Common-mode (CM) radiation from a cable attached to a conducting enclosure has a typical dipole-type antenna structure, in which an equivalent noise voltage source located at the connector excites the attached cable against the enclosure to produce radiated emissions. Based on this mechanism, a simple method for predicting the CM radiation from the cable/enclosure structure was proposed. The method combines an equivalent dipole approximation with sinusoidal current distribution and CM current measurement at a specified location on the cable. Its validity was examined in comparison with the far-field measurement and finite-difference time-domain (FDTD) modeling. The predicted resonance frequencies and CM radiation levels were validated with engineering accuracy, i.e., within 30 MHz and 6 dB, respectively, from the measured and FDTD-modeled results in the frequencies above 150 MHz.

In general, the attenuation characteristics of band-pass filters can be improved by generating attenuation poles in the stop band. In this paper, a design method for a planar band-pass filter with attenuation poles based on a half-wavelength resonator is proposed. According to this design, the attenuation poles can be obtained at any desired frequency by means of coupling structures. Two kinds of filter with the characteristics of steep skirt and wide stop-band were designed and fabricated with the result that the validity of the design method was demonstrated. Therefore, a filter with excellent attenuation characteristics for various applications can be achieved.

New bandpass filters (BPFs) with stub resonators are proposed for creating multiple attenuation poles. Firstly, the stub-dependent characteristics of the distributed-element stubs are examined theoretically. Secondly, the new BPFs with resonators of combined stubs are proposed. An advantage of these filters is the possibility of controlling the number of attenuation poles. The design of the proposed filter is carried out based on the general filter design with the narrow-band approximation technique. The transmission and reflection characteristics of the proposed BPFs are also examined theoretically and experimentally. The miniaturization of the filters is also carried out using the resonator with loaded-element stubs. The discussions lead us to the conclusion that the proposed design method of the filters are useful for controlling the number of attenuation poles of the BPF.

A simple method for improving out-of-band characteristics of a planar microwave filter is proposed. We clarify the close relationship among 'tap connection,' 'attenuation pole' and 'spurious responses' in filter design, theoretically and experimentally. Firstly, the basic characteristics of the resonator depending on the excitation method are examined. We show that skirt characteristics can be improved and spurious responses can be suppressed by using the tap connection technique. Secondly, the application examples of bandpass filters (BPFs) on the basis of the resonator with our principle are provided. It is confirmed that the resonator depending on the excitation method is useful for improving out-of-band characteristics of the planar microwave filter.

This paper describes an estimation method for an antenna current distribution including the interaction between a cellular telephone antenna and a human body. In our experiments, current distributions on a half wavelength dipole antenna at 900 MHz are evaluated by measuring the magnetic field near the antenna, when a human head-sized phantom model is located near the dipole antenna. From the experiments, the antenna current around a feed point is confirmed to increase by 30% due to the interaction effect. This result shows that antennas of portable phones should be designed by considering the effect of a human presence for the development of the higher performance antenna, and our estimation method will contribute to optimizing the design of such antennas.

This paper presents a novel design method for reducing the complexity of the design procedure for diversity antennas on the hand-held phone. Recently, antenna selection diversity has been widely used for hand-held phones in order to overcome a problem of fading. A monopole antenna and an inverted-F antenna are the typical combination for this purpose. In the case of the conventional design method, the mutual coupling between two antennas are used for improving the diversity performance. However, strong mutual coupling often makes the diversity antenna design difficult and degrades the radiation performance. The proposed design method suppresses this coupling by tuning the terminating impedance on the unselected antenna and improves the diversity performance by modifying the shape of inverted-F antenna. The validity of the proposed method is investigated under the effect of the user's hand and head by FDTD simulation.

This paper proposes serially arranged two parasitic elements above a fed dipole to obtain broad bandwidth in resonant frequency of a parasitic element. The above antenna can be used in triple-bands with one feed point. Its design method using FDTD is also presented. Next, application of the triple-bands antenna is proposed for 3-sector base station antenna. Its characteristics of return loss and radiation patterns are indicated. Calculated values are in good agreement with measured ones.

As a solver in a simulator, advantages of use of a wavelet function were investigated for analysis of a dipole antenna using the Moment Method. Realization of a sparse matrix due to orthogonality and due to inherent nature of the wavelet is confirmed by observing an impedance matrix using each Daubechies' wavelet. Calculated results of the input impedance, the impedance matrix, and the current distribution are compared in variation of the wavelet in two integral equations for a dipole antenna. Use of the Daubechies' wavelet of the high number with a small matrix and a threshold in the Hallen's Integral Equation is suitable for the reduction of the matrix size and of the calculation cost.

