Dual-Band Bandpass Filter Using a Single Short-Ended Dual-Mode Resonator With Adjustable First Passband

Abstract

Abstract-In this paper, a novel dual-band bandpass filter (BPF) based on a single short-ended dual-mode resonator (SEDMR) is presented. According to the voltage distribution of the resonator, two pairs of loaded open stubs, inside and outside of the resonator, are utilized to tune the center frequency and the external quality factor of the first passband respectively, while there is no influence on the second passband. Meanwhile, source-load coupling is introduced to produce transmission zeros to improve the passband selectivity and band-to-band isolation. For demonstration, a dual-band filter working at 1.52 GHz for GPS and 3.5 GHz for WiMax is designed, fabricated and measured with insertion losses of 1.47 and 0.95 dB. In addition, two transmission zeros, introduced by source-load coupling, located at 2.19 and 2.67 GHz between the first and second passband improve passband selectivity and band-to-band isolation better than 50 dB.

A Novel Quad-Mode Resonator and Its Application to Dual-Band Bandpass Filters

“…For a compact size, filters based on dual-mode resonators have been attracting much more attention [8][9][10][11][12]. In [13][14][15][16][17][18][19], a single dual-mode resonator is employed to realize a dual-band bandpass filter (BPF) with compact size and high passband selectivity. Here, the first-order harmonic is adopted to form the second passband.…”

Two Kinds of Dual-Band Bandpass Filter Based on a Single Square Ring Resonator

“…The stepped impedance resonators (SIRs) and stub loaded resonators (SLRs) are also employed for dual-band operation [4][5][6], and at least two resonators are required. Other methods such as, defected ground structure (DGS) [7,8], shorted-ended dual-mode resonator (SEDMR) [9], coupled line resonator [10], and low temperature cofired ceramic (LTCC) [11] have also been proposed for dual-band applications.…”

“…Up to now, there are not so many reports on dual-mode dual-band filter using a single ring resonator [13][14][15][16][17]. In [17], a novel short-ended stepped-impedance dual-resonance resonator, which is evolved from SEDMR [9,18], was proposed and applied to design filters with one, two, and three passbands. The resonator appears to be a ring, however, its working principle is equivalent to a stepped-impedance resonator (SIR) with two ends shorted.…”

A Compact Dual-Band Band-Pass Filter With Wide Stop-Band Using Two Resonators Combined by via-Hole

“…Besides, two independent resonators are combined [3,4]. Recently, dual-feeding structures [5], the parallel coupled microstrip line [6], dual-plane defected structures [7], multi-stub-loaded resonators [8], the circuit consisting two two-port networks in shunt connection [9], square loop resonators [11], short-ended dual-mode resonators [12] and coupled three-line resonators [14] are all introduced in dual-band performance design. However, these methods are at the sacrifice of relative large size and the stop-band of those filters is not wide enough.…”

“…Dual-band band-pass filters are the important components for the communication systems. The methods have been already proposed to implement the dual-band band-pass filter [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. The stepped impedance resonators (SIRs), E-shaped microstrip SIRs and GSIRS are also employed to achieve dual-band performance utilizing the fundamental frequency and second harmonic passband [1,2,10,13] but it is not convenient to meet a specific bandwidth requirement.…”