General Theory and Computational Techniques

Dual-Mode Reciprocal Ferrite Phase Shifters

Rotary-Field Reciprocal Ferrite Phase Shifters

Phased-Array Antenna Topics

General Theory and Computational Techniques

Duplexing Ferrite Reciprocal Phase Shifters

Charles R. Boyd, Jr.

The basic structure of microwave ferrite reciprocal phase shifters of the Dual-Mode and Rotary-Field types can readily be adapted to incorporate the function of a circulator outside the phase shifting region. The circulator effect is realized in the form of orthogonal polarization of waves in the two directions of propagation in circular or square waveguide at the input of the device. A mode-separating waveguide junction is required to resolve these orthogonal modes into two single-mode waveguides.

Stress-Related Insertion Loss in Longitudinal-Field Ferrite Devices

Charles R. Boyd, Jr.

Some microwave ferrimagnetic materials, e.g. compositions of the yttrium-iron garnet family, are known to exhibit sensitivity to intrinsic or externally applied mechanical stress. This stress can cause the magnetic properties of the material to be inhomogeneous, resulting in undesirable insertion loss increases in devices such as Dual-Mode ferrite phase shifters that use variable longitudinal-field bias. Typically the insertion loss increases appear as “spikes” at low bias field magnitudes.

Optimum Filling of Ferrite Phase Shifters of Uniform Dielectric Constant

IEEE Transactions on Microwave Theory and Techniques, Vol. MTT-22, No. 4, April 1974
H. Clark Bell, Jr. and Charles R. Boyd, Jr.

Approximation methods are used to calculate the phase shift and loss for phase shifters containing ferrite and dielectric, with a uniform dielectric constant throughout the waveguide. If the RF magnetic loss in the ferrite is a significant fraction of the total loss, the overall performance of a phase shifter that is partially filled with ferrite may be superior to the fully filled case. Theoretical results relating performance to the amount of partial filling are presented for Faraday rotators in square and circular waveguides and a twin-slab phase shifter. Experimental results were obtained for a circular Faraday rotator.

Design of Ferrite Differential Phase Shift Sections

1975 IEEE MTT-S International Microwave Symposium, Palo Alto, CA, May 1975
Charles R. Boyd, Jr.

Ferrite differential phase shift sections are useful as nonreciprocal circular polarizers in dual-mode phase shifters, as half-wave plates in precision rotary-field phase shifters, and in other devices where nonreciprocal birefringence is desirable. This paper presents a simple design model that provides accurate estimates of the differential phase shift and frequency dispersion of sections using transverse quadrupole magnetic field biasing in a circular waveguide completely filled with ferrite.

A Transmission Line Model For The Lossless Ferrite-Loaded Nonreciprocal Waveguide

1985 SBMO International Microwave Symposium, Campinas, SP, Brazil, July 1985
Charles R. Boyd, Jr.

In this paper, the lossless TE mode waveguide equivalent-circuit model is extended to permit a description of nonreciprocal phase shift effects by incorporation of distributed gyrators into the elemental line length prototype. The gyrators provide antireciprocal coupling between the series and shunt inductive elements of the transmission line model. Simple perturbational formulas are presented and used for computing some elementary geometries.

Microwave And Millimeter-Wave Ferrite Phase Shifters

Microwave Journal State-of-the-Art Supplement, September 1989
William E. Hord

Three ferrite phase shifters–the twin toroid, the dual-mode and the rotary-field–which have found widespread application at microwave frequencies are discussed. Performance characteristics of the devices are detailed. The useful frequency range of the devices, determined by available values of the saturation magnetization of the ferrite, is described.

Microwave Phase Shift Using Ferrite-Filled Waveguide Below Cutoff

IEEE Transactions on Microwave Theory and Techniques, Vol. 45, No. 12, Dec. 1997
Charles R. Boyd, Jr.

Unlike conventional waveguides, lossless ferrite-filled guides may exhibit a complex propagation factor below cutoff of the dominant TE mode when a transverse magnetic bias field is applied. In that case, the field in a very long waveguide has the character of a traveling wave whose amplitude decays exponentially with distance from the driven end. The wavelength and the magnitude of the applied bias field are inversely related, and at zero field as the gyromagnetic effects vanish in the ferrite the wavelength becomes infinite. For a bias field of one polarity, the traveling wave will be a forward wave, and for the opposite polarity a backward wave.

This peculiar behavior allows phase shift to be produced in a band pass filter-like structure in which small cross-section, below-cutoff ferrite waveguide sections alternate with sections of high dielectric constant material.

