Electronically switchable beam patterns using leaky-wave antenna

A beamforming technique for leaky-wave antennas (LWA) which can switch electronically in three different radiation patterns on the H plane has been developed. A simple two-terminal feeding microstrip-line LWA works as a radiating element. By varying the phase of the two injection signals from 0, 90 to 180 degrees, the emitting power from the LWA can produce three different radiation modes: the normal mode (one sharp beam), the difference mode (/spl Delta/) and the sum mode (/spl Sigma/). The antenna displays large-bandwidth characteristics and can be useful near crossroads for collision avoidance, or in the radiolocation of vehicles.