Ferrite Circulator Research Articles

Design of X-Band Circulator and Isolator for High-Peak-Power Applications.

This paper presents a design of a X-band circulator-isolator for handling high-peak-power applications. The device consists of two cascade-connected ferrite circulators, with one dedicated to transmission and the other to small-signal reception coupled with high-power signal isolation. To improve the power capacity, a layer of poly-tetra fluoroethylene (PTFE) film is placed above and below the circulator's and the isolator's center conductors. Measurement results show that the device is capable of withstanding a peak power of 7000 W, with an insertion loss of <0.3 dB at the transmitting port. Similarly, it sustains a peak power of 6000 W with an insertion loss of <0.5 dB at the reception port. Moreover, the proposed design achieved isolation between the transmitting and receiving ends of >20 dB with a VSWR < 1.2 at each port. Thermal analysis shows that the maximum relative ambient temperature rise is 15.11 ∘C. These findings show that the proposed device achieves low-loss transmission of high-peak-power signals in the transmit channel and reverse isolation of high-peak-power signals in the receive channel.

Reconfigurable metasurface array for diverse retrodirective reflections and radar cross section reduction

Abstract Retroreflectors can scatter the arbitrarily incident wave back to incoming direction, demonstrating great potential in wireless communication. However, there are limitations in adaptive retroreflection and polarization modulation with the existing retroreflectors. In this paper, a novel metasurface array with a reconfigurable transmission line (TL) network has been proposed to flexibly achieve multiple manipulation functions of electromagnetic wave including upper half-space cross-polarized retroreflection and circularly polarized retroreflection in the diagonal planes and radar cross section (RCS) reduction. To accomplish these capabilities, a novel transmission mode for ferrite circulators has been developed, enabling precise phase control of the TL. By adjusting the operation states of the circulators, multiple phase differences between forward and reverse transmission directions including ±90° and ±180° are generated. With the obtained phase differences, the metasurface array can flexibly achieve the adaptive retroreflection fields with multiple polarization characteristics based on the spatial field superposition and the RCS reduction based on the phase cancellation. To validate the concept and feasibility of the proposed reconfigurable retrodirective metasurface, an X-band prototype has been fabricated and measured. Good agreement between the simulation and the experiment is observed to verify the effectiveness of our retrodirective design in upper half-space wave manipulation.

Compact Four-Port Waveguide Circulator Using Discrete Ferrites for Injection-Locking Magnetron System

A compact high-power four-port circulator aiming to simplify the conventional, complex, and bulky injection-locking magnetron system is proposed. To reduce the performance deterioration and the risk of ferrite rupture under long-term high-microwave-power condition, the method of breaking a monolithic ferrite into three discrete ferrites in a conventional three-port circulator is proposed. To miniaturize the size and cost of the four-port circulator, a butterfly-shaped waveguide structure is proposed, with a stub inserted into the cavity at the central point and with no connecting waveguide. Multiphysics simulation results show that the temperature coefficient of variation (COV) at the surface of the discrete ferrites is 12.4% lower than that of a monolithic ferrite circulator, with input microwave power of 10 kW. The size of the proposed four-port waveguide circulator is 27% less than the assembly of two three-port circulators, and way smaller than a conventional differential phase shift circulator (DPSC). The simulated and measured S-parameters match well, and the measured power capacity of the fabricated circulator is higher than 3 kW (limited by the experimental condition). A magnetron is successfully locked using only one designed compact circulator. The research in this paper promotes the development of injection-locking magnetron and provides a design example for the compact, high-power circulator.

On the Design of Broadband Asymmetric Y-Junction Ferrite Circulator for 60-GHz Inter-Satellite Communication

On the Design of Broadband Asymmetric Y-Junction Ferrite Circulator for 60-GHz Inter-Satellite Communication

Computer model of the transponder for the analysis of phase distortions of the signal

The article discusses issues related to the development of a computer model of an on-board relay complex with linear signal retransmission for the analysis of phase distortion of the signal. It is very important to know the phase distortion (foray) when determining the coordinates of the radio source by the phase method using a virtual antenna array in satellite communication systems. The literature review given in the article showed that it was not possible to conduct these studies on existing computer models. Based on the classical version of the block diagram of the on-board relay complex, a computer model was developed in the MATLAB R 2016b (Simulink) environment. The model includes a receiving device, an input and output multiplexer and power amplifiers. Mathematical models of Saleh and Gorbanni amplifiers implemented on traveling wave lamps and solid-state amplifiers, respectively, were taken as nonlinear amplifiers. Multiplexers are implemented in the form of bandpass filters connected in parallel. The hybrid divider and ferrite circulators were not included in the model. In the model, it is possible to investigate the dependence of the phase distortion of the signal on the characteristics of the structural blocks of the on-board relay complex. The computer model also provides for the possibility of studying the effect of noise on phase distortion.

