Xiaochuan Zhang

Novel Band-Pass Substrate Integrated Waveguide (SIW) Filter Based on Complementary Split Ring Resonators (CSRRs)

A novel band-pass Substrate Integrated Waveguide (SIW) filter based on Complementary Split ring Resonators (CSRRs) is presented in this work. Three different CSRRs cells are etched in the top plane of the SIW for transmission zero control. A demonstration band-pass filter is designed, fabricated and measured. It agreed with the simulated results well.

Design of Microstrip Dual-Mode Filters Based on Source-Load Coupling

In this letter, a novel circular open-loop resonator is presented. The field patterns of this type of dual-mode resonator are investigated using full-wave electromagnetic simulations. The applications of the dual-mode resonator as bandpass filters are proposed. A coupling and routing scheme is presented to model the operations of these filters. Advantages of using this type of filter are not only its low insertion loss, but also its controllable transmission zeros. Both simulated and measured results are presented.

Improved Extraction of Coupling Matrix and Unloaded Q from S-Parameters of Lossy Resonator Filters

Abstract—This paper presents a two-stage optimization method for accurately extracting the coupling matrix (CM) and the unloaded quality factor (unloaded Q) of each resonator from the measured (or simulated) S-parameters of lossy cross-coupled resonator bandpass filters. The method can be used in computer-aided tuning (CAT) of microwave filters to accelerate filter design and physical realization. In our method, the Cauchy method is employed for determining characteristic polynomials of the S-parameters in the normalized lowpass frequency domain, and the CM and unloaded Q are extracted by two-stage optimization method using genetic algorithm. With respect to the previous methods available in the literatures, the proposed method allows the CM extraction of the filter with sourceload coupling. Moreover, the accuracy and robustness of the method can be improved due to the usage of the second stage optimization. The proposed method is applied to the diagnosis of a general coupled resonator filter with/without source-load coupling.

Microstrip Wide Band-pass Filter Based on Substrate Integrated Waveguide (SIW)

A novel microstrip wide band-pass filter using the substrate integrated waveguide (SIW) technique (K. Wu et al., 2003) is described in this paper. The SIW is one of alternatives for packaging the microwave components on the same substrate. The filter exhibits 52.7% bandwidth (6.67 GHz-11.45 GHz in the center frequency 9.06 GHz) for -10.2 dB return loss and 2.3 dB insertion loss in the pass-band. The proposed filter has a compact size and it is suitable for designing microwave and millimeter-wave circuits.

Design of Quasi-Elliptic Bandpass Filter Based on Slow-Wave Open-Loop Resonators

A microstrip bandpass filter implemented with slow-wave open-loop resonators is described in this letter. The slow-wave open-loop resonators make the filter compact and allow implementation of positive and negative inter-resonator couplings. Implementation of the positive and negative couplings is used to introduce a pair of finite frequency transmission-zeros in the filter response. The two zeros are designed to be close to the passband, thus improving the selectivity of the filter. As an example, a quasi-elliptic filter is fabricated. The quasi-elliptic filter has a compact dimension of 22.1 mm × 21.16 mm, which is approximately 0.1705λg × 0.1634λ g . The experimental results are demonstrated and discussed.

Compact ultra-wide stopband lowpass filter using transformed stepped impedance hairpin resonator

A compact microstrip lowpass filter (LPF) with ultra-wide stopband using transformed stepped impedance hairpin resonator is proposed. The transformed resonator consists of a stepped impedance hairpin resonator and an embedded hexagon stub loaded coupled-line structure. Without enlarging the size, the embedded structure is introduced to get a broad stopband. A prototype LPF has been simulated, fabricated and measured, and the measurements are in good agreement with simulations. The implemented lowpass filter exhibits an ultra-wide stopband up to 12.01fc with a rejection level of 14 dB. In addition, the proposed filter features a size of 0.071λg× 0.103λg, where λg is the waveguide length at the cutoff frequency 1.45 GHz.

Numerical simulation on electromagnetic properties of the solid rocket plume affected by the environmental pressure

The effect of environmental pressure of reflection and transmission coefficients of the solid rocket plume at 2000K region is studied by using the propagation matrix method. The complex relative permittivity of dusty plasma, the concept of charging response factor and the propagation matrix method are introduced in this paper. The change of environment pressure will induce variation in the electron concentration, collision frequency between electrons and molecules, as well as charging frequency of electrons in rocket plume. As a result, the changes will influence the complex relative permittivity of the rocket plume which in fact is the weakly ionized dust plasma. Numerical results show that the pressure decreases, the reflection coefficient and the transmission coefficient decrease with the increase of flight height. The transmission signal is reduced, the theoretical results and experimental observations are consistent.

Investigation of material parameters and SAR distribution in human tissue using FDTD method

This paper firstly introduces elementary knowledge of bio-electromagnetic dose, and then elaborates on the method and steps of theoretical bio-electromagnetic dose used to compute the electromagnetic dose absorbed by human body at the frequency 300MHz and 3GHz. Afterwards, the finite-difference time-domain (FDTD) method is utilized to analyze the dielectric property and calculate the specific absorption rate (SAR) in several biological organizations of human body and the results produced from this calculating process are compared with proven conclusions. The method and implementation steps used in this article suits for computing dielectric property of multi-layered biological tissue under the irradiation of arbitrary frequency electromagnetic wave. Therefore, the analysis method can lay quantitative foundation of research on the bio-effects of electromagnetic waves, on the mechanism of the bio-effect, on application of the bio-effects, and on the formulation for safety standard of electromagnetic wave radiation.

Design of Wilkinson power divider with filtering response and controllable transmission zeros

A kind of Wilkinson power divider with bandpass filtering response is presented in this letter. In the proposed power divider, two bandpass filters are used to substitute two quarter-wavelength transformer in a conventional Wilkinson power divider. This kind of Wilkinson power divider has two transmission zeros out of the passband. One transmission zero is created by the dual mode resonator intrinsic characteristics. The other is introduced by the source-load coupling. Different transmission zeros could be achieved by changing the dimension of the dual mode resonator or the source-loading coupling. Two experimental circuits are fabricated by the traditional printed circuit board technology. The measured and simulated results are in good agreement.

Compact Half-Mode Substrate Integrated Waveguide (HMSIW) Filter with Dual-Mode Microstrip Resonator

Abstract—A novel fourth-order half-mode substrate integrated waveguide (HMSIW) filter with dual-mode microstrip resonator is presented. The dual-mode resonator is etched on the top metal layer of HMSIW cavity, so the size can be reduced greatly. The filter has compact size and wide stopband in comparison with conventional SIW filters. Microstrip resonators and cavity resonators are integrated in one filter to achieve the goal of smaller size and better performance. Two filter samples are designed and fabricated, with good agreement between the measured and the simulated S-parameters.