In this study, the shielding effect of high-loss dielectric and magnetic materials themselves and also an oval human model placed behind these material, were investigated by the FDTD method, for near- and far-field exposure, using the half-wave length dipole antenna. According to the results, a high-loss magnetic material showed a large shielding effect (average 20 dB) compared to the high-loss dielectric material, for near- and far-field shields. Also, the reduction of the shielding effect was small (2 dB) for the high-loss magnetic material, while it was large for the high loss dielectric material, on decreasing the distance between the antenna and shield. Moreover, the variation of the shielding effect on a human model placed behind the shield was small (0.2-1.5 dB) for the high-loss magnetic material, but large for the high-loss dielectric material. This is similar to the results of the shield materials themselves, for the close antenna-shield and human-shield distances, respectively.

The aim of this study was to quantify the effects of inhomogeneities on magnetocardiography (MCG) forward solutions. It can serve to guide the selection of inhomogeneities to include in any geometric model used to compute magnetocardiographics fields. A numerical model of a human torso was used which construction included geometry for major anatomical structures such as subcutaneous fat, skeletal muscle, lungs, major arteries and veins, and the bones. Simulations were done with a single current dipole placed at different sites of heart. The boundary element method (BEM) was utilized for numerical treatment of magnetic field calculations. Comparisons of the effects of different conductivity on MCG forward solution followed one of two basic schemes: 1) consider the difference between the magnetic fields of the homogeneous torso model and the same model with one inhomogeneity of a single organ or tissue added; 2) consider the difference between the magnetic fields of the full inhomogeneous model and the same model with one inhomogeneity of individual organ or tissue removed. When single inhomogeneities were added to an otherwise homogeneous model, the skeletal muscle, the right lung, the both lungs and the left lung had larger average effects (15.9, 15.1, 14.9, 14.4% relative error (RE), respectively) than the other inhomogeneities tested. When single inhomogeneities were removed from an otherwise full inhomogeneneous model, the both lungs, the left lung, and the skeletal muscle and the right lung had larger effects (17.3, 14.9, 14.3, 14.2% relative error (RE) respectively) than other inhomogeneities tested. The results of this study suggested that accurate representation of tissue inhomogeneity has a significant effect on the accuracy of the MCG forward solution. Our results showed that the inclusion of the boundaries also had effects on the topology of the magnetic fields and on the MCG inverse solution accuracy.

The sharpness of the roll-off response of bandpass filters is a major concern for wireless communication systems. Bandpass filters with attenuation poles provide sharp roll-off. This paper investigates the performance of a ceramic comb-line filter with attenuation pole resonators (APRs), and studies the effects of the attenuation pole resonators on the filter response. The presented APRs are improved versions of previous ones and they are modeled here. The obtained results show that the length of APRs can be miniaturized via the loading capacitance. The resultant volume is about 400 mm3, which is very small comparing to coaxial type filters with the same attenuation rate in the stopband. With attenuation pole resonators added, skirt attenuation is greatly improved. Narrow bandwidth bandpass filters with attenuation poles in the stopband are designed and tested. Two designed examples demonstrate the flexibility of the attenuation pole resonator in the filter configuration. Experiments show good agreement with simulation results.

The abilities of fuzzy inference methods in modeling of complicated systems are implemented to electromagnetics for the first time. The very popular and well known monopole antenna is chosen as a general example and a fast, simple and accurate fuzzy model for its input impedance is made by introducing a new point of view to impedance basic parameters. It is established that a surprisingly little number of input data points is sufficient to make a full model and also the system behavior (dominant rules) are saved as simple membership functions. The validity of the derived rules is confirmed through applying them to the case of thin-angled monopole antenna and comparing the results with the measured. Finally using the spatial membership function context, input impedance of thick-angled monopole antenna is predicted and a novel view point to conventional electromagnetic parameters is discussed to generalize the modeling method.

In this paper, a novel design method for bandpass filter with attenuation poles (BAP) is presented. The changed inverter element values due to inserting either capacitors or inductors can be optimized using the linear relationship between inverter element values of a conventional bandpass filter (BPF) and those of the BAP using the Touchstone program. A 1800-1825 MHz bandpass filter with attenuation poles for duplexers is designed and fabricated using coaxial dielectric resonators. The validity of this design approach is demonstrated by a computer simulation. The resonators are simulated equivalently as shorted lossy transmission lines. The measured results of center frequency, bandwidth, and attenuation pole frequencies closely agree with the design values.

