Optimum Filling of Ferrite Phase Shifters of Uniform Dielectric Constant

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.     

Nonreciprocal Remanence Ferrite Phase Shifters Using the Grooved Waveguide

For the purpose of improving the performance charasteristics of the nonreciprocal remanence ferrite phase shifter, a new configuration with a grooved waveguide is proposed and analyzed. Some results calculated as functions of dielectric and ferrite thickness, waveguide dimensions, and frequency are shown and compared as being in good agreement with experiments at the X band. The figure of merit (differential phase shift per insertion loss) and the handling power of the proposed phase shifter are discussed in comparison with those of the conventional waveguide geometry.     

Double ridged waveguide phase shifters for broadband applications

The author presents an electromagnetic mode matching analysis of dual ridged waveguide phase shifters. The waveguide is loaded with a high dielectric material between the ridges, and the troughs are filled with ferrite toroids. The present structure offers nearly twice the bandwidth and less variation in nonreciprocity versus frequency as compared to the conventional dual toroidal phase shifter. An optimum design that maximizes nonreciprocity has been found. Effects of the dielectric constant and the trough dimensions are also presented. A differential phase shift of more than 100°/cm has been predicted for the new phase shifter     

背脊波导双环铁氧体移相器

本文导出双环背脊波导锁式铁氧体移相器的传播常数公式。在典型参数下,计算了该器件的差相移和插入损耗。结果表明,该移相器的优值和差相移比同一条件下的矩形波导的同类移相器的大。为了验证文中所给方程的正确性,对差相移作了实验,其结果与计算值基本相符。     

Improved analysis of nonreciprocal remanence ferrite phase shifter in grooved waveguide

In this paper, the nodal finite-element method is used to analyze the differential phase shift of a nonreciprocal remanence ferrite phase shifter in a grooved waveguide. Instead of the former twin-slab model, an improved analytical model is adopted, where the effect of every part of a ferrite toroid on the differential phase shift has been considered. This analysis may replace the correcting factor with good agreement with the experimental data. Furthermore, this analysis is employed to investigate the effect of corner chamfering on the figure-of-merit (differential phase shift per decibel insertion loss) of a ferrite phase shifter. The numerical results are found to agree with the experiments in the literatures.     

Reciprocal Ferrite Phase Shifters in Rectangular Waveguide (Correspondence)

A recent article by Reggia and Spencer describes a reciprocal ferrite phase shifter for rectangular waveguide, This phase shifter consists of a pencil of ferrite suspended along the central axis of the waveguide by means of a dielectric. The phase is controlled by an applied longitudinal magnetic field. This geometry is shown in Fig. 1. Large amounts of phase shift are produced by this geometry with low insertion loss, and application to antenna beam scanning appears likely, as suggested by Reggia and Spencer.     

Theory and Operation of a Reciprocal Faraday-Rotation Phase Shifter

The operation of a longitudinally magnetized fully filled square-waveguide reciprocal-ferrite phase shifter is described. The frequency characteristics of the phase shifter are predicted and measured. An error analysis, including rotational errors incurred in wide-band operation and manufacturing tolerances, is used to predict the loss performance of the device. The effect of the ferrite parameters and the waveguide geometry on phase-shifter performance may be calculated using this analysis. The variation of the phase shift with temperature as well as high-power effects are presented, and design considerations, including choice of ferrite saturation magnetization for wide-band performance, are discussed. Experimental results closely confirm the key aspects of this theory.     

Design and performance of a new digital phase shifter at X-band

A new digital phase shifter design at X-band is presented. The phase shifter operates based on converting a microstrip line to a rectangular waveguide and thus achieving the phase shift by changing the wave propagation constant through the medium. As a proof of principle, a 3-b phase shifter has been designed and constructed using PIN diode switches. An average insertion loss of 1.95 dB and phase shift error of less than 4/spl deg/ at 10.6 GHz are achieved.     

