Hybrid Metamaterial Structure for Asymmetric Horn of Secondary Radar System

The hybrid metamaterial is proposed for the performance improvement of an asymmetric horn for the secondary radar system. The hybrid metamaterial is the unification techniques of the structures of wire medium and woodpile Electromagnetic Band Gap (EBG), which designed at the operating frequencies of 1,060 MHz and 1,300 MHz, respectively. We used the EBG structure for improving the radar main beam with horizontal polarization, while the wire medium structure has been organized beside the EBG structure to improve the main beam of IFF (Identification Friend or Foe) of the secondary radar system with vertical polarization. The objective of the proposed hybrid metamaterial structure is to enhance the gain of dual-band and dual-polarized pyramidal horn antenna, while the directions of radar and IFF main beams be retained at 0° and 6 °, respectively (as original standard). Such the proposed structure has been installed in front of the aperture of asymmetric horn with the appropriated distance and parameters, which are optimized by using CST software. From the simulation results, we found that such the structure can improve the gain of both main beams more than 3 dB when compared to the gain that obtained from the original asymmetric horn. Moreover, we could retain the different directions of both main beams as followed the specification of the original secondary radar system.