Dual-band resonance antennas using epsilon negative transmission line

Two types of dual-band resonance antennas based on the epsilon negative (ENG) transmission line are presented in this study. The first antenna has two unit cells with mushroom-like structure in which two notches are cut from their edges. This antenna has two different radiation patterns at its operating frequencies and hence it is a dual-mode antenna. In the second antenna, the structure of unit cells is modified in order to have the same radiation patterns at two operating frequencies. This antenna has two orthogonal polarisations at its operating frequencies and hence it is a dual-polarised antenna. The operating frequencies of the presented antennas correspond to the zeroth- and first-order resonance frequencies of the ENG resonator. Two prototypes of the proposed antennas have been fabricated and tested. The measured return loss and radiation patterns are given and discussed.