This paper theoretically and experimentally investigates the mutual coupling between two ports of dual slot-coupled circular microstrip antennas. Presented are the effects of feed configuration, slot length, slot offset from the circular disk center, circular disk radius and the dielectric constant of the feed substrate on the mutual coupling. Based on these results, the antenna with low mutual coupling was designed. The mutual coupling of under -35dB at the resonant frequency was obtained.

A novel analysis method of the intermodulation (IM) and the noise power ratio (NPR) of multiple-carrier amplifiers is descrided. This method, based on Discrete Fourier Transform, allows an accurate calculation of IM and NPR of the amplifier having multiple carriers by directly using measured single-carrier amplitude and phase characteristics. This method has an outstanding feature in that it can be applied to the general case of n carriers having an arbitrary power level as long as frequency-dependence of amplitude and phase characteristics is negligibly small. Applying this method to the linearized amplifier, a good agreement between measured and calculated results for IM3, IM5, and NPR has been obtained for operation from linear up to saturation, which shows this method would be a good candidate for calculating IM and NPR of multiple-carrier amplifiers.

In this paper, we discuss an application of range Doppler imaging to measurement of reflected wave intensity from a moving object without using an anechoic chamber. The wave intensity reflected from a metal plate moving in the horizontal direction toward the antenna is typically 40-50 dB higher than that in the case without using the plate, and the estimated radar cross sections for a metal plate and sphere show good agreement with the theoretical value. The measurement of wave absorption by the present method suggests that frequency characteristics of the observed reflection loss are in close agreement with those of the calculated loss. These results show the reliability of the present experimental system and suggest that the method is applicable to wave reflection measurement not in an anechoic chamber but in an ordinary laboratory room.

We developed an automatic data processing algorithm for a ground-probing radar which is essential in analyzing a large amount of data by a non-expert. Its aim is to obtain an optimum result that the conventional technique can give, without the assistance of an experienced operator. The algorithm is general except that it postulates the existence of at least one isolated target in the radar image. The raw images of underground objects are compressed in the vertical and the horizontal directions by using a pulse-compression filter and the aperture synthesis technique, respectively. The test function needed to configure the compression filter is automatically selected from the given image. The sensitivity of the compression filter is adjusted to minimize the magnitude of spurious responses. The propagation velocity needed to perform the aperture synthesis is determined by fitting a hyperbola to the selected echo trace. We verified the algorithm by applying it to the data obtained at two test sites with different magnitude of clutter echoes.

A simple adapter de-embedding method is presented in a six-port calibration process using only one sliding load and one standard short. Adapter de-embedding is performed to extract the S-parameters of the adapter from the six-port system parameters. The concept of this method is based on the relations between the S-parameters and the Fourier coefficients of the periodic return loss of the adapter. To complete the de-embedding procedure, there are two measurement steps: one is return loss measurement with the sliding load, and the other, sidearm power measurement with the standard short. Using these measured values, unique solutions of the S-parameters are determined. A computer-controlled six-port with 2.4 mm coaxial-type connector was designed for calibration using a waveguide-type sliding load over the frequency range of 8.5-12.0 GHz. Through experiments, the adapter for joining two unlike connector types was measured. Then the reflection coefficients of the adapter with the sliding load measured by the calibrated six-port and those calculated from the S-parameters were compared with each other. As a result, an overall good agreement with standard deviation of less than 0.1% was found at all setting frequencies. One of the main features of the method is that the S-prameters of a two-port as well as the system parameters of a six-port can be determined by means of simple scalar measurement.

This paper describes a nondestructive measurement method for complex permittivity of dielectric material at pseudo microwave frequencies. The resonator used in this study has a cylindrical cavity filled with a sapphire material of a well known complex permittivity. The resonator is divided into two parts at the center. A dielectric substrate specimen is clamped with these halves. Relative permittivity εand loss tangent tan δ of the specimen are obtained at 3 GHz using the TE011 resonance mode. The accuracy of the present method is evaluated through the comparison of the measured values by the new method with those at around 10 GHz by the conventional empty cavity resonator method. The errors of measurements are smaller than 1% and 1105 for εand tan δ, respectively.

It is important to obtain a low coefficient sensitivity digital filter. This paper presents a new low coefficient sensitivity network structure that consists of a second order digital filter and a feedback path. This network structure is based on the effectiveness of the feedback path in an analog system. The coefficient sensitivity of the proposed digital filter can be control with the coefficient of the feedback path. Using this property, the digital filter with the low coefficient sensitivity is obtained. To add the feedback path makes the frequency response deviate from the characteristic of the original second order digital filter, but the deviation can be compensated with the other coefficients. A nonlinear optimization technique is employed to determine the coefficients of the digital filter. The proposed method is not effective only to narrow-band low-pass but wide-band low-pass filters.

