Chang-Sin Ye

DESIGN OF DUAL-BAND BANDPASS FILTERS USING A DUAL FEEDING STRUCTURE AND EMBEDDED UNIFORM IMPEDANCE RESONATORS

In this paper, a simple method and structure to design a dual-band bandpass fllter (BPF) by using a dual feeding structure and embedded uniform impedance resonator (UIR) is presented. In this structure, two passbands can be designed individually and several transmission zeros can be created to improve the band selectivity and stopband performance. The flrst passband is determined by the dual feeding structure and the second passband is determined by the UIR. Moreover, by using the inter coupling in the UIR, the performance of the second passband can be easily tuned without degrading the flrst passband. In order to verify the design concept, two fllter

A HIGH BAND ISOLATION AND WIDE STOPBAND DIPLEXER USING DUAL-MODE STEPPED-IMPEDANCE RESONATORS

In this paper, a high performance diplexer is designed and fabricated for Global Positioning System (GPS) and wireless local area network (WLAN) applications simultaneously. The diplexer mainly comprises two dual-mode ring bandpass fllters (BPFs), operated at 1.575GHz and 2.4GHz, respectively. By using the stepped-impedance resonator (SIR) in the BPFs, the size reduction and wide stopband from 2.8GHz to 6GHz are obtained. Moreover, several transmission zeros are located at the passband edges, thus improving the passband selectivity. Due to impedance matching between two BPFs, a high

DESIGN OF THE COMPACT PARALLEL-COUPLED LINES WIDEBAND BANDPASS FILTERS USING IMAGE PARAMETER METHOD

In this paper, the design of compact and high performance parallel coupled line wideband bandpass filter using image parameter method are proposed. The filter mainly comprising one-stage parallel coupled line and two open stubs are designed and implemented on commercial RT/Duroid 5880 substrate. The equivalent circuit of the proposed structure is initially derived by using the image parameter method. It is found that, the normalized bandwidth (NBW) of image impedance for the one-stage parallel coupled line has a relation to the electromagnetic (EM) simulated bandwidth. To further improve the selectivity, two open stubs are connected near the input/output (I/O) ports. The design procedures and their limitations are discussed in detail. The proposed filters are fabricated, measured and showing good characteristics of 87% fractional bandwidth as well as good insertion/return loss, flat group delay varies between 0.3–1.5 ns. High passband selectivity and wide stopband from 8–14GHz are observed. The measured results are also having a good agreement with the simulated results.

A Compact-Size and High Isolation Dual-Band Coplanar-Waveguide Bandpass Filter

A compact and high isolation CPW dual-band bandpass filter using the interdigital resonator structures (IDTRS) is presented for application in GPS and IEEE 802.11 b WLANs. Since the two passbands can be tuned individually, the filter has more design freedoms. IDTRS are used to generate and control the second passband frequency. Two transmission zeros in the stopband are realized to improve the selectivity of the filter, and to achieve a high isolation higher than 30 dB between two passbands. Good agreements between the simulated and measured results demonstrate our proposed structure.

New compact tri-band bandpass filter with transmission zeros designed by using stub-loaded resonators

A new compact tri-band microstrip bandpass filter (BPF) designed based on a tri-mode stub-loaded resonator (SLR) is proposed. The SLR equivalent circuit, consisting of one even mode and two odd resonant modes, can be used to create passbands operated at 2.4, 3.5, and 5.2 GHz, corresponding to the wireless local area networks and WiMAX applications. The filter is compact in size because only two sets of resonator are employed by means of the tri-mode behaviors, and the three band can be designed independently. Furthermore, transmission zero on each passband edges can be created by using 0° feed structures, resulting in high skirt selectivity. Experimental results show good agreement with the simulated ones.

Compact quad-band bandpass filter based on uniform impedance stub-loaded resonators

A new quad-band bandpass filter for Global System for Mobile Communications, Wireless Local Area Network, and Worldwide Interoperability for Microwave Access is designed and fabricated using the stub-loaded resonator (SLR) technology without complex fabrication process, such as via-hole or multi-layer substrate. Owing to the embedded SLR, the proposed quad-mode resonator is compact. Equivalent circuits of the proposed quad-mode resonator are analyzed in detail, and high design freedom is shown because of shifting the passband frequencies individually. Good passband selectivity and isolation of the each passband at 1.8, 2.4, 3.5, and 5.2 GHz can be well achieved due to the transmission zeros appeared near the each passband edges. Experimental results show good agreement with the simulated results.

A compact dual-band UWB filter based on the parallel line structure with the slot-line

In this letter, we proposed a compact dual-band UWB filter based on the parallel line structure with the slot-line (Thomson and Hong, 2007) to achieve a high channel selectivity due to transmission zeros located near the passband edge, which are produced by the all stop response introduced by the quarter-wavelength parallel-coupled line. Additionally, the wide passband response is excited by the U-shaped slot-line resonator (SLR) and further improved by shorted slot stubs to form the dual-band performance. The proposed wideband BPF, as shown in Figure 1, can exhibits good passband selectivity and out-of-band performances and is experimented to verify the design concept.