Abstract: A reflector for an antenna includes a plurality of reflector elements, each having a transmission line and an aperture at a distal end of the transmission line. Each transmission line having a length which varies in accordance with the position of each aperture relative to the antenna. The varying length of transmission creates a time delay that phases re-radiated waves.

Abstract: A beacon system wherein a beacon station is placed at a landmark such as a state line adjacent a major highway to broadcast information-containing alternating directional signals. In addition, each vehicle may be equipped with a radio receiver, a receiving decoder and a data analysis processor for receiving data signals from the beacon station. The beacon station includes an information encoder for generating first and second alternating but distinct location signals, first and second directional antennas disposed to radiate in opposite directions along the path of travel, the directional antennas having a significant back attenuation, a radio frequency transmitter for broadcasting the two location signals, preferably as data packets, to vehicle-mounted receivers along the path of travel, and an r.f. switcher for switching signal output of the transmitter between the two antennas in synchronization with the two location signals.

Abstract: A microstrip antenna having approximately an octave bandwidth comprises a planar radiating element disposed approximately coplanar with and in front of an upper ground plane and spaced above a lower ground plane at a distance equal to approximately one-tenth wavelength at the lowest operating frequency (one-quarter wavelength at the upper operating frequency). A thin dielectric layer is disposed on top of the upper ground plane which is coupled to the lower ground plane. The antenna, which is linearly polarized, is fed from the rear by a launcher that is approximately coplanar with the radiating element and mounted above the dielectric layer. Impedance matching means are provided for improved performance.

Abstract: An antenna structure in which two or more microstrip arrays are disposed on op of each other to minimize the required space. The shape of the microstrip elements and the polarization thereof are chosen so that the individual elements radiate only in specific areas along the edges of the elements with the remainder of the element having no appreciable electric field concentration. Because of the operating frequency of a microstrip element is a function of the size of the element, a second antenna of smaller higher-frequency elements may be disposed over a larger lower-frequency antenna such that the higher frequency antenna does not cover the areas of the lower antenna that radiate but lies over only those areas having no appreciable electric fields concentrations. Increasingly higher-frequency antennas can be placed on top of the lower-frequency antennas if the foregoing conditions are maintained with respect to all of the covered antennas.