Circular Cavity Resonator Research Articles

A dual mode circular waveguide cavity resonator based frequency tunable band pass filter using a single tuning element

AbstractIn this letter, we present a tunable band pass filter (BPF) using a dual‐mode circular waveguide cavity resonator using a single tuning element. For the proof of the concept, a 2nd order tunable BPF has been designed and developed over a tuning range from 4.92 to 6.1 GHz (21.4%). The measured bandwidth is 85 ± 10 MHz over the entire tuning range. The peak insertion loss is within 1.3 dB and return loss is better than 15 dB. The tunable filter is proposed to be used in high Q reconfigurable radio systems.

Microwave Dynamical Conductivity in the Quantum Hall Regime.

Dynamical conductivity contains information of dissipative and nondissipative processes induced by ac-electric fields. In the integer quantum Hall (QH) effect where the nondissipative Hall current is the most prominent feature, its robustness is assured by localized states within the Landau levels. We establish a noncontact method with a circular cavity resonator and detect the real and imaginary parts of the longitudinal and Hall conductivities at a microwave frequency in magnetic fields. The conventional Shubnikov-de Haas oscillations and QH plateaus are observed in the real parts of longitudinal and Hall conductivities, respectively, while periodic structures can be seen in the imaginary parts which are scaled by the QH filling factor. The latter originates from intra-Landau level transitions between different orbital angular momenta. The results demonstrate that the dynamical conductivity measurement provides microscopic information which is not accessible by conventional static methods. The present noncontact method would pave the way to reveal the electron dynamics in other two-dimensional systems such as twisted bilayer graphene.

New phase noise X‐band VCO using perturbed dual‐mode SIW filter

AbstractThis letter discusses a complete implementation of high performance voltage‐controlled oscillators using enhanced group delay SIW filters. Through precisely adjusting the perturbing via‐hole position inside dual mode circular cavity resonator, phase noise of the oscillator can be minimized. The planar SIW X‐band voltage‐controlled oscillation prototypes were additionally analyzed, fabricated, and measured. Experimental results achieve the best phase noise reaching to −134.31 dBc/Hz@1 MHz. The advantages of this voltage‐controlled oscillator are simple design processes, planar compact structure, and improved figure of merit. A set of parameters that evaluate the performance of the proposed oscillator are used, and then compared with the existing ones.

Compact SIW directional filter using substrate integrated circular cavities

AbstractIn this paper, a novel directional filter (DF) is proposed and implemented using substrate integrated waveguide (SIW) technology which exhibits the advantages of compact size and simple structure. The proposed DF is realized by two half mode substrate integrated waveguides (HMSIWs) and two substrate integrated circular cavity (SICC) resonators operating in the TM110 degenerate modes in which an aperture is utilized to realize the coupling between HMSIWs and SICCs. Two slotlines with appropriate dimensions, etched on the top and bottom planes, are utilized in order to control coupling strength between two cascaded SICC resonators. The proposed two-circular cavity SIW DF at 12.3 GHz is designed and fabricated with a normal printed circuit board process. Measured and simulated results indicate that the DF has a 3.25% bandwidth, and the return loss as well as isolation are better than 10.5 and 15 dB, respectively.

Substrate integrated circular cavity resonator filled with nano-fibrillated cellulose for humidity detection

Substrate integrated circular cavity resonator filled with nano-fibrillated cellulose for humidity detection

SIW Circular Cavity Single Mode Filter With Triangle Probe

A novel substrate integrated waveguide (SIW) circular cavity using triangle probe are proposed in this paper. Prior to this research work, circular cavity resonator was used to achieve a miniaturization for the overall circuit size. The proposed filter provides single resonant mode, TE110. The resonant frequency of TE110 can be adjusted by varying the length and width of the SIW cavity. The proposed filter are designed to operate at frequency 3.75 GHz and implemented on Rogers 3210 substrate with thickness of 0.64 mm. The insertion loss in operating band is less than 0.6 dB and the return loss is better than 24 dB. Simulated result obtained using Ansoft HFSS software.

Optical coupling characteristics between a circular defect resonator and a waveguide in a two-dimensional photonic crystal slab

To develop a wavelength division multiplexing (WDM) device using a photonic crystal (PC), we investigate coupling strength between a circular cavity resonator and a waveguide with various structural parameters. In the WDM device, light signals with various wavelengths generated in different cavity resonators travel through a single waveguide. Careful tuning of the cavity-waveguide coupling is necessary for practical operations, since the light signals must have the same intensities in the waveguide. Carrying out three-dimensional finite-differential time-domain (FDTD) calculations along with photonic bands, we search for the optimum structure for the WDM.