铁氧体大功率移相器研究

介绍了大功率背脊波导锁式铁氧体移相器的一般设计方法。首先讨论了器件的铁氧体材料参数的选取和器件结构的设计以及提高器件差相移的方法。然后介绍了器件相位的温度补偿的方法。最后给出了Ｓ 波段器件的性能     

A Dual-Mode Latching Reciprocal Ferrite Phase Shifter

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 transmission phase. 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.     

Theoretical Analysis of Twin-Slab Phase Shifters in Rectangular Waveguide

The differential phase shift and the losses to be expected in phase shifters using two oppositely magnetized ferrite slabs located symmetrically in a rectangular waveguide have been calculated for various locations and thicknesses of the ferrite slabs. For small thicknesses of the ferrite slabs, the differential phase shift increases rapidly with increasing thickness reaching a maximum when the thickness is approximately 1/10 of the free space wavelength. The calculated insertion loss of a 360-degree phase shifter decreases with increasing slab thickness for small thickness, reaching a minimum when the thickness is approximately 1/25 of the free space wavelength. The minimum insertion loss calculated with the assumption that the imaginary part of the diagonal component of the permeability tensor is 0.01 and that dielectric loss can be neglected is approximately 0.85 dB. The peak power handling capability has also been analyzed. It can conveniently be summarized in terms of a high-power figure of merit. For reasonably high values of this figure of merit, a peak power capability of the order of 100 kW is anticipated.     

Theory of the Suppressed-Rotation Reciprocal Ferrite Phase Shifter

A theory for the Reggia-Spencer reciprocal ferrite phase shifter is presented which explains the characteristic behavior of this device in terms of a nonreciprocal coupling of cross-polarized waveguide modes. The dominant mode is a distorted TE/sub 10/-like mode similar to that of a dielectric slab-loaded waveguide. The cross-polarized mode is a hybrid mode which is below cutoff. If this mode propagates, Faraday rotation occurs. The boundary value problem for these modes, in a ferrite described by a scaIar, frequency-dependent permeability, is solved and theoretical design data is presented. The frequency-dependence of phase shift and the onset of Faraday rotation is predicted and compares well with experimental results.     

Rigorous theoretical study of longitudinally magnetised partially filled TEM phase shifter

Rigorous theoretical study of a parallel-plate waveguide fully filled with longitudinally magnetised ferrite has been made possible by the transverse operator formulation. The analysis is extended to a partially filled quasi-TEM structure showing improved performance in differential phase shift. A calculation model for the reduced-height rectangular waveguide phase shifter is obtained by making use of the present analysis. The measured characteristics are compared with predictions.<>     

A 500 kW X-Band Air-Cooled Ferrite Latching Switch

The design of a high-power air-cooled microwave SPDT switch which is capable of operation at peak and average power levels of 500 kW and 666 watts, respectively, is described. The unit is of a differential phase shift circulator design employing 90/spl deg/ nonreciprocal phase shift elements which are forced air cooled. The phase shifter design employs dual ferrite toroids, "floating" in reduced height RG-51 waveguide. Two approaches are compared for heat sinking the phase shifter; namely the "H-beam" and the "I-beam" configurations. The results obtained indicate that the I-beam configuration is superior to the "H-beam" configuration. The switch exhibits an insertion loss of 0.6 dB maximum and isolation greater than 20 dB over a 100 MHz bandwidth centered at 9.375 GHz. The input VSWR of the switch over the frequency band is less than 1.28:1.     

Some Effects of Dielectric Loading on Ferrite Phase Shifters in Rectangular Waveguide

The use of dielectric loading with the ferrites in nonreciprocal transmission lines has becolme quite prevalent. The theoretical analysis of unloaded ferrite phase shifters in rectangular waveguide has been extended to the dielectrically loaded case by Soohoo. The boundary-value problem of ferrite phase shifters in dielectrically loaded coaxial lines, which possesses a transcendental equation similar to the waveguide case, has been throughly discussed by several authors. The present commumcation reports the solution of the boundary-value problem of a dielectrically loaded ferrite phase shifter in rectangular waveguide to yield values of the lossless propagation constant for various slab positions for both directions of propagation. The theoretical values of the differential phase shift for slab positions about the center of the waveguide were compared with the measured values for three different applied magnetic fields.     

