Abstract: A multibeam antenna having a plurality of radiators arranged in a form of a dipole field and configured to generate a plurality of lobes, a main antenna including a first set of the plurality of radiators, and an acillary antenna including a second set of the plurality of radiators and configured to suppress disturbances received by the main antenna, wherein each radiator of the second set of radiators makes no significant contribution to lobe generation in the main antenna and whose omission has no effect on the output and directionality of the main antenna.

Abstract: Conventional secondary radar systems use mechanically rotating antennas to radiate a concentrated beam that rotates in a horizontal plane. Data exchange between ground stations and airborne transponders can only take place if the aircraft is struck by the antenna lobe. The distance from the aircraft to the ground station is determined from the signal transit time. Directional information is derived from the antenna position. The secondary radar system according to the invention uses an omnidirectional antenna, so that data can be exchanged between ground station and aircraft at any time. To determine the position of the aircraft, interrogation signals are transmitted by a single active ground station such that the reply signal from a transponder falls within the common system time frame of the ground station. The times of arrival of the reply signals at different ground stations are then directly proportional to the distances from the aircraft to these ground stations.

Abstract: A TACAN beacon is disclosed in which the pulse-modulated carrier signal generated in a transmitter is applied to the elements of a circular antenna array through controllable phase shifters that generate 15-Hz and 135-Hz sidebands through, switches, and through a Butler matrix. A switching facility generates two states. In the first state, the phase shifters are controlled to generate the upper and lower 15-Hz sidebands and the upper 135-Hz sideband, respectively. In the second state, they are controlled to form the respective opposite sidebands.The Butler matrix generates, radio-frequency phase-rotation fields at the antenna. In the two states, the ordinal numbers of the radio-frequency phase-rotation fields differ in their signs. The absolute value of the largest ordinal number is smaller than or equal to six, and the sum of the absolute values of the ordinal numbers for the carrier signal and the upper or lower 135-Hz sideband is equal to 9.