Frequency tunable directive antenna by ferromagnetic photonic crystals

We theoretically and experimentally demonstrate that the frequency tunable directive radiation can be achieved by the current line source embedded in two dimensional magnetic photonic crystals (PC). By lowering the symmetry of the PC, the source radiation can radiate in one direction with high directivity when it operates at the band edge of the PC. The radiation frequency can be tuned in a broadband frequency range through change the magnitude of bias magnetic fields. For the magnetic PC made of MgMn ferrite and designed in microwave X-band, the source radiation has a sharp main beam and no sidelobes. The dynamic tunable frequency range is up to 2.1 GHz in which the average directivity is about 30. The directive radiation and its frequency tunability are further demonstrated by experiments.