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A planar composite microwave resonator based on a bilayer structure comprising a single-crystal yttrium iron garnet (YIG) ferrite film on a lead magnesium niobate-lead titanate (PMN-PT) piezoelectric plate has been studied. The possibility of electric and magnetic tuning of the resonance frequency in this structure is demonstrated. The magnetic tuning in the frequency range of 2–18 GHz is effected by varying the magnetic bias field and the electric tuning within a 20 MHz bandwidth is achieved by applying a dc bias voltage to the piezoelectric layer. An increase in the central frequency of a YIG/PMN-PT composite resonator is accompanied by a growth in the resonator Q from 110 to 990, while the electric tuning bandwidth remains unchanged [ABSTRACT FROM AUTHOR]

On the basis of analyzing the expression for the input electric impedance of a composite microwave acoustic resonator, its equivalent electric circuit is constructed. It is shown that, for high-order harmonics, the difference between the antiresonance and resonance frequencies is determined not only by the electromechanical coupling coefficient, but also by the loss in the structure. The conditions under which this difference corresponds to the bandwidth of the equivalent parallel electric oscillatory circuit are formulated. Expressions for the resonance and antiresonance frequencies are derived. The procedures of determining the Q factor and the electromechanical coupling coefficient from the measured resonance and antiresonance frequencies of the structure are justified. [ABSTRACT FROM AUTHOR]

A systematic study of the high frequency electrical properties of electro-textiles is presented in this paper. First, conductive thread characterization is completed with a wave- guide cavity method. The effect of conductive thread density and comparison of several different types of conductive threads are included. Second, comparisons of knitted patterns and weave patterns are made in terms of effective electrical conductivity through a microstrip resonator method. The effect of various weave patterns on conductive and dielectric loss is detailed. Finally, the relevance of the high frequency characterization of the electro-textile materials is shown through electro-textile patch antenna fabrication and measurements. The efficiency of the fully fabric patch antenna is as high as 78% due to the use of low loss electrotextiles characterized in this paper. [ABSTRACT FROM AUTHOR]

A double-layer frequency selective surface (FSS) is proposed as a means to enhance the bandwidth of an electromagnetic band gap (EBG) resonator antenna. Due to its inverted reflection phase variation and its wide selectivity bandwidth, the structure used in the radiating wall of the resonator allows increasing the radiating bandwidth of the last one. The resonator is fed by a patch feeding source placed inside the cavity at the proximity of its metallic ground. The antenna bandwidth is significantly improved by virtue of employing the double-layer FSS. Modelled results of an antenna working at 5GHz are shown. [ABSTRACT FROM AUTHOR]

This paper presents a novel technique for synthesizing a given radiation pattern from an EBG antenna with an array feed. The method determines the optimum sets of input waves and input impedances for the feed ports in order to perform simultaneously the radiation pattern and the impedance matching of all the radiating probes that form the array feed. The method is validated through a numerical design of an EBG antenna excited with four patch antennas. The structure is designed to radiate with a single lobe scanned at θ = 30° in the E-plane. The interactions between each patch inside the EBG resonator are characterized with the CST MWS software. The optimum weights and the input impedances which simultaneously perform the objective radiation and the matching of all feeding ports are calculated by the developed global synthesis method. The feed network is designed with the Agilent ADS software in order to perform the specified weights and the impedances matching. [ABSTRACT FROM AUTHOR]

In this paper, we derive quasi-static equivalent-circuit models for the analysis and design of different types of artificial magnetic resonators-i.e., the multiple split-ring resonator, spiral resonator, and labyrinth resonator-which represent popular inclusions to synthesize artificial materials and metamaterials with anomalous values of the permeability in the microwave and millimeter-wave frequency ranges. The proposed models, derived in terms of RLC equivalent circuits, represent an extension of the models presented in a recent publication. In particular, the extended models take into account the presence of a dielectric substrate hosting the metallic inclusions and the losses due to the finite conductivity of the conductors and the finite resistivity of the di-electrics. Exploiting these circuit models, it is possible to accurately predict not only the resonant frequency of the individual inclu-sions, but also their quality factor and the relative permeability of metamaterial samples made by given arrangements of such inclusions. Finally, the three models have been tested against full-wave simulations and measurements, showing a good accuracy. This result opens the door to a quick and accurate design of the artificial magnetic inclusions to fabricate real-life metamaterial samples with anomalous values of the permeability. [ABSTRACT FROM AUTHOR]

