Theory and design of leaky-wave antennas on a curved surface

Leaky-wave antennas (LWAs) are usually planar in nature, being based on a guiding structure that is oriented along a fixed direction. The phase constant of the radiating leaky wave determines the beam angle, while the attenuation constant determines the beamwidth of the radiated beam. For a periodic LWA, radiation occurs from the n = -1 space harmonic, and the phase constant β-1 can be either positive or negative, resulting in radiation either in the forward direction or the backward direction. Creating a beam at broadside is usually difficult, since this corresponds to the “open stopband at broadside”. Special designs, such at the metamaterial-inspired CRLH LWA, must normally be used to allow for radiation at broadside.