Patent GB-1365027-A (GB)
Title: Multiple source phased array radars
IPC: H01Q3/34
Filed: 1972-11-08
Abstract: 1365027 Pulse radar; aerials INTERNATIONAL STANDARD ELECTRIC CORP 8 Nov 1972 [23 Nov 1971] 51448/72 Headings H4D and H4A A pulse multiple-source aerial array radar comprises a plurality N of radiating elements 10 each of which is associated with a transmit/ receive module 1 which includes an injection phase locked microwave diode transmitter 11 (such as a Gunn oscillator), a reception channel, transmit/receive switching means for the element 10, and a variable phase-shifter 17. A common generator device supplies a composite signal through the phase-shifter, and the arrangement is such that, during pulse transmission periods a locking signal is supplied to the transmitter, whereas during reception periods a reference signal is supplied to the reception channel. As described, when using heterodyne reception, the composite signal is made up of CW portions of frequency FO during transmission periods and of CW portions of frequency F1 during reception periods (Fig. 3, not shown). In the generator device a stabilized local oscillator 28 (of frequency F1) controls a reference oscillator 29 (of frequency F0) through a frequency control loop 30 and also supplies a power divider D via a switch 27 during reception periods. The control loop 30 may comprise a mixer receiving signals from the oscillators 28, 29, and a frequency discriminator, or it may utilize a phase loop in which a phase discriminator is fed by such a mixer and by a high stability oscillator, and provides an error signal to the oscillator 29 (Fig. 2, not shown). Said oscillator 29 is coupled through a circulator 26 to a pulsed oscillator 24 which is thereby locked in phase when rendered operative by a modulator 25, receiving synchronizing pulses Sy. Power from the oscillator 24 is coupled via the circulator 26 and the switch 27 to the divider D during transmission periods. The variable phase shifter 17 of each module is connected to a respective output terminal of the divider D and is controlled by a common means 23, whereby scanning is effected. During transmission periods locking signal output from the phase shifter 17 is coupled through a switch 15, and a circulator 13 to the transmitter 11, which is thereby locked in phase. The synchronizing pulses Sy are fed to a control circuit 16 for the switch 15, and to a pulse modulator 12 for the transmitter 11. Output from said transmitter is coupled through the circulator 13 and another circulator 14 to the radiating element 10. During reception periods output from the said radiating element is coupled through the circulator 14 and a limiter 18 to one input of a hybrid junction 19. Reference signal output from the phase shifter 17 is coupled through the switch 15 to the other input of said hybrid junction, and the outputs thereof are coupled through respective diodes 20, 21 to the input terminals of an intermediate frequency (F1-F0) amplifier 22. In another embodiment, homodyne reception is used (Fig. 4, not shown). The composite signal is of one frequency (F0), but the locking signal portions are of greater amplitude than the reference signal portions (Fig. 5, not shown). In the generator device a single stable reference CW oscillator is provided which is coupled through a circulator either to a pulsed oscillator, which is thereby phase locked during transmission periods, or directly to the power divider, during reception periods. The outputs from the balanced mixers in the modules are at video frequencies in this embodiment. The variable phase-shifters 17 allow scanning in azimuth to be effected. Each element 10 is in the form of a vertical array of radiators along a dispersive feed line, and by varying the frequency of the signal supplied, i.e., according to the frequency of the reference oscillator, scanning in elevation may be effected.