Experimental study of the near field distribution around the dielectric waveguide end has been carried out on the microwave region. The result will be used for detail discussion of reflection, deflection and radiation phenomena of electromagnetic wave in the integrated circuit of microwave through optical wave regions. Transverse component of the near field is picked up by a movable small antenna and detected by a network analyzer with a reference signal. The measured results are separated into amplitude and its phase, and expressed by both equi-amplitude, equi-phase contour maps. From the experimental study, followings are resulted: (1) At the tilted type end, the near field in front of the facet is bent toward an apex of the guide end. (2) Measured equi-phase contours clearly show the direction of local power flow around the guide end. (3) In the equi-phase contours, there are several points where the contour lines concentrate each other. These points correspond to minimum amplitude position. At that point the electromagnetic energy is circulating. (4) Equivalent reflection coefficient of a guide mode at the end facet can be determined by the phase distribution of a standing wave field on the guide.

A series of transverse electromagnetic transmission cells (TEM cells) developed at the National Bureau of Standards (NBS) is three-dimensional analyzed using a mixed discretization based on both of constant and linear elements in a boundary element method (mixed BEM). Mixed BEM presented here is generalized in order to be usable in two and three dimensions. Conductor surface of TEM cell models is discretized using non-uniform elements so that the flux distribution can be approximated more accurately in the less number of elements. The distributed characteristic impedance, which is important to design the cell, in the main line section is evaluated through the flux induced in the center conductor. The calculated results are in good agreement with those in two dimensions in spite of the small number of elements. As a result, it is proved that three-dimensional cell models are effectively and accurately solved by using mixed BEM and non-uniform elements together. The present work plays a preliminary part in an analysis of more realistic NBS cell models taken into account a tapered section. In future, therefore, we will be able perform a reliable analysis of TEM cells using mixed BEM and non-uniform elements.

The wavelength shift of a dynamic-single-mode (DSM) laser directly modulated by sinusoidal current has been investigated using the large-signal analysis. A rate equation which includes carrier diffusion terms is solved numerically. The variation of the carrier density as an origin of the dynamic wavelength shift is calculated. The calculated dynamic wavelength sifts are in good agreement with experiments. At high modulation frequency range, the dynamic wavelength shift is mainly caused by relaxation oscillations and the shift is almost constant to the stripe width of active guide. It shows that the dynamic wavelength shift in pulse modulation is also independent of the stripe width of active guide. An analytical expression of dynamic wavelength shift is given at low modulation frequency range. When the modulation depth is below 30 percent, the small-single analysis is in agreement with large-signal analysis. By considering the effect of spontaneous emission, a modified small-signal analysis presented here is applicable to a modulation depth of 100 percent in the case of low frequency limit.

This paper relates to a designing method of microstrip antenna considering the bandwidth. The bandwidth becomes a maximum for a special value of characteristic impedance of the feeder. Also, the unloaded Q and resonant frequency of the microstrip antenna are shown as a function of substrate thickness with the dielectric constant as a parameter. These relation can be shown on the drawings, which are very useful for the designing of microstrip antenna considering the bandwidth. Finally, a circular microstrip antenna, of which bandwidth for VSWR2 is 8.75%, is manufactured as a designing example by using the paper honeycomb substrate and is measured for the return loss characteristic. From the fact that the measured result agrees well with the calculated result, the usefulness in this method is verified.

In this paper we analyze the samples of a signal in time and frequency from a unique point of view. Besides the unified treatment of the subject and the insight gained from this approach, the following original results are claimed. A new method is proposed to estimate the bandwidth and the shape of the spectrum of a signal. The most important part of the paper is the contribution on the frequency spectrum of the interpolating functions of the samples of a signal. As a consequence a novel method is proposed for equalizing the distortion of an interpolating function such as sample and hold signal. The realization is fairly simple and modular in concept.

Mode conversion induced by magnetostatic surface waves (MSSW) has a great potential for a variety of optical signal processing devices. However, till now, analysis of optical-MSSW interaction has been limited planar waveguides. We investigate into the mode conversion induced by MSSW in three-dimensional optical waveguides. In this paper, at first, the problem faced in propagating MSSW in three-dimensional waveguides is discussed and a device configuration is presented to overcome the problem. Next, an analysis of the MSSW induced optical mode conversion in the proposed configuration is given. The coupling coefficient between the E^z_pq and the E^x_pq modes of the waveguide is derived and its variation with the waveguide dimensions is discussed. Finally, the feasibility of the proposed configuration is demonstrated by a numerical example.

An optical time domain reflectometer for single-mode fibers has been designed and constructed at a 1.3 µm wavelength. A fast digital averager enables 44 dB signal-to-noise ratio improvement within about 40 seconds. Curve fitting by a least squares method reduces the variation in fiber loss measurements. By using an acoustooptical directional coupler, Fresnel reflection is removed. In addition, backscattered signal fluctuation caused by polarization fluctuation is suppressed to a negligible extent. Current drift in receiving circuits is decreased by using a drift compensation circuit. The optical time domain reflectometer that has been built can locate breaks in single-mode fibers with attenuations as high as 17.5 dB.

A pair of Hallen-type integral equations is formulated for general coupling problems of wires excited through slots in a conducting screen. The number of wires and slots, and their orientation can be chosen arbitrarily in these integral equations. The integral equations have simplified kernels in which neither derivatives nor integrals are contained. The electric and magnetic scalar potentials are also derived to analyze electromagnetic coupling between slots and wires of bent configuration. Results of the magnetic current in the slot and the electric current on the wire are given for a few typical cases.

The prototype of a newly proposed ac-powered Josephson Programmable Logic Array (JPLA) has been fabricated and experimentally investigated. The JPLA can operate more than 10 times as fast as a semiconductor PLA and with one-thousandth of its power dissipation.

The warm carrier devices which have thin-film antennas were fabricated, and their detection properties were studied at RF, microwave and CO₂ laser frequencies. It is found that the static TV characteristic of the fabricated devices persists up to 9.5 GHz microwave frequencies, but does not at CO₂ laser frequency.

Effects of the element radiation pattern on characteristics of the spherical array antenna composed of turnstile elements is discussed. It is found by numerical calculations that scanning characteristics of the directivity and the axial ratio do not so much depend on element radiation patterns.

It was experimentally verified that the rain attenuation at 140 GHz depends not only on the rain rate but also appreciably on the raindrop size distribution. The size distributions inferred from the attenuation and the rain rate measurements show excellent agreements with those measured by the filter paper method.

A sampling basis in the space of periodic spline functions of degree 2 is derived, given that knots are spaced equidistantly. Using the sampling basis, a smooth interpolation function can simply be composed from a given sample value vector.