Design and construction of ferrite waveguide circulator with short wall in S band

AbstractOne of the most important components in the radar and microwave industry that provides transmitting and receiving features for an antenna at the same time is called a circulator. Ferrite circulators are passive three‐port devices in which the RF or microwave signal is transmitted from one port to other port without leakage to the third port. One of the main disadvantages of these waveguide elements is their large dimensions and especially their height, which cannot be used in some systems due to the limited workspace. This paper solves this problem by exploiting an incomplete wall waveguide to reduce the height of the circulator by 50%. These changes always reduce the frequency bandwidth of the element, the proposed technique optimizes the dimensions of the ferrite and its magnetic characteristics and increases the bandwidth to 400 MHz in 2.9 GHz, which is the ideal bandwidth required by many radar systems that have been reached. The ferrite circulator designed and built in this article has a port with a width of 72.13 mm and a height of 17 mm in the S‐band. The method results in a low insertion loss which is less than 0.5 decibels and a high isolation which created more than 20 decibels. The designed and optimized elements have been implemented and the test results verify the theoretical results.

General Coupling Method for Stripline Ferrite Circulators: Application on Dual-Band Devices With Complex Central Conductor Shape

This article presents two original, efficient, and rigorous methodologies for coupling ferrite circulators of complex shapes. Indeed, by using a central conductor of any shape or geometry, an optimized circulation phenomenon can be achieved because of both methods. This article details and analyzes the two methods developed. They will be validated by the measurement of a stripline circulator with a triangular central conductor operating around 8 GHz. At the end of this first study, one of the two methods will be selected and implemented in a more complex case since we will adapt it to a dual-band operation.

Waveguide power phase shifter with a ferrite circulator in S-band

Abstract This paper presents the application of a phase shifter with a ferrite Y-circulator in band S. Global literature addresses primarily the basic types of power waveguide phase shifters, however, there has been minimal literature on a phase shifter that uses a ferrite circulator for phase shifting. The paper describes theoretical and practical results where a ferrite circulator is used to shift the phase. A power phase shifter utilizing a ferrite circulator could be used in power applications where high demands are placed on the phase shift accuracy with minimal power losses. The phase shift is handled by a tunable waveguide short circuit that is connected to the port 2 of the ferrite circulator. By changing the waveguide length, the phase is changed. The measured results are compared with theoretical calculations and evaluated. The proposed phase shifter utilizing the ferrite circulator has its advantages in its simple design, in the accuracy of the phase adjustment and in the speed of the tuning. Another great advantage is its quite low cost due to its simple design.

Chiral quantum network with giant atoms

In superconducting quantum circuits (SQCs), chiral routing quantum information is often realized with the ferrite circulators, which are usually bulky, lossy and require strong magnetic fields. To overcome those problems, we propose a novel method to realize chiral quantum networks by exploiting giant atom effects in SQC platforms. By assuming each coupling point being modulated with time, the interaction becomes momentum-dependent, and giant atoms will chirally emit photons due to interference effects. The chiral factor can approach 1, and both the emission direction and rate can be freely tuned by the modulating signals. We demonstrate that a high-fidelity state transfer between remote giant atoms can be realized. Our proposal can be integrated on the superconducting chip easily, and has the potential to work as a tunable toolbox for quantum information processing in future chiral quantum networks.

