A beam-forming technique for leaky-wave antennas

A beam-forming technique for leaky-wave antennas (LWAs) which can switch el ectronically in three different radiation patterns is developed in this let ter. A simple two-terminal feeding microstrip-line LWA works as a radiating element. By varying the phase of the two injection signals from 0 to 180 d egrees, the emitting power from the LWA can produce three different radiati on modes: the normal mode (one sharp beam), the difference mode (Delta), an d the sum mode (Sigma). The antenna displays large-bandwidth characteristic s, and can be useful near crossroads for collision avoidance or in the radi o location of vehicles. (C) 2001 John Wiley & Sons, Inc.