Phase Shift Section Research Articles

Computer Analysis of Microwave Propagation in a Ferrite Loaded Circular Waveguide---Optimization of Phase-Shifter Longitudinal Field Sections

A theoretical analysis of the microwave propagation in a circular TE/sub 11/ waveguide partially or completely loaded with an axially magnetized ferrite rod is presented. This study is based upon an exact analytical treatment of the Maxwell's equations, together with an original numerical method of solving transcendental equations with a complex variable. The introduction of the complex propagation constant /spl Gamma/ = /spl alpha/ + j/spl beta/, taking in account the losses in the filling medium, had never been attempted because of the mathematical difficulties involved making essential the use of a large capacity computer. The developed program not only supplies all the propagation characteristics for a given structure but also enables us to optimize a phase-shift section in accordance with the user's requirements. This study is a first step towards the theoretical optimization of two types of reciprocal phasers: the dual mode phaser (DMP) and the polarization insensitive phaser (PIP), both widely used in array antenna systems. The computed results obtained for the basic section of such phasers operating at a central frequency of 9.5 GHz are given. Obviously, this work is still incomplete since it does not include the optimization of all the components of a practical phase shifter, for example, the polarizers. Moreover, we have assumed the ferrite partially magnetized by a continuously variable bias field, although the PIP and the DMP are normally operated in a latching configuration; we presently complete our study according to these practical considerations.

Generalized Theory of Waveguide Differential Phase Sections and Application to Novel Ferrite Devices

Since Fox introduced the concept of differential phase shift(DPS) sections in TE/sub 11/ mode cylindrical waveguide, most interest has been concentrated on devices having fixed DPS of 90/spl deg/ or 180/spl deg/. This paper gives exact solutions for the magnitude, phase, and polarization of the wave output from three sections having variable DPS and orientations. The RF field is, successively resolved into components along the birefringence axes. Experimental results of tests carried out at X band, using a transversely magnetized ferrite tube, closely support the theory. It is shown how the latter can be applied, not only to familiar devices such as the rotary phase shifter or single sideband modulator, but also to new devices using ferrite sections of variable DPS or of switchable birefringence axes. A three-section power divider and attenuator is explained, together with a new two-section polarizer, with possible applications to satellites and search RADAR. It is also shown how one section can be used as a phase shifter. Some experimental results are given. Thus complete characterization of DPS section devices is offered by the theory, together with the quantitative effect of any of their parameters.

A High-Accuracy Microwave Phase Standard for Use in Primary Calibration Laboratories

This paper describes the theory and construction of a broad-band, differential phase shifter for use over the frequency range of from 4.25 to 6.20 GHz. Perturbations of the phase shifter which cause it to deviate from the ideal 2/spl theta/ operation are discussed. The analysis follows that of Fox, but is carried out in the exponential form, and includes both phase and attenuation constants. A set of nonideal conditions are postulated: improper positioning and matching of the constituent components, improper electrical Iengths of the differential phase shift sections, and loss in the dielectric slabs. Expressions are derived for each of the above conditions that demonstrate the effect on the 2/spl theta/ operation of the phase shifter. Evaluation of the experimental model shows that it operates within the predicted limits of error, /spl plusmn/ 0.5/spl deg/.

Three New Ferrite Phase Shifters

Three new devices for the electrical control of microwave phase shift are discussed. The first of these, the bucking rotator phase shifter, is a reciprocal unit. It employs two series ferrite rotators, the field coils of which are connected so as to produce opposing longitudinal magnetic fields. It is shown that the total rotation is zero independent of coil current, whereas the phase shift is a function of the current. The operation and limitations of the device are discussed. Curves of phase shift vs coil current for several configurations are presented. The other two devices are based on the use of a circular polarized phase shifter between quarter wave plates. In the new types, a reflection technique is described wherein only one quarter wave plate is required and the phase shift section is used twice. A nonreciprocal phase shifter and an electrically controllable short circuit based on this technique are described. The principles of operation are discussed, and the devices are compared with other types as to performance, size, and bandwidth.

An Adjustable Wave-Guide Phase Changer

A very interesting and useful component of the waveguide art is the differential phase-shift section, wherein dominant waves of one polarization are caused to travel through a section of wave guide at a different velocity than waves polarized at right angles to the first. Particularly useful are the Δ90-degree and Δ180-degree differential phase-shift sections which produce differential delays between the two polarizations of 90 degrees and 180 degrees, respectively. The properties of these sections are discussed, and it is shown how they may be combined to form a phase changer which will transmit substantially 100 per cent of the incident power with a phase which is readily adjustable. Several different methods of building these sections are finally described.