A new class of wideband microstrip bandpass filters is proposed under multiple resonances of an asymmetric ring resonator. Two capacitive coupling elements are placed at two perpendicular positions of a squared ring, whereas a pair of open-circuited stubs is formed in the symmetrical plane of these two excited ports similar to a dual-mode ring filter in shape. By stretching the paired stubs close to one-eighth of a wavelength, the first two even-order resonances move down to be quasi-equally located at two sides of the first odd-order resonance, thus forming a triple-resonance ring resonator. As interdigital coupled lines are installed at two ports instead of lumped capacitors, two extra resonances can be moved into passband, thereby making up a quintuple-resonance ring resonator. To provide an insight into their operating mechanism, these ring resonators are characterized in terms of transmission line theory. Afterwards, various wideband microstrip ring resonator bandpass filters with one or two asymmetric ring resonators are optimally designed and fabricated. Simulated results are confirmed via experiment, showing good wideband filtering performance with widened/deepened upper stopband and sharpened rejection skirts outside the wide passband. [ABSTRACT FROM AUTHOR]

Abstract: Based on rigorous analysis of finite element method (FEM), moment method (MoM), and curves fitting techniques, a set of closed-form formulas for the characteristic impedance and the primary (L and C) parameters of the shielded split ring line, are presented. The general expressions give a good accuracy for a wide-range of discontinuity angles and are suitable for all shielded split ring lines which have an outer–inner conductors radius ratio between 2 and 10. These expressions can be easily implemented in CAD simulation tools, to design many components as RF resonators, filters, transmission lines, for wireless communication and probes for material characterization. The results of the design of an RF resonator using the shielded split ring line are presented. [Copyright &y& Elsevier]

Thin film integrated circuits compatible resonant structures using the lowest order symmetric Lamb wave propagating in thin aluminum nitride (AlN) film membranes have been studied. The 2-µm thick, highly c-oriented AIN piezoelectric films have been grown on silicon by pulsed, direct-current magnetron reactive sputter deposition. The films were deposited at room temperature and had typical full-width, half-maximum value of the rocking curve of about 2 degrees. Thin film plate acoustic resonators were designed and micromachined using low resolution photolithography and deep silicon etching. Plate waves, having a 12-µm wavelength, were excited by means of both interdigital (IDT) and longitudinal wave transducers using lateral field excitation (LW-LFE), and reflected by periodical aluminum-strip gratings deposited on top of the membrane. The existence of a frequency stopband and strong grating reflectivity have been theoretically predicted and experimentally observed. One-port resonator designs having varying cavity lengths and transducer topology were fabricated and characterized. A quality factor exceeding 3000 has been demonstrated at frequencies of about 885 MHz. The IDT based film plate acoustic resonators (FPAR) technology proved to be preferable when lower costs and higher Qs are pursued. The LW-LFE-based FPAR technology offers higher excitation efficiency at costs comparable to that of the thin film bulk acoustic wave resonator (FBAR) technology. [ABSTRACT FROM AUTHOR]

One of the main problems in the design of high intensity rf accelerators is the presence of higher order modes (HOMs) which might degrade the beam quality. Accelerating cavities require HOMs suppression, whereas keeping a high quality factor (Q) for the fundamental mode. Both these requirements can be hardly met in closed metallic cavities, especially at high frequency where the configurations become cumbersome and technically unviable. Cavities based on photonic band gap (PBG) concepts showed that HOMs can be efficiently suppressed without affecting the fundamental mode. We present here simulations and measurements at room and cryogenic (77 K) temperature on some metallic (Copper) and metallo-dielectric (Copper + sapphire) PBG based cavities, in order to study their rf behavior as resonant element in particle accelerators. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 2486–2491, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22016 [ABSTRACT FROM AUTHOR]

