Switchable microstrip bandpass filters with reconfigurable frequency responses

High requirements on the electrical parameters of the filters are made in wireless radio communication systems. A number of tasks require bandpass filters with relative bandwidths of 8-12 %. In this case, the filter must have insertion losses of not more than 10 dB, have a rejection is not worse than 40 dB, unevenness in the bandwidth of not more than 1 dB. In addition, the amplitude frequency responses of the filter must have steep slopes due to the closely spaced frequency bands of neighboring communication systems. Due to its small size and other advantages, ladder resonator filters on surface acoustic waves are widely used in communication systems. To realize the high requirements of this type of filters, it is necessary not only to select all the topology parameters of the individual resonators included in the filter very accurately, but also to have a good computational theory and the necessary material parameters for the selected model at the design stage. Purpose: to show on the example of comparison of calculated and experimental frequency responses of ladder filters the validity of the method of extraction of the necessary parameters obtained for an infinite periodic structure by the finite element method for calculating of finite structures of real inter digital transducer and reflective gratings. Results: the method of extraction of parameters necessary for calculation by the method of connected modes on the basis of P-matrices is offered. The technique is based on the analysis of infinite periodic electrodes by the finite element method. Bandpass filters with a relative bandwidth 8-12 % on a piezosubstrate 49° YX LiNbO3 were designed and manufactured based on the proposed theory. It is shown that for this material, the calculation must take into account the direct radiation of bulk acoustic waves, since the design of ladder type filters, the radiation falls into the projected bandwidth of the filters. These calculations are confirmed by the results of experiments.

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Quasi-Reflectionless Microstrip Bandpass Filters With Improved Passband Flatness and Out-of-band Rejection

10.36227/techrxiv.12276524 ◽

2020 ◽

Author(s):

Xiaohu Wu ◽

Yingsong Li ◽

Xiaoguang Liu

Keyword(s):

Impedance Matching ◽

Cross Coupling ◽

Bandpass Filters ◽

Output Analysis ◽

Design Concepts ◽

Frequency Responses ◽

Transmission Zeros ◽

Prior Art ◽

Coupled Lines ◽

Stopband Attenuation

High-order quasi-reflectionless bandpass filters with improved passband flatness and good impedance matching both in-band and out-of-band are proposed in this work. The proposed design consists of conventional coupled-lines bandpass sections loaded with the presented absorptive stubs at the input and output. Analysis shows that the absorptive stub is equivalent to a 2-pole bandstop filter. Compared to the prior art, the higher-order nature of the presented absorptive stub enables a flatter passband and better out-of-band rejection. The overall filter stopband attenuation can be readily improved by increasing the number of coupled-lines sections without altering the passband responses. Furthermore, cross-coupling between the two absorptive stubs can be used to improve the out-of-band rejection by introducing two transmission zeros without affecting the absorption characteristics. The proposed design concepts are experimentally validated by the design and fabrication of a set of 2.4-GHz 1-, 2-, and 3-pole microstrip quasi-reflectionless bandpass filters. Measured frequency responses of these filters closely match those of the simulation.

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Switchable Microstrip Bandpass Filters With Reconfigurable On-State Frequency Responses

IEEE Microwave and Wireless Components Letters ◽

10.1109/lmwc.2010.2045581 ◽

2010 ◽

Vol 20 (5) ◽

pp. 259-261 ◽

Cited By ~ 23

Author(s):

Wen-Hua Tu

Keyword(s):

Bandpass Filters ◽

Frequency Responses ◽

State Frequency

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Switchable microstrip bandpass filters with reconfigurable frequency responses

2010 IEEE MTT-S International Microwave Symposium ◽

10.1109/mwsym.2010.5514831 ◽

2010 ◽

Cited By ~ 1

Author(s):

W. Tu

Keyword(s):

Bandpass Filters ◽

Frequency Responses

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Miniaturized Microstrip Diplexer Based on FR4 Substrate for Wireless Communications

Elektronika ir Elektrotechnika ◽

10.5755/j02.eie.28942 ◽

2021 ◽

Author(s):

Hussein Ali Hussein ◽

Yaqeen Sabah Mezaal ◽

Ban M. Alameri

Keyword(s):

