Dielectric constant characterization using a numerical method for the microstrip ring resonator

A new method of dielectric-constant measurement is developed. The dielectric constant epsilon(r) RF/microwave substrate is extracted by combining the microstrip ring resonator measurement with Ansoft HFSS electromagnetic simulation software. The developed method has two advantages: (i) characterization of dielectric constant versus multiple frequency points, and (ii) compatibility with electronics design automation (EDA) software tools. This characterization method can reduce the design cycle of microwave circuits and devices. (C) 2004 Wiley Periodicals, Inc.

Helical resonator filters with improved power handling capabilities for space applications

The power-handling capabilities of helical resonator filters for space applications are discussed. Emerging difficulties due to the multipaction effects are highlighted. A method is proposed to increase specified power handling without significantly sacrificing the size/quality factor. Experimental verification is attained by means of a fabricated prototype for which measured filter response and multipaction test results are obtained and presented.

Inline Interdigital Pseudo-Elliptic Helical Resonator Filters

A new inline coupling topology for narrowband helical resonator filters is proposed that allows to introduce selectively located transmission zeros (TZs) in the stopband. We show that a pair of helical resonators arranged in an interdigital configuration can realize a large range of in-band coupling coefficient values and also selectively position a TZ in the stopband. The proposed technique dispenses the need for auxiliary elements, so that the size, complexity, power handling and insertion loss of the filter are not compromised. A second order prototype filter with dimensions of the order of 0.05 lambda, power handling capability up to 90 W, measured insertion loss of 0.18 dB and improved selectivity is presented.

Nonlinearity and nonclassicality in a nanomechanical resonator

We address quantitatively the relationship between the nonlinearity of a mechanical resonator and the nonclassicality of its ground state. In particular, we analyze the nonclassical properties of the nonlinear Duffing oscillator (being driven or not) as a paradigmatic example of a nonlinear nanomechanical resonator. We first discuss how to quantify the nonlinearity of this system and then show that the nonclassicality of the ground state, as measured by the volume occupied by the negative part of the Wigner function, monotonically increases with the nonlinearity in all the working regimes addressed in our study. Our results show quantitatively that nonlinearity is a resource to create nonclassical states in mechanical systems.

Variable centre frequency resonator based bandpass Σ-Δ modulator

A novel resonator-based bandpass Σ-Δ modulator with an in-built variable centre frequency feature is presented. This structure is designed by analytically determining and subsequently verifying through behavioural level simulations the necessary compensation hardware to be placed in the feedback to ensure stability and good dynamic range performance.

Tunable centre frequency resonator based bandpass Σ-Δ modulators

This paper presents a methodology for the design of oversampled narrow-band single-loop and multi-stage resonator-based bandpass Σ-Δ modulators that can accommodate different passband centre to sampling frequency ratios. These tunable bandpass configurations are designed by analytically determining the required compensation hardware to deliver good resolution. Thorough simulations demonstrate that comparatively superior in-band signal-to-noise ratios (SNRs) and dynamic ranges (DRs) are attributed to the inclusion of appropriate feedforward and feedback compensators within these structures.

Effective-fourth-order resonator based MASH bandpass sigma-delta modulators

Two novel effective-fourth-order (eighth-order) resonator based MASH (MultistAge noise SHaping) bandpass Σ-Δ modulators are introduced at the behavioural level and subsequently examined by simulations utilising the ALTA SPW environment. The considered bandpass configurations have in their loop filter a cascade of standard second-order resonator structures in order to achieve appropriate noise shaping. The quantisation noise in each stage is suppressed by feeding the error of each section into the input of the following stage. It is demonstrated in this paper that the quadruple effective-first-order cascade configuration has significantly better performance as well as conforming more closely with theory in comparison with the effective-second-order effective-second-order cascade. The superior performance of the former can be attributed to the cumulative effect of the multi-bit outputs as well as the presence of more notch filters.

Broadband Cylindrical Dielectric Resonator Antenna Excited by Modified Microstrip Line

The impedance bandwidth of a high permittivity cylindrical dielectric resonator antenna excited by a micro strip line was significantly improved by modifying the feed geometry. The 10 dB return loss bandwidth is enhanced from 12 to 26% without much affecting the gain and other radiation properties of the antenna. Good agreement has been observed between the predicted and measured results

Dielecting-resonator-loaded microstrip antenna for enhanced impedance bandwidth and efficiency

A new method for enhancing the 2.1 VSWR impedance bandwidth of microstrip antennas is presented. Bandwidth enhancement is achieved by loading the microstrip antenna by a ceramic microwave dielectric resonator (DR). The validity of this technique has been established using rectangular and circular radiating geometries. This method improves the bandwidth of a rectangular microstrip antenna to more than 10% (= 5 times that of a conventional rectangular microstrip antenna) with an enhanced gain of I dB

Excitation of low-profile equilateral-triangular dielectric resonator antenna using a conducting conformal strip

A new configuration that employs a conducting conformal strip to excite the low-profile equilaterial-triangular dielectric resonator antenna (DRA) of very high permittivity is proposed. As compared with the previous aperture-coupling configuration, the new configuration has a wider impedance bandwidth (- 5.5%) and a higher front-to-back radiation ratio. The return loss, radiation patterns, and antenna gain are measured and discussed

A Microstrip Patch Resonator with a Via Connecting Ground Plane

patch resonator with a via connecting ground plane is proposed and studied experimentally. The resonant frequency of this patch resonator is tunable up to about 34 % by adjusting the via position in the center line. The lowest resonant frequency of this patch resonator has been reduced by more than 64% of the same size patch resonator

A compact very-high-permittivity dielectric-eye resonator antenna for multiband wireless applications

very-high-permittivity (e, = 100) multiband dielectrice> e resonator antenna is presented. The compact antenna, excited by a m:'crostrip line, resonates at two frequencies centered around the 1.9- GHz and 2.4-GHz bands with identical polarization . The behavior of the antenna at different positions along the feed line is studied and optimized. Multiple resonances with the same polarization and broad radioticn patterns suggest the suitability of the antenna for multiband wireless application

Characteristics of a Microstrip-Excited High-Permittivity Tectangular Dielectric Resonator Antenna

The radiation characteristics of a microstrip-line-excited rectangular dielectric resonator antenna (DRA) are studied experimentally.The radiation charactristics and excitation of different modes are highly influenced by the orientation of the DR,feed line parameters ,and finite size of the ground plane