Microstrip Dual-band Bandpass Filter Research Articles

Compact and high selectivity dual-band dual-mode microstrip BPF with single stepped-impedance resonator

A novel dual-band dual-mode microstrip bandpass filter (BPF) with compact size and high selectivity performance is proposed using a single short-stub-loaded stepped-impedance resonator (SIR). Owing to the source–load coupling and the intrinsic characteristics of the SIR, five transmission zeros can be generated near the passband edges and in the upper-stopband to improve the selectivity. A dual-band filter located at 1.57 GHz (GPS application) and 5.35 GHz (WLAN application) has been designed, fabricated and measured. Good agreement between simulation and measurement verifies the validity of this design methodology.

이중 모드 공진기를 이용한 이중 대역 대역 통과 필터 설계

A compact microstrip dual-band bandpass filter with controllable bandwidth for each passband is proposed. Each passband is independently designed using two different dual-mode resonators. The proposed dual-band bandpass filter has three transmission zeros. Two transmission zeros are generated by each dual-mode resonator. An additional transmission zero is generated by input/output port coupling. The dual-band bandpass filter application is designed for 2.4/5.7 GHz WLAN. Experimental results are presented to validate theory.

A New Dual-Band Microstrip Bandpass Filter Using Net-Type Resonators

In this letter, a new dual-band microstrip bandpass filter is developed using net-type resonators. The net-type resonator is designed to simultaneously operate at two closely specified resonant frequencies, f1 and f2, and then applied to construct a dual-band filter based on the filter design concept of adding extra coupled resonators. The dual-band filter with the elliptic function response is designed, implemented and experimentally verified in this letter. The measured results of the developed filter are in a good agreement with the simulated results by full-wave electromagnetic simulator. In addition, the developed filter not only has an excellent mid-band rejection, but also provides a wide stopband suppression.

Design of a microstrip dual‐band filter with modified short‐circuit quarter‐wavelength resonators

AbstractA dual‐band microstrip bandpass filter is proposed. With the assistance of modified short‐circuit quarter‐wavelength resonators, the dual‐band bandpass filter can be developed. Theoretical analysis and design procedures are provided; the prototypical bandpass filter with dual passbands is fabricated and measured as well. Well‐matched simulated results and experimental data validate the proposed filter. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 236–239, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24889

High-selectivity dual-band bandpass filter using asymmetric stepped-impedance resonators

A dual-band bandpass filter with high selectivity is presented. Using only a single set of asymmetric stepped-impedance resonators, this filter can create five transmission zeros near the passband edges and between the two passbands to improve the selectivity. Based on the proposed idea, a microstrip dual-band bandpass filter is implemented.

Dual-Mode Dual-Band Bandpass Filter Using an New Open-Loop Resonator

This paper presents a dual-mode dual-band microstrip bandpass filter based on an open-loop resonant structure. By introducing a square notch and slots in the resonator, one of the passband can be controlled easily. Several finite transmission zeros are realized to improve the selectivity of the proposed dual-band filter and the isolation between the two passbands. To verify the proposed filter, an experimental filter is implemented. Both the simulated and measured results are presented.

Compact Dual Band Bandpass Filter Using Novel E-Type Resonators With Controllable Bandwidths

A compact microstrip dual band bandpass filter (BPF) using novel E-type resonators is presented in this letter. The E-type resonator is a short-circuited stub loaded hairpin resonator, two passband frequencies of which can be regulated by adjusting the characteristic impedance and electrical length of the hairpin and the stub. By combining pseudo-interdigital coupling structure, the coupling coefficients of two bands can be adjusted to a desired value in a relatively wide range. In addition, hook feed line is introduced to obtain desired external coupling degrees for two bands. Thus, controllable fractional bandwidths (FBWs) can be achieved. Two two-order 2.45/5.25 GHz dual band BPFs with 3 dB FBW 7%/7% and 5%/5%, respectively, are designed. The measured result agrees well with the simulation.

Microstrip dual-band bandpass filters using parallel-connected open-loop ring resonators

This article proposes a microstrip dual-band bandpass filter that uses parallel-connected open-loop ring resonators. Compared to many microstrip dual-band filters, the advantages of using microstrip open-loop ring resonators are easy calculation (half-guided-wavelength), easy fabrication (equal width for all 50-Ω lines and without grounding holes), and direct connection to external feed lines (reducing insertion loss caused by gap couplings). Another advantage of the filter is an asymmetrical feed on the ring resonator that provides sharp rejections at its adjacent bands. The input and output matches of resonators to the external feed lines are derived using a simple transmission-line theory. The results of the derivation provide a simple design rule for filter designers. Simulated and measured results are presented with good agreement. The filter has minimum insertion loss of 1.25 dB at 1.85 GHz and 1.6 dB at 2.33 GHz. The 3-dB fractional bandwidths are 5.9% for the 1.9-GHz bandpass filter and 4.7% for the 2.4-GHz bandpass filter, respectively. © 2008 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2008.

Synthesizing Microstrip Dual-Band Bandpass Filters Using Frequency Transformation and Circuit Conversion Technique

A novel method is proposed to synthesize dual-band bandpass filters (BPFs) from a prototype lowpass filter. By implementing successive frequency transformations and circuit conversions, a new filter topology is obtained which consists of only admittance inverters and series or shunt resonators, and is thereby easy to be realized by using conventional distributed elements. A microstrip dual-band BPF with central frequencies of 1.8 GHz and 2.4 GHz is designed and fabricated using microstrip lines and stubs. The simulated and measured results show a good agreement and validate thereby the proposed theory.

Novel Design of Microstrip Bandpass Filters with a Controllable Dual-Passband Response: Description and Implementation

SUMMARY Novel microstrip dual-band bandpass filters with controllable fractional bandwidths and good in-between isolation are presented and implemented. A half-wavelength stepped-impedance resonator is firstly characterized, aiming at producing the two resonant frequencies at 2.4 and 5.2 GHz. Two types of coupled microstrip lines in the parallel and anti-parallel formats are then investigated in terms of unified equivalent J-inverter network. Extensive results are derived to quantitatively show their distinctive frequency-distributed coupling performances under different coupling lengths. The coupling degrees of these two coupled lines at the two resonances are properly adjusted to achieve the dual-passband response with varied or tunable bandwidths. In addition, the parallel coupled line is modeled to bring out a transmission zero between the two resonances so as to achieve the good in-between isolation. The three two-stage bandpass filters are initially designed to exhibit their dual-band response with changeable dual-band bandwidths. A three-stage dual-band filter is in final optimally designed and its predicted performance is confirmed in experi

Compact dual-band microstrip bandpass filter without external feeds

A compact dual-band microstrip bandpass filter is proposed and designed to operate at 2.4 and 5.2GHz without needing any external impedance-matching block. The modified half-wavelength stepped-impedance resonator with sinuous configuration is constructed to simultaneously excite the dual resonances at these two specified frequencies with miniaturized overall size. The parallel-coupled microstrip line is properly characterized to minimize the return losses within both dual passbands. The optimized results exhibit the good dual-band filtering performances with return losses higher than 20dB as well being confirmed by experimentation with a fabricated filter circuit.