Pattern-Reconfigurable Printed Dipole Antenna Using Loaded Parasitic Elements

A printed dipole antenna is designed with two parasitic elements loaded by embedded resonators to provide reconfigurable patterns. The embedded resonators in the parasitic elements are loaded by varactor diodes, which change the phase and the transmission coefficient responses of the parasitic elements. This allows the parasitic elements to act as either a director, a reflector, or a neutral element. The proposed printed dipole antenna with two loaded parasitic elements acts as a printed Yagi-Uda antenna. Because the parasitic elements can act as either a director or a reflector, the directed gain can be increased, and the front-to-back ratio (FBR) may be improved up to 42 dB. It is also possible to achieve different target FBR if broadcasting is needed in two directions of the boresight. This pattern reshaping can be obtained as quickly as the diodes can change their capacitance. The antenna is designed to operate at 2.4 GHz, but this design approach can be applied to other frequency bands. The simulation and measurement results are in good agreement.