Improvements relating to radar aerial systems

摘要

767,537. Radio direction-finding. BRITISH THOMSON-HOUSTON CO., Ltd. June 21, 1955 [July 2, 1954], No. 19493/54. Class 40(7) Radar equipment of the kind in which error signals are derived so that the aerial system may be maintained i n alignment with the target includes an aerial system consisting of three aerials having overlapping beam patterns symmetrica 1 1 y arranged about an axis and such that comparison of the signals derived from two of the aerials determines an error signal in respect of one plane and comparison of the signal from the third aerial 'and the combined signals from the first two determines a error in a second plane - perpendicular to the first. The aerials may - be waveguide horns arranged as shown at A, B and C and facing out of the plane of the paper; a common focusing lens is placed in front of the horns to give over-' lapping divergent radiation patterns (Fig. 1, not shown). It is shown by means of a mathematical discussion referring to Figs. 2 and 4 (both not shown) that if a, b and c 'are the signals obtained from aerials A, 'B, and C respectively then the azimuth error will be proportional to: and the elevation error to: In the preferred waveguide network for obtaining signals-of these values the signal b is first retarded in phase by 90 degrees .arid then fed to a 3dB coupler X along ,with signal c. The output of the coupler at CSP1/SP is #¢ (c - b) which is the azimuth error divided by #SP3/SP/ 2 . The other output of coupler X is fed to 4.77dB coupler Y along with signal a to give an output at ASP1/SP of #2/3 (a-b/2 - c/2) which is the elevation error divided by the same constant #3/2. It may be noted that the signals fed through a 90 degree phase advancer if required, add at the output B' and that, regarding the network from this end, a transmitter may'be connected at this point to give an equal intensity of transmission from each of the aerials A, B. and C. The error signals at ASP1/SP and CSP1/SP may be combined in a further 3dB coupler to give two output signals either of which represents the resultant error signal in magnitude and phase angle relative to the combined sum signal output at BSP1/SP. (The phase angles of these outputs are measured in opposite directions from the reference.)