Xiang-Zheng Xiong

A Dual-Wideband Bandpass Filter Based on E-Shaped Microstrip Sir with Improved Upper-Stopband Performance

A novel dual-wideband microstrip bandpass fllter (BPF) with improved upper-stopband performance is presented. With the use of some special structures such as E-shaped microstrip Stepped- Impedance Resonator (SIR) and input-output cross-coupling feed structure, this fllter can generate flve transmission zeros which are beneflcial for improving its frequency selectivity and upper-stopband performance. Finally the microstrip dual-wideband BPF has been simulated, fabricated and measured. Measurement results show that the two passbands are centered at 3.7GHz and 5.8GHz with the fractional bandwidth of 31% and 13% respectively. Meanwhile more than 50% relative upper-stopband bandwidth with 20dB rejection has been realized. The simulated and measured results are in good agreement.

THE FINE-GRAINED PARALLEL MICRO-GENETIC ALGORITHM AND ITS APPLICATION TO BROADBAND CONICAL CORRUGATED-HORN ANTENNA

The flne-grained parallel micro-genetic algorithm (FGP- MGA) is developed to solve antenna design problems. The synthesis of uniformly exited unequally spaced array is presented. Comparison with the micro-genetic algorithm (MGA) has been carried out. It is seen that the FGPMGA signiflcantly outperforms MGA, in terms of both the convergence rate and exploration ability. The FGPMGA can also reduce the optimization time. Then the FGPMGA and the body of revolution flnite-difierence time-domain (BOR-FDTD) are combined to achieve an automated design process for conical corrugated-horn antenna. Numerical simulation results show that the horn antenna has good impedance matching (the VSWR is less than 1.5), stable beamwidth and gain, as well as good rotation symmetry patterns over the whole band 8»13GHz.

DESIGN FILTERS USING TUNABLE E-SHAPED DUAL- MODE RESONATORS FOR LOWER-ULTRA-WIDEBAND AND UPPER-ULTRA-WIDEBAND APPLICATIONS

Two ultra-wideband (UWB) microstrip bandpass fllters (BPFs) are proposed by using tunable E-shaped dual-mode microstrip Stepped-Impedance Resonator (SIR). For the lower band fllter measurement results show there is a passband of 3.1GHz to 5.2GHz and its 3dB fractional bandwidth is 51%. The UWB upper band fllter may be obtained by tuning E-shaped SIR. The measurement results show there is a passband of 6GHz to 10.6GHz and its 3dB fractional bandwidth is 55%. Compared with the similar investigation using the cascade of electromagnetic band gap (EBG)-embedded multiple-mode resonator (MMR) and fork resonator, the proposed approach has some advantages, such as easier adjustment of bandwidths, better passband performances and smaller size etc..

Design of dual-mode dual-band bandpass filters with controllable frequencies for multimode wireless communication applications

A flexible approach for designing dual-mode dual-band bandpass filters with controllable passband frequencies is presented. Two dual-mode dual-band bandpass filters are proposed for experimental verification. The first filter, whose two passbands are centered at 3.4 and 5.5 GHz with the corresponding fractional bandwidth of 19 and 13%, respectively, is suitable for the applications of worldwide interoperability for microwave access (WiMAX) and wireless local area network. The second filter, whose two passbands are centered at 4 and 7.4 GHz with the corresponding fractional bandwidth of 25 and 13%, respectively, is suitable for the downlink of C-band and X-band satellite communication systems. Both filters have been designed, fabricated, and measured. The measured results show good agreements with those of the simulation.

Design Dual-Mode Bandpass Filters Based on Symmetrical T-Shaped Stub-Loaded Stepped-Impedance Resonators with High Frequencies Selectivity