This paper surveys the researches on biological and electeromagnetic environments in RF (radio frequency) and microwave regions in Japan. Publicized research reports on biological objectives, evaluation of exposure rate, electromagnetic environments and guideline for the protection from radio wave nuisances are briefly introduced. Some researches on the evaluation of the exposure rate caused by the near field effect of portable radio transceiver are reviewed. Radio frequency exposer protection guidelines in Japan are also described.

The biological effects of power frequency electric and magnetic fields have been a source of concern for the past many years, especially since 1979 when an epidemiological study report suggested a positive relationship between childhood cancer and exposure to power frequency electromagnetic fields from residential overhead power lines. The extensive studies of dosimetry and biological effects have since been carried out. It is believed that power frequency electromagnetic fields does induce biological effects (no serious threat to human health). The clear explanations for the possible interaction mechanisms remain to be identified. The problem with the study on dosimetry has been lack of theory that applies to the physical interaction of power frequency electric and magnetic fields with humans. At present, it seems to be widely accepted that the density of induced currents in the human body can be used as the decisive parameter in evaluating human exposure to these fields. In order to predict the distribution of induced current density inside a human body exposed to electric fields, magnetic fields, or electric and magnetic fields that coexist, the precise measurements of electromagnetic environments are necessary. According to necessity, the fields have to be characterized in terms of strength, orientation and phase angle. This paper presents: (1) Measurements of power frequency electromagnetic environments in 187kV substation yard and in the vicinity of the ground under 187 kV line using laboratory-made instruments; (2) Development of magnetic field exposure monitor; and (3) Review of state of the art of theoretical dosimetry for electric fields, magnetic fields and combined electric and magnetic fields, and evaluation method of human exposure for the future research.

It is well known that weather conditions affect the performance of satellite broadcasting receiving systems. For example, snow accretion on antennas degrades the receiving performance seriously because it reduces received signal power and also can increase antenna noise. Since effects of the weather are considered to differ for various types of receiving antenna, an investigation on this phenomenon is very important. A study on weather effects to three types of satellite broadcasting receiving antenna, a planar antenna, a center-fed parabolic reflector antenna, and an offset parabolic reflector antenna, is presented in this paper. Since the performance of receiving antennas can be determined by a parameter G/T, a long-term and continuous measurement of G/T must be performed. Furthermore, the measurement of more than one receiving system should be performed simultaneously. Also, the measurement should be performed in a snowy area (in winter) and a rainy area (in the other seasons) to evaluate the effect of the weather. To fulfil the criterion, a continuous measurement system of G/T has been built in Hokkaido University, Sapporo. Sapporo, which is located at latitude 42 degrees north, has a long and snowy winter, and also has rainy days in the other seasons so that we can evaluate the effect of weather. Using this measurement system, cumulative distributions of measurement results are obtained so that the performance of different types of receiving system can be evaluated. In this paper, some considerations on the noise level are also discussed briefly to evaluate the performance degradation of the receiving systems.

This paper discusses a common channel signaling system in which multiple micro-switching systems can converse as though configured like a conventional centralized switching system. A micro-switching system is a switching system whose main functions are integrated on a chip, like a microprocessor. Progress in MOS technology will soon make micro-switching systems possible, and their small scale and economy will allow subscriber switching systems to be distributed closer to subscribers. This will allow shorter subscriber loops, so subscriber networks will be able to reuse existing metallic lines as H1 (1.544/2.048Mb/s)-class subscriber loops. Economical micro-switching systems and reuse of existing network resources will contribute to the establishment H0 (384kb/s)-ISDN, so that every subscriber will be able to enjoy multimedia communications through HO-calls as simply as using present telephones. Four alternative signaling network architectures are examined, classified by arrangement of their signaling transfer junctions and signaling links, and a new signaling system featuring cell-based transfer functions is proposed. This is suitable for a distributed micro-switching-system network in order to minimize the figures of merit, which collectively estimate network cost and signaling delay.

