Stepped-impedance Stub-loaded Resonator Research Articles

A Bandwidth Reconfigurable Bandpass Filter for Ultrawideband and Wideband Applications

In this brief, a reconfigurable filter is proposed for simultaneous usage as ultra-wideband and wideband filters. The ultra-wideband (UWB) section is designed by constructing three parallelly connected quarter-wavelength transmission lines with two high impedance quarter-wavelength shorted stubs. The wideband (WB) section is implemented using an open stepped impedance stub-loaded resonator (OSSLR) and a shorted stepped impedance stub-loaded resonator (SSSLR). Nine pin diodes are embedded to switch the passband from UWB to WB and vice versa configuration. The filter in UWB mode produces a passband bandwidth ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$|{\mathrm{ S}}_{11}|$ </tex-math></inline-formula> dB more than 10 dB) of 9.03 GHz from 2.15 GHz to 11.18 GHz, and the WB mode reports a passband bandwidth of 2.8 GHz, which ranges from 3.25 GHz to 6.05 GHz. Further, a lowpass filter is integrated with the design to obtain a wide upper stopband. The proposed prototype is fabricated and tested to validate the collaborative design concept. The overall circuit size of the prototype is <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.80\lambda _{g}\,\,\mathbf {\times }\,\,0.42\lambda _{g}$ </tex-math></inline-formula> at 4.70 GHz.

CSRR metamaterial based BPF with wide attenuation band

Abstract A bandpass filter (BPF) of 2.24 GHz centre frequency and 44.6% fractional bandwidth, with a wide attenuation band is proposed in this article. The paper is focused on the analysis of complementary split ring resonator (CSRR) as a unit section of metamaterial and its application in designing of a bandpass filter. The proposed BPF structure consists of a stepped impedance stub-loaded resonator incorporated with the CSRR to suppress the harmonics to improve the attenuation band characteristics. A brief parametric study of the CSRR cell is done to demonstrate its role while suppressing the unwanted harmonics. The structure is fabricated, and measured to show a consistency with the IE3D simulated results.

Dual‐band bandpass filter with wide upper stopband using quad‐mode stepped impedance stub‐loaded resonator

A novel quad-mode stepped impedance stub-loaded resonator is presented. The even–odd-mode method is applied twice to analyse the modal resonance characteristics due to its symmetry. All the four modes' equivalent circuits are quarter-wavelength stepped impedance resonators, so the proposed resonator has a compact size and higher harmonic frequencies. Stub-to-stub coupling is introduced to split two identical modes and produce two transmission zeros. A dual-band bandpass filter operating at 1.5 and 2.4 GHz is designed using the proposed resonator. The centre frequency and bandwidth of each passband can be controlled by tuning the corresponding physical dimensions, and a wide upper stopband is achieved. Finally, the designed filter was fabricated and measured, and the measured results have good agreement with the simulated ones.

Analytical design of a microstrip UWB BPF with sharp rejection

This paper presents a new Ultra-WideBand (UWB) BandPass Filter (BPF) using half-wavelength (λ/2) Stepped-Impedance Stub-Loaded Resonator (SISLR). Analytical equations derived by the even-odd mode analysis show the new filter has two tunable transmission zeros at both sides of the passband to provide a sharp rejection and seven transmission poles inside the passband to achieve U.S. UWB performance. For verification, a UWB BPF is designed, fabricated and measured. The measured results show that the fabricated filter has a -3 dB fractional bandwidth from 3.0 GHz to 10.9 GHz and its insertion loss less than 0.9 dB over the whole passband. Furthermore, the new filter exhibits a simple topology, sharp rejection, and deep stopband suppression.

Design of UWB bandpass filter with dual notched bands

An ultra-wideband (UWB) bandpass filter (BPF) with dual sharply rejected notch-bands to eliminate the interference from coexisting radio systems is presented in this paper. The characteristics of the proposed notched structure are investigated using simulations to demonstrate the design flexibility of the notchband performance. After integrating the proposed notched structure into the basic UWB BPF based on a stepped-impedance stub loaded resonator (SISLR), a UWB BPF with dual sharply rejected notched bands at 5.2 and 5.8 GHz is constructed. Finally, the designed filter is built and tested. The simulated and measured results are found to be in good agreement to verify the proposed design.

COMPACT NOTCHED ULTRA-WIDEBAND BANDPASS FILTER WITH IMPROVED OUT-OF-BAND PERFORMANCE USING QUASI ELECTROMAGNETIC BANDGAP STRUCTURE

In this paper, a compact notched ultra-wideband (UWB) bandpass fllter with improved out-of-band performance using quasi electromagnetic bandgap (EBG) structure is proposed. Firstly, a UWB bandpass fllter based on a stepped-impedance stub-loaded resonator (SISLR) is combined with quasi-EBG structures, which suppress the undesired spurious bands to improve the out-of-band performance. In order to eliminate the interference caused by WLAN, a notched band is introduced at 5.2GHz, which is implemented by adding a folded stepped-impedance resonator (SIR) near the stub of the SISLR. At last, the proposed fllter is fabricated and measured. Good performances of the UWB fllter have been demonstrated both in the simulated and measured results.

A COMPACT UWB BANDPASS FILTER WITH IMPROVED OUT-OF-BAND PERFORMANCE USING MODIFIED COUPLING STRUCTURE

A compact ultra-wideband (UWB) bandpass fllter (BPF) with improved harmonic suppression using a modifled coupling structure is presented in this paper. The modifled coupling structure is constructed by taper-connecting two folded open stubs to the traditional parallel-coupled lines, which shows an improved characteristic in harmonic suppression. By integrating the proposed coupling and the stepped-impedance stub loaded resonator (SISLR), a UWB BPF is flnally built and tested. The simulated and measured results are in good agreement with each other, exhibiting good wideband flltering characteristic and improved out-of-band performance.

Compact and Sharp Rejection Microstrip UWB BPF with Dual Narrow Notched Bands

This paper presents a new ultra-wideband bandpass (UWB) bandpass filter (BPF) based on the half-wavelength (λ/2) stepped-impedance stub-loaded resonator (SISLR). Classical even- and odd-mode analysis shows that the new filter has multiple transmission poles and two tunable transmission zeros on both sides of the filter passband. In order to reject the interfered signals, the technique of generating a notched band inside the UWB passband is studied. As examples, two UWB BPFs, one without the notched band and the other with dual narrow notched bands at 5.8/8.0 GHz, are designed, fabricated and measured. The notched band at 5.8 GHz is realized by an embedded open-circuited stub (EOCS) while the notched band at 8.0 GHz is implemented by a folded stepped-impedance resonator (FSIR). The simulations and measurements agree well with each other. Two filters show the simple topologies, compact sizes, low insertion losses and sharp rejections.

Design of UWB Bandpass Filter Using Stepped-Impedance Stub-Loaded Resonator

In this letter, an ultra-wideband (UWB) bandpass filter (BPF) using stepped-impedance stub-loaded resonator (SISLR) is presented. Characterized by theoretical analysis, the proposed SISLR is found to have the advantage of providing more degrees of freedom to adjust the resonant frequencies. Besides, two transmission zeros can be created at both lower and upper sides of the passband. Benefiting from these features, a UWB BPF is then investigated by incorporating this SISLR and two aperture-backed interdigital coupled-lines. Finally, this filter is built and tested. The simulated and measured results are in good agreement with each other, showing good wideband filtering performance with sharp rejection skirts outside the passband.