Saab AB

About: Saab AB is a company organization based out in Thun, Switzerland. It is known for research contribution in the topics: Signal & Antenna (radio). The organization has 862 authors who have published 928 publications receiving 8807 citations. The organization is also known as: Saab AB & Svenska Aeroplan AB.

Optimization of radar cross section by a gradient method

Abstract: Analytical expressions are derived for the derivatives of radar cross sections (RCS) with respect to scatterer shape in two and three dimensions. Using the adjoint formulation, the derivatives of the RCS, with respect to an arbitrary number of design parameters, are found from a single solution of the scattering problem. In two dimensions, gradient-based optimizations converge with a small number of iterations to shapes with strongly reduced RCS in specified angular intervals. The optimal shapes have sharp corners in directions where the RCS is minimized and exhibit corrugations, which can be suppressed by use of penalty functions. The method is also applied to RCS optimization using dielectric and magnetic absorbing materials.

Dual frequency antenna aperture

Abstract: An antenna structure including at least two stacked antenna apertures, a first antenna aperture with first antenna elements and at least a second antenna aperture with second antenna elements. The antenna structure is arranged for operation in at least a high and a low frequency band. The first antenna elements are arranged for operation in the high frequency band and the second antenna elements for operation in the low frequency band. The first antenna elements are arranged to have a polarization substantially perpendicular to the polarization of the second antenna elements. The second antenna elements are arranged in at least one group and each of the group includes a number of second antenna elements coupled in series and arranged to have a common feeding point on a straight feeding structure. One feeding structure is located adjacent to each group of second antenna elements. The direction of the feeding structure is substantially perpendicular to the polarization of the first antenna elements. A corresponding method and a radar system including the antenna structure.

Validity check of vehicle position information transmitted over a time-synchronized data link

Abstract: The present invention provides a method for validating positional data in vehicle surveillance applications wherein vehicles transmit positional data indicating their own position to surrounding vehicles using a data link over which a transmission is initiated at a given transmission point in time that is known by all users of said data link. The method comprises the steps of: receiving, at a receiving unit, a signal carrying positional data indicating an alleged position of a vehicle, transmitted from a radio source over said data link; estimating the distance between the receiving unit and the radio source based on the time of flight, TOF, and the propagation velocity of the received signal, said TOF being determined based on the time elapsed from the transmission point in time of said signal to the time of reception of at least a first part of the signal; and, determining a deviation value indicating the difference between the distance to the position of a vehicle according to the received positional data and the estimated distance to the radio source.

Device at an airborne vehicle and a method for collision avoidance

Abstract: A device at an airborne vehicle including a flight control system configured to control the behavior of the airborne vehicle based on acceleration commands, a first control unit configured to provide the acceleration commands to the flight control system, and a collision avoidance unit. The collision avoidance unit includes a detection unit arranged to detect whether the airborne vehicle is on a collision course and a second control unit arranged to feed forced acceleration commands to the flight control system upon detection that the airborne vehicle is on a collision course. A method for collision avoidance in an airborne vehicle.