The design of a novel ultrawideband printed-circuit antenna is presented. By using a stepped-patch in combination with multiple resonating elements, a bandwidth of more than 150% is obtained. The performance is demonstrated through measurements and calculations with a commercially available field solver. A phase center analysis shows very small variations over the entire available bandwidth. [ABSTRACT FROM AUTHOR]

The authors propose a modelling methodology which combines finite element method (FEM) and artificial neural networks (ANNs) techniques for the design and optimisation of integrated circuits (ICs) incorporating one-port radio frequency microelectromechanical systems (RF MEMS) resonating structures. The FEM is employed to predict the electro-mechanical performance of MEMS resonators. ANNs are utilised to model complex relationships between the physical parameters of the MEMS resonator and the corresponding electrical equivalent circuit parameters. These parameters are extracted directly from the FEM analysis and used for training the ANNs. It is shown that the relative error of the ANN model for a single MEMS device is less than 0.5% while the computational time is more than 40 times reduced compared to the FEM. To extend the capabilities of the proposed methodology, the developed ANN model is implemented into a commercially available circuit simulator, Agilent's Advanced Design System (ADS). This allows a seamless modelling process for the design and optimisation of MEMS resonators embedded ICs at both the device and circuit levels. As an example, a 30 MHz Pierce oscillator with the ANN model of a free-free beam MEMS resonator is optimised within the circuit simulator. [ABSTRACT FROM AUTHOR]

The mode structure in a 2D open resonator is reconstructed with the probe method in numerical and full-scale experiments. The domain of applicability of this method, which is specified by the continuous variation of the eigenmode phase in the open resonator, is found. A probe-induced change in the diffraction Q factor of the eigenmode does not necessarily meet its amplitude distribution in the open resonator. The potential of the probe method for estimation of the energy characteristics of modes in open resonators is discussed. [ABSTRACT FROM AUTHOR]

Microwave multislot transmission lines formed on (Ba,Sr)TiO 3 –BST ferroelectric films were studied using full-wave analysis and resonator measurements. The BST films were grown on sapphire, MgO and alumina substrates in the process of RF sputtering. The multislot resonators formed on different types of BST films were measured at frequency ∼⃒30 GHz. The slot and multislot resonator topologies measured in rectangular waveguide had similar quality factor (100–120). The BST film dielectric characteristics were obtained: ε = 1100–1800; tan δ = 0.02–0.03. The coupled multislot structures were simulated to realize tunable band-pass filters of various tunability range, pass band and microwave losses in the band. [ABSTRACT FROM AUTHOR]

In this paper, a method for reducing the size of coplanar-waveguide (CPW) resonators, used in the design of compact bandpass filters, is presented. This is accomplished by incorporating a distributed array of capacitive loads along a resonant CPW line. Design of a miniaturized bandpass filter using capacitively loaded CPW resonators, which are inductively coupled, is presented. Inductively coupled bandpass filters with the proposed capacitively loaded CPW line resonators are designed and a size reduction of 25%, compared with filters using a standard CPW line resonator, is demonstrated. It is shown that, through this size reduction, the insertion loss is minimally increased (<0.4 dB). A hybrid algorithm, combining the method of moments (MOM) and circuit simulation is used to facilitate design process. Few filters using this technique are designed, fabricated, and measured at W-band. An excellent agreement between the simulation and measurement responses of these filters is presented. [ABSTRACT FROM AUTHOR]

A rigorous analysis of the conformal-strip-excited hemispherical dielectric resonator antenna (DRA) with multiple parasitic strips is presented in this paper. The problem is formulated using the Green's function approach, with the strip currents solved by using the method of moments. It is found that the strips can be used to tune the operating frequency of both the linearly polarized (LP) and circularly polarized (CP) DRAs. In designing the LP DRA, the parasitic strips are placed symmetrically in pairs to minimize cross-polarized radiation fields. For the CF DRA, however, the parasitic strips are asymmetric, with their parameters determined by using the Genetic Algorithm. Measurements were carried out to verify the calculations, and reasonable agreement between theory and experiment is obtained. [ABSTRACT FROM AUTHOR]