Design of SIW cavity‐backed self‐triplexing antenna

A novel substrate integrated waveguide (SIW) cavity-backed self-triplexing slot antenna, consisting of a hybrid SIW cavity resonator is proposed for tri-frequency operation. The hybrid cavity resonator is an amalgamation of a half-mode circular and half-mode rectangular SIW cavity resonator. A radiating slot is etched on its top surface, which produces three distinct resonant frequencies (5.57, 7.17 and 7.65 GHz) when it is excited by three microstrip lines. The lower band around 5.57 GHz is achieved due to a half-mode circular cavity resonator, when the corresponding microstrip line is excited. On the other hand, remaining two bands around 7.17 and 7.65 GHz are achieved due to half-mode rectangular cavity resonator when excited by the corresponding microstrip lines. The experimental isolation level between any two feed lines is better than 20 dB, which helps to introduce the self-triplexing phenomenon. Moreover, the proposed design is realised on a single-layered copper-laminated dielectric substrate, maintaining planar configuration.

Ultrasharp Fano Resonances Based on the Circular Cavity Optimized by a Metallic Nanodisk

A compact structure is proposed to achieve double ultrasharp Fano profiles, which comprises with a metal-insulator-metal (MIM) bus waveguide coupled with a circular cavity and groove resonator. Simulation results show that this two sharp Fano profiles both originate from the interference between the circular cavity and the groove resonator. To optimize the Fano profiles, we introduce a metallic nanodisk in the middle of the circular cavity. The peak of the double Fano resonances can be independently tuned within a certain range by changing the radius of the nanodisk. We can utilize these characteristics to design devices with high performance, such as a highly efficient nanosensor with a sensitivity of ∼1450 nm/RIU and a figure of merit (FOM) about ∼3.51 × 10 4 and a switch with an on/off contrast ratio of about 91 dB. Our structures may have promising applications in nanosensors, switches, and slow-light devices.

Ultra Sharp Fano Resonances Induced by Coupling between Plasmonic Stub and Circular Cavity Resonators

A plasmonic waveguide system composed of metal-insulator-metal (MIM) stub coupled with circular cavity resonator was proposed to produce ultra sharp Fano resonances, which resulted from the coupling between the ultra narrow discrete resonances and the ultra broad spectrum of the plasmonic circular cavity and stub resonator, respectively. The spectral line shapes of the Fano resonances can be easily adjusted by changing the structure parameters. And the transmittance of the system can sharply decrease from peak (“on state”) to valley (“off state”) with wavelength shifts of only about 8 nm. Due to the sharp phase change of the ultra asymmetric Fano resonance, a maximum group index of about 180 can be realized. Also, the ultra sharp spectrum contributes to a highly efficient plasmonic refractive index sensor, which can yield a linear sensitivity of 1277 nm/RIU and figure of merit of about 2.1 × 104. The proposed structure may have potential applications in nanoscale filter, slow light, and refractive index sensor.

High-frequency dielectric and mechanical properties of cyclo-olefin polymer/MgO composites

Variations in the high-frequency dielectric, thermal and mechanical properties of cyclo-olefin polymer (COP)/MgO composites with MgO content were investigated. Dielectric properties were measured using a circular cavity resonance method at approximately 12 GHz and dielectric constants (e r) were found to increase with increasing MgO concentration. The variations in the observed e r values were in good agreement with Bruggeman mixing theory, and the dielectric loss (tan δ) values of the composites were consistently in the order of 10−4. It was confirmed that exposure to humid conditions had little effect on the dielectric properties of the composites. The temperature coefficient of the dielectric constant (TCe) and the coefficient of thermal expansion (CTE) were improved as the MgO fraction was increased due to the superior thermal properties of MgO. The mechanical properties of the composites were assessed by Charpy impact and flexural tests. The flexural moduli of the composites increased with higher MgO concentrations in accordance with Nielsen’s theory, while deteriorations in the flexural and impact strengths were observed.

Cavity Resonator Measurement of Dielectric Materials Accounting for Wall Losses and a Filling Hole

A cavity resonator technique for the measurement of isotropic homogeneous nonmagnetic dielectric materials is addressed. The materials to be measured are placed in a well-defined position inside a circular cylindrical cavity resonator through a filling hole in the head end cap of the resonator. The measurement procedure solves the inverse problem based on a variational formulation in terms of the magnetic field in the resonator. The effects of lossy walls and of the filling hole are taken into account by using inhomogeneous surface impedance boundary conditions. In order to reduce the problem to matrix form, the magnetic field in the variational formulation is expanded in terms of undamped eigenmodes of the lossless cavity. The resulting equation is a generalized eigenvalue problem for the unknown material parameters. It is solved by using standard techniques such as the generalized Schur decomposition. The proposed method is tested against experimental data, including measurements at various temperatures, in order to show its capabilities as well as to see the effect of the filling hole on the results.

