Wideband dual-mode bandpass filter using a modified right-triangular patch resonator overlapped with input/output DMS

Abstract

A novel and compact dual-mode wideband bandpass filter (BPF) with multiple transmission zeros is designed, fabricated, and measured in this paper. This filter consists of a modified right-triangle patch resonator with two orthogonal narrow-strip stubs and improved input/output defected microstrip structure (DMS). The designed resonator and DMS show dual-mode and dual-bandgap characteristics, respectively. The equivalent circuit models are described and their element values are also extracted by the full-wave EM simulator. The presented BPF is constructed by cascading the stub of patch resonator with the input/output DMS and overlapping partly with each other between the stub of resonator and middle conductor strip of input/output DMS. The EM simulated result has been confirmed by an experimental one and they have shown good agreement with each other. The measured result exhibits wide passband and low insertion loss characteristics for the proposed filter. IntroductionWith the rapid development of modern mobile communication systems, the miniaturized, low-cost, and wideband filters with lower insertion loss and higher frequency selectivity have been increasing demands in many wireless applications. Among these filters, dual-mode resonator filters have been widely used for their compact size.[1-7] The microstrip dual-mode triangular patch resonators and their applications for dual-mode filters with less than 10% 3-dB fractional bandwidth (FBW) have been investigated in [1]. A dual-mode bandpass filter (BPF) with 3-dB FBW of 16% using a pair of spur-line resonators has been reported in [2]. A single-slotted circular patch resonator has been used to design a dual-mode dual-band BPF, which has a 3-dB FBW of less than 10% in any passband.[3] A BPF based on E-shaped dual-mode resonator has been designed and implemented, which has a FBW of 2%.[4] In [5], a dual-mode half wavelength resonator filter with centrally loaded open stub and quasi-L-shaped feed-lines has been reported, which has a narrow FBW of 4.7% at the central frequency. A fourth-order dual-mode microstrip BPF with a FBW of 11% has been developed in [6]. In general, the insertion losses of above-mentioned filters are greater than 1.0 dB within their passbands. A coupled-line BPF using dual-mode half-wavelength SIR centrally loaded with shorted stub has been studied in [7], which has a suppression characteristic for high-order harmonics, however, the dual-mode filter still has a narrow bandwidth and high insertion

A Novel Wideband Bandpass Filter Using Coupled Lines and T-Shaped Transmission Lines With Wide Stopband on Low-Cost Substrate

“…However, RF filters present several problems of spurious responses mainly due to the presence of the second harmonic if such conventional designs are used. Various filters are designed with different methods, in order to obtain wide bandwidth, wide upper stopband, and high selectivity [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21]. Methods using the three-line microstrip coupled structure, split ring resonators (SRRs), multimode resonators, open-ended stubs, transversal signal interaction concepts and defected ground surface have been introduced for the WBPF designs with good wideband responses.…”

“…In [9], a quad-mode wideband BPF with about 43.3% fractional bandwidth based on a stub-loaded MMR is constructed using two parallel coupled feeding lines connected with a Tshaped resonator. In [13], the designed filter having an FWB of 36.1% was composed of a modified dual-mode patch resonator and a pair of input/output DMSs with dual-bandgap characteristics. Novel defected ground structures were used to design a wideband BPF with high selectivity in [16,17,20,21].…”

A Compact High-Pass Filter Using Hybrid Microstrip/Nonuniform CPW with Dual-Mode Resonant Response

“…Generally, the dual-mode (or multimode) resonant characteristics have been extensively applied to design UWB BPF and dual-band (or multiband) filters [8][9][10][11][12][13]. However, they are rarely used to implement the HPF.…”

A novel microstrip bandpass filter with an elliptic-function response using improved dual-stub resonator

“…[1,2] In order to obtain high selectivity, many approaches of generating multiple transmission zeros have been reported. [3][4][5][6][7][8][9][10][11][12][13][14][15] In [3], four types of half-wavelength resonator BPF with MTZs have been implemented, which are based on the tapping I/O and tapped interstage coupling. In [4], the trisection and quadruplet BPFs using folded quarter-wavelength resonators have obtained both compact circuit sizes and one or two transmission zeros.…”

“…Therefore, the desired bandwidth in a large range and a shifting transmission zero can be easily achieved by adjusting the width of upper-or bottom-coupling gaps between inverted I-shaped resonator and two adjoining same open-loop resonators. In [14], a wideband microstrip BPF with four TZs has been studied which is comprised of a modified dual-mode patch resonator and a pair of input/output DMSs with dual-bandgap characteristics. The two orthogonal stubs of resonator are cascaded with the input and output DMSs, respectively.…”