Abstract: An array antenna includes a patch arrayed on a metal backing plate and a plurality of inputs connected to the patch so as to radiate and receive an electromagnetic wave via the patch. The array antenna includes a transmitting/receiving circuit for feeding or receiving signals at a specific frequency to or from the array antenna. A waveguide divided into sections is provided to feed the electromagnetic wave to the radiating antenna. Each waveguide section produces a specific phase difference along the array antenna which accumulates and causes the electromagnetic wave to focus at a particular angle. Each waveguide section therefore produces a wave focused at a different angle, allowing the antenna to generate a plurality of focused waves.

Abstract: An microstrip antenna for use in a vehicle collision system is described wherein an array of rectangular patch elements are arranged in rows and columns on a substrate. A feed structure is used whereby a high gain highly efficient flat plate antenna is produced. The feed structure includes a pair of main lines to which feed points are connected. A plurality of branch lines connect at right angles to the main lines and extend alongside columns of patch elements. The patch elements are so spaced that they are electrically separated by a whole multiple of the dielectric wavelength. The main lines are connected to the branch lines by coupling traces whose widths are selected to establish a desired power distribution. A plurality of strip transformers are distributed along the main lines and connected to junctions with the branch lines to reduce reflections.