EMPIRICAL RELATIONS FOR THE EVALUATION OF RESONANT FREQUENCY AND QUALITY FACTOR OF THE TM<sub>010</sub> MODE OF CIRCULAR SUBSTRATE INTEGRATED WAVEGUIDE (SIW) RESONATORS

In this paper, empirical relations for the evaluation of both the resonant frequency fr and the quality factor Q for the dominant TM010 mode of a circular substrate integrated waveguide (SIW) cavity resonator are proposed and validated. These formulas are based on well established analytical expressions valid for the case of circular metallic cavity resonator, in which an equivalent radius Req, empirically derived, is employed. Their efiectiveness is demonstrated by comparing the empirical predictions with the full wave results.

Dependence of ion beam current on position of mobile plate tuner in multi-frequencies microwaves electron cyclotron resonance ion source

We are constructing a tandem-type electron cyclotron resonance ion source (ECRIS). The first stage of this can supply 2.45 GHz and 11-13 GHz microwaves to plasma chamber individually and simultaneously. We optimize the beam current I(FC) by the mobile plate tuner. The I(FC) is affected by the position of the mobile plate tuner in the chamber as like a circular cavity resonator. We aim to clarify the relation between the I(FC) and the ion saturation current in the ECRIS against the position of the mobile plate tuner. We obtained the result that the variation of the plasma density contributes largely to the variation of the I(FC) when we change the position of the mobile plate tuner.

Measurement of Complex Permittivity for Liquid Materials Using the Open-Ended Cut-Off Waveguide Reflection Method

Various studies of specific absorption rates (SARs) using liquid phantoms imitating human body tissues have been widely carried out in electromagnetic compatibility (EMC) research fields. In order to establish accurate SARs for measurement, a faithful mockup of human body tissue is needed. Therefore, knowledge of the accurate measurement of sample materials with high permittivity and high loss is very important. In this study, the complex permittivity of tap water, ethanol, methanol and isopropanol is measured by the open-ended cut-off circular waveguide reflection method. The effectiveness of the method presented here of measuring a liquid phantom with high-permittivity and high-loss is also confirmed by comparing the measured results with the results obtained by the TM010 circular cavity resonator method. At this time, the effects on the input impedance under variations of the insertion length and termination conditions were studied. Then the complex permittivity of tap water, ethanol, methanol and isopropanol was measured at frequencies ranging from 0.5 to 3.0GHz using the measurement procedure above. As a result, we confirmed the frequency characteristics of the complex permittivity for a wide variety of high-loss liquid materials.

Frequency Dependence Measurements of Complex Permittivity of Dielectric Plates Using TE0m1 Modes in a Circular Cavity

A circular cavity resonance method is improved to measure the frequency dependence of complex permittivity of a dielectric plate by using multimode TE0m1 with integer m. The measurement principle is based on a rigorous analysis by the Ritz-Galerkin method. A new circular cavity with lowered height is designed from a mode chart of a cavity to decrease the number of unwanted modes near the TE0m1 modes. A copper cavity having 20GHz for the TE011 mode was constructed based on this design. For glass cloth PTFE, RT/duroid 6010 and FR-4 dielectric plates, the frequency dependences are measured from resonant frequencies for the TE0m1 (m =1, 2, 3 . . .) modes. These measured results agree well with ones measured by using the conventional four different size cavities with TE011 mode. It is verified that the designed cavity structure is useful to measure the frequency dependence of low loss dielectric plates.

LOD-BOR-FDTD Algorithm for Efficient Analysis of Circularly Symmetric Structures

The unconditionally stable locally 1-D (LOD) scheme is used to develop an efficient implicit body-of-revolution (BOR) finite-difference time-domain (FDTD) method. In the LOD-BOR-FDTD, the number of arithmetic operations of the resultant finite-difference equations is significantly reduced, when compared with the alternating-direction implicit (ADI) BOR-FDTD. Numerical results of circular cavity resonators reveal that the LOD-BOR-FDTD provides resonance frequencies identical to the ADI counterparts, with the computational time being reduced to 70%.

