Dual-mode composite right/left-handed resonator microwave bandpass filters

This thesis discusses the design and implementation of new dual-mode ring resonator filters using composite-right/left-handed (CRLH) line. Standard lowpass prototype design procedure for a Chebyshev response is employed in the design. Before the resonator filters are designed, the theory of the left and right handed lines are discussed The left handed line which can be modeled as lumped elements LC (inductor and capacitor) iterative networks is considered. The principle of suppression of the second harmonic in CRLH resonators is explained. New CRLH resonator configurations are proposed and implemented. These resonators are analyzed and modeled in a greater detail using circuit modeling technique, which serves as an initial design approach to acquire desirable circuit dimensions before the design layouts are simulated using commercial electromagnetic simulator. Apart from resonator filters, a 4-order Chebyshev bandpass filter with a centre frequency of approximately 0.6GHz is reported. The measured insertion loss and 3dB bandwidth are 1.2dB and 14% respectively. The measurement results showed good agreement with the simulated results. Harmonic suppression is evident and promising by using CRLH line in a ring resonator. In this design, a harmonic occurs at a frequency more than 3 times the centre frequency of the filter.