SYSTEMATIZATION OF THE FORMULAS OF THE RESONANT FERRITE ISOLATOR LOSS

Context. The problem is to systematize and improve the models of a resonance ferrite isolator in the rectangular waveguide for the antenna-feeder devices, generating, receiving, measuring microwave equipment containing ferrite decoupling devices: ferrite isolators and circulators. Objective. The goal of the work is to verify the formula for the losses of the resonant ferrite isolator in the direct and reverse directions, as well as the isolator ratio. Method. The research method of the work is a critical analysis of literary sources, which was carried out, but did not bring the desired results, since it did not allow to verify the correctness of the derivation of the formula [17]. Therefore, a number of hypotheses were put forward, what the formula might mean. The difficulty lay in the presence in the formula of the product of trigonometric functions that can be attributed to frequency properties, which was taken as an initial hypothesis, which was not subsequently confirmed. The check included transformation of formulas using mathematical physics in terms of microwave electrodynamics, trigonometry and algebra. The beginning was the formula of the classics [16], similar to the formula of [18], accepted without proof. As it is known, for the main type of wave in a rectangular waveguide, the components of the magnetic field strength, obtained as a solution to the wave equation under the boundary conditions inherent in a rectangular waveguide. One component of the magnetic field strength is along the direction of wave propagation, and the second one is in the transverse direction in the section of the waveguide are proportional to the trigonometric functions cosine and sine with the same arguments. The equality of the two components of the strengths is traditionally uses to find the plane of circular polarization where to place the ferrite isolator, and so the authors use this proportionality to trigonometric functions in their derivation, namely the formulas of trigonometric functions of a double angle, the basic trigonometric identity sine squared plus cosine squared is equal to one for replacing the propagation constants with trigonometric functions, this allows to get rid of radicals in the formulas, these radicals in the formula are due to the phenomenon of dispersion in a rectangular waveguide. The rest of the manipulations with the formula are the reduction of similar terms. Results. There was obtained analytical expressions for the losses of the resonant ferrite isolator in the forward and reverse directions, as well as the isolator ratio by strict mathematical transformations. There was performed such transformations. The ratios of the longitudinal propagation constant to the transverse propagation constant are replaced by the ratios of the trigonometric functions sine and cosine, since they are continuous as opposed to tangents and cotangents. Such a transformation allows to avoid square roots in the formula for the losses of the ferrite isolator in the forward and reverse directions, which are associated with the presence of dispersion in the waveguide, as in the formula for wavelength in the waveguide. The conversion is based on microwave electrodynamics. The formulas are used for the distribution of fields in a rectangular waveguide for the main type of wave. Further transformations consist in taking the common factor out of brackets and other arithmetic transformations. Conclusions. Тhrer was obtained results partially coincide with the well-known [17], the derivation of the formula [17] was obtained for the first time, the studies carried out allowed us to reject the hypothesis that the product of cosines and sines in the loss formula of a ferrite isolator is a frequency characteristic, it appears as a result of arithmetic transformations. To take into account the frequency range, it is used that there is circular polarization at the middle frequency, there will also be circular polarization at the extreme frequency of the range, but the plane of circular polarization will shift in comparison with the position of the plane of circular polarization at the middle frequency. That is, a peculiar system of two equations is obtained with respect to two positions of the polarization plane relative to the wide side of the rectangular waveguide section. The scientific novelty consists in systematization and generalization of the formulas of the loss of the resonance ferrite isolator, the connection between the formulas from different literature sources, both foreign and domestic, is proved, which saves time for researchers of ferrite isolators for the verification of the formula. The practical significance. It may be useful for teaching purposes and in optimization of the ferrite isolator design.

A Novel Circulator Construction With High Multipactor Threshold and High Isolation for Aerospace Applications

In this article, a tapered matching structure in a circulator junction is employed in order to achieve the purpose of high isolation and multipactor suppression in spacecraft electronic equipment. This matching structure consists of multiple ramped metal steps. Compared with the traditional flat steps, it changes the electric field distribution in the circulator junction, thus destroying the resonance condition of the secondary electrons. And it changes the trajectory of the secondary electrons. These particles tend to escape the multipactor sensitive region. So, the purpose of multipactor suppression is reached. Besides, a good match between the circulator junction and the waveguide is obtained by using multiple ramped metal steps. So, high isolation is achieved. Finally, an S-band ferrite waveguide circulator with these characteristics operating at frequencies in the range of 3.4–4.2 GHz is designed, fabricated, and measured. The isolation value of the circulator achieves a maximum value of 43 dB near 4 GHz. And the isolation exceeds 25 dB and the insertion loss is less than 0.3 dB over a bandwidth of 21% centered at 3.8 GHz. In addition, the experimental results show that the multipactor threshold of the circulator reaches 10000 W.