In this work, a new strategy for the design of microstrip filters with ultra-wide bandwidths is proposed. This is based on the combination of square-shaped complementary split-ring resonators (CSRRs) etched in the ground plane and grounded stubs. Coupling between adjacent resonators is achieved by means of λ/4 lines, acting as impedance inverters. To illustrate the potentiality of the approach, a prototype device with 90% fractional bandwidth has been designed for operation at C-band. The measured fractional bandwidth (87%), in-band losses (<1.3 dB), and out-of-band rejection (>30 dB), obtained on a device scaled down in frequency, point out the high performance achievable with this design methodology. Moreover, the first frequency parasitic (spurious) does not appear up to three times the central filter frequency. Due to the small dimensions, wide bandwidths, and compatibility with planar circuit technology, it is believed that the approach presented in this work can be of actual interest to the design of filters for ultra-wideband applications. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 46: 283–286, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20966 [ABSTRACT FROM AUTHOR]

The miniaturization of hairpin bandpass filters by employing two high-permittivity ceramic substrates (with respective dielectric constants of 9.7 and 20) are investigated. Microwave dielectric ceramics with high permittivity are commonly applied in several microwave communication components. With the advantages of compact size, high-permittivity ceramics can be used as the substrate for bandpass filters. Moreover, the fundamental characteristics of newly developed compact stepped-impedance hairpin resonators with parallel coupled lines have also been described and applied to the design of bandpass filters. In this paper, the designed mixed-coupled structures are simulated using an IE3D simulator. The responses of the fabricated filters using Al2O3 (ℇr = 9.7, Q × f = 350000 GHz) and MgNb2O6 (ℇr = 20, Q × f = 110000 GHz) ceramic substrates are designed at a center frequency of 2 GHz. The compact size and performance of this class of filters are demonstrated. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 45: 222–225, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20776 [ABSTRACT FROM AUTHOR]

A class of novel compact filters with quasi-hairpin structure using stepped-impedance resonators (SIRs) is presented. The SIR open stub is used as the loaded structure for the filter design with the merit of small size and sharp transition band (TB). Additionally, these filters achieve sharp TB for lowpass filters (LPFs) and improved selectivity for bandpass filters (BPFs) at 2.45 GHz. All of the filters retain the dimensions of the circuit by more than 60%, as compared to the conventional one. These filters are very useful for applications in wireless-communication systems. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 45: 251–255, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20787 [ABSTRACT FROM AUTHOR]

Capacitively coupled resonators with wide tuning range have been proposed in coplanar waveguide (CPW) technology, based on the concept of electromagnetic bandgaps (EBGs). By loading the resonator with shunt-connected varactor diodes, the phase velocity of the line and, hence, the resonant frequency of the structure can be electrically controlled. Due to the slow-wave effect related to the presence of the varactors, a certain level of miniaturization is also achieved. Moreover, the frequency-selective properties of EBGs are used to reject the first spurious frequency of the resonators. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 45: 229–232, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20779 [ABSTRACT FROM AUTHOR]

Advances in wireless systems have placed increased demands on high performance frequency control devices for operation into the microwave range. With spectrum crowding, high bandwidth requirements, miniaturization, and low cost requirements as a background, the thin film resonator technology has evolved into the mainstream of applications. This technology has been under development for over 40 years in one form or another, but it required significant advances in integrated circuit processing to reach microwave frequencies and practical manufacturing for high-volume applications. This paper will survey the development of the thin film resonator technology and describe the core elements that give rise to resonators and filters for today's high performance wireless applications. [ABSTRACT FROM AUTHOR]

An improved filter design of a dual-mode double-ring resonator with radial stub for ultra-wideband (UWB) applications is presented in this paper. Based on the double-ring resonator and adjusted voltage/current couplings, two radial stubs are added to the outer ring in order to construct the band-pass filter. The dual-mode double-ring resonator exhibits wideband responses, and the radial stubs enhance the bandwidth of the operating-frequency band. Thus, an alternative approach to improve the bandwidth of the conventional dual-mode double-ring resonator, is presented. The experimental and simulation results are given and discussed. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 44: 219–222, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20593 [ABSTRACT FROM AUTHOR]

