Microwave voltage tuned microstrip ring resonator oscillator

A microwave oscillator incorporating a varactor-tuned microstrip ring resonator was developed using a single packaged varactor diode which together with other required components was mounted inside the ring structure. A tuning bandwidth of ~30% was achieved with forward and reverse biasing of the varactor diode. The measured phase noise of the new oscillator was found to be better than -90 dBc kHz from the carrier     

Compact DGS resonator with improvement of Q-factor

A new design of a compact two-layer bandstop filter using a defected ground structure (DGS) resonator with a parasitic stub is proposed. The proposed filter is composed of a H-slot DGS resonator located on the two stacked layer and a stub placed on the bottom layer. The parasitic stub modelled as an additional capacitance increases the effective capacitance of the resonator and lowers the resonance frequency. In addition, the rejection bandwidth is decreased and the quality (Q)-factor is also improved owing to enhancement of the stored energy in the resonator.     

Capacitively loaded microstrip loop resonator

A novel capacitively loaded microstrip loop resonator has been developed. It has been shown theoretically and experimentally that the novel resonator has not only a smaller size, but also a higher Q factor as compared with the conventional half-wavelength resonator     

Dynamic permittivity of microstrip ring resonator

A simplified method for calculation of the dynamic dielectric constant for a microstrip ring resonator is presented. Attention is also given to the sectors of the annular structure. The new results are compared with earlier work.     

Accurate conductor Q-factor of dielectric resonator placed in anMIC environment

The unloaded Q-factor of a dielectric resonator is degraded due to conductor loss when it is placed in an MIC environment. The authors report approximate but quite accurate closed form expressions for the Q-factor due to conductor loss. The results obtained are in good agreement with those of rigorous numerical methods. The effect of geometrical parameters on the useful tuning range of the structure is studied. Finally, an explicit relationship between the resonant frequency sensitivity factors and the conductor Q-factor is derived     

Josephson-Junction driven submillimeter wave microstrip resonator

A microstrip resonator driven by a resistively shunted Josephson junction has been used for submillimeter-wave surface resistance measurements to about 400 GHz. A simple, analytical analysis of the resonator-induced structure in the junction's I-V characteristic gives the resonator surface resistance in the range of 2-160 mΩ with an accuracy of better than 30%     

A modified microstrip circular patch resonator filter

Circular holes are etched off a microstrip disk resonator. This results in a size reduction of 30%. By offsetting the positions of some of these holes, a degenerate orthogonal mode is excited, resulting in a split-mode bandpass filter. This filter can be considered as a lattice-type structure. A filter with a bandwidth of 8% centered at 2.0 GHz was designed. The measured insertion loss is 0.6 dB     

Magnetically tunable microstrip resonator based on polycrystallineferrite

A conventional microstrip ring resonator consisting of a polycrystalline ferrite substrate is demonstrated. This resonator produces improved tunability compared with other available versions. Resonators with tunability approaching 31% at a minimum insertion loss of 11.17 dB in a magnetic field of 3 kG applied longitudinally along wave propagation have been demonstrated using LiZiTi ferrite composition. Tunability of 31% is the best reported for any tunable structure     

Directly coupled multiple resonator wide-band microstrip antennas

Three new configurations for increasing the impedance bandwidth of the microstrip patch antennas are described. In these configurations, additional resonators are directly coupled through short sections of microstrip line to the radiating edges, nonradiating edges, and all the four edges of the rectangular patch antennas, respectively. Green's function approach and segmentation method are used for the analysis. The experimental results are in reasonable agreement with the analysis and impedance bandwidths of 548 MHz, 605 MHz, and 810 MHz are obtained for these three configurations, respectively inS-band (substrate thickness = 0.318 cm andepsilon_{r} = 2.55). The variation in the radiation pattern over this impedance bandwidth is discussed.     

Simple resonator method for measuring dispersion of microstrip

The method uses the resonant frequencies of a simple straight microstrip resonator, short-circuited at both ends. It is excited by passing a current through one of the short circuits. Graphs of effective relative permittivity against frequency are given for resonators on alumina and quartz substrates, with an error of within only ±0.1%.     