An intrinsic property of a tapped resonator is elucidated here, and a novel bandpass filter (BPF) with improved skirt characteristics based on a tapped half-wavelength resonator is proposed by this intrinsic property. "Tapping" for both I/O and interstage couplings of the resonator is the key concept here because a resulting open-ended resonator makes shunt open stubs which give anti-resonance near the center frequency. Multiple attenuation poles appear near the center frequency, namely, close to the passband. A BPF is designed on the basis of the general filter theory with a narrow band approximation. An experiment is carried out to confirm the concept by using a coplanar structure. The expected bandpass characteristics with multiple attenuation poles have been obtained by the novel BPF designed by the present concept.

Lots of self-tuning control schemes have been proposed for tuning the parameters of control systems. Among them, pole-assignment schemes have been widely used for tuning the parameters of control systems with unknown time delays. They are usually classified into two methods, the implicit and the explicit methods according to how to identify the parameters. The latter has an advantage to design a control scheme by taking account of the stability margin and control performance. However, it involves a considerably computational burden to solve a Diophantine equation. A simple scheme is proposed in this paper, which can construct a multivariable self-tuning pole-assignment control system, while taking account of the stability margin and control performance without solving a Diophantine equation.

A unified theory for the characteristics of dual modes in a circular resonator is elucidated in simple analytical expressions. First, a circular resonator is considered as a ring transmission line which allows two oppositely traveling waves. The essential quantities that characterize a transmission line, i. e. , the propagation constant and characteristic impedance are obtained theoretically and/or experimentally. Secondly, any circular resonator is described by a ring resonator model which can be treated analytically, and the resonant frequencies are obtained when perturbations are added along the periphery of a circular resonator. A two stage BPF is created by adding I/O ports to the perturbed circular resonator. Its center frequency and bandwidth is calculated based on the ring resonator model. The circuit condition for obtaining two attenuation poles at both sides of the passband is given together with the method for their control.

This paper presents a relationship between the near-field shielding effectiveness (SE) and the far-field SE of an infinite planar shield for dipole fields. The penetration fields through the shield and the near-field SE are deduced analytically from an explicit integral expression based on certain assumptions. They further give us approximate formulas for the near-field SE. The near-field SE depends on not only wavelength and material used, but also on the distance r from a source to an observation point through the shield, the source type (magnetic dipole or electric dipole) and the orientation (vertical or horizontal to the shield face) in general. The results we obtained are as follows. The near-field SE for magnetic dipole fields vertical to the shield face is the same as that horizontal to the shield face, and their absolute values equal that of the far-field SE multiplied by k0r/3 (k0 is the wave number). The near-field SE for electric dipole fields vertical to the shield face doubles that horizontal to the shield face, and the absolute value of the latter equals that of the far-fields SE divided by k0r. The validity of the assumptions used to obtain the approximate formulas are examined. The range of r (an application range), over which the difference between the approximate value and the true value is under 1 dB, is determined, where the former value is calculated by the approximate formula of the SE and the latter value is etsimated by direct integration of the related integral expression. For instance, an application range of the approximate formula for magnetic dipole fields vertical to the shield face is from larger one of 50δ and 33µrδ to 0. 11λ0, where µr is specific permeability, δ is skin depth of the shielding material used and λ0 is wavelength in the free space.

This paper presents a variant of the "Third-Order Recursion (TOR)" method for bispectral estimation of transfer-function parameters of a non-minimum-phase all-poles system. The modification is based on the segmentation of system-output data into coupled records, instead of independent records. It consists of considering the available data at the left and the right of each record as not null and taking them as the data corresponding to the preceding and succeeding record respectively. The proposed variant can also be interpreted as a "Constrained Third-Order Mean (CTOM)" method with a new segmentation in overlap records. Simulation results show that this new segmentation procedure gives more precise system parameters than the TOR and CTOM methods, to be obtained. Finally, in order to justify the use of bispectral techniques, the influence of added white and colored Gaussian noise on the parameter estimation is also considered.

2-pole band-pass filters (BPFs) with tap-excitation are prepared by using high temperature superconductors (HTS). The possibility of realizing superconducting coplanar filters with attenuation poles is revealed.

A two stage Combline Bandpass Filter (C-BPF) of the Vertically Installed Planar (VIP) structure has been investigated, which is essentially composed of a strongly coupled microstrip lines terminated with a planar fin and through-hole combined with the tapping feed approach. The principle and performance of this filter is studied approximately by an equivalent circuit model and also by the normalized 3D-FDTD method more exactly. The time domain iteration in the FDTD analysis is performed in an expanded time dimension resulting in a reduced CPU time. Some of the obtained numerical results are compared well with the measured ones. A modified VIP combline BPF has the advantages of simple structure, easy tuning, low cost, versatile bandwidth control and good skirt characteristics brought about by two attenuation poles.