Wireless Communications ◽

Group Delay ◽

Narrow Band ◽

Bandpass Filters ◽

Substrate Material ◽

Negative Group ◽

Input Output ◽

Scattering Parameter ◽

Frequency Responses ◽

Dual Channels

In this paper, the miniaturized microstrip diplexer has been designed for dual channels based on FR4 substrate material. It consists of two bandpass filters (BPFs) functioning under dissimilar frequency bands coupled with a unified junction. Every BPF has been created by a meandered line resonator, step impedance resonator, uniform impedance resonator, and input/output feed lines. The AWR electromagnetic simulator has been used for characterizing the frequency responses of the projected diplexer. Noble scattering parameter results with narrow band responses and negative group delay values are obtained for the proposed diplexer. The microstrip diplexer has an interesting band isolation between the two filters around 31 dB. The device has been successfully fabricated and verified with the simulations.

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Dual-Mode Microstrip Patch Bandpass Filters With Generalized Frequency Responses

IEEE Access ◽

10.1109/access.2019.2952403 ◽

2019 ◽

Vol 7 ◽

pp. 163537-163546 ◽

Cited By ~ 2

Author(s):

Qing Liu ◽

Dong-Fang Zhou ◽

Dei-Wei Zhang ◽

Da-Long Lu ◽

Yi Zhang

Keyword(s):

Bandpass Filters ◽

Dual Mode ◽

Microstrip Patch ◽

Frequency Responses

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Quasi-Reflectionless Microstrip Bandpass Filters With Improved Passband Flatness and Out-of-band Rejection

10.36227/techrxiv.12276524.v1 ◽

2020 ◽

Author(s):

Xiaohu Wu ◽

Yingsong Li ◽

Xiaoguang Liu

Keyword(s):

Impedance Matching ◽

Cross Coupling ◽

Bandpass Filters ◽

Output Analysis ◽

Design Concepts ◽

Frequency Responses ◽

Transmission Zeros ◽

Prior Art ◽

Coupled Lines ◽

Stopband Attenuation

High-order quasi-reflectionless bandpass filters with improved passband flatness and good impedance matching both in-band and out-of-band are proposed in this work. The proposed design consists of conventional coupled-lines bandpass sections loaded with the presented absorptive stubs at the input and output. Analysis shows that the absorptive stub is equivalent to a 2-pole bandstop filter. Compared to the prior art, the higher-order nature of the presented absorptive stub enables a flatter passband and better out-of-band rejection. The overall filter stopband attenuation can be readily improved by increasing the number of coupled-lines sections without altering the passband responses. Furthermore, cross-coupling between the two absorptive stubs can be used to improve the out-of-band rejection by introducing two transmission zeros without affecting the absorption characteristics. The proposed design concepts are experimentally validated by the design and fabrication of a set of 2.4-GHz 1-, 2-, and 3-pole microstrip quasi-reflectionless bandpass filters. Measured frequency responses of these filters closely match those of the simulation.

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Real Ear Sound Pressure Levels Developed by Three Portable Stereo System Earphones

American Journal of Audiology ◽

10.1044/1059-0889.0104.52 ◽

1992 ◽

Vol 1 (4) ◽

pp. 52-55 ◽

Cited By ~ 4

Author(s):

Gail L. MacLean ◽

Andrew Stuart ◽

Robert Stenstrom

Keyword(s):

High Frequency ◽

Sound Pressure ◽

Low Frequency ◽

Test System ◽

Output Frequency ◽

Frequency Effects ◽

Adult Men ◽

Frequency Responses ◽

Significant Difference ◽

Sound Pressure Levels

Differences in real ear sound pressure levels (SPLs) with three portable stereo system (PSS) earphones (supraaural [Sony Model MDR-44], semiaural [Sony Model MDR-A15L], and insert [Sony Model MDR-E225]) were investigated. Twelve adult men served as subjects. Frequency response, high frequency average (HFA) output, peak output, peak output frequency, and overall RMS output for each PSS earphone were obtained with a probe tube microphone system (Fonix 6500 Hearing Aid Test System). Results indicated a significant difference in mean RMS outputs with nonsignificant differences in mean HFA outputs, peak outputs, and peak output frequencies among PSS earphones. Differences in mean overall RMS outputs were attributed to differences in low-frequency effects that were observed among the frequency responses of the three PSS earphones. It is suggested that one cannot assume equivalent real ear SPLs, with equivalent inputs, among different styles of PSS earphones.

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