Abstract: The invention relates to an antenna installation with an omni-directional antenna (M) and with an auxiliary antenna (A1) the reception signals from which can be combined in respect of amplitude and phase in such a way that a reception miniumu is produced in a desired orientation in space.

Abstract: Two-frequency transmitting apparatus (S1, S2, LA) for instrument-landing systems is insensitive to so-called difference in depth of modulation (DDM) distortions caused by reflections of a clearance signal from obstacles (H) located near the runway (RW). This insensitivity is achieved by providing different phase shifts to the equal modulation frequencies (90 Hz and 150 Hz) used for the course and clearance signals. The different phase shifts correspond to a phase shift of a common fundamental frequency (30 Hz). The two-frequency transmitting apparatus can be used to specify a localizer course or a glide path.

Abstract: The antenna has a main reflector (1), a subreflector (4a, 4b, 5a, 5b), and a feed radiator (2) which are all rotationally symmetric about a common axis (10). In a section in the direction of this axis of symmetry (10), the subreflector has the shape of two curves meeting in the axis of symmetry. Seen from the feed radiator, these curves are concave. Each of the two curves has at least one step (6a, 6b) for matching the feed radiator to the transmitter or receiver.

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.

Abstract: A vertical dipole array (2, 3 to 2.sup.(n), 3.sup.(n)) is formed on a substrate (1) using stripline techniques. The dipoles are supplied with RF energy from a feed system consisting of stripline conductors (4, 4', 5, 6, 7, 7', 9, 12). By a parasitic compensating radiator (11) provided opposite these conductors on the same side of the substrate, the influence of the conductors on the radiation pattern of the dipoles is largely compensated for.The conductors of the feed system are arranged so that a combination of a parallel feed and an equal line length series feed (or, if the radiation pattern is to be raised, a series feed with suitably chosen line lengths) is obtained.