Design and Synthesis of Ferrite Strip-Line Circulator Based on Enhanced Closed Form Solution and Power Handling Analysis

In this article, Y-junction strip-line circulators are designed using an enhanced closed form solution consisting of unified key equations and a flowchart design, which serves as a direct procedure for designing a ferrite circulator. This design methodology is combined with a 3D EM simulation that allows for the calculation of the saturation magnetization, uniform biasing, and ferrite dimensions needed for a circulator to operate in both modes. In addition, the closed form can be used to calculate the Y-junction parameters and allow the matching network to be calculated and the uniform circulator biasing design ended. Our analysis starts with the ferrite calculation to ensure that it is uniformly biased magnetically, and this is followed by strip-line design, Y-junction matching, and biasing circuit design. Using full-wave electromagnetic (EM), HFSS and magnetostatic (MS), Maxwell3D simulations, several key design parameters such as the saturation magnetization, coupling angle, and various external permanent magnetic biases are investigated. To validate the proposed concept, two strip-line circulators are designed and fabricated for operation in wide-bandwidth and narrow-bandwidth applications. Good agreement is found between the simulated and experimental responses for the S-parameters of the circulators. We also present a semi-analytical analysis of the concept of breakdown, which enables calculation of the peak power and total thermal rise in the strip-line structure. The average power handling capability of a strip-line circulator is studied for the first time. The proposed closed form expressions can also be implemented in various ferrite circulators using different guiding technologies for millimeter-wave applications.

Low-Loss Ferrite Circulator as a Tunable Chiral Quantum System

Microwave circulators are usually treated as auxiliary, classical components in superconducting quantum computing. This study integrates the cavity-magnon polariton modes of a custom-built circulator with superconducting microwave cavities to implement a tunable nonreciprocal interaction. The apparatus is well described by a non-Hermitian Hamiltonian, yielding a theoretical framework to model other nonreciprocally coupled circuit elements on the same platform in the future. The experiment also showcases an experimental probe of the left and right eigenvectors associated with the non-Hermitian Hamiltonian.

Synthesis of low-temperature sintered M-type barium ferrites with enhanced microstructure, magnetic and dielectric properties

M-type barium ferrites (BaM) are utilized in the preparation of ferrite circulators due to their excellent magnetic properties. However, high sintering temperature of BaM is one of the major problems unsuitable for actual production requirements. In this study, Bi3+ ions from the low-melting point oxide bismuth(III) oxide (Bi2O3) were made to substitute Fe3+ ions to reduce the sintering temperature and control the magnetic properties. Addition of an appropriate content of Bi3+ ions at the sintering temperature of 900 °C led to the disappearance of the second phase, and a pure BaBix(CoTi)1.2Fe9.6−xO19 phase was formed. The results exhibited the existence of dense microstructure in BaM ceramics. Moreover, when the x value of Bi2O3 was 0.45, the permeability of the sample increased from 12.59 to 21.6 at 10 MHz, the saturation magnetization reached 3313.34 gauss, and the permittivity increased from 10.75 to 21.24. Permeability and permittivity were found to be approximately equal. Interestingly, addition of excessive Bi2O3 led to the formation of the second phase, and the microstructure exhibited the appearance of abnormal grains. However, BaM still maintained acceptable magnetic properties. The results showed that the addition of Bi3+ ions could reduce the sintering temperature of the ferrite and simultaneously adjust the magnetic and dielectric properties. Therefore, this material may have good performance in the preparation of ferrite circulators.