Microwave performance of nonlinear optoelectronic microstrip ring resonator

Difference and sum frequency generation at frequencies from 0 to 14 GHz has been obtained by mixing of a microwave local oscillator and a modulated optical carrier in a microstrip ring resonator with Schottky contacts on a semi-insulating GaAs substrate.<>     

Compact superconducting dual-log spiral resonator with high Q-factor and low power dependence

A new dual-log spiral geometry is proposed for microstrip resonators, offering substantial advantages in performance and size reduction at subgigahertz frequencies when realized in superconducting materials. The spiral is logarithmic in line spacing and width such that the width of the spiral line increases smoothly with the increase of the current density, reaching its maximum where the current density is maximum (in its center for /spl lambda//2 resonators). Preliminary results of such a logarithmic ten-turn (2 /spl times/ 5 turns) spiral, realized with double-sided YBCO thin film, showed a Q.-factor seven times higher than that of a single ten-turn uniform spiral made of YBCO thin film and 64 times higher than a copper counterpart. The insertion loss of the YBCO dual log-spiral has a high degree of independence of the input power in comparison with a uniform Archimedian spiral, increasing by only 2.5% for a 30-dBm increase of the input power, compared with nearly 31% for the uniform spiral. A simple approximate method, developed for prediction of the resonant frequency of the new resonators, shows a good agreement with the test results.     

Electronically tunable ring resonator microstrip and suspended-substrate filters

Electronically tunable ring resonator microstrip and suspended substrate microwave filters with high tuning speed are presented. The filters are realised using two coupled ring resonators with GaAs varactors as the tuning elements. Computer optimised circuits are used at the input and the output to obtain better than 10 dB return loss across the tuning band. Tuning ranges of 1.075-2.25 GHz for the microstrip filter and 1.35-2.075 GHz for the narrower suspended substrate filter are predicted by computer simulation.<>     

Q-factor computation of radiation loss corresponding to surfacewave in a patch circular resonator

The authors present a new approach for the Q-factor computation of radiation loss in a circular patch with surface wave TM₀. The circular patch resonant frequency (f) problem is formulated in terms of an integral equation using the transverse resonance method. First, the computed real part of f is found to compare closely with the published results considering space wave TM₁₁. Next, the Q-factor of the surface wave as a function of physical resonator parameters is presented     

Superconducting microstrip resonator with yttrium iron garnetsingle crystals

A magnetically tunable microstrip superconducting resonator using an yttrium-iron-garnet (YIG) single crystal was demonstrated experimentally. Tunability of 200 MHz at a center frequency of 5.3 GHz was observed, and a quality factor of 965 with minimum insertion loss of 19.5 dB was measured for a half-wavelength microstrip line consisting of a YIG-YBCO-MgO composite structure. The dispersion relation of the resonator was analyzed using the spectral-domain method and discussed with experimental results on the mixed states of TEM and magnetostatic-wave modes. Power dependence of the characteristics is also discussed     

Dual-band microstrip bandstop filter using dual-mode loop resonator

A dual-band bandstop filter (DBBSF) with a dual-mode loop resonator is presented. In order to allow the DBBSF to exhibit high skirt selectivity and to generate a wide rejection bandwidth a capacitive coupled-line section is introduced. By properly controlling the length of the coupled-line section and the cross-coupled capacitor, more than two finite transmission zeros were inserted at the stopband and enhanced the rejection bandwidth.     

Experimental investigation of microwave-optoelectronic interactionsin a microstrip ring resonator

Microwave optoelectronic mixing on a semi-insulating gallium arsenide substrate performed by monolithically integrating Schottky diode photodetectors into a microstrip ring resonator is discussed. When operated in the resistive mixing mode, a low frequency difference signal is extracted from the bias pad of the circuit. In the parametric mode, both degenerate and non-degenerate parametric amplification of an optical carrier signal takes place. The circuit shows good potential for application in wide-band fiberoptic systems     

Dual-mode microstrip bandpass filter using ring of arrows resonator

A dual-mode microstrip bandpass filter using the degenerate modes of a modified square ring structure is proposed. The size of the new structure is 50% less than conventional dual-mode bandpass microstrip square resonator filters at the same centre frequency. Measurements are in good agreement with designed values.     

Resonant frequency of an air gap tuned circular disc microstrip antenna

In this study, the formulation and the computation of the resonant frequency of an air gap tuned circular disc microstrip antenna are simplified, with improved accuracy, by using a new and very simple effective permittivity expression which is valid for thin and thick gaps. Very good agreement between the theoretical and the experimental resonant frequency values is obtained for the various structural parameters and operational modes.     

Aperture-backed microstrip stepped impedance resonator with ultra-broad rejection bandwidth

An improved microstrip stepped impedance resonator (SIR) with backed aperture is developed for the purpose of effective suppression of multiple spurious resonances. By backing the aperture at the centre and widening the strip widths at two sides, this novel SIR with miniaturised size achieves the ultra-broad rejection bandwidth of 4.0 to 17.6 GHz, as exhibited in the simulated and measured results.