This paper describes an analytical consideration for mode-coupled multimode optical fibers. First in this paper a novel theory for analysing the baseband transfer function of mode-coupled multi-mode fiber is briefly described. This theory is based on Scattering Matrix method and makes it possible to analyse the baseband transfer function for arbitrary mode dispersion, attenuation, coupling coefficient and excitation condition. Second the results of the simulation based on this theory is compared with the experimental study of the transmission characteristics of multimode W-type fibers with various numerical apertures. This theoretical and experimental approach leads to the necessity of the introduction of the selection rule or the restriction of the maximum difference of the wave constants of the coupled modes. It is shown that coupling intensity and selection rule of mode coupling dominate the transmission characteristics. As for multimode W-Fiber, almost all transmission characteristics such as the transmission loss and bandwidth vs. the intermediate layer width, fiber length and the excitation condition can be analysed by introducing suitable selection rule and coupling intensity. From the view point of the optical fiber transmission system design up to about ten kilometers, it may become convenient that the only two factors: selection rule and coupling intensity are the design parameters. Finally the heuristic fact that multimode W-fiber has smaller microbending loss than singly clad step index fiber on the basis of the same dispersion is proved theoretically.

The operating life for a newly developed millimeter-wave silicon DDR IMPATT diode, which is hermetically sealed in a mechanically rugged miniature ceramic package with a diamond heat sink, is evaluated by accelerated life tests consisting of high-temperature storage and high-temperature DC operation. A mean time to failure (MTTF) value of approximately 2.6105 h (3800 FIT) is predicted at a junction temperature of 235, where the diode is capable of delivering an output power of 100 to 150 mW at 80 CHz band. The predominant failure mode is a junction short caused by gold diffusion into the silicon layer. An rf operating life test is also conducted. There has been no failure for 12,000 h.

This paper deals with the effect of core deformations caused by a periodic external on the transmission characteristics of an optical fiber. For simplicity, the distribution of the periodic external force is assumed to be a sinusoidal, and the slab waveguide model is analyzed to clarify the loss mechanism of the round optical fiber under the periodic external force. In theoretical investigations, the Green's function for the displacements of the axis of a slab waveguide model is obtained. By using the Green's function of the displacements and the mode coupling theory, we clarify the relation between the radiation loss due to the core deformations and the external force. It is found that the radiation loss of the fundamental mode or the lowest order mode decreases as the spatial wave number of the periodic external force and the cladding radius increases. Experimental investigations on the excess loss of the single mode fiber have also been made, the results can be explained qualitatively by the theoretical results of the slab waveguide model.

Profiles of radar Z-factor are presented which are obtained from the C-band radar along the path Kashima to the ETS- satellite during May 1977 to April 1978. The whole data are classified into three rainfall types of the stratus, the cumulus, and the others, where the time percentages for these types are 45, 10, and 45, respectively. There exists a characteristics difference between the stratus and the cumulus with respect to the profile.

Monochromatic light source that is variable in wavelength is necessary for examining spectral characteristics of photo-detector and general characteristics of optical filter. These characteristics are measured generally by the comparison method. We have researched such a monochromatic light source using a halogen lamp, of which wavelength can be selected by the electronical operation of a TeO2 acousto-optic tunable filter. The spectral output of the TeO2 acousto-optic filter is diffracted into ordinary and extraordinary rays. One side of diffracted light is monitored by a photo-detector in the equipment, and the monitor signal is supplied for controlling acoustic driving circuit by negative feedback. It is found by the experiments that light output with variable wavelength depends only on spectral sensitivity of the monitor photo-detector. Consequently we could easily examined, using this equipment, spectral characteristics of the optical fiber, photo detection element, etc. in the same way as we measure frequency characteristics in the LF or HF band region, using the sweep generator.

Annual cumulative time distributions of basic transmission loss were obtained by measuring the received power on trans-horizon propagation path over sea for three years. Strong effect of radio-duct upon transmission loss on the path was found.

The microwave network approach has been applied to the guided wave problems in the dielectric waveguides for millimeter waves made of a dielectric strip and a planar dielectric layer. This approach utilizes transmission-lines and equivalent networks which furnish physical insight, and application of the so-called transverse resonance technique yields, in very simple fashion, approximate but fairly accurate analytical expressions for the dispersion relations of these dielectric waveguides. The results computed from these relations for the strip dielectric guide, the insulated image guide, the single material guide and the inverted strip dielectric guide which have recently received considerable attention agree well with the experimental results by McLevige et al. and Azarmanèche et al. and the results obtained numerically by Ogusu.

The current distribution along a square spiral arm is determined by using Mei's integral equation. The data concerning radiation pattern, power gain, axial ratio and input impedance are presented with good agreement between theoretical and experimental results over a frequency range of 3 to 7 GHz. It is revealed that similar decay in the current distribution, which is necessary to keep wide-band characteristics of the radiation, is obtained in spite of the change of frequency. The data show that the input impedance is nearly a pure resistance, and that, when the radiation pattern in the spiral plane becomes almost omnidirectional, phase of the radiation field varies linearly with the change of the azimuth.

