Zeroth-Order Resonators With Variable Reactance Loads at Both Ends

Effects of the reflection condition at both ends of a zeroth order-resonator are investigated. The proposed resonator is composed of a composite right/left-handed transmission line (CRLHTL) and two reactive elements as reflectors at both ends. The load reactance at one end is chosen as the complex conjugate of the other. The balanced case without bandgaps between right- and left-handed passbands, as well as the unbalanced cases, are discussed for CRLHTLs employed in the resonators. The superposition of stored energies of series resonance in the series branch and parallel resonance in the shunt branch in the ladder network can be continuously and arbitrarily controlled by changing only the load reactance at the terminals. For unbalanced cases, the resonance occurs within the bandgap. Coexistence of the two different resonances is verified by directly observing the near-field distribution of the resonator in the numerical simulation and the measurement.