Tunable left-handed monopole and loop antennas

Abstract

Left-handed (LH) loading has been applied to printed wire antennas, such as dipole antennas and the loop antenna. These antennas are based on periodic LH cells. The resonant frequency depends on the components of the LH cells, which can be used to develop small antennas. Moreover, LH loading provides new capabilities in the design of wire antennas. For example, a meandered dipole with LH loading provides orthogonal polarization to the dipole length. A loop antenna with omnidirectional radiation pattern in the plane of the loop can be obtained with LH loading. In this paper, two tunable printed antennas with LH loading, mounted over a ground plane, are proposed. Simulations show that wide frequency tunability can be obtained by changing the value of some of the components, which can be easily implemented with varactor diodes. Thus, a wide frequency range is achieved with good matching within the range.