Yong-Jiu Zhao

A COMPACT UWB HMSIW BANDPASS FILTER BASED ON COMPLEMENTARY SPLIT-RING RESONATORS

A novel complementary split ring resonators (CSRR) is applied to realize a compact Ultra-Wide Band (UWB) bandpass fllter based on half-mode substrate integrated waveguide (HMSIW) in this paper. Sharpened rejection skirts and widened upper stopband are achieved due to the two resonant frequencies of the proposed CSRR. Very good agreement is observed between measurement and simulation results.

EFFECTIVE SKIN DEPTH FOR MULTILAYER COATED CONDUCTOR

Abstract—In this paper, the effective skin depth which provides a useful evaluation for field penetration in multilayer coated conductor is proposed. The reflection on the interface between the adjacent conductors is considered in theoretical derivation. It is found that the effective skin depths of the gold and gold-nickel coated copper rapidly vary with the thickness of the outer layer (gold) when the gold thickness is less than twice the gold skin depth and achieve stabilization as the gold thickness increases to five times the gold skin depth.

High selectivity and CM suppression microstrip balanced BPF and balanced-to-balanced diplexer

In this paper, a new compact microstrip balanced bandpass filter (BPF) and balanced-to-balanced diplexer are designed with high selectivity and common-mode (CM) suppression. The equivalent differential-mode (DM) and CM half-circuits of the proposed balanced BPF and balanced-to-balanced diplexer are analyzed in detail. Under the DM excitation, the filtering topology is formed by two coupling quarter-wavelength resonators (QWR) and source-load short-ended feedlines. Two transmission zeros can be generated near the DM passband edge to achieve high selectivity. Under the CM excitation, the transmission zero generated by the coupling between the QWR and short-ended feedline can be adjusted by the shorted stub loaded at the center to the DM passband. Moreover, the mutual loading effect of the filters with two coupling uniform resonators is approximately equivalent to a uniform resonator coupling shorted stub. Hence, the mutual loading effect of two balanced BPFs can generate new transmission zeros to deepen the stopband and improve CM suppression without deterioration of high selectivity and CM suppression performance within the DM passband. Finally, the compact balanced BPF and balanced-to-balanced diplexer by combining two balanced BPFs without extra matching network are designed and fabricated, and good agreement can be obtained between the experimental and simulated results.

Calibration of the Three-Port VNA using the General 6-Term Error Model

A general 6-term error model is presented for the calibration of the three-port vector network analyzer (VNA). In the general two-port 6-term error model where port i (i ≤ 3) is the signal source, and other unexcited ports are regarded as a general port. The nodes and coefficients related with the general port are replaced by the complex vectors and square matrixes. With every port connected to the power source, the actual S-parameters of the three-port device can be finally solved from the general 6-term error model. Experiment results of a three-port device attest the good performance of the general 6-term error model.

Application of 4-Component Compact 2-D FDFD Method in Analysis of Lossy Circular Metal Waveguide

A 4-component compact 2-D finite-difference frequency-domain (FDFD) method is utilized for the analysis of dispersion characteristics of lossy circular metal waveguide. In the analysis, the surface-impedance boundary condition (SIBC) can be implemented as easy as that in 6-component method in literature. The phase constant and attenuation constant can be obtained as solution of eigen value problem for a given frequency. The results agree very well with the theoretical solutions.

Integrated Dual-Band BPF and Single-Band BSF for Tri-Band Filter Design

This paper presents a tri-band bandpass filter in which a dual-band bandpass filter (BPF) and a single-band bandstop filter (BSF) are integrated into a single circuit of short length. The dual-band BPF contains several two-section stepped-impedance stubs which are mounted onto a main transmission line. The BSFs are constructed using capacitor-loaded shunt stubs which are connected by transmission lines. After circuit embedding, one wide passband of the dual-band BPF is converted into two passbands by the stopband of the BSF, resulting in a total of three passbands. A prototype tri-band filter is designed according to prescribed specifications: the required passbands are 1–1.4, 1.8–2.0 and 2.42–2.66 GHz with return loss above 10 dB, while the expected isolations between bands are above 40 dB. Optimization method is adopted for extracting the circuit parameters. The simulated and measured results are compared, and good features such as low insertion loss and high isolation are demonstrated.

COMPACT AND HIGH ISOLATION MICROSTRIP DIPLEXER FOR BROADBAND AND WLAN APPLICATION

In this paper, a compact and high isolation microstrip diplexer is designed for broadband and wireless local area network (WLAN) application, simultaneously. The bandpass fllter (BPF) for broadband channel is formed by three-coupled-line structure and two short stubs with difierent size loaded in 50› feed lines, and the BPF for WLAN channel consists of two coupling quarter-wavelength resonators (QWR) and one open stub loaded in short parallel-coupling feed structure. Multiple transmission zeros can be generated due to their intrinsic characteristics, so the broadband BPF with sharp skirt and wide upper-stopband performance and the WLAN BPF with sharp roll-ofi and lower-stopband characteristic can be realized. The tapped stub not only can generate new transmission zeros to deepen the stopband, but also can connect other BPF as an its part without deterioration of in-band performance. Hence, a compact microstrip diplexer combines of two BPFs without the extra junction matching network. The mutual loading efiect approximately equivalent to a coupled QWR can also generate new transmission zero at the passband edge to improve the isolation. A microstrip diplexer with the 3dB fractional bandwidths (FBW) of 80% for broadband channel and 5% for WLAN channel is designed and fabricated. Good agreement between the simulated and measured results is observed.

A planar ultra-wideband antenna with dual notched bands based on SCRLH resonator

A new ultra-wideband (UWB) antenna with dual notched bands utilizing a simplified composite right/left-handed (SCRLH) resonator is presented. By tuning the dimension of the SCRLH resonator, dual notched bands with sharp rejection can be achieved at desired frequencies to overcome interference with some already existing standards. The dual notched bands of UWB antenna at 3.5 GHz (WiMax) and 5.8 GHz (WLAN) are designed. The measurement of voltage standing wave ratio (VSWR) is in agreement with simulation. The results show that proposed antenna not only retains an ultrawide bandwidth but also owns dual band-rejections capability. The UWB antenna demonstrates omnidirectional radiation patterns across nearly whole operating bandwidth that is suitable for UWB applications.

A MINIATURIZED UWB BPF BASED ON NOVEL SCRLH TRANSMISSION LINE STRUCTURE

A miniaturized ultra-wideband (UWB) bandpass fllter (BPF) with U-slot etched around the metallic via in the ground is proposed based on a simplifled composite right/left-handed transmission line (SCRLH TL) structure. The U-slot etched in the ground makes it feasible to reduce the overall size. A demonstration of FCC standard UWB bandpass fllter (BPF) is designed, fabricated and measured. Very good agreement is shown between measurement and simulation.

High selectivity and common-mode suppression combline balanced BPF

In this study, new balanced microstrip bandpass filter (BPF) based on stepped-impedance combline structure is proposed with high selectivity and high common-mode (CM) suppression performance In the beginning, a single-ended compact stepped-impedance resonator (SIR) combline BPF with enhanced performance including low insertion loss, sharp skirt and wide stopband response is designed by consisting of an array of short quarter-wavelength bi-section SIRs with a new scheme of tapped-transformer coupling at input and output ports. Under CM excitation, no special consideration or design procedure is required to suppress the CM, and the CM suppression is the nature of the parallel-coupled filter. Finally, the second- and third-order SIR combline balanced BPFs for WLAN application, without loss of generality, have been designed and implemented. The simulated and measured results show a good agreement and validate the proposed theory.