High Power Reciprocal Ferrite Switches Using Latching Faraday Rotators

2003 IEEE MTT-S International Microwave Symposium, Philadelphia, PA, June, 2003
Charles R. Boyd, Jr.

This paper reviews the basic properties of the microwave bridge circuit containing Faraday rotators, with particular emphasis on the fact that high isolation can be preserved over moderate frequency and temperature ranges at the expense of a small increase of insertion loss. The computational model for Faraday rotation is closely linked to the model for dual-mode reciprocal ferrite phase shifters. Measurement of the Faraday rotation amount is easily implemented by converting the rotation angle to an insertion phase value at the output of a septum polarizer. A few variants of the basic bridge are presented for (a) improving the robustness at high peak and average power levels, and (b) allowing three switched outputs. Finally, the paper also presents examples of practical switches being produced for use in radar systems.

Dual-Mode Reciprocal Ferrite Phase Shifters

A Dual-Mode Latching, Reciprocal Ferrite Phase Shifter

IEEE Transactions on Microwave Theory and Techniques, Vol. MTT-18, No. 12, Dec. 1970
Charles R. Boyd, Jr.

A ferrite phase shifter has been developed to provide latching reciprocal phase shift over a moderate frequency band. The principle of operation is based on the use of dual-mode circularly polarized waves in the active ferrite with nonreciprocal polarizers to select modes that provide reciprocal phase shift. The physical structure of the phase shifter consists of a metallized assembly of ferrite and ceramic dielectric. A ferrite yoke is fitted over a portion of this assembly to permit latching operation.

The completed phase shifter has a very simple geometry that can be produced at low cost and has relatively low insertion loss. The maximum cross-sectional dimensions are small and are consequently compatible with application in two-dimensional electronically scanned arrays Experimental results are presented for an X-band design having a 10-percent bandwidth centered near 9 GHz.

Comments on the Design and Manufacture of Dual-Mode Reciprocal Latching Ferrite Phase Shifters

IEEE Transactions on Microwave Theory and Techniques, Vol. MTT-22, No. 6, June 1974
Charles R. Boyd, Jr.

The design principles for dual-mode reciprocal latching ferrite phase shifters are relatively well understood at present. Discussions of a few selected topics not previously studied are presented in this paper. A tradeoff analysis is carried out for X-band units to show the interrelation between phase-shifter weight and insertion loss. An interesting consequence of this analysis is the theoretical prediction of an optimum range of values for the saturation moment of the ferrite material. Switching energy in the presence of shorted-turn damping is also analyzed and related to the geometry and hysteresis loss of the ferrite material. Finally, a discussion of manufacturing considerations and unit cost at high rates of production is carried out. The major conclusion is that unit cost levels approaching $10.00 are possible for a production run sufficiently large to justify the substantial cost of engineering and tooling for high rates of manufacture.

Accuracy Study for a Moderate Production Quantity of Reciprocal Ferrite Phase Shifters

1979 IEEE MTT-S International Microwave Symposium, Orlando, FL, April-May 1979
C. R. Boyd

A moderate quantity of X-band dual-mode reciprocal, latching ferrite phase shifters has been built and tested in a computer-controlled station. Ensemble phase shift distributions and statistics have been investigated using stored test data. Variation with frequency is small over the design band, and the phase-state dependent data show the effects of curve-fitting computed during testing.

A 60 GHz Dual-Mode Ferrite Phase Shifter

1982 IEEE MTT-S International Microwave Symposium, Dallas, TX, June 1982
C. R. Boyd, Jr.

This paper presents the results obtained from an investigation of the feasibility of constructing a dual-mode, latching, reciprocal ferrite phase shifter designed to operate in the 60 GHz frequency region. Design considerations, problems, experimental data and future prospects are discussed. The data presented in this paper show that it is possible to build "conventional" dual-mode type ferrite phase shifters at 60 GHz with reasonable performance characteristics.

A New Type Of Fast-Switching Dual-Mode Ferrite Phase Shifter

IEEE Transactions on Microwave Theory and Techniques, Vol. MTT-35, No. 12, Dec. 1987
William E. Hord, Charles R. Boyd, Jr., and Daniel Diaz

A new type of dual-mode phase shifter which uses a transversely magnetized variable field section is described. The device retains the features of the conventional dual-mode phase shifter - low insertion loss, moderate amplitude modulation, adequate frequency bandwidth, simple physical geometry - which allow it to be considered for use in two-dimensional scanning arrays. However, because of the transverse magnetizing field, the shorted-turn resistance is increased which results in either reduced switching time or reduced switching energy when compared with the conventional dual-mode unit which utilizes a longitudinal magnetizing field.

Rotary-Field Reciprocal Ferrite Phase Shifters

An Accurate Analog Ferrite Phase Shifter

1971 IEEE MTT-S International Microwave Symposium, Washington, DC, May 1971
Charles R. Boyd, Jr.

An analog ferrite phase shifter has been developed for applications requiring an accurate relationship between phase shift and control current. A prototype unit is described that operates over a 1.3 GHz range at X-band with VSWR under 1.2:1, loss under 1 dB, hysteresis at ±1 degree and negligible frequency dispersion of phase shift.

