Research On Resonant-Type Left-handed Transmission Line Structures And Their Application

Left-handed material (LHM) is a newly discovered artificial metamaterial with negative permittivity and negative permeability simultaneously. From the first realization of LHM at 2000, it has been the front and focus area in physics and electromagnetics research. In recent years, several methods have been proposed to realize LHM, and among them planar composite right/left-handed (CRLH) transmission line structures have shown their tremendous potential in microwave circuits and components design. This dissertation mainly analyzes the propagation characteristics of coplanar waveguide resonant-type CRLH transmission line structure based on split ring resonator (SRR) and microstrip resonant-type CRLH transmission line structure based on complementary split ring resonator (CSRR), and presents some novel microwave components using them. The original works and valuable results of this dissertation are as follows:1. The microstrip resonant-type balanced composite right/left-handed (CRLH) transmission line structure based on CSRR and its equivalent circuit model are proposed. The influence of variation of circuit parameters in the circuit model on the propagation characteristics is analyzed. A method using the shape of CSRR as an adjusting factor to adjust the propagation characteristics of the resonant-type balanced CRLH transmission line structure is proposed. Three different resonant-type balanced CRLH transmission line structures based on different rectangular CSRRs are designed for demonstration, which have the same transition frequency. Through simulation, measurement and extraction of equivalent circuit parameters, the validation of this method is verified. The analytical process is helpful for other adjusting methods. In addition, this work will widen the application range of CSRR .2. A coplanar waveguide resonant-type balanced CRLH transmission line structure based on SRR is presented for the first time. The feasibility of our idea is analyzed using equivalent circuit model firstly. For further validation, a coplanar waveguide resonant-type balanced CRLH transmission line structure based on SRR is fabricated, which has the transition frequency 3.28GHz . Simulated results, measured results are in good agreements with theoretical analysis, which demonstrate the balanced CRLH propagation characteristics. Subsequently, an ultra-wide band coplanar waveguide band pass filter using this resonant-type balanced CRLH transmission line structure is designed, which has more than 90% fractional bandwidth. Good performance at pass band and stop band can be found from the simulated and measured results and the size is compact.3. Arbitrary dual-band microwave components using resonant-type CRLH transmission line structure are presented. Resonant-type CRLH transmission line can provide nonlinear negative phase shift and positive phase shift at left-handed transmission band and right-handed transmission band respectively. Furthermore, the phase shift and characteristic impedance can be adjusted. Based on these transmission characteristics, arbitrary dual-band components can be designed as the resonant-type CRLH transmission line is used to instead of conventional transmission line. To demonstrate the validity and correctness of this method, The dual-band quarter-wave open-circuit stub, dual-band wilkinson power divider, and dual-band branch line coupler using the resonant-type CRLH transmission line are designed . Simulated results, measured results are in good agreements with theoretical analysis and good performance at the first and second operation frequency can be observed. Because no lumped elements and grounded via are need, these dual-band components can operate at higher microwave frequencies and is easier to be fabricated. 4. A novel miniaturized hybrid ring using the resonant-type CRLH transmission line structure is designed. In this novel hybrid ring, conventional 270 tranmission line is replaced by resonant-type CRLH tranmission line structure based on CSRR, which can produce ?9 0 phase shift at designed frequency. ?9 0 phase shift is equivalent to 270 phase shift. Because the length of resonant-type CRLH tranmission line structure is much smaller than that of conventional 270 tranmission line, the occupied area of this novel hybrid ring can be reduced by 60% from that of conventional hybrid ring. Good performance for in-phase operation and 180 -out-of phase operation at operation frequency can be found from the simulated and measured results.5. A method using CSRR to suppress the harmonics of microstrip patch antenna is presented. CSRR is fabricated on the ground plate below the feed line and the stop-band is designed to coincide with that of harmonic. Because of the negative permittivity effect of CSRR around its resonant frequency, the power of harmonic can not be transmitted and harmonic will be suppressed. Because the power transmission of dominant mode remains unaffected, the performance will not be influenced. The validation of this method can be verified from the simulated and measured results.