Gain Enhancement of Asymmetric Horn for Secondary Radar Antenna System using Hybrid Metamaterials

摘要

This paper presents the combination technique of two different structures of metamaterials (hybrid) in order to enhance the gain of an asymmetric horn for the secondary radar system. The hybrid metamaterials consist of a structure of woodpile Electromagnetic Band Gap (EBG) for gaining the radar main beam at 0 of direction and wire medium structure for gaining the IFF (Identification Friend or Foe) main beam at 6 shifted left from main direction. While the EBG and wire medium structures are designed at 1,300 MHz and 1,060 MHz of the center frequencies, respectively. Furthermore, the EBG structure must also response to the horizontal polarization of the radar main beam, whereas the wire medium structure must response to the vertical polarization of the IFF main beam. These are necessary to use the hybrid metamaterials to overcome such conditions. The hybrid metamaterial that is placed at the front of the aperture of asymmetric horn with the proper spacing is calculated by using CST software to consider its performance. We found that this proposed metamaterial could maintain the different directions of both main beams. While the gain of both frequencies, which have different polarization, are enhanced more than the single asymmetric horn around 2 dB.