The Study Of Miniaturzied Microwave Passive Components Based On The Composite Right/Left Handed Transmission Line Structure

As a new type of transmission line structure, the composite right/left handed (CRLH) transmission line has some unique features. For instance, it can exhibit left handed (LH) properties in the lower frequencies whereas exhibiting right handed properties in the higher frequencies. Due to these unique features, the CRLH transmission line has been a very hot research topic for the past decade, and many researchers have been working in the area. Numeric applications based on the CRLH transmission line have been developed. Since the CRLH transmission line can exhibit the left handed features in the low frequencies, it has big advantages in designing the miniaturized microwave passive components at the low frequencies, as compared to the traditional right handed transmission line structure, and would contribute a lot to the modern communication systems which are required to be much smaller and lighter.This dissertation starts with the study of the miniaturized resonators based on the CRLH transmission line structure. The miniaturized microwave passive components are then investigated based on the proposed miniaturized resonators. Miniaturized passive components such as single band bandpass filter, dual band bandpass filter, balun bandpass filter, diplexer, triplexer, leaky-wave antenna and wideband antennas are successfully developed with good performance, as well as very small circuit size. The main contents of this dissertation are summarized as follows,1. By using the left-handed properties at low frequencies of the CRLH transmission line, the negative resonance modes of the CRLH transmission line with one side short circuited and the other side open circuited are investigated, and several miniaturized resonators based on the negative resonance are proposed accordingly. Based on these miniaturized resonators, several bandpass filters such as single band bandpass filter and dual band bandpass filter are developed. All these filters have achieved very good performance, as well as very small sizes.2. By using the low temperature co-fired ceramic (LTCC) technology and the CRLH transmission line theory, a new type of LTCC CRLH resonator is proposed. This new resonator does not only have super compact size, but also can introduce an intrinsic transmission zero to improve the stopband suppression in filter design. Based on the proposed resonator, two LTCC filters are given in this dissertation as a demonstration. Both filters have achieved very good performance, as well as supper compact size.3. A new circuit model of the balun filter based on the CRLH transmission line structure is proposed. This new model can easily integrate the balun function and the filter function into a single circuit model. The size of the resulted system can be reduced in a large degree whereas maintaining a good performance. Based on the proposed circuit model, three balun filters including a second order balun filter in the printing circuit board (PCB), a fourth order balun filter in PCB, and a second order balun filter in LTCC are given for a demonstration purpose. All the balun filters have very good performance, as well as very small circuit size.4. By using the common resonator technology and the CRLH transmission line theory, a new type of diplexer and a new type of triplexer are proposed in this dissertation. The new diplexer and triplexer have much smaller size than the conventional diplexer and triplexer, specifically, about 50% to 76% smaller than conventional diplexer and triplexer, respectively. Two diplexers and one triplexer are given in this paper for the demonstration purpose. Both diplexer and triplexer have very compact size and very good performance.5. Leaky-wave antennas and wideband antennas are investigated based on the CRLH transmission line structure. By making use of the phase propagation constant of the CRLH transmission line which can be negative, zero and positive, leaky-wave antennas with full plane beam scanning are achieved. By combing the negative order resonance, zero order resonance, and positive order resonance, very wideband antenna was achieved with constant radiation patterns in the whole operation frequencies.