A Y-Junction Strip-Line Circulator

Summary--The theoretical approach to the three-port symmetrical circulator is reviewed and presented in a form valid for the most general waveguide case. A strip-line Y-junction circulator is described and the performance of different units in the band 800-1600 mc is illustrated. The new type of device described offers, for the low-frequency region of the microwave spectrum, advantages of simple design, light weight, and great compactness with respect to the classical types. When operated with a permanent magnet it gives--in a bandwidth of about 4 per cent--isolation greater than 20 db, insertion loss /spl les/0.4 db, and input VSWR/spl les/1.20.     

Design Note on an L-Band Strip-Line Circulator (Correspondence)

The technique of using magnetized yttrium-iron-garnet slabs in dielectrically-loaded strip transmission Iine as the reciprocal elements in a UHF and low-microwave frequency, 4-port circulator has been demonstrated most effectively by Arams, et al. This communication reports the results of an independent and concurrent development program at our laboratory which led to a similar L-band circulator using a some what different configuration.     

圆波导Y结环行器

本文介绍一种Y型波导结环行器———圆波导环行器 ,它由装有铁氧体样品的圆柱形结腔及其侧面连接的三段互成 12 0°的圆波导组成 ,并在Ku波段上利用有限元法对这种Y结环行器的性能进行数值计算和实验测量。所得结果表明这种结构的环行器可以实现环行性能。本文从理论上也分析了腔体内上下介质不对称对环行性能和圆波导主模TE11极化面的影响     

Thin-Film Lumped-Element Circulator (Correspondence)

A photolithographically produced lumped-element circulator is described. Complete physical and electrical symmetry is assured by interweaving the junction conductors using either dielectricor air crossovers and by employing symmetrically configured interdigital capacitors. Series resonant matching circuits compatible with photoetching techniques are proposed. The device is designed for operation at fields below the field for gyromagnetic resonance so that all of the circulator elements, as well as connecting circuitry, may be generated on the ferrite as a substrate without the necessity of magnetizing the entire substrate. This approach, which is applicable to any stripline configuration, makes it feasible to produce lumped element circulators for microwave integrated circuits at frequencies well above the range for previously reported lumped-element devices consisting of an assemblage of discrete components.     

Pulse-Operated Circulator Switch (Correspondence)

One of the major disadvantages of employing a ferrite circulator as a microwave switch is the holding current required to maintain the circulator in the switched position. One solution to this problem, reported by Levey and Silber, is the utilization of ferrite tubes as the differential phase shift element in a circulator. Switching is accomplished with a single pulse of current which reverses the magnetization in the closed ferrite tubes, and by virtue of the closed magnetic path, remains permanently magnetized in this new state. Using this technique, microsecond switching speeds have been obtained. This approach requires a ferrite that has both the requisite microwave and dc magnetic characteristics which all too often are unattainable in a commercially available material and necessitates the development of a special material.     

Miniature Strip-Line to Waveguide Slot Adapter--Co-Linear (Correspondence)

An inline adapter from miniature air dielectric strip transmission line with a ground plane spacing of 0.130 in to half height X-band waveguide has been developed by the Microwave Design Group at Hycon Manufacturing Company, Monrovia, Calif. The upper wall of the waveguide was used as the lower ground plane for the strip-line. Unity coupling was accomplished through a transverse slot in the common wall. The slot was 0.066-in wide by 0.750-in long surrounded by a metal cavity 0.250 in by 1.000 in built into the ground planes. (See Fig. 1.) The slot junction was matched by use of tunable shorts both in the strip-line and the waveguide. The output of the 50-ohm stripline was terminated by a built-in strip-line load whose VSWR was 1.04.     

W Band Circular Waveguide Y-Junction Circulator

In this paper, a new type of W band circular waveguide Y-junction circulator is presented. The structure of this type of Y-junction is a cylindrical cavity connecting with three circular waveguides. The performances of the type of circulator are analyzed by the edge-based vector finite element method hybridized with the modal expansion. The numerical results show that this type of waveguide Y junction circulator has good circulation performance.     

Low-Loss Cryogenic L-Band Circulator (Correspondence)

It is shown that a three-port stripline circulator can be constructed to operate in Z-band at 15/spl deg/K with 0.5 dB insertion loss and up to 20-percent bandwidth for the 20-dB isolation.     

An Integrated Microstrip Circulator (Correspondence)

Ferrite circulators, incorporated as integral parts of a microstrip circuit on a copper-clad dielectric substrate, have been developed and tested. These circulators do not require the machining of a hole in the dielectric substrate or etching of the ferrite metalization. 20-dB isolation bandwidths of 3.5 to 4 percent in the frequency range 1.75 to 2.23 GHz were measured.     

A 30-GHz Inverted-Microstrip Circulator (Correspondence)

A 3-port inverted-microstrip circulator has been built which operates near 30 GHz with an isolation of greater than 20 dB over a 6-percent bandwidth. The circulator junction has an insertion loss of less than 0.4 dB over the band exclusive of losses in transitions used for testing the device.     

Design of a High-Power CW Y-Junction Waveguide Circulator

A junction circulator appears inferior in average power-handling capability, although it is compact and light-weight and has good performance. A new type of 100-kW CW waveguide Y-junction circulator is realized by dividing the junction of the circulator into four equal unit junctions in a so-called "multilayer structure," which is water-cooled easily. This circulator has an insertion loss of 0.18 dB and an isolation of 20 dB, and it is compact and economical to build. The design of 30- and 100-kW CW waveguide Y-junction circulators is presented in this paper, which discusses determination of ferrite dimensions and air gap, considers heat generation in the ferrite, and the influence of dc magnetic-field distribution on its performance. The ferrite dimensions and air gap are determined very easily by using this design method, and these have been confirmed by experiment. It was found that a uniform distribution of internal dc magnetic fieId, obtained by considering the demagnetizing dc magnetic field, gives optimum performance. This is a significant design factor for high-power circulators which require minimum insertion loss.     

Input Impedance Behavior of Stripline Circulator (Correspondence)

The input impedance of the Bosma model for a stripline circulator has been computed for light coupling in below-resonance operation. The result agrees with the two-tank circuit model proposed by Fay and Comstock and with experimental measurements.     

An Accurate Junction Circulator Design Procedure (Correspondence)

A two-step design procedure for the accurate synthesis of a junction circulator is given. The procedure is accurate to within a few decibels for isolation in the 20- to 40-dB range.