Generation of Radiation Null for Periodic Leaky-Wave Antennas

In this paper a method for generating null region in the radiation pattern of periodic leaky-wave antennas is proposed. The method is based on the concept of effective radiation sections. The effective radiation section of the radiating mode (the $\mathrm{n}=-1$ harmonic) is calculated and studied. Then by suppressing the effective radiation sections corresponding to the radiating mode, the radiation null region can be introduced in a desired direction. Using this method, a periodic-strip leaky-wave antenna is designed. Both of simulated and experimental results show an obvious radiation null in the desired direction in the radiation pattern.