A novel compact lowpass filter with sharp roll-off and wide stopband

2019 ◽  
Vol 12 (1) ◽  
pp. 21-33
Author(s):  
M. Hayati ◽  
AS. Abdipour ◽  
AR. Abdipour
Keyword(s):  
Transmission Lines ◽  
Lowpass Filter ◽  
Transmission Zeros ◽  
High Impedance ◽  
Attenuation Level ◽  
Measurement Results ◽  
High Figure ◽  
Frequency Behavior ◽  
Better Than ◽  
Resonance Cell

AbstractIn this paper, a microstrip lowpass filter adopting two main resonators with steep transition band and wide rejection band has been introduced. The first main resonance cell consists of meandered transmission lines which are loaded by modified T-shaped patches. The second main resonator is composed of high-impedance lines loaded by polygon patches. To obtain a steep skirt performance, the first and second resonators have been combined. Moreover, employing eight high–low impedance folded stubs and two rectangular open-stubs as suppressing cells has resulted in improving the stopband features. To comprehend the frequency behavior of the employed resonators and also their combination, the formulas of the transmission coefficient, reflection coefficient, and the transmission zeros of their equivalent LC circuits have been extracted, separately. According to the measurement results, the −3 dB operating frequency of this filter is 1.65 GHz. Moreover, a relative stopband bandwidth equal to 166% with a corresponding attenuation level of 23 dB and a sharp roll-off rate (393.61 dB/GHz) have been achieved. In the passband region from DC to 1.632 GHz, the insertion loss and return loss are better than 0.0763 and 15.85 dB, respectively, proving an acceptable in-band performance. Finally, the implemented structure brings about a high figure-of-merit equal to 81 672.

Microstrip lowpass filter with wide stopband and sharp roll-off using modified radial stub resonator

2016 ◽  
Vol 9 (3) ◽  
pp. 499-504 ◽  
Author(s):  
Mohsen Hayati ◽  
Mehrnaz Khodadoost ◽  
Hamed Abbasi
Keyword(s):  
Transmission Lines ◽  
Insertion Loss ◽  
Return Loss ◽  
Lowpass Filter ◽  
Transition Band ◽  
Attenuation Level ◽  
Radial Stub ◽  
Better Than ◽  
Good Agreement

In this paper, a microstrip lowpass filter with wide stopband and sharp roll-off is presented. The proposed filter consists of a modified radial stub resonator which is cascaded by four suppressing cells. To reduce the overall size, the transmission lines are folded. The cut-off frequency of the proposed filter is 1.19 GHz. The transition band is approximately 0.2 GHz from 1.19 to 1.39 GHz with corresponding attenuation levels of 3–20 dB. The stopband is from 1.39 to 19 GHz with attenuation level of <20 dB. The insertion loss and return loss in the passband from DC to 0.8 GHz are better than 0.26 and 14 dB, respectively. The proposed filter is fabricated and measured. The simulated and measured results are in good agreement.

Miniature UWB Filter Using Three-Quarters Wavelength Resonator with Direct-Connected Feed Method

2012 ◽  
Vol 571 ◽  
pp. 721-724
Author(s):  
Cai Peng
Keyword(s):  
Transmission Lines ◽  
Linear Structure ◽  
Ultra Wideband ◽  
Input Output ◽  
Transmission Zeros ◽  
Full Wave ◽  
Quarter Wavelength ◽  
Ring Structures ◽  
Loss Characteristic ◽  
Better Than

A miniature ultra-wideband (UWB) bandpass filter using three-quarters wavelength resonators is presented in this paper. Direct-connected feed method is employed between the input/output ports and the resonators in order to overcome the shortcomings due to the gap-coupled feed method and produce two transmission zeros in the lower and upper stopbands. On the other hand, two quarter-wavelength matching transmission lines are introduced to the input/output ports to improve the reflection loss characteristic in the passband of the filter. In addition, the resonators are folded to be open ring structures, which are more miniaturized than the conventional linear structure. As a consequence, the filter is compact in size and exhibits good performance. The filter is successfully realized in theory and verified by full wave EM simulation, and simulated frequency response results show that the fabricated filter has an insertion loss of better than 1dB in the passband and two rejections of greater than 25dB in most of the stopbands.

