The Research Of Planar Filters Based On Composite Right/Left Handed Transmission Line

Recently, composite right/left handed transmission line (CRLH TL) has drawnattention of researchers in and abroad since its unique electromagnetic properties. Itsleft hand properties find great importance in passive components miniaturization.Based on the interdigital CRLH TL unit cell structure, some basic electromagneticproperties such as mixed coupling, resonance mode will be analyzed. The unit cell isthen applied in various filter designs as a novel type of resonator. The original work andvaluable results of the dissertation is as follows:1. The CRLH TL dispersion curve is analyzed and key parameters that decide thedispersion relationship are found. Then, negative order resonance mode andzeroth order resonance mode of the unit cell are analyzed. Besides, the methodof parameter extraction for the interdigital CRLH TL unit is given.2. Based on the CRLH resonator, a second order wide stopband bandpass filterwith chebysheve response is designed, and by utilizing cross coupling andmixed coupling techniques, bandskirt of the filter is improved while otheradvantages in size and stopband performance of the original filter remain.3. Based on two of the most commonly used methods for dual-bandpass filterdesign, two novel CRLH dual-bandpass filters are given. The first one is in aparallel topology and the second one is based on a CRLH dual-mode resonator.This novel resonator has two resonance modes with only one unit cell.4. Some bandstop filters are designed based on the CRLH resonator.Miniaturization is realized by making use of its novel resonance modes. Theproposed dual-bandstop filter has advantages both in size and filteringperformance compared with some typical dual-bandstop designs. In the end, anovel broadband bandstop filter is realized based on signal interferencetechnique with a-90degree CRLH transmission line.