In this paper, ring-resonator bandstop filters (BSFs) with three attenuation poles are designed and analyzed using a two-port ABCD matrix of the transmission-line model. The symmetrical geometry of the ring-type BSFs allows us to explain the resonance operation via even and odd modes. Moreover, perturbation elements are employed to control the attenuation poles and obtain good performances. In order to validate the analytic method, three different BSFs are built using the microstrip-ring resonator. The simulated and measured results are presented and compared with the theory over a wide frequency range. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 44: 114–118, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20562 [ABSTRACT FROM AUTHOR]

In this article, a novel and efficient approach for modeling radio-frequency microelectromechanical system (RF MEMS) resonators by using artificial neural network (ANN) modeling is presented. In the proposed methodology, the relationship between physical-input parameters and corresponding electrical-output parameters is obtained by combined circuit/full-wave/ANN modeling. More specifically, in order to predict the electrical responses from a resonator, an analytical representation of the electrical equivalent-network model (EENM) is developed from the well-known electromechanical analogs. Then, the reduced-order, nonlinear, dynamic macromodels from 3D finite-element method (FEM) simulations are generated to provide training, validating, and testing datasets for the ANN model. The developed ANN model provides an accurate prediction of an electrical response for various sets of driving parameters and it is suitable for integration with an RF/microwave circuit simulator. Although the proposed approach is demonstrated on a clamped-clamped (C-C) beam resonator, it can be readily adapted for the analysis of other micromechanical resonators. © 2004 Wiley Periodicals, Inc. Int J RF and Microwave CAE 14: 302–316, 2004. [ABSTRACT FROM AUTHOR]

This paper discusses a method used to design planar bandpass filters for millimeter-wave applications in U- and W-band frequency ranges. For technical reasons, these filters have to be implemented on silicon-based technology. So as to decrease the insertion losses levels inherent in silicon substrate, we propose a thin-film microstrip-like technology implemented on a benzocyclobutene layer. In addition, a dual-behavior resonator-based filter topology enabled us to fit a hardened specification. In association with this new topology, we employed an automated design procedure that combines both circuit and full-wave simulations. It is based on a statistical sensitivity study performed by design-of-experiment analysis. [ABSTRACT FROM AUTHOR]

A dynamical system of equations describing parametric sound generation (PSG) in a dispersive large aspect ratio resonator is derived. The model generalizes previously proposed descriptions of PSG by including diffraction effects and is analogous to the model used in theoretical studies of optical parametric oscillation. A linear stability analysis of the solution below the threshold of subharmonic generation reveals the existence of a pattern forming instability, which is confirmed by numerical integration. The conditions of emergence of periodic patterns in transverse space are discussed in the acoustical context. [ABSTRACT FROM AUTHOR]

This paper presents an analysis of the sensitivity of coupled resonator filters in which some direct couplings are missing. The effect of changes in the coupling coefficients and resonant frequencies of the resonators is investigated by directly computing the gradient of the scattering parameters. It is shown that structures that are modular in the input-to-output direction are much less sensitive than those with modularity in the orthogonal direction for the same frequency response. [ABSTRACT FROM AUTHOR]

In a one-wavelength ring resonator formed by a transmission line, there exist two orthogonal modes. In this paper, an excitation method for these orthogonal resonant modes is explained. In addition, the coupling between the orthogonal resonant modes, which is important for applications, is considered in detail. An analysis method is presented for the coupling factor between the modes, and the attenuation poles generated by the present configuration. Further, an analysis and an experimental investigation are carried out in the case where the open stub and the impedance step are used for configuration of coupling between the modes. The validity of the proposed analysis method is shown and the fundamental characteristics of filter synthesis are obtained. © 1999 Scripta Technica, Electron Comm Jpn Pt 2, 82(9): 19–28, 1999 [ABSTRACT FROM AUTHOR]

Proposes a novel technique for feeding microstrip antenna arrays. The H resonator; Experimental results on a subarray of four patches fed by an H feed; Generalization of the concept of large arrays; Conclusion of the study.

