Compact Dual-mode Dual-band Bandpass Filter Research Articles

Compact dual‐mode dual‐band bandpass filter with inside–outside–reversed dual‐ring topology

A compact dual-mode dual-band bandpass filter is proposed based on the inside–outside–reversed dual-ring topology. Different from the traditional design, the total size of the filter is limited by the second passband with shorter wavelength at higher frequency, instead of the first passband with longer wavelength at lower frequency. By loading four square patches in the inner ring, the degenerate modes of the inner ring move down and form the first passband, whereas the second passband is constructed by the outer ring. By utilising the coplanar-waveguide feeding at ground plane, a prototype of the dual-band filter with two operating frequencies at 0.92 and 1.47 GHz is designed and verified experimentally.

Compact dual‐mode dual‐band bandpass filter with wide stopband for WLAN applications

A compact dual-mode dual-band bandpass filter (BPF) for WLAN applications is presented. On the basis of a primary passband formed by a ring resonator, a second passband is introduced by taking advantage of its tightly coupled input and output structures. Therefore, a dual-band performance is achieved without increasing the overall circuit size. Shorting vias and spurlines are adopted separately to realise the dual-mode excitation of each passband. Finally, a compact dual-mode BPF centred at 2.4 and 5.2 GHz is designed and fabricated, along with four transmission zeros, leading to sharp skirts and a wide stopband. Experimental results reveal good agreement with simulation results.

Erratum: A compact dual-mode dual-band bandpass filter design with controllable first passband [IEICE Electronics Express Vol. 11 (2014) No. 23 pp. 20140991

Erratum: A compact dual-mode dual-band bandpass filter design with controllable first passband [IEICE Electronics Express Vol. 11 (2014) No. 23 pp. 20140991

A compact dual-mode dual-band bandpass filter design with controllable first passband

A compact dual-mode dual-band bandpass filter design with controllable first passband

A novel compact configuration for dual-mode microstrip resonators and dual-band bandpass filter applications

In this article, a novel compact dual-mode resonator formed by a square loop having folded arms and mitered bends is proposed.Degenerate modes can be excited by shifting the gaps between the folds. Thus, the center frequency can be arranged at a fixed value because the total electrical length of the proposed configuration is not changed. A novel compact dual-mode dual-band bandpass filter is also designed by locating the one resonator within the other. Additionally, to suppress the harmonic of the first passband, open-circuited stubs are connected to the end of the feedlines. Two dual-mode dual-band bandpass filters with the elliptical and linear phase filtering characteristics for both passbands have been designed, fabricated, and tested. Calculated, simulated, and measured results are in a good agreement. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:775–779, 2013; View this article online at wileyonlinelibrary.com. DOI: 10.1002/mop.27444

Compact dual-mode dual-band bandpass filter with wide stopband

A compact microstrip bandpass filter (BPF) with dual-band and wide stopband based on a single dual-mode stepped-impedance resonator (SIR) and defected ground structures (DGSs) is investigated in this paper. The proposed BPF is composed of one dual-mode resonator with metalized via hole to ground, one spiral slot and three DGSs. The dual-mode SIR is studied and employed to generate two desired independent passbands. The DGSs are used to improve the stopband performance. The predicted results are compared with measured data, and a good agreement is reported.

A Dual-Band Ring-Resonator Bandpass Filter Based on Two Pairs of Degenerate Modes

In this paper, a class of dual-band ring-resonator bandpass filters is proposed based on a single ring resonator. As its most distinctive feature, two pairs of first- and second-order degenerate resonant modes in a ring resonator are simultaneously excited, resulting in a compact dual-mode dual-band bandpass filter with two transmission poles in both passbands. Firstly, two capacitors or parallel-coupled lines are placed at two nonorthogonally excited positions along a ring resonator in order to excite the two first-order degenerate modes and create multiple transmission zeros. Next, a set of perturbations is introduced on the ring to excite the two second-order degenerate modes. In our design, two excitation positions are first placed with between 45°- and 135°-separation on a ring. Simulations show that, with a proper arrangement of the excitation angle, two transmission poles in the first passband can be excited and more transmission zeros can be generated. Four and eight open-circuited stubs are loaded symmetrically along the ring, resulting in synchronous excitation of two poles in the second passband. Of the two designed filters with 135°- and 45°-separation, the one with 45° exhibits much better out-of-band performance with three additional transmission zeros at frequencies lower than the first passband, between the two passbands and higher than the second passband. Finally, two filter prototypes are fabricated and their measured results are found to be in good agreement with theory.