Compact LowPass Filter with Wide StopBand Using Non-Uniform Microstrip Resonant Cells

2012 ◽  
Vol 263-266 ◽  
pp. 15-19
Author(s):  
Yan Liang ◽  
Xiao Ming Wu ◽  
Bi Hua Tang ◽  
Yong Le Wu
Keyword(s):  
Microstrip Line ◽  
Photonic Bandgap ◽  
Impedance Matching ◽  
Stop Band ◽  
Cutoff Frequency ◽  
Harmonic Suppression ◽  
Lowpass Filter ◽  
Measurement Results ◽  
Better Than

In this paper, a novel compact microstrip lowpass filter is designed. The proposed filter which is etched on the 50 Ω microstrip line consists of four non-uniform 1-D microstrip photonic bandgap (PBG) cells with different cutoff frequency.. The demonstration lowpass filter with 2.2 GHz cutoff frequency is designed, fabricated and measured. The measurement results show that the band rejection effect is better than -20 dB from 2.8 GHz to 10 GHz, the insertion is less than 2 dB, and the length of filter is 5.6 cm long. Compared with the conventional filter, the proposed filter has smaller size. Meanwhile, it overcomes the problems of narrow stop-band and low harmonic suppression. Furthermore, the impedance matching is not need to be considered. This template explains and demonstrates how to prepare your camera-ready paper for Trans Tech Publications. The best is to read these instructions and follow the outline of this text.

Improved Design of Microstrip-to-Slotline Transition

2014 ◽  
Vol 668-669 ◽  
pp. 844-847
Author(s):  
Yuan Zhao ◽  
Bing Liang Hu ◽  
Chao Deng ◽  
Hong Wei Wang ◽  
Lei Li ◽  
...  
Keyword(s):  
Wide Band ◽  
Ultra Wide Band ◽  
Equivalent Circuits ◽  
Commercial Software ◽  
High Impedance ◽  
Measurement Results ◽  
Improved Design ◽  
Traditional Structures ◽  
Better Than

A novel compact Ultra-Wide Band (UWB) microstrip-slotline transition utilizing high impedance chip resistor is proposed and analyzed. The reactance introduced by the microstrip open end and slotline short end, which is the main limitation to the bandwidth in the traditional structures, is minimized in the design. The model is analyzed with the method of equivalent circuits and simulated by the commercial software HFSS. To test the performance of this transition a back-to-back structure is fabricated. The measurement results show that the bandwidth of 45 octaves can be obtained while the insert loss is better than 0.7dB within the band.

Ultra-wide stopband lowpass filters using ring resonators

2021 ◽  
pp. 1-7
Author(s):  
Mohsen Hayati ◽  
Sajjad Mohanad Mustafa ◽  
Farzin Shama ◽  
Hamed Abbasi
Keyword(s):  
Transition Region ◽  
Insertion Loss ◽  
Return Loss ◽  
Ring Resonator ◽  
Ring Resonators ◽  
Lowpass Filter ◽  
Sharp Transition ◽  
Attenuation Level ◽  
Ring Structures ◽  
Better Than

Abstract A microstrip-based lowpass filter (LPF) containing modified ring structures has been presented. Ring resonators are used to form a sharp transition region. In addition, rectangular- and tapered-shaped suppressing cells are used to create an ultra-wide stopband region. By combining the designed ring resonator and suppressors, an LPF has been designed with −3 dB cut-off frequency at 1.83 GHz. A sharp transition region has been achieved from 1.83 (at −3 dB) to 2.1 GHz (at −60 dB). A stopband region has been concluded from 2 to 21 GHz (with the corresponding attenuation level of at least 20 dB). The measured insertion loss is better than 0.1 dB (equal to a return loss of 18.1 dB) in the passband region. The proposed circuit is fabricated and measured. The measured results have an appropriate adaption with the simulated results.

A novel compact microstrip lowpass filter with wide rejection band and sharp transition band using diamond-shaped resonator

2013 ◽  
Vol 5 (6) ◽  
pp. 713-719 ◽  
Author(s):  
Mohsen Hayati ◽  
Mozhgan Amiri ◽  
Zahra Faramarzi
Keyword(s):  
Insertion Loss ◽  
Lowpass Filter ◽  
Sharp Transition ◽  
Transition Band ◽  
Communication Circuits ◽  
Compact Size ◽  
Attenuation Level ◽  
Measurement Results ◽  
Filter Size ◽  
Rejection Band

In this paper, a novel compact microstrip lowpass filter (LPF) using diamond-shaped resonator with wide rejection and sharp transition band is presented. The proposed filter has −3 dB cut off frequency at 2.6 GHz. The maximum insertion loss is only 0.1 dB in the passband and the rejection band extends from 2.89 to 20.84 GHz with the attenuation level better than −21 dB. The transition band is only 0.288 GHz, from 2.606 to 2.894 GHz with corresponding attenuation levels of −3 and −20 dB, respectively. The filter size is 12.4 × 11.5 mm2. The proposed filter is fabricated and tested, where the measurement results are in good agreement with the simulation results. The proposed LPF has compact size, simple structure, wide rejection band, and low insertion loss, where all of these characteristics are essential for LPF in the modern communication circuits.