It is shown that VHF coaxial cavity resonators give higher unloaded Q for the same overall dimensions if the cross-section of the outer conductor is square rather than circular. Experimental results to confirm the theory are included. [ABSTRACT FROM AUTHOR]

A simple but efficient synthesis method of microstrip bandpass filters using particularly compact resonators is proposed. [ABSTRACT FROM AUTHOR]

Investigates different thickness shear mode resonators (TSMRs) with fundamental frequencies of 10 and 30 MHz and surface acoustic wave devices with fundamental frequencies of 80 and 433 MHz. Noise levels and signal-to-noise ratios; Influence of polymer film thickness; Influence of temperature on the transducer signal.

The radial line slot antenna (RLSA) is a thin planar antenna developed for satellite broadcast reception and has been introduced into general households. In the RLSA used at present, a coaxial probe is employed for feeding the antenna at the center. A circular polarization is realized by arranging the slots as radiating elements in a spiral fashion. An RLSA with concentric element arrangement has been proposed in which these radiating elements are arranged in a concentric manner for improving the efficiency. However, in order to arrange slots in a concentric manner, it is necessary to excite a rotating mode by a feed network. For this purpose, a resonant cavity with an electric wall type has been proposed and its effectiveness has been demonstrated. In this paper, as a feed circuit to excite a rotating mode, three magnetic wall-type feed networks are proposed: the step type, the patch-antenna type, and the dielectric-resonator type. By the analysis based on the mode-matching method, their characteristics are evaluated and compared. With respect to the patch-antenna type, the analytical results are confirmed by an experiment. © 1997 Scripta Technica, Inc. Electron Comm Jpn Pt 1, 80 (1): 78–88, 1997 [ABSTRACT FROM AUTHOR]

This paper discusses the phase regeneration characteristics of the three-mode oscillator with two-phase PSK signal injection composed of three resonators for the fundamental, second and third harmonics and a negative resistor. As the basic synchronization property of the oscillator, it is shown that two stable phase synchronization modes exist as follows. When the oscillators oscillates synchronously to the fundamental and the third harmonic frequencies, and the external signal with the frequency equal to the second harmonic is injected, synchronization takes place migrating among three frequencies with two stable phases. Then the phase regeneration of the oscillator for the injected phase-modulated signal is discussed. When the change of the input signal phase is small, the oscillator output phase tends to remain at the original stable phase. When, however, the input phase approaches the other stable phase, the output phase changes stepwise to the other stable phase. Thus, the output signal has the phase fixed to either of the two stable phases. Such a phase regeneration phenomenon is demonstrated by the numerical solution of the simplified equation of the amplitude and phase of the oscillator. Finally, a three-mode oscillator is constructed which oscillates at the fundamental frequency of 3.5 MHz. It is verified experimentally that the characteristics as analyzed by the theory are realized. [ABSTRACT FROM AUTHOR]

Resonator coupled filters can be designed and tuned in terms of the group delay of the reflection coefficient. This group delay is an effective way to measure the filter parameters and set them to the precise values to generate a specific response. The basic method was outlined previously, but this was restricted to in-line coupled resonators. In this paper, the method is expanded to include parallel and cross-coupled resonators, and the effect of finite Q of the resonator is analyzed in more detail. Finally, some comments on the meaning of the group delay measurement and the possibility of a negative delay are discussed. © 1998 John Wiley & Sons, Inc. Microwave Opt Technol Lett 18: 174–179, 1998. [ABSTRACT FROM AUTHOR]

