Radiation characteristics of finite-length 1D-uniform leaky wave antennas radiating at broadside

Leaky-wave antennas can be classified into two basic types, depending on whether the geometry of the guiding structure is uniform or is periodically modulated along its length. In a uniform leaky-wave antenna, the fundamental mode is a fast-wave (meaning that the phase velocity is greater than that of the light in free space) and therefore radiates whenever the structure is open. In the second type of leaky-wave antenna, the periodic leaky-wave antenna, a periodic modulation of the guiding structure is introduced, and it is this periodicity that produces the leakage. In a periodic leaky-wave antenna the fundamental mode is a slow-wave that does not radiate, with radiation occurring from one of the space harmonics.