Four-Arm Log-Periodic Toothed Antenna With Hybrid Reflector Composed of Inhomogeneous Metamatarial Elements for Electronic Support Measures

A novel method of enhancing radiation performance is demonstrated by applying a hybrid reflector composed of inhomogeneous metamaterial elements to a four-arm log-periodic toothed antenna. The operation of the antennas by various metamaterial cells is observed, and the causes of the radiation performance deterioration and narrow bandwidth are investigated through the field distribution analysis. The metamaterial cells are arranged in suitable positions under the antenna for good radiation performance and wide bandwidth according to AMC and EBG characteristics. In the proposed hybrid reflector, surface wave suppression characteristics are used for impedance stabilization by placing the I-shaped EBG cell under the inactive region of the antenna. The performance of the fabricated antenna with dual linear polarization capability is verified by measuring co- and cross-polarization radiation patterns. The newly proposed hybrid reflector for the four-arm log-periodic toothed antenna represents an over 4 dBi realized gain within an impedance ratio bandwidth of over 11.6:1.