A novel printed leaky-wave ´bull-eye´ antenna with suppressed surface-wave excitation

We propose a novel microstrip leaky-wave antenna, based on a multiple-ring (´bull-eye´) structure, with a high radiation efficiency and reduced edge-diffraction effects. Such favorable properties are achieved by properly choosing the relevant physical and geometrical parameters in order to operate the antenna in a frequency range in which no surface wave may propagate and the only physical leaky wave is the fundamental TM₀ mode. A directive conical radiation pattern, frequency-scannable in a wide angular region, is thereby achieved. Numerical results on dispersion properties of the involved TM and TE modes and full-wave simulations of representative structures are provided to demonstrate the feasibility of the proposed design.