band satellite communications. In conventional dual-polarized planar array antennas using strip lines and microstrip patch antennas, it is difficult to obtain low sidelobe characteristics because the aperture distribution is deformed from the desired one by electrical coupling(More)
In this paper, a new type of antenna without the contact feed point is proposed for mobile information terminals. The whip antenna is excited by the built-in antenna with electromagnetic coupling. The built-in antenna acts as a radiator when the whip antenna is pulled in. The built-in antenna acts as not only a radiator but also an exciter for the whip(More)
We have proposed a novel type of diversity antenna construction for compact mobile telephones. The proposed diversity antenna basically consists of one excitation element, the conducting-plate, and the reactance-switching circuit connecting between the end of the element and the conducting-plate, and need not install two excitation elements. We have(More)
Measurements using a field probe in the radiating near-field region based on defocusing techniques are practical and useful to approximately determine far-field antenna patterns. Especially for measurements of huge scale antennas the defocusing techniques are essential. However, the test distance to focus is generally limited due to both amplitude and phase(More)
We propose a new indoor surface measurement method using the REV (Rotating Element-field Vector) method. In contrast to the standard holographic methods, in which both amplitude and phase are measured, the REV method requires only amplitude measurement. In this paper, properties of the proposed method are studied by simulation, and main error factors that(More)
The brightness and color of pearls varies among different pearl-producing shellfish and have been a source of human fascination since ancient times. When produced through cultivation, the characteristics and quality of a pearl depend on the kind of shellfish used and also the transplanted mantle graft. This suggests that the Akoya pearl oyster, which is(More)
The authors propose a bifilar helical antenna with a self-complementary shape. Bifilar helical antennas having an omnidirectional radiation pattern often have been composed of thin wires . In these conventional shapes, it is difficult to design an antenna satisfying both desired characteristics of the radiation and the reflection because the design(More)
We propose a new satellite communication system using inclined GEO satellites which mount deployable phased array antennas. An example is shown of the inclined GEO locus. In this system, the satellite illuminates multiple beams to a certain area from a high elevation angle, so that the degradation due to shadowing effect can be reduced. When large aperture(More)
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