GB848830A - Improvements in radar systems - Google Patents

Abstract

848,830. Directive radio systems. COMPAGNIE GENERALE DE TELEGRAPHIE SANS FIL. Feb. 12, 1959 [Feb. 18, 1958], No. 4934/59. Class 40(7). An aerial system for a radar providing azimuth, elevation, and range information comprises a reflector P of part paraboloid form, asymmetric with respect to the axis VF and a plurality of primary elements S 1 , S 2 , S 3 -S n arranged along a straight line Fy passing through the reflector focus F. If the point M, located at substantially the mid-height of the reflector, is the point which receives the greatest amount of energy from the sources S 1 -S n then the line along which the primary elements lie should, according to theory, be the line Ft<SP>1</SP> parallel to the tangent Mt to the reflector at M. However, it is stated that it has been found that better results are obtained in practice if the line Fy along which the primary elements lie makes a small angle with the line Ft<SP>1</SP> as shown. Each primary element produces a single lobe radiation pattern and the strength of the energy fed to each may be controlled to produce a set of radiation patterns as shown in Fig. 2. These patterns give coverage in elevation from almost horizontal up to above 45 degrees and the strength of the patterns is graded so that their effective upper limit does not exceed a certain height. The sources may be fed from the radar transmitter by a single vertical rectangular guide fed at its lower end. This main guide may carry a T-junction adjacent each source at which a branch guide is coupled to the main guide by a diaphragm controlling the power passing and is terminated in a radiating source of small dimensions such as that described in Specification 838,287. Each branch guide is provided with duplexing arrangements so that radar echo signals received can be fed out to individual receiver arrangements. The receiving arrangements are thus each associated with a radiation pattern directed at a certain angle of elevation and, if the whole aerial system is scanned in azimuth, range azimuth and elevation information about objects can be determined.