Font Size: a A A

The Design Of Band-pass Filters Based On DGS

Posted on:2015-02-07Degree:MasterType:Thesis
Country:ChinaCandidate:Z J LiFull Text:PDF
GTID:2268330428968468Subject:Electronics and Communications Engineering
Abstract/Summary:PDF Full Text Request
In recent years, with the rapid development of modern microwave communication technology, the spectrum is becoming more and more precious and crowded. So the higher requirements for microwave filters with high performance, small size and low cost are increasing. The volume of planar coupling microwave filters with traditional strip line and coaxial line is too big to meet the needs of modern technology. We need to find new materials and technologies in order to design the microwave filters with good performance, small size and low cost. The applications of Defected Ground Structure (DGS) and Composite Right/Left-Handed (CRLH) transmission line in the microwave filter improve the performance of microwave filters with small size and low cost. Therefore the research on the characteristics of DGS and CRLH transmission line and their applications on the design of the filter have a very significance in the development of microwave filters. The research results of band-pass filters’simulation, experiment and application based on DGS and CRLH transmission line in this thesis can be summarized as follows.Firstly, a band-pass filter based on the dumbbell-shaped DGS using a combination method is designed. The principles and advantages of the combination method are given. The performance of dumbbell-shaped DGS is improved by modification of the structure in order to meet the design needs. Then a band-pass filter using the modified DGS is designed. Within the scope of the passband, its return loss (S11) is less than-10dB. The passband of the filter ranges from2.6GHz to4.6GHz at-3dB. Its center frequency is3.6GHz, and relative bandwidth is55.6%. The selectivity characteristic is18.89dB/GHz in the low frequency, and the selectivity characteristic is42.5dB/GHz in the high frequency. Simulation results show that the designed model has filtering characteristic. But the out-of-band rejection is not high at low frequency band, and it needs improvement.Secondly, the design and analysis of the bandpass filter based on CRLH transmission line are given. For the poor out-of-band rejection of BPF based on DGS, a better performance bandpass filter with CRLH transmission line is designed. Within the scope of the passband, the filter’s return loss (S11) is less than-10dB. The passband of the filter ranges from1.3GHz to2.75GHz at-3dB. Its center frequency is2.025GHz, and relative bandwidth is71.6%. The selectivity characteristic is56.67dB/GHz in the low frequency, and the selectivity characteristic is113.3dB/GHz in the high frequency. The measured results show a good agreement with the simulated results. It validates that the designed model has filtering characteristic and the better performance.Main innovation of this thesis is the application of electromagnetic metamaterials in the filter. The microwave bandpass filter using electromagnetic metamaterials can effectively improve its performance. It can achieve the miniaturization design of filter for the unique performance of electromagnetic metamaterials.
Keywords/Search Tags:band-pass filter, Composite Right/Left-Handed transmission line, Defected Ground Structure, Complementary Split Ring Resonator
PDF Full Text Request
Related items