A Lowpass Filter Design Using Curved and Fountain Shaped Resonators

Frequenz ◽  
2019 ◽  
Vol 73 (7-8) ◽  
pp. 267-272 ◽  
Author(s):  
Sobhan Roshani ◽  
Khatereh Dehghani ◽  
Saeed Roshani
Keyword(s):  
Transmission Lines ◽  
Return Loss ◽  
Filter Design ◽  
Lowpass Filter ◽  
Transmission Zeros ◽  
Compact Size ◽  
Filter Response

Abstract In this paper a new lowpass filter (LPF) with curved line resonators and fountain shaped resonators is proposed. The proposed filter has achieved wide stopband, compact size, sharp roll-off rate and low return loss. Two tapered resonators are used to produce transmission zeros and widen the stopband. Also, a fountain shaped resonator is proposed using curved transmission lines to obtain good sharpness in the filter response. The cut-off frequency of the designed LPF is 1.74 GHz and the overall size of the designed LPF is 0.135 λg × 0.132 λg where λg is the guided wavelength at the cut-off frequency. The results show that the overall size of the lowpass filter could be reduced using curved line resonators and curved transmission lines.

scholarly journals Tunable Lowpass Filter with RF MEMS Capacitance and Transmission Line

2012 ◽  
Vol 2012 ◽  
pp. 1-5
Author(s):  
Shimul C. Saha ◽  
Ulrik Hanke ◽  
Håkon Sagberg ◽  
Tor A. Fjeldly ◽  
Trond Sæther
Keyword(s):  
Transmission Lines ◽  
Parallel Plate ◽  
Rf Mems ◽  
Cutoff Frequency ◽  
Lowpass Filter ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Measurement Results ◽  
Low Pass ◽  
Lumped Elements

We have presented an RF MEMS tuneable lowpass filter. Both distributed transmission lines and RF MEMS capacitances were used to replace the lumped elements. The use of RF MEMS capacitances gives the flexibility of tuning the cutoff frequency of the lowpass filter. We have designed a low-pass filter at 9–12 GHz cutoff frequency using the theory of stepped impedance transmission lines. A prototype of the filter has been fabricated using parallel plate capacitances. The variable shunt capacitances are formed by a combination of a number of parallel plate RF MEMS capacitances. The cutoff frequency is tuned from C to X band by actuating different combinations of parallel capacitive bridges. The measurement results agree well with the simulation result.

Wilkinson Power Divider with Band-pass Filtering Response and Harmonics Suppression Using Open and Short Stubs

Frequenz ◽  
2020 ◽  
Vol 74 (5-6) ◽  
pp. 169-176
Author(s):  
Saeedeh Lotfi ◽  
Saeed Roshani ◽  
Sobhan Roshani ◽  
Maryam Shirzadian Gilan
Keyword(s):  
Transmission Lines ◽  
Power Divider ◽  
Initial Structure ◽  
Fractional Bandwidth ◽  
Transmission Zeros ◽  
Measurement Results ◽  
Good Accordance ◽  
Operational Frequency ◽  
Band Pass ◽  
Wilkinson Power Divider

AbstractIn this paper, a new Wilkinson Power Divider ‎‎(WPD) using open and short stubs is proposed. ‎Open and short stubs are utilized instead of 1/4 wave transmission lines in initial ‎structure to achieve harmonics suppression. The proposed WPD is designed for ‎operational frequency of 0.9 GHz and creates 3 transmission ‎zeros at 1.8 GHz, 2.7 GHz and 3.6 GHz, for suppressing second, third and fourth harmonics. The proposed WPD has been fabricated and the ‎measurement results are in good accordance with simulation results. The designed ‎WPD has a 22 % fractional bandwidth with 0.1 dB insertion loss.‎

scholarly journals A balanced-to-balanced directional coupler based on branch-slotline coupled structure

Frequenz ◽  
2020 ◽  
Vol 74 (11-12) ◽  
pp. 427-433
Author(s):  
Yaxin Liu ◽  
Feng Wei ◽  
Xiaowei Shi ◽  
Cao Zeng
Keyword(s):  
Directional Coupler ◽  
Return Loss ◽  
Design Method ◽  
Differential Mode ◽  
Arbitrary Power ◽  
Measurement Results ◽  
Transition Structures ◽  
Coupled Structures ◽  
Better Than ◽  
Good Agreement

AbstractIn this paper, a balanced-to-balanced (BTB) branch-slotline directional coupler (DC) is firstly presented, which can realize an arbitrary power division ratios (PDRs). The coupler is composed by microstrip-to-slotline (MS) transition structures and branch-slotline coupled structures. The single-ended to balanced-ended conversion is simplified and easy to implemented by the MS transition structures, which intrinsically leads to the differential-mode (DM) transmission and common-mode (CM) suppression. Moreover, the different PDRs which are controlled by the widths of branch-slotlines can be achieved. In order to verify the feasibility of the proposed design method, two prototype circuits of the proposed coupler with different PDRs are fabricated and measured. The return loss and the isolation of two designs are all better than 10 dB. Moreover, the CM suppressions are greater than 35 dB. A good agreement between the simulation and measurement results is observed.

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