Slow-wave Open-loop Resonators Research Articles

Design and Fabrication of a Novel Compact Bandpass Filter to Improve Spurious-Free Band

AbstractIn this paper, a new microstrip slow wave open loop resonator is proposed. This resonator overcomes the substantial limitation of the conventional slow wave open loop resonators, which limits the spurious-free band of those resonators. The new proposed resonator improves the spurious-free band up to 8 times of the fundamental frequency, which is 3.16 times of the conventional slow wave open loop resonators. For the proposed resonator the coupling factor and the external quality factor curves, which are the design curves of a narrowband filter, are extracted using a full wave simulator, i. e. HFSS. These curves are utilized for the design of two three-pole Chebyshev bandpass filters. One of these filters is fabricated. Simulation and measurement results are reported which are in good agreement. Designed filters provide 75 % and 83 % of footprint reduction in comparison with the conventional open loop resonator filters. Different parameters which can improve the spurious-free band are explained in the paper.

A slow wave structure and its application in bandpass filter design

This paper presents a new slow wave open-loop resonator filters with reduced size and improved stopband characteristics. A comprehensive treatment of different kind of coupling in this structure is demonstrated. Two and four resonator band pass filters at center frequency 2.15 and 2.30 GHz with different bandwidth are designed. The simulated results are verified with the help of two different software packages (IE3D and Sonnet Lite).

Design of Quasi-Elliptic Bandpass Filter Based on Slow-Wave Open-Loop Resonators

A microstrip bandpass filter implemented with slow-wave open-loop resonators is described in this letter. The slow-wave open-loop resonators make the filter compact and allow implementation of positive and negative inter-resonator couplings. Implementation of the positive and negative couplings is used to introduce a pair of finite frequency transmission-zeros in the filter response. The two zeros are designed to be close to the passband, thus improving the selectivity of the filter. As an example, a quasi-elliptic filter is fabricated. The quasi-elliptic filter has a compact dimension of 22.1 mm × 21.16 mm, which is approximately 0.1705λg × 0.1634λ g . The experimental results are demonstrated and discussed.

Microstrip Slow-Wave Open-Loop Resonator Filters with Reduced Size and Improved Stopband Characteristics

This paper presents a new class of microstrip slow-wave open-loop resonator filters with reduced size and improved stopband characteristics. A comprehensive treatment of both ends loaded with triangular and rectangular ends is described, leading to the invention of a microstrip slow-wave open-loop resonator. Two-resonator and four-resonator bandpass filters are designed at the operating frequency of about 2 GHz, and a bandwidth of 60 MHz. The size of the slow-wave open-loop resonator is optimized from the standpoint of the unloaded Q-factor. The filters are not only compact in size due to the slow-wave effect, but also have a wider upper stopband resulting from the dispersion effect. The filter designs of this type are described in details. The experimental results are demonstrated and discussed.

A compact open-loop resonator filter with a wide stopband response

This paper presents a new class of microstrip slow-wave open-loop resonator filter with reduced size and improved stopband characteristics. A comprehensive treatment of both resonator ends loaded with triangular and rectangular shapes is described, leading to the invention of a microstrip slow-wave open-loop resonator. A four-resonator bandpass filter is designed at the operating frequency about 2 GHz, bandwidth of 60 MHz. The size of the slow-wave open-loop resonator is optimized from the standpoint of the unloaded Q -factor. The proposed filter is not only compact size due to the slow-wave effect but also has a wider upper stopband resulting from the dispersion effect. The filter design of this type will be described in detail. The experimental results are demonstrated and discussed.

A compact bandpass filter using microstrip slow‐wave open‐loop resonators with high impedance lines

AbstractIn this paper, a bandpass filter using a microstrip slow‐wave open‐loop resonator with high impedance lines is presented. This resonator has the high impedance of a loaded microstrip line, which significantly increases not only the slow‐wave effect but also the dispersion effect. These effects result in the reduction of its size and the widening of an upper stop‐band region compared to that of a conventional microstrip slow‐wave open‐loop resonator with a low impedance line. The new proposed filter and conventional filters are simulated and tested. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 38: 185–187, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.11009

A novel dual-mode bandpass filter with wide stopband using the properties of microstrip open-loop resonator

A novel dual-mode microstrip square loop resonator is proposed using the slow-wave and dispersion features of the microstrip slow-wave open-loop resonator. It is shown that the designed and fabricated dual-mode microstrip filter has a wide stopband including the first spurious resonance frequency. Also, it has a size reduction of about 50% at the same center frequency, as compared with the dual-mode bandpass filters such as microstrip patch, cross-slotted patch, square loop, and ring resonator filter.

Theory and experiment of novel microstrip slow-wave open-loop resonator filters

This paper presents the theory and experiment of a new class of microstrip slow-wave open-loop resonator filters. A comprehensive treatment of capacitively loaded transmission line resonator is described, which leads to the invention of microstrip slow-wave open-loop resonator. The utilization of microstrip slow-wave open-loop resonators allows various filter configurations including those of elliptic or quasi-elliptic function response to be realized. The filters are not only compact size due to the slow-wave effect, but also have a wider upper stopband resulting from the dispersion effect. These attractive features make the microstrip slow-wave open-loop resonator filters promising for mobile communications, superconducting and other applications. Two filter designs of this type are described in detail. The experimental results are demonstrated and discussed.