A novel approach for designing planar dual-mode bandpass fllters using symmetrical T-shaped stub-loaded stepped- impedance resonators (TSLSIRs) with high frequencies selectivity is presented. The proposed symmetrical TSLSIR structure is mainly composed of three elements, i.e., a stepped-impedance resonator (SIR), and two T-shaped stubs which symmetrically loaded at the middle sections of the SIR. Two dual-mode bandpass fllters based on TSLSIRs with high frequency selectivity are proposed for experimental veriflcation. Firstly, a dual-mode single passband fllter with two transmission zeros located at the both sides of passband is presented, whose passband is centered at 5.23GHz with the fractional bandwidth of 10.1%, and a wide upper-stopband with harmonic suppression better than 20dB in the range of 5.9GHz to 12.9GHz is achieved. Secondly, a dual-mode dual-band bandpass fllter with four transmission zeros located at the both sides of the two passbands is presented, whose two passbands are centered at 3.4GHz and 4.54GHz with the corresponding fractional bandwidth of 8.4% and 7.5% respectively, and the spurious frequencies from 4.9GHz to 8.45GHz are successfully suppressed to the level of lower than i20dB. Both fllters have been designed, fabricated and measured. The measured results show good agreements with those of the simulation.

A compact microstrip wideband bandpass filter with excellent out-band performance

A compact microstrip wideband bandpass filter (BPF) using Stepper-Impedance Resonator with wide stopband is presented. In addition, a input-output cross-coupling was introduced which generated a pairs of attenuation poles at each side of the passband. A wideband microstrip BPF has been designed, fabricated, and measured. The measured filter has a 3 dB fractional bandwidth of 50% with a minimum passband IL of 0.52 dB at 3.71GHz and a maximum group delay variation of 0.48 ns, respectively. The filter has the advantages of extremely sharp rejection skirts, wide bandwidth, low passband insertion loss (IL), low group delay variation and ease of fabrication.

An optimised calibration method of six-port reflectometer

A developed calibration method of six-port junction is proposed, in which a dual-tone technique is used to produce multi-samples and more accurate results are achieved by use of the least-square method and excluding those samples which may cause bigger errors. A 0.9 ~5 GHz MIC six-port reflectometer was constructed and the Engens robust calibration procedure was used for comparison. Eight test samples were used in the measurement. For Engens calibration procedure, the difference between the HP8510 and the six port reflectrometer is in the order of 0.3 dB/1.6deg for most cases, but at the boundary frequencies the biggest differences are 0.65 dB/2.6deg; while this method give the difference range between the HP8510 is less than 0.1 dB/1deg for most cases and a biggest error of 0.35 dB/1.7deg for boundary frequencies. This method can apparently increase the measure accuracy especially at the boundary frequencies of six-port junction.

Comparison Study on Single-layered and Double-layered Differential Symmetric Circular Spiral Inductors

Based on the Ansoft 3D electromagnetic field software HFSS and the typical lumped equivalent-circuit model of spiral inductors on silicon (SIOS) for RF integrated circuits (RFICs), the comparison study of single-layered and double-layered differential symmetric circular spiral inductors has been given. The numerical analyses showed that the former can give better results of quality factor (QF) and self-resonant frequency (SRF) and the L value of the former can satisfied the nH level requirements where the Q factor obtains its highest value. Experimental results showed that the former can gives a 50.5% increase for the maximum Q value and 164.5% increase for the SRF whereas the latter can supply over 3 times larger L value. The simulation results have good agreements with the theoretical analyses. At last the design guidelines were given according to the simulation and experimental results.

Design of microstrip tapped-hairpin dual-band pass filter for Ku-band application

This paper presents the design and analysis of a microstrip tapped-hairpin dual bandpass filter for Ku-band application. A new method for designing a dual bandpass filter with typical hairpin structure has been proposed. By adjusting the tapped positions and distances between two hairpin resonators, a dual bandpass filter is obtained. The designed dual bandpass filter operates at 13.3GHz and 14.7GHz. The result from simulation shows that the filter operates at the desired specification. In the passbands, S21 is above −1dB, S11 is blow −20dB.

Researchment and design of CMOS low noise amplifier in UHF band

To overcome difficulties among power, noise figure(NF) and match in the design of low-noise amplifier(LNA), a novel approach that can realize effective compromise among them is presented through analyzing the cascade LNA configuration. Under the premise that power can be accepted, the new approach can be achieved by adopting series inductors in input port, adding capacitors between gate and source nodes and appending series inductor-resistance to the output port. Experimental results show that, with the proposed approach, a 0.18 mum CMOS LNA at 2.4 GHz could provide a maximum NF of 0.46 dB, a minimum power gain of 22 dB in 3 dB bandwidth, input and output VSWRs which are better than 1.12, the output P1dB power of 1.07 dBm and 25.02 mW whole power consume. Theory analysis agrees well with the simulation results.