| Summary: | 碩士 === 國立臺灣大學 === 電信工程學研究所 === 101 === This thesis analyzes a cross-type (X-type or lattice network) composite right/left-handed (CRLH) transmission line using ABCD matrix. The proposed model can provide the dispersion relation and the bloch impedance (input impedance) for arbitrary inductance and capacitance. Furthermore, this thesis provides design procedures and parameters analysis for the design of leaky-wave antennas using the X-type CRLH transmission line. The X-type CRLH TL has several advantages. First, input impedance is independent of frequency. Second, if this CRLH TL is built in a balanced structure, it has broadband behavior. Third, the group velocity of this structure is larger than that of traditional CRLH TL. For antenna applications, the X-type structure can provide stable input impedance, improve frequency scan range, and reduce the beam shifting. Different antenna designs are proposed, including two edge-fed leaky-wave antennas and two center-fed leaky-wave antennas with a phase delay line and a symmetry structure. These two center-fed leaky-wave antennas are then backed by a reflector to enhance the broadside gain. This thesis investigates the radiation patterns, s-parameters, and the cross polarization issue. An edge-fed LWA prototype has a co-pol gain of 5 dBi and a cross-pol gain of -15 dBi. The center-fed LWA prototype has a co-pol gain of 6.5 dBi and a cross-pol gain of -20 dBi. The center-fed LWA prototype with a reflector has an improved co-pol gain of 11.5 dBi and a cross-pol gain of -20 dBi.
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