A new analysis method for resonant characteristics that takes into account the effect from the external circuit on the whispering gallery (WG) mode dielectric disk resonator coupled electromagnetically with the external circuit is presented. The disk resonator is divided into the part not affected by the external circuit (uncoupled part) and the affected (coupled part). The variation of the phase constant in the coupled part is considered to alter the resonant frequency. In the analysis of the coupled part, the coupled transmission equation for the disk and the straight waveguide is solved approximately to obtain the distributed coupled characteristics. From the results, the equivalent circuit containing the coupled part is constructed and the resonant characteristics of the disk resonator are analyzed. In the numerical example, a rectangular dielectric waveguide is used as the external circuit, and the variation of the resonant frequency is computed as the gap between the disk resonator and the waveguide is varied. It is shown that the resonant frequency of the resonator can increase or decrease depending on the phase constant of the externally excited mode. Hence, useful data for accurate design are obtained for the WG mode dielectric resonator. © 1998 Scripta Technica. Electron Comm Jpn Pt 2, 80(11): 48–57, 1997 [ABSTRACT FROM AUTHOR]

Use of a shortened dipole with its element length fixed at the 80-MHz resonator length or a half-wavelength is studied for the site-attenuation measurement of the interference-wave measurement field. Since this shortened dipole antenna is specified as the standard antenna for interference wave measurement, the antenna factor and the impedance characteristics are investigated by numerical calculations and measurements. Next, in regard to the measurement of the site attenuation with this antenna, the theoretical values are derived by the method of moments. Further, actual measurement is carried out at three outdoor locations. It is confirmed that the obtained theoretical values agree well with the measured data. As a result, it is found that the theoretical values can be used sufficiently well as normalized values. Therefore, a measurement method of the site attenuation using a shortened dipole has been established. It is found that the use of the shortened dipole is better in terms of measurement error and labor than the conventional half-wave dipole in site attenuation measurements at these frequencies. © 1998 Scripta Technica. Electron Comm Jpn Pt 1, 81(8): 81–88, 1998 [ABSTRACT FROM AUTHOR]

A 60-GHz on-chip multimode bandpass filter (BPF) is implemented using a sandwich capacitor. The proposed loaded sandwich capacitor shows functions of multimode perturbation and stopband control in the BPF design. An additional magnetic coupling path from the source to the load is introduced to generate two extra zeros. Thus the quasi-elliptical filter response is achieved. The proposed filter implemented with a commercial SiGe BiCMOS process demonstrates a low insertion loss of 4 dB and compact size of only 0.16 mm^2. [ABSTRACT FROM PUBLISHER]

Commercial electron spin resonance spectroscopy and imaging systems make use of the so-called 'induction' or 'Faraday' detection, which is based on a radio frequency coil or a microwave resonator. The sensitivity of induction detection does not exceed ∼3 × 108 spins/[Square_Root]Hz. Here we show that through the use of a new type of surface loop-gap microresonators (inner size of 20 μm), operating at cryogenic temperatures at a field of 0.5 T, one can improve upon this sensitivity barrier by more than 2 orders of magnitude and reach spin sensitivities of ∼1.5 × 106 spins/[Square_Root]Hz or ∼2.5 × 104 spins for 1 h. [ABSTRACT FROM AUTHOR]

A novel semi-circle-shaped aperture ultra-wideband (UWB) antenna with triple band-notched characteristics is proposed. The band notches are realised by etching one complementary split-ring resonator inside a circular exciting stub on the front side, employing a interrogation-shaped defected ground structure in each side of the ground plane as well as symmetrically adding a pair of open-circuit stubs at the edge of the slot, and tri-band rejected filtering properties in the WiMAX/WLAN are achieved. Experimental results show that the designed antenna, with compact size of 24×30 mm2, has an impedance bandwidth of 2.6-12 GHz for VSWR less than 2, except three freqency stop-bands of 3.3-4, 5.15-5.4, and 5.8-6.1 GHz. Moreover, the antenna has good omnidirectional radiation patterns in the H-plane. [ABSTRACT FROM AUTHOR]