A 2-bit RF MEMS phase shifter in a thick-film BGA ceramic package

The development of a thick-film hermetic BGA package for a radio-frequency (RF) microelectromechanical systems (MEMS) 2-bit phase shifter is presented. The measured packaged MEMS phase shifter average in-band insertion loss was 1.14 dB with an average return loss of 15.9 dB. The package transition insertion loss was less than 0.1 dB per transition with excellent agreement between simulated and measured results. It was also demonstrated that the RF MEMS phase shift performance could be improved to obtain a phase error of less than 3.3 degrees. The first reported measurements of the average rise and fall times associated with a MEMS circuit (in this case a 2-bit phase shifter) were 26 and 70 /spl mu/s, respectively. The advent of packaged RF MEMS phase shifters will reduce the cost (both design and building) of future phase arrays.     

Design of Composite Magnetic Circuits for Temperature Stabilization of Microwave Ferrite Devices

The magnetic flux density of unsaturated microwave ferrites can be made almost constant although microwave ferrite saturation magnetization, coercive force, and hysteresis loop shapes change substantially. Temperature stabilization of flux is achieved by a composite series magnetic circuit consisting of microwave, driver, and flux-limiter ferrites, and a control coil. The flux limiter constrains the circuit flux to an almost constant level throughout the operating temperature range, despite large changes in the size and shape of the microwave ferrite hysteresis loop. The driver ferrite supplies the MMF necessary to sustain the flux. Current impulses in the control coil energize and switch the circuit flux. Estimates of the required lengths and cross-sectional areas of the circuit elements, and of the required switching field and energy for a waveguide remanence phase shifter are given, along with the effects of leakage and fringing fluxes. Composite circuit techniques have been applied to an experimental remanence phase shifter. Unstabilized, a 16 percent loss of phase shift was incurred as a result of an 80/spl deg/C rise in temperature. By applying composite circuit techniques, this value was reduced to less than 2 1/2 percent for the same temperature range.     

介质加载双环背脊波导移相器的相—频特性

本文给出介质加载双环背脊波导移相器的传输常数方程,计算了典型参数的相移,和损耗的频率特性。不但给出了最佳的差相移的频率特性,还指出了该器件的优值比普通矩形波导的高,另外,背脊的存在提供了良好的热传导,因此它具更高的平均功率容量。     

Millimetre-wave dielectric waveguide ferrite phase shifter with longitudinal magnetisation

A dielectric waveguide structure, containing an NiZn ferrite as phase-shifting medium is described. By applying a longitudinal static magnetic field to the ferrite, a reciprocal phase shift is obtained. Broadband characteristics are achieved by tapering the ferrite. Experimental results in the frequency range of 60?90 GHz for the phase shift and insertion loss of the device are presented.     

Optimum field theory design of broad-band E-plane branchguide phase shifters and 180° couplers

Optimum rectangular waveguide E-plane branch guide phase shifters and 180° branch guide couplers are designed with the rigorous method of field expansion into normalized eigenmodes. The design includes both the higher order mode interaction between the step discontinuities and the finite step and branch heights. The phase shifter design applies the Schiffman principle to branch guide couplers where two ports are short-circuited. The 180° coupler design combines the advantage of the broadband potential of multiple-branch couplers with the low-insertion-loss qualities of E-plane stub-loaded phase shifters. A computer-optimized phase shifter prototype for the waveguide Ku-band (12-18 GHz) shows a 90°±1° differential phase shift with reference to an empty waveguide within about 23% bandwidth. Five-branch three-stub coupler prototypes, designed for 3±0.2 dB coupling, for the waveguide Ku- and Ka-bands (26-40 GHz) achieve a 180°±1° differential phase shift at the output ports within about 19% bandwidth, as well as more than 30 dB isolation and return loss. The theory is verified by measured results