Polarization-controllable zeroth-order-resonator antennas with reactance loads at both ends

Polarization-controllable zeroth-order-resonator antenna with reactance loads at both ends is proposed and demonstrated. The zeroth-order resonator antenna is composed of a microstrip-line-based composite right/left handed transmission line with reactive loads. The impedance of one load is the complex conjugate of another. By changing the end condition under the resonance, superposition of energies of dual resonances in series and shunt branches of the unit cell can be simultaneously and arbitrarily controlled. When the center microstrip line is perpendicular to the stubs, the polarization of radiation fields from the center microstrip line is orthogonal to that from stubs. By changing the terminating condition, we can continuously rotate the co-polarization direction of the linearly-polarized radiation. The numerical and experimental results verified the basic concept.