This paper describes a trial of evaluating the proper characteristics of multiple sound insulatain systems from their output responses contaminated by unknown background noises. The unknown parameters of sound insulation systems are first estimated on the basis of hte linear time series on an intensity scale, describing functionally the input-output relation of the systems. Then, their output probability distributions are predicted when an arbitrary input noise passes through these insulation systems.

A flat stick-shaped whip antenna was developed for Japanese commercial portable telephones. It provides a high gain even though it is short and retractable. It is an open-sleeve type antenna. i.e., the inductance-loaded dipoleantenna element parallels a twin-lead type feeder. It suppresses the currents on the radio housing even at short antenna lengths. Moreover, it is easy to achieve two resonant characteristies and able to construct retractable type. A relatively high gain is gotten even when the antenna is in a retracted state. This antenna has a suitable configuration for commercial portable telephones. This paper first calculates, the current suppression of the housing on a principal model of this antenna, i.e., without a twin-lead feeder. The second analysis determines the effects of the twin-lead feeder and the dielectric coat on the antenna. Next,the two resonant technique and the configuration for the retractable-type antenna describes. In addition, the return loss and radiation pattern for the trial model were measured. The return loss shows that the two resonant characteristics and the bandwidths of the high and low resonant frequencies are 2.2% and 1.5%(VSWR2), respectively. For when the antenna is extended, radiation patterns are nearly the same as for the case of the 1/2 wavelength dipole antenna, and the antenna efficiencies are -1.6 dB at 820 MHz and -1.1 dB at 950 MHz. Other hand, for the retracted state, they are destroyed by the housing currents, but the efficiency is relatively high of -1.8 dB at 950 MHz. In these experiments, it is clear that the antenna achieves high performances.

The coupling response of an external transient electromagnetic field to a transmission line is considered. An experiment has been conducted to verify the line equations for a transmission line excited externally by a transient near field. The model field is generated by a monopole antenna installed in the vicinity of the transmission line and driven by a step waveform. The waveform is analyzed into discrete spectrum components using a Fourier transform. The frequency-domain field components affecting the transmission line are estimated by the moment method, and then the induced frequency-domain voltage at the terminal load is converted into a time-domain voltage using an inverse Fourier transform. Comparison between the measured and the computed values provides verification of the line equations. The coupling mechanism is discussed from the experimental results. It seems equivalently that the transmission line picks up the field, generated at the feed point and the top point of the monopole antenna, at both terminal ends.

The interstitial hyperthermia is an invasive heating method applied by inserting the applicator into the human body. We have been studying on coaxial-slot antennas for interstitial microwave hyperthermia. The characteristics of the square antenna array were theoretically examined. Firstly, the basic structure of the antenna, and a simplified analysis model taking account of the effect of the boundary surface were explained. Then analysis was performed by using the moment method. Finally, the calculated results were discussed. The catheter thickness has much effect on the characteristics and must be considered both in designing and in using the antenna. When the array spacing was increased, the effective heating area became larger and more uniform. As the insertion depth was increased, the effective heating area was also enlarged.

In this paper, electromagnetic scattering by infinite double two-dimensional periodic array of resistive upper and lower elements is considered. The electric field equations are solved by using the moment method in the spectral domain. Some numerical results are shown and frequency selective properties are discussed.

The back-propagation algorithm has been applied to many fields, and has shown large capability of neural networks. Many people use the back-propagation algorithm together with a momentum term to accelerate its convergence. However, in spite of the importance for theoretical studies, theoretical background of a momentum term has been unknown so far. First, this paper explains clearly the theoretical origin of a momentum term in the back-propagation algorithm for both a batch mode learning and a pattern-by-pattern learning. We will prove that the back-propagation algorithm having a momentum term can be derived through the following two assumptions: 1) The cost function is Enαn-µEµ, where Eµ is the summation of squared error at the output layer at the µth learning time and a is the momentum coefficient. 2) The latest weights are assumed in calculating the cost function En. Next, we derive a simple relationship between momentum, learning rate, and learning speed and then further discussion is made with computer simulation.

