GB1314199A - Primary radar - Google Patents

Abstract

1314199 Pulse radar; aerials A C COSSOR Ltd 23 Dec 1971 [29 Dec 1970] 61650/70 Headings H4A and H4D A radar aerial system comprises rotating aerial means having two ports 5, 6, a ferrite or other circulator 4, and a single rotating H.F. connection 8. The port 5 is directly coupled to a port 1 of the circulator 4, the port 6 is coupled through a P.I.N. diode or other switch 7 to a port 2 of said circulator, and one side of the rotating connection 8 is coupled to a port 3 of said circulator. In operation, a system trigger 12 initiates a pulse from a transmitter 10 which is coupled through a TR cell 9 to the rotating connection 8 and thence via ports 3 and 1 of the circulator 4 to the aerial means port 5, which provides a standard directional pattern in elevation. The switch 7 being closed, early echo signals from short ranges are received via aerial means port 6, which provides an upwardly tilted directional pattern inelevation, consequently avoiding returns from clutter, and are coupled through the rotating connection 8 and the TR cell 9 to a receiver 11. After a short time, which is determined by a fixed or adjustable delay element 13 connected between the trigger 12 and the control terminal of the switch 7, said switch opens. The port 6 is then disconnected, and echo signals from longer ranges received via aerial means port 5, are coupled through the circulator, the rotating connection and the TR cell to the receiver 11.