In this paper an exact field theory treatment for the N-port E-plane full-height ferrite rod junction circulators is presented. Field expressions are written in each region of the junction in the form of infinite modes. Matching of the fields at the common boundaries is used to get a set of infinite nonhomogeneous equations in these mode amplitudes. The point matching technique is used to obtain an approximate solution for the field amplitudes by taking a finite number of modes in each region. Three types of junctions have been analyzed by this technique. These junctions are the symmetrical Y junction and two types of T junctions. Experimental measurements have been carried out to verify the obtained numerical results.

General Field Theory Treatment of E-Plane Waveguide Junction Circulators---Part I: Full-Height Ferrite Configuration

A technique is described for constructing a high-performance nonradiative dielectric waveguide (NRD guide) circulator for use at 50 GHz. A mode suppressor, which serves to reduce unwanted modes to a negligible level, was devised and used to improve circulator performance significantly. A half-wavelength step transformer was installed at each port of the circulator to increase the operational bandwidth. The insertion loss of this circulator is less than 0.3 dB, and the 20-dB isolation bandwidth is about 2.6 GHz. Characteristics of the NRD guide circulator are analyzed based on an equivalent circuit representation. This analysis considerably facilitates the design procedure of the circulator. >

Design and fabrication of a nonradiative dielectric waveguide circulator

This report describes the design and performance of an improved E-plane waveguide circulator. Although the E-plane circulator has the advantages of higher power operation and more compactness, it has received much less attention than its H-plane counterpart. This has probably been due to the difficulty of achieving broadband performance and the lack of adequate design information. It is proposed in this report that best performance occurs when the dimensions of the ferrite cylinder are adequate to support the fundamental cylindrical dielectric resonator mode. The junction dimensions are reduced to enhance the coupling of the incident energy to this dielectric resonator. At the junction, a novel approach is employed to convert the absorption type cavity to a transmission type. Reduced height transformers match the junction to the standard waveguide ports.

An Improved E-Plane Waveguide Circulator

The resonator structure employed in an E-plane circulator may be described by a series-resonant circuit as opposed to a parallel circuit in the case of comparable H-plane devices. This is shown to result in a change of the direction of circulation at the edges of the circulator passband. Employing the equivalent circuit representation methods to increase the bandwidth of the E-plane circulator are discussed.

Equivalent Circuit Representation for the E-Plane Circulator

In this paper the exact analysis on the waveguide junction circulator and Faraday rotator are presented in detail. The correctness of analysis is demonstrated by its successful prediction about the performance of the devices. Many calculation results are presented by comparing with the experimental results. The approaches of expanding bandwidth of devices at W band are stated.

Millimeter wave ferrite circulators and rotators

When a circulator is used with a parametric amplifier or maser, the noise contribution of the circulator may be reduced by cooling it in liquid nitrogen or liquid helium. Compact devices are required to put in the dewar and, depending on the microwave frequency, a compromise may be necessary in choosing between a compact stripline circulator and a comparatively bulky H-plane waveguide circulator, because waveguide feeds will have lower loss than coaxial line. This problem may be eased by using a very compact E-plane waveguide circulator, as shown in Fig. 1(a).

L.E. Davis

Papers

E-Plane 3-Port X-Band Waveguide Circulators (Correspondence)