A compact elliptic function lowpass filter using a stepped impedance hairpin resonator is proposed. The filter has the advantages of compact size, low insertion loss, easy fabrication, a wide stopband, and sharp cutoff frequency response. In order to cause a sharp cutoff frequency response and the wide stopband suppression, a coupled stepped impedance resonator is taken into consideration for the newly proposed lowpass filter. A demonstration filter has been designed, fabricated and tested, and the results agree well with the theory. The size of the filter is less than 0.037λg×0.093λg, where λg is the waveguide length at the cutoff frequency 1.5 GHz, and the 10 dB rejection stopband can be extended to more than 15 GHz. The filter is useful for many microwave system applications. [ABSTRACT FROM AUTHOR]

In this article, several square open-loop resonators with transmission lines are proposed to design the optimized bandpass filters. A compact microstrip filter using an open-loop resonator was designed, fabricated and measured. At the center frequency f0 = 1.80 GHz, a 3-dB bandwidth of 5% can be varied from 1.76 to 1.85 GHz. The filter shows a maximum insertion loss in passband of 0.1 dB. A transmission zero is realized at about 3.1 GHz, and the attenuation at this frequency exceeds 70 dB. When compared with the conventional filters using coupled square open-loop resonators, the proposed filter has a size reduction of 30%. Good agreement between measurements and simulations are obtained. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2755–2757, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22837 [ABSTRACT FROM AUTHOR]

We present results for a compact, multiple gap and multiple pass band microstrip resonator filter. The microstrip resonator filter, consisting of a sandwich substrate with a metallic fractal pattern, shows multiple gaps from 40 MHz to 10 GHz. The transmission characteristics of the microstrip resonator filter show multiple pass bands and stop bands for electromagnetic waves over the microwave frequency range. Experimental observations are in good agreement with the results of finite difference time domain (FDTD) simulations. These properties can be useful in the application in compact microwave circuits, microwave filters, and microwave switches. [ABSTRACT FROM AUTHOR]

A new planar slotted-patch resonator is proposed for RF and microwave bandpass filter design. The novelty of the proposed resonator is that it can reduce the size of the filter significantly. It is found that the resonant frequency of the resonator is reduced (for example, by 61%). A dual-mode filter operating at 2.39 GHz with 1.7% bandwidth and a three-pole bandpass filter operating at 2.375 GHz with 8.8% bandwidth are designed and fabricated. The measured results agree very well with the full-wave EM simulation. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 1110–1112, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21557 [ABSTRACT FROM AUTHOR]

This paper presents a diplexer with good isolation constructed by two high-selectivity bandpass filters. The high-selectivity filter is designed by an asymmetrically fed structure that shows two transmission zeros next to the passband of the filter. By using a simple equation, the locations of the transmission zeros are designed at the passbands of the filters in order to filter out unwanted signals and obtain good isolation for the diplexer. The insertion loss of the diplexer is less than 2.2 dB and the isolation is greater than 41 dB. This high-performance diplexer can be used in many wireless communication systems. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 44: 396–398, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20647 [ABSTRACT FROM AUTHOR]

A novel dual-mode uniplanar square slot-loop resonator, using an inset-coupling mechanism with capacitive gaps is proposed. The mode splitting of the uniplanar resonator is described with respect to the perturbation size. A dual-mode uniplanar filter using such a resonator is designed and fabricated with 5% bandwidth at the center frequency of 2.97 GHz for demonstration. The measured filter performance is presented. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 41: 481–483, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20178 [ABSTRACT FROM AUTHOR]

A ridged-waveguide diplexer incorporating integrated compact ridged-waveguide filters and a ridged-waveguide T-junction is presented. The compact size of the filter is achieved by integrating a bandpass periodic filter, and a low-pass structure is used in order to suppress spurious responses. Simulation using the mode-matching method has been carried out for ridged-waveguide filters and T junctions and the results are presented. The measured results are in good agreement with the simulated results. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 41: 465–467, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20173 [ABSTRACT FROM AUTHOR]

A new kind of planar inverted F antenna (PIFA) is presented. To reduce the size of the structure, the resonator has been curled under itself. A capacitive load is added to decrease the frequencies of higher resonances. The result is the achievement of a dual-band antenna. Theoretical results are computed by the software design package IE3D. The effects of various physical parameters are presented and discussed. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 38: 40–42, 2003 [ABSTRACT FROM AUTHOR]