A X-Band 3-D SICC Filter with Low-Loss and Narrow Band using LTCC Technology

In this paper, a novel compact X-band band pass filter with low loss and narrow-band using low temperature co-fired ceramic (LTCC) technology is proposed. The filter is based on the substrate integrated Circular Cavity (SICC) resonator and fed by transmission line, and it exhibits excellent performance (IL 0.61 dB, 3-dB bandwidth (BW) 3.4%). To validate the design method of the structure, two different 3D simulation tools are employed.

Practical electromagnetics: from biomedical sciences to wireless communication

Preface. 1. INTRODUCTION. 1.1 Electrical sources and fundamental quantities. 1.2 Static and dynamic fields. 1.3 Working with complex numbers and functions. 2. VECTORS AND FIELDS. 2.1 Working with vectors. 2.2 Coordinate systems. 2.3 Differentiation and integration of vectors. 2.4 Gradient of the scalar field and its applications. 2.5 Divergence of the vector field and its applications. 2.6 Curl of the vector field and its applications. 2.7 The divergence theorem. 2.8 Stokes' theorem. DELTA. 2.9 Other operations involving 2.10 Helmholtz theorem. 3. BASIC LAWS OF ELECTROMAGNETICS. 3.1 Maxwell's equations in large scale/integral form. 3.2 Maxwell's equations in point/differential form. 3.3 Constitutive relations. 3.4 Boundary conditions. 3.5 Lorentz force equation. 3.6 Poynting vector and power flow. 4. UNIFORM PLANE WAVES. 4.1 The wave equation and uniform plane wave solutions. 4.2 Plane electromagnetic waves in Lossy media. 4.3 Uniform plane wave incident normally on an interface. 4.4 Uniform plane wave incident obliquely on an interface. 5. TRANSMISSION LINES. 5.1 Transmission line equations. 5.2 Finite length transmission line. 5.3 Smith chart. 5.4 Transients on transmission lines. 6. MODIFIED MAXWELL'S EQUATIONS AND POTENTIAL FUNCTIONS. 6.1 Magnetic charge and current. 6.2 Magnetic vector and electric scalar potentials. 6.3 Electric vector and magnetic scalar potentials. 6.4 Construction of solution in rectangular coordinates. 6.5 Construction of solution in cylindrical coordinates. 6.6 Construction of solution in spherical coordinates. 7. SOURCE IN INFINITE SPACE. 7.1 Fields of an infinitesimal source. 7.2 Antenna parameters. 7.3 Linear antennas. 7.4 Antenna arrays. 7.5 Friis transmission formula and the radar range equation. 8. ELECTROSTATIC FIELDS. 8.1 Laws of electrostatic fields. 8.2 Gauss' law. 8.3 Poisson's and Laplace's equations. 8.4 Capacitors and energy storage. 8.5 Further applications of Poisson's and Laplace's equations. 9. MAGNETOSTATIC FIELDS. 9.1 Laws of magnetostatic fields. 9.2 Inductors and energy storage. 9.3 Magnetic materials. 9.4 Magnetic Circuits. 10. WAVEGUIDES AND CAVITY RESONATORS. 10. 1 Metallic rectangular waveguide. 10. 2 Metallic circular cylindrical waveguide. 10.3 Rectangular cavity resonators. 10.4 Circular cylindrical cavity resonators. 11. NUMERICAL TECHNIQUES. 11.1 Finite difference methods. 11.2 The method of moments. 11.3 Scattering of plane EM waves from an infinitely long cylinder. Appendix A. Mathematical formulas. Appendix B. Delta function and evaluation of fields in unbounded media. Appendix C. Bessel functions. Appendix D. Legendre functions. Appendix E. Characteristics of selected materials. Appendix F. Physical constants. Appendix G. Decibels and Neper. Appendix H. Nomenclature and characteristics of standard rectangular waveguides. SELECTED REFERENCE BOOKS . Index.

Production of multicharged ions and behavior of microwave modes in an electron cyclotron resonance ion source directly excited in a circular cavity resonator

Electron cyclotron resonance ion sources (ECRIS) have been widely used for production of high-intensity multicharged ion beams. Making good use of microwave modes is proposed for enhancing the efficiency of ECR for production of multicharged ions (TAIKO II). We can assign the peak position of the electric field of the standing waves to the ECR zone in the directly excited cavity resonator, i.e., the vacuum chamber with the fixed and the mobile plates for selecting and tuning the modes. Periodicity of the extracted multicharged ion currents and plasma parameters is observed as the position of the mobile plate moves. We measure the intensity of the electric field in the ECR plasma by using the insulated semidipole probe and the standing waves are observed. The correlation between the production of multicharged ions and the microwave modes is clarified by measuring the electric field and plasma parameters in the circular cavity resonator.