In this paper, a waveguide-fed slot-coupled microstrip antenna is proposed as enhanced feeding structure of microstrip antenna and an analysis is pesented. The presence of dielectric substrate between a strip and a slot is explicitly taken into account in this analysis. The evaluation of the antenna characteristics is carried out using the method of moments and the spectral domain approach in terms of the electric current distribution on the strip and the magnetic current distribution on the slot.

This paper describes that the dielectric characteristics of a catheter around the interstitial antenna have an effect on the wavelength for current, and this effect results in the variation of the SAR (Specific Absorption Rate) distribution around the antenna. A theoretical study of SAR distribution ground a coaxial-slot antenna is performed. Analytical technique used is the moment method. Result and discussion on the effect of material and thickness of the catheter are presented. The wavelength for the current shortens with increasing dielectric constant or decreasing thickness of the catheter. Due to this variation of the wavelength for current, the SAR distributions take various shapes.

Broadband antennas such as biconical antennas and log-periodic dipole antennas are generally used in automatic EMC measurements. However, these broadband antennas have not been used for accurate measurement because accurate specifications for them are lacking. Therefore, more accurate analysis is urgently required by the CISPR (International Special Committee on Radio Interference), to establish the specifications for broadband antennas for EMC measurements. In this paper, the AF of biconical antennas is calculated by using Moment Methods. The frequency characteristics and antenna height dependency of AF are presented. AF is also measured and compared to the data obtained by the calculations. Good agreement between the calculations and measurements is achieved, indicating the usefulness of our computation method. In addition, the effect of antenna separation distance and transmitting antenna height on AF is investigated. The calculated AF deviation from the reference value is nearly 0dB except for certain antenna arrangements. In these antenna arrangements, the field becomes null at the receiving antenna and widely varies in magnitude and phase around the null points. Therefore, the antenna is immersed in a non-uniform field, while the AF is defined on the assumption of a uniform field. Consequently, the erroneous AF will be derived from measurements around these null points and it will be greatly different from that obtained at other antenna heights. Thus, it is better to avoid these conditions during actual measurements. The effect of the ground plane on AF is also evaluated. AF is shown to be seriously affected by the ground plane especially at frequencies around 90MHz. It should be noted that AF deviation has crests corresponding to the null field at 300MHz. The obtained data will be useful in establishing specifications of biconical antennas for EMC measurements.

An efficient full–wave spectral domain moment method is developed to compute the current distribution and the radiation associated with microstrip discontinuities. Two techniques are used to increase the efficiency of the method of moments algorithm so that a transmission line of moderate electrical size can be analyzed in reasonable time.

On ranging system on short distance using spread spectrum, we examine waveform responses to predict the state of electromagnetic waveform propagation while the signal is received after scattered by a target. Then this system and the numerical results are discussed.

By applying Wigner distribution, which has high time resolution and high random noise reducing capability, to the acoustic bio–signals, the possibility of early diagnosis in both intracranial vascular deformation and prosthetic cardiac valve malfunction increased. Especially in latter case, 1st–order local moment of the distribution showed its effectiveness.

A radial line slot antenna (RLSA) is a slotted waveguide planar array for the direct broadcast from satellite (DBS) subscriber antennas. A single-layered RLSA (SL-RLSA) is excited by a radially outward traveling wave. The antenna efficiency of more than 85% has already been realized. These antennas are designed on the assumption of perfectly rotationally symmetrical traveling wave excitation; the slot design is based upon the analysis of a slot pair on the rectangular waveguide model with periodic boundary walls. However, the slots perturb the inner field and the actual antenna operation is not perfectly symmetrical. This causes the efficiency reduction especially for very small size antenna. This paper presents a fundamental analysis of the inner field of the radial waveguide. It is impossible to analyze all the slot pairs in the aperture as it is and only the slots in the inner few turns are considered since these provide dominant perturbation. The calculated results are verified by the experiments and reasonable agreement is demonstrated. Some design policies are suggested for enhancing the rotational symmetry.

