Microwave Circuitry Research Articles

Solid-state microwave relay systems in Japan

In response to the rapidly increasing demand for communication facilities, microwave relay systems have played an important role in Japan's telecommunications network because of their economy and capability for broadband transmission. Their progress has been marked during the past 20 years and this development has been supported by advances in such diverse fields as radio propagation, antennas, microwave and electronic circuitry, electron devices, and, particularly, in solid-state techniques. This article reviews the history of microwave relay systems and describes the past and expected future contributions of the solid-state technology to these systems.

Oscillations covering 4 Gc/s to 31 Gc/s from a single Gunn diode

By changing the microwave circuitry, appreciable power at fundamental frequencies from 4 Gc/s to 31 Gc/s has been obtained from a single Gunn diode. A tentative explanation is given by assuming that the r.f. voltage is comparable to the bias voltage. The r.f. voltage then triggers both the formation and quenching of the high-field domain which is a characteristic feature of Gunn oscillations.

Microwave High-Pass Filter

MICROWAVE High-Pass Filters form important elements in microwave circuitry particularly in the design of 'up-converter type of parametric amplifiers1 when the pump is to be isolated from the other frequencies to facilitate independent tuning adjustments. Impedance matching devices are also required to match the input guide to the filter impedances. This paper discusses the use of waveguide as a High-Pass Filter element. This design of a filter with a cut-off at 9300 Mc/s as well as the design of a linear double taper are also considered.

A method for the observation of cyclotron resonance at millimeter wavelengths

Abstract A method is described for observing cyclotron resonance in materials whose extrinsic photoconductivity depends on carrier energy. Because of the high sensitivity which may be achieved with a minimum of microwave circuitry, the method is especially useful for experiments at the shorter mm wavelengths. Typical results for electrons and holes in germanium at wavelengths of 2mm and 4mm are presented.

Microwave Operation of Drift Transistors in Transit-Time Mode

The transit-time transistor and its operation was first proposed by Weinreich <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">^1</tex> in relation to a diffusion transistor. The similarity to the diffusion-delay diode and the existence of a negative resistance has been pointed out in accord with the original theoretical work by Shockley <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">^2</tex> . In this paper the drift transistor is analyzed in respect to transit-time effects of minority carriers across the base region, which appear at frequencies above the normal cutoff frequency and are more favorable than in a diffusion transistor due to larger excess phase shifts in the base transport factor. Amplification and power-generation properties at frequencies properly related to the base transit time are theoretically predicted and lie within frequency bands above the cutoff frequency. Experimental vertification of gain and power have been obtained with some commercial and developmental high-frequency mesa-type drift transistors. The results are reported, together with the special microwave circuitry utilized in the experiments. Although realization of gain and power in the microwave region with present transistor encapsulations encounters difficulties in the form of parasitic circuit elements, e.g., lead inductances, and interelectrode capacities, a promising application of suitably designed and packaged drift transistors in the microwave-frequency region will be demonstrated. The operation of the drift transit-time transistor is similar to its vacuum-tube counterpart. Microwave performance to date is very encouraging, and certain advantages over its vacuum-tube equivalent are indicated.

Analysis for a 3 kMc Ultrasonic Liquid Interferometer

The equivalent electrical circuit for a variable path liquid interferometer employing an X-cut quartz crystal in the gap of a reentrant cylindrical 3 kMc electromagnetic cavity resonator will be presented. This will be employed in an analysis of the optimum design of the cavity-crystal transducer system and associated microwave circuitry to determine the change in the radiation impedance as the acoustic path is varied. The analysis of the atter to yield values of the acoustic velocity and high attenuation in the liquid and reflection at the liquid-solid interfaces and the design of the acoustic interferometer will also be discussed.

Tapered Velocity Couplers

The advent of very broad band microwave amplifiers and oscillators necessitates microwave circuitry of comparable frequency range. A scheme is presented which makes it possible to build microwave couplers of various kinds having bandwidths of well over two octaves. A preliminary investigation of mechanical and mathematical analogs is described; and some particular devices using the new principle are mentioned.

The Use of Scattering Matrices in Microwave Circuits

Difficulties arising from the use of the impedance concept in microwave circuitry have led to the introduction of the scattering representation for work at these frequencies. This paper presents a development of the scattering approach in terms of fundamental transmission-line phenomena. The physical meaning of the quantities involved is brought out wherever possible and the relationships among the various elements of the scattering matrix are given. Several examples of the application of scattering techniques to analysis of the properties of microwave junctions are presented, and methods for measuring scattering parameters of such junctions are outlined.

Characteristics and Applications of Microstrip for Microwave Wiring

Microstrip has been developed as a substitute for waveguides or coaxial lines, especially for the development of microwave components and Microwave circuitry.

Resonator and Preselector in Balanced Strip Line

One of Raytheon's commercial applications involves microwave circuitry in balanced strip line, with a 3/8" spacing between ground planes. Though the less critical parts of the unit are etched in copper-clad Teflon-Fibreglas, two of the components are of higher Q than can reliably be obtained in the presence of plastic. They are: 1. a resonator, for use as a frequency stabilizing reference element in an AFC circuit; and 2. a four-stage maximally flat preselector filter. These units are made of separate strips of metal, and do not depend on the plastic sheet for their support.

Ferrites at Microwaves

After a preliminary discussion of the propagation of waves in an unbounded ferromagnetic medium, and in waveguides containing ferrites, the results of an experimental study of the propagation characteristics of waveguides containing ferrites are presented for some samples of commercially available ferrites. Some of the applications of ferrites to microwave circuitry are briefly described.