This paper discusses the potential benefits of H0-based ISDN. By providing widespread H0 (384kb/s) call services, much like today's telephone systems, it should be possible to bring multimedia public communication services to the general public. Small distributed switching systems and reuse of existing metallic loops will contribute to its economical construction and rapid expansion into general use. System-on-a-chip technology, expected to appear soon, will make the necessary small switching systems cost-effective. The short loops resulting from the distribution will allow Hl-band (1.5/2.0Mb/s) metallic loops to be used. In terms of function, the distributed switching nodes will permit node-by-node customization, which will make switching systems simple and flexible. The proposed node-by-node customization will allow subscribers in each different node to choose they prefer. H0-based ISDN will provide various type of nodes, supporting various types of subscriber loops, whereas present public networks enforce standardized subscriber loops. Furthermore, when customized subscriber switching systems accommodate star-LAN interfaces as subscriber loops, the public network will be able to provide LAN services in a closed area as part of the public network services. The LAN users will be able to converse with ordinary residential subscribers through H0-calls. This will lead to the integration of LANs and public networks.

This paper proposes using an adaptive array in a base station for signal reception and transmission in order to increase the spectral efficiency without decreasing the cell radius. The adaptive array controls the directivity pattern of the base station to reduce co-channel interference during reception; the same array pattern is applied during transmission to prevent unnecessary illumination. Computer simulation results show that the cluster size can be reduced to one with time division duplexing (TDD), indicating that we can reuse the same frequency group at all cells. Thus, the improvement in spectral efficiency is as much as 16 fold that of an omni-antenna. Moreover, load sharing, which is expected to improve the channel utilization for unbalanced load situations, is available by cell overlapping. Frequency division duplexing (FDD) requires a weight adjust function to be applied for transmission since the difference in frequency between signal reception and transmission causes null positioning error. However, simple LMS-adjusting can provide a cluster size of one as well as cell overlapping when the frequency deference is 5%.

When measuring the ejection fraction for the evaluation of the ventricular pumping function by means of the thermodilution technique, the slow response a conventional thermistor has caused it to be considered unsuitable, and fast thermistors have been proposed as an alternative. However, in this paper we propose improving the time-domain response of a conventional thermistor using a signal processing technique composed of a series of first-order high-pass filters which is known as the natural observation system. We considered the rise time of the thermistor in response to a step temperature change to effect correction for the measurement of the ejection fraction. The coefficients of the natural observation system were calculated by minimizing the square error between the step-response signal of the thermistor and the band-limited reference signal. In an experiment using a model ventricle, the thermodilution curve obtained from a conventional thermistor was improved using the proposed technique, thus enabling successful measurement of the ejection fraction of the ventricles.

The generation and design of a stationary Markov signal are discussed as an inverse problem, in which one looks for a transition probability when a stationary probability distribution is given. This paper presents a new solution to the inverse problem, which makes it possible to design and generate a Markov random signal with arbitrary probability distribution and an exponential correlation function. Several computer results are illustrated in figures.

Electrical and optical properties of organic multilayer structure have been investigated. Two types of current-voltage characteristics have been found for thin multilayer structure of organic films. Optical property and its application for electroluminescent diode have been presented. The diode characteristics have been discussed in terms of energy band scheme.

This paper addresses the problem of estimating the parameters of multivariate ARMA processes by using higher-order statistics called cumulants. The main objective in this paper is to extend the idea of the q-slice algorithm in univariate ARMA processes to multivariate ARMA processes. It is shown for a multivariate ARMA process that the MA coefficient matrices can be estimated up to postmultiplication of a permutation matrix by using the third-order cumulants and of an extended permutation matrix by using the fourth-order cumulants. Simulation examples are included to demonstrate the effectiveness of the proposed method.

This paper presents a structure of adaptive equalizer equipped with a neural network and a Viterbi decoder, and evaluates its performance under a fading environment by means of computer simulation.

We report the dispersion of two-photon absorption (TPA) coefficient, (β), in polydiacetylene (12, 8) thin film waveguides in the wavelength range less than the one-photon band-gap with a 100 femtosecond mode-locked Ti: Sapphire laser pulses. The TPA coefficient was found to be 4 cm/GW for TE polarization at 900 nm (1.38 eV) by taking into account a Gaussian intensity distribution as well as a temporal pulse shape. We observed a sharp resonance in β above the first one-photon allowed transition with a full width at half maximum (FWHM) of 90 meV.

We fabricated junctions with a porphyrin polyimide (PORPI) monolayer, and then investigated the electron transport properties of the junctions from the current-voltage (I-V) and d2V/dI2-V measurements. Polyimide LB films without porphyrin were used as tunneling barriers. One large peak was seen at a voltage around 1.9 V, due to the excitation of electron transitions in PORPI molecules, whereas a step structure was not observed in the I-V characteristic.