In this paper, we analyze high-Tc superconducting (HTS) microstrip antenna (MSA) using modified spectral domain moment method. Although it is assumed that the patch and the ground plane of the MSA are perfect electric conductors (PECs) in the conventional spectral domain method, we modify this method to compute the conduction loss of the HTS-MSA. In our analysis, the effect of the HTS film is introduced by the surface impedance which we can estimate by using the three fluid model and experimental results. This paper presents numerical results about the HTS-MSA, for example, the relations between the thickness of the substrate and the radiation efficiency, the temperature and the resonant frequency, and so forth. And we discuss the effective power range where the performance of the HTS-MSA is superior to that of the Cu-MSA.

We propose a new structure of antenna system to enhance the horizontal plane gain and control the antenna pattern, using passive loading. Our proposed structure can be applied to various kinds of antennas on a handset. We discuss the case of a λ/4 monopole antenna on a handset in this paper. In a new structure of λ/4 monopole antenna system, we show that, 1) the increase of the average gain about 5dB in the horizontal plane can be realized by an optimum load, 2) the antenna pattern can be controlled by changing the value of the passive load so as to have some desirable shapes, and 3) the antenna size can be made smaller by about 6% than the one with no loading because the optimum loading makes the resonant frequency lower. These results were confirmed by the calculations using the method of moments for the EFIE and the measurements.

The invariant imbedding method combined with the time domain wave splitting technique is applied to the inverse problem for the telegraph equation t2u=(1/r)(pu)-btu+qu in a stratified half-space. The zeroth, second and fourth moments of the 3-D fields are used to reduce the three-dimensional problem to a set of one-dimensional problems. The imbedding equations for R0, R2 and R4, respectively the zeroth, second and fourth moments of the reflection operator, are derived. Numerical results for the reconstruction are presented using the reflection data on the surface.

A full-wave analysis for the scattering problem of infinite periodic arrays on dielectric substrates excited by a circularly-polarized incident wave is presented. The impedance boundary condition is solved by using the moment method in the spectral domain. Numerical results are given and scattering properties are discussed.

A theoretical and experimental study of a thin card-sized antenna is presented. The method of moment with a wire-grid model is used to analyze this antenna. In order to validate numerical efficiency, measurements using Wheeler method are preformed on this antenna and its wire-grid models. The experimental and theoretical results are in good agreement if the wire conductivity is well chosen. And the noise reduction of measured Wheeler efficiency using least mean square method is also examined.

The relation between the radiation pattern and the dimension of the conducting box for a portable telephone is illustrated both theoretically and experimentally. The Galerkin-moment method using the Fourier series expansion for the surface current of the conducting box, which has a great advantage of having a high accuracy, is employed to obtain the radiation pattern. As an example of antennas, a quarter-wavelength monopole antenna having a sinusoidal current distribution is used. As a result, it is pointed out that the radiation pattern of a monopole antenna mounted on the box tends to tilt in a lower direction both in theory and in experiment as well. The relation between the radiation pattern and the location of the monopole antenna is also described. An asymmetrical, or distorted pattern is observed when the monopole antenna moves away from the center of the top plane.

Numerical analysis of the electromagnetic radiation from conducting surface structures is concerned. The method of moments is discussed with the surface-patch modeling in which the surface quantities, i.e. the current, charge and impedance are directly introduced and with the wire-grid modeling in which the surface quantities are approximated by the filamentary traces. The crucial element to a numerical advantage of the wire-grid modeling lies in the simplicity of its mathematical involvements that should be traded for the uncertainties in the construction of the model. The surface-patch techniques are generally not only clear and straightforward but also more reliable than the wire-grid modeling for the computation of the surface quantities. In this work, we bring about a comparative discussion of the two approaches while the analysis of a built-in planar antenna is reported. For the purpose of the comparison, the same electric field integral equation and the Galerkin's procedure with the linear expansion/testing functions are used for both the wire-grid and surface-patch modeling.