A 1 Mbit/s optical data bus employing micro-optic directional couplers, which can compatibly replace an electrical bus cable in an in-line work station computer system connecting a central processor and four work stations up to 1.5 km apart, has been developed, and the feasibility has been confirmed.

In this letter, we deal with the microcomputer-based ultrasonic pulsed Doppler flowmeter system developed to detect the blood flow in human heart noinvasively. This system provides a new and necessary tool for accurate quantitative measurements in study of cardiovascular disease.

We propose the notion of noise to a biological system without interactions, and define the adult language with noise which is a generalization of the regenerative adult language by A. Walker. This leads to another L-system theory characterization of well-known families of EOL, and ETOL languages in terms of the adult language with noise.

It is shown that ion-implanted polycrystalline-silicon (polysilicon) resistors are suitable for load elements of high speed logic n-channel MOSIC or memory cell of static RAM's. Electrical characteristics and fabrication processing tolerance of resistor load MOS circuits using the scaled-down MOS FET's are comparable with and superior to those in MOS circuits of depletion-type MOS FET's load, respectively. Resistor load MOS circuits are shown to be one of a promising technology to realize VLSI of the future scaled-down MOS FET's.

In this paper, we characterize the structure generating function of a strongly connected automaton. It is proved that poles of the minimal absolute value of the structure generating function are , e2πi/h, , e2πi( h 1)/ h where h is the period of a strongly connected automaton and r is the Frobenius's root of its incidence matrix. This result is a specialization of Berstol's result which characterizes the structure generating function in general. His method is based on the analysis. But we prove our results using some facts in linear algebra and graph theory. And we obtain analogous results for an automaton by considering the strongly connected automaton which contains as a subautomaton.

This paper describe a new analysis on nonlinearity of a satellite born transponder by using Chebyshev transform technique and shows that the nonlinearity is measurable even in case of the satellite being on orbit and/or an AGC amplifier being equipped in the transponder.

This paper gives another canonical section of degree four for reactance one-port synthesis.

The nonlinear recurrence of initial wave profiles were observed experimentally in electrical ladder-type networks having quadratic or cubic nonlinearities. Theoretical foundations on the estimation of the recurrence length are also given. The results show that nonlinear networks of the form shown here can be used as efficient higher-harmonic frequency generators.

In this paper, we report the calculations of the quantum efficiencies of new types of photodiodes that have the ability to demultiplex the incident light beam into two or three independent outputs according to its wavelength, and determine the diode parameters that give maximum efficiency and low crosstalk. Two types of diodes were fabricated with LPE grown InGaAsP/InP quaternary system which is one of the most useful materials in the 1.01.7 µm low-loss spectral window of optical fiber. One diode divides the input light beam into two outputs and the other does in three outputs. The experimentally obtained spectral responses of the diodes were in good agreement with the calculated ones. The fabricated diodes exhibited nearly 100% internal quantum efficiency and crosstalks of 34 dB at λ1.0 µm and below 50 dB at λ1.35 µm, respectively, where the efficiencies of two outputs take their maximum values.

A finite element method is used to analyze the vibrational characteristics of a quartz crystal tuning fork. From the information obtained by the calculation, the base length of a symmetrical tuning fork can be determined for stability of the fundamental resonant frequency and for very small stresses at the base end. Moreover, the quantitative reason why the effective resonant quality factor Qe of the supported tuning fork with arm corners cut off is highly promoted becomes clear from the analysis in this paper. This desirable characteristic is also realized in the tuning forks either with the circle hole at slit end or with the wide base portion. As for an unsymmetrical tuning fork which is frequently made in manufacturing process, the effects of dimensional unsymmetry on the resonant frequency are analyzed. For compensation of its characteristics caused by unsymmetry, the method of adjusting the length of an arm is usually adapted. It is ascertained whether or not this method is effective for high Qe and high stability of the resonant frequency against change of support condition.

A congestion control method for international packet switched networks, which strengthens packet flow restrictions to virtual calls in a congested outgoing route in a switch gradually, is proposed. Basic traffic characteristics of the system under the proposed congestion control are analyzed theoretically. A simple queuing model is developed and state probabilities of the system under the congestion control are obtained analytically. Using the probabilities, equations to evaluated the performance of the congestion control such as throughputs and buffer overflow probabilities are derived. Several numerical examples are obtained and which show the effectiveness of the proposed congestion control method. Packet flow restrictions can be strengthened from virtual calls with low priorities first. By making the number of virtual calls which are controlled simultaneously small, the amount of processing loads for carrying out congestion controls can be decreased. A mechanism for realizing the proposed method is also discussed.

A minimum phase split-electrode CCD lowpass filter having a considerably reduced number of taps was designed and fabricated. Calculated frequency responses with varieties of tap gain errors and observed response were compared. Reducing the number of taps was shown to be less sensitive to tap gain errors.