Autogenerator with Ferrite Circulator Powered Hybrid Electron Accelerator Characteristics Modeling

Autogenerator with Ferrite Circulator Powered Hybrid Electron Accelerator Characteristics Modeling

Analysis of two‐dimensional multipactor model for ferrite circulator junction

Analysis of <scp>two‐dimensional</scp> multipactor model for ferrite circulator junction

Quadrupole resonator mode versus dipole one in photonic crystal ferrite circulators

We propose a photonic crystal circulator based on quadrupole resonance of a magnetized ferrite cylinder. This device consists of a T-junction composed by three waveguides in a two-dimensional photonic crystal with square lattice. The ferrite cylinder is placed in the center of the T-junction. The scattering matrix, analytical model and the numerically calculated frequency characteristics of the circulator for the central frequency 94.5 GHz are presented. This device is compared with the previously suggested T-type circulator based on the dipole resonance mode. In particular, we show that the use of the quadrupole resonance permits to reduce the necessary DC magnetic field in comparison with dipole mode case by six times and this is important at THz frequencies where the necessary field is excessively high. Besides, quadrupole resonance requires the higher diameter of the ferrite resonator. The ferrite cylinders are produced by a special technology, and higher dimensions lead to a better reproducibility of such elements. However, these advantages are achieved at the expense of higher insertion losses and lower bandwidth of the circulator.

Complex Envelope Hybrid Implicit–Explicit Procedure With Enhanced Absorption for Bandpass Nonreciprocal Application

For bandpass simulation of nonreciprocal devices with fine and complex structures, hybrid implicit-explicit (HIE) perfectly matched layer (PML) which is incorporated with the higher order concept and complex envelope (CE) method is proposed in finite-difference time-domain (FDTD) lattice. The proposed implementation shows advantages in terms of efficiency, accuracy, and absorption. The effectiveness is demonstrated through the simulation and measurement of ferrite circulator. Through numerical results, the proposed scheme can obtain considerable efficiency and enhanced absorption. From the measurement results, it can be seen that the proposed scheme impacts entire performance in bandpass nonreciprocal simulation.

A Full-Duplex Receiver With True-Time-Delay Cancelers Based on Switched-Capacitor-Networks Operating Beyond the Delay–Bandwidth Limit

Wideband self-interference cancellation (SIC) in full-duplex (FD) radios requires the achievement of large delays to accurately emulate the SI channel. However, compact, power-efficient, low-loss/noise/distortion nanosecond-scale delays are extremely challenging to achieve on silicon. Passive transmission lines on silicon are lossy and area-intensive and exhibit reduced bandwidths when miniaturized using inductors and capacitors, whereas active approaches are noisy and power-hungry. In this work, we present a technique that leverages switched-capacitor circuits with multiphase clocking to obtain large on-chip delays over wide bandwidths with the low area and power consumption, thus exceeding the delay-bandwidth product (DBW) limits offered by conventional linear time-invariant (LTI) circuits. This technique is demonstrated in an FD receiver with time-interleaved switched-capacitor-based delay cells in RF and BB domains. The FD receiver is implemented in a standard 65-nm CMOS process and operates from 100 MHz-1 GHz with gain tunability of 15-38 dB, a noise figure of 5.4 dB, and power consumption of 31 mW. The RF/BB canceler delay cells have real-/complex-valued weighting with delays ranging from 0.2-1.1 ns/10-75 ns while consuming 25.5 and 6.5 mW, respectively. These large tunable delays perform FIR-filtering-based cancellation, enabling 30-35-dB integrated SI cancellation over 20 MHz on top of an off-the-shelf ferrite circulator when terminated by a dipole antenna (isolation of 22 dB), and can handle TX power of up to +9 dBm. Under SIC, the RF and BB cancelers degrade the RX noise figure by 1.1 and 0.8 dB, respectively.

Efficient and Low-Backaction Quantum Measurement Using a Chip-Scale Detector.

Superconducting qubits are a leading platform for scalable quantum computing and quantum error correction. One feature of this platform is the ability to perform projective measurements orders of magnitude more quickly than qubit decoherence times. Such measurements are enabled by the use of quantum-limited parametric amplifiers in conjunction with ferrite circulators-magnetic devices which provide isolation from noise and decoherence due to amplifier backaction. Because these nonreciprocal elements have limited performance and are not easily integrated on chip, it has been a long-standing goal to replace them with a scalable alternative. Here, we demonstrate a solution to this problem by using a superconducting switch to control the coupling between a qubit and amplifier. Doing so, we measure a transmon qubit using a single, chip-scale device to provide both parametric amplification and isolation from the bulk of amplifier backaction. This measurement is also fast, high fidelity, and has 70% efficiency, comparable to the best that has been reported in any superconducting qubit measurement. As such, this work constitutes a high-quality platform for the scalable measurement of superconducting qubits.