Medium Power S-Band Rotary Field Ferrite Phase Shifters

1986 IEEE MTT-S International Microwave Symposium, Baltimore, MD, June 1986
C. M. Oness, W. E. Hord, C. R. Boyd, Jr.

Reciprocal rotary field phase shifters have been developed at S-band frequencies with peak power capacity of 40 kW, average power of 600 W and switching times of 100 microseconds. Data is presented on a production lot of these devices showing the statistical properties of the peak and RMS phase error and the peak and average insertion loss.

Recent Developments In The Average Power Capacity Of Rotary-Field Ferrite Phase Shifters

1992 IEEE MTT-S International Microwave Symposium, Albuquerque, NM, June 1992
William E. Hord

An air-cooled experimental S-band rotary-field ferrite phase shifter with an average power capacity of 3 Kilowatts is described. The increase in average power capacity was achieved without noticeable degradation of RF performance. An equivalent circuit model for thermal analysis is developed. The model parameters are determined by RF and temperature measurements. The parameters are compared with those of a conventional rotary-field phase shifter.

Ferrite Rotary-Field Phase Shifters: A Survey of Current Technology and Applications

Charles R. Boyd, Jr.

Ferrite Rotary–Field Phase Shifters have been used for more than two decades in applications that require highly accurate phase control at moderate to high microwave power levels. During this period, work has been carried out continuously to improve the basic understanding and computational models for this class of device, as well as to extend its power handling capability and frequency regions of practicality. This paper reviews the progress that has been made in the past few years in selected topics, namely, understanding of the sources of phase error, switching considerations, especially “hot” switching with power applied, extending the region of applicability to the 1–2GHz. band, and increasing the average power handling capability through improved heat transfer geometry.

Design Considerations for Rotary-Field Ferrite Phase Shifters

William E. Hord

Key factors influencing the design of a rotary-field ferrite phase shifter are the required r-f performance, the desired control characteristic and the switching time. These factors are examined as a function of the saturation magnetization of the ferrite and the number of turns on the drive yoke. A performance table is presented giving the characteristics of these phase shifters in the 2-20 GHz range.

A Latching Ferrite Rotary-Field Phase Shifter

1995 IEEE MTT-S International Microwave Symposium, Orlando, FL, May 1995
Charles R. Boyd, Jr.

For more than two decades ferrite rotary-field phase shifters have offered highly accurate reciprocal phase control at moderate to high microwave power levels, at the expense of continuous current excitation. This paper presents the concept, basic design considerations, and initial data for the first realizations of latching versions of the ferrite rotary-field phase shifter. These versions operate at remanent magnetization and provide frequency-independent and temperature-independent phase changes using state-independent switching pulses, with substantial reduction of control power for low or moderate switching rates. However, the changes in configuration desirable for latching operation imply slightly larger RMS phase errors and a reduced capability for average RF power handling. Data are presented for laboratory-type C-Band and S-Band units.

Phased-Array Antenna Topics

Impedance Matching of Open-Ended Waveguide Radiating Elements

1987 SBMO International Microwave Symposium, Rio de Janeiro, Brazil, July 1987
Charles R. Boyd, Jr.

Impedance matching of open-ended waveguide radiators in a planar phased-array environment is a nontrivial problem that is aggravated by the constraints placed on the element size by antenna needs. The approach discussed here achieves an efficient matching structure, based on the use of a waveguide simulator approximating the free-space impedance presented to the element in the array environment

Ferrite Phased Array Antennas: Toward a More Affordable Design Approach

1987 IEEE AP-S International Symposium Digest, Vol. II, pp. 1168-71.

Very great improvements have been realized in the design and manufacture of ferrite phase control elements for electronically scanning phased-array antennas, resulting in a continuing advance in the performance-quality-cost relationship. Nevertheless, end users continue to point to the "high cost" of ferrite phase control elements as a barrier to more widespread use of this type of electronically scanning antenna. This paper presents a design approach that may reduce significantly the cost per element for a two-axis scanning ferrite phased array.

Greater cost reductions in two-axis scanning ferrite phased arrays are likely to come from closer integration of the phase shifters into the antenna structure, and better optimization of the electronic circuitry, rather than from improvements in phase shifter configuration and manufacturing methods.

A Novel X-Band, Circularly Polarized Feed For The I-30 Radar Antenna System

F. A. Lauriente and W. E. Hord

This paper describes a novel application of septum polarizers in the realization of a feed system for I-30 Radar Antenna System. The I-30 antenna is an electronically steerable phased array employing nonreciprocal, circularly polarized ferrite phase shifters in a transmission (bootlace) lens arrangement with a space feed. The feed is required to provide monopulse operation with either sense of circular polarization on receive, as well as the duplexing function between the transmit and receive modes of operation with the sense of the transmit polarization being opposite to that on receive.