Mitsuo Taguchi

Dual-band circularly polarized microstrip antenna for GPS application

In this paper, the small dual-band circularly polarized square MSAs for GPS application is proposed and the operational principles and the characteristics of the antenna are clarified by the simulator. The antenna consists of a square patch with slits and four T-shaped elements. The T-shaped element is loaded at each slit of the square patch.

Analytical and experimental investigations of the diffraction field of a Gaussian beam through a sequence of apertures: applicability of the beam mode expansion method

The beam mode expansion method is used to approximate the diffraction field through a sequence of apertures for Gaussian beam incidence. Each aperture is assumed to be located in the Fraunhofer region. The results show good agreement with the experiment if the aperture radii are not too small compared to the field spread.

Sleeve antenna with ground wires

Pocklingtons integral equation for a sleeve antenna with ground wires is formulated. By applying the Galerkin method to this equation, a sleeve antenna, a monopole antenna with ground wires, and a sleeve antenna with ground wires are analyzed, and numerical results for these antennas are compared with measured data. The sleeve antenna features the leakage current on the surface of the coaxial feeder, suppressed by a sperrtopf, but it is mismatched with the 50- Omega feeder. The monopole antenna with inclined ground wires may be adjusted to match the 50- Omega feeder, but the leakage current induced on the feeder cannot be neglected. It is found that the sleeve antenna with ground wires has the advantages of both antennas. >

Analysis of Dead Zone of RFID System

The dead zone of RFID system has been numerically and experimentally investigated. The electric field distribution near the square conducting plate was numerically obtained when the plane wave is incident. The current distribution on the conducting plate in the case of spherical wave incidence is expressed by the integration of induced current due to the plane wave incidence. The scattered electric field was calculated and discussed. The electric field distribution near the conducting plate was measured and the existence of the dead zone was shown

Quasi-diffraction-free beams.

A diffraction-free beam is obtained by the superposing of plane waves whose wave vectors make an angle with the propagation axis. These plane waves are realized with point sources that are distributed uniformly around a circle and an infinitely large aperture lens. After the field passes through the lens it has nondiffracting properties and is described by the zero-order Bessel function. Relaxing these conditions makes the beam diffraction free within only a limited region. The beam generated from such a geometry is referred to as a quasi-diffraction-free beam. The effects of the width of the annular source on the beam spread are discussed and compared with those for a Gaussian beam. Approximate expressions for quasi-diffraction-free beams are also obtained.

Heterodyne efficiency for a partially coherent optical signal

Heterodyne efficiency is discussed for a partially coherent signal and a coherent local oscillator beam. Both fileds are assumed to have Gaussian amplitude distributions. An input aperture is used to reduce the background noise. As the coherence of the signal decreases, the efficiency also decreases. However, there is a simple relation between the beam parameters and the detector dimensions to maintain optimum efficiency. The effect of the offset of the signal from the detector axis is also discussed, assuming the Gaussian probability of the deviation. In this case, the optimum parameters that give the maximum efficiency change with the average deviation.

Analysis of arbitrarily shaped dielectric lens antenna by ray tracing method

The authors have reported the three dimensional ray tracing method for the analysis of dielectric lens antenna with arbitrarily shaped inner and outer surface. However. the multiple reflections are not considered. In this paper, the ray tracing method is applied to the dielectric lens antenna. The primary radiator of this lens antenna is the H-sectral horn fed by the rectangular waveguide. The multiple reflection of a ray is considered.

Fraunhofer diffraction of a plane wave by an elliptical annular aperture with offset or tilt

Abstract Fraunhofer diffraction field through an elliptical annular aperture is obtained for plane wave incidence when there is offset or tilt of the inner ellipse. The effects are observed through the field distribution.

Circular polarized antenna composed of unbalanced fed ultra low profile inverted L antenna and slot

The circular polarized antenna composed of an unbalanced fed ultra low profile inverted L antenna and a L shaped slot is proposed for the reader antenna of the portable terminal of RFID. At UHF band from 915 MHz to 930 MHz, the S11 less than-10dB and the axial ratio less than-3dB are satisfied. In the numerical analysis, the electromagnetic simulator “WIPL-D” based on method of moment is used.

High gain planar antenna composed of unbalanced fed inverted L antenna

The high gain planar antenna excited by the ultra low profile inverted L antenna is proposed and analyzed numerically. The strong electromagnetic field between two conducting planes is excited by the inverted L antenna. The design frequency is 2.45 GHz. The size of proposed antenna is 40 mm by 60 mm by 9 mm (0.327 λ by 0.49 λ by 0.074 λ). The return loss bandwidth larger than 10 dB is 4.16 % and the directive gain in the z direction becomes to be 7.98 dBi.