Planar antennas based on surface-to-leaky wave transformation

Advances in spiral circularly polarized surface wave antennas are presented. Such antennas are designed by using the concept of modulation of surface reactance. The surface impedance is reconstructed by printing a dense texture of sub wavelength metal patches on a grounded dielectric slab. The final devices are planar thin antennas with a simple layout and feeding. Numerical results are present and discussed for a prototype.