Patent GB-1308978-A (GB)
Title: Compact steerable antenna array
IPC: H01Q3/30
Filed: 1970-06-30
Abstract: 1308978 Aerials INTERNATIONAL STANDARD ELECTRIC CORP 30 June 1970 31553/70 Heading H4A An aerial array comprises a plurality of spaced apart aerial elements, and a first means coupling the aerial elements into a plurality of groups, each of which provides a radiation pattern which is substantially invariant with wavelength above a predetermined value of wavelength, and which is a cardioid or a cardioid multiplied by a figure-of-eight. A means coupled to the first means combines the signals from the groups, and provides a signal which is equivalent to a directive radiation pattern. As described, six aerial elements 1-6, Fig. 1, are arranged symmetrically around the circumference of a circle of diameter 2#/X (where # is the minimum operational wavelength and X is an integer greater than 2), and a seventh aerial element 7 is located at the centre of the circle. The said elements are vertical monopoles of height ##/4, and the spacing between adjacent pairs is #/X. The elements 1-6 are coupled to the inputs of respective distribution amplifiers A1-A6, and the element 7 is coupled to the inputs of two distribution amplifiers A7, A8. The outputs of the pairs of amplifiers A1, A2; A6, A7; A3, A8; A4, A5 are coupled to the plus and minus inputs of respective subtractors 12, 13, 14, 15, respective delay elements 8, 9, 10, 11 being interposed between the outputs from the amplifiers A1, A6, A8, A5 and the corresponding subtractor inputs. The output (A) of the subtractor 12 is directly coupled to one input of a subtractor 18, and the output (B) of the subtractor 13 is coupled through a delay element 16 to the other input of the subtractor 18. The outputs (C), (D) of the subtractors 14, 15 are similarly coupled to the inputs of a subtractor 19. The output of the subtractor 18 is directly coupled to one input of a subtractor 21, and the output of the subtractor 19 is coupled through a delay element 20 to the other input thereof. Output from the subtractor 21 is fed to the input of receiving equipment 23. It is stated that the output signals from the subtractors 12-15 are each equivalent to a cardioid radiation diagram (Fig. 2A, not shown). Combination of pairs of said signals in the subtractors 18, 19 results in signals equivalent to radiation patterns having nulls at 0 and 60 degrees clockwise from the null of each original cardioid (Fig. 2B, not shown). Combination of the signals from the subtractors 18, 19 in the subtractor 21 results in a signal equivalent to a move directional radiation pattern having nulls along lines at 0, + 60 and - 60 degrees from the null of each original cardioid (Fig. 2c, not shown). The resultant pattern may be steered either by mechanical rotation or by combining the outputs of the aerial elements 1-7 in different ways. Many receivers, each having its own combining circuits, may be coupled to the outputs of the distribution amplifiers A1-A8, and the combining circuits of each receiver may sum the aerial element outputs differently, independently of the others. In a second embodiment, four aerial elements (30), (32), (33), (35), Fig. 3 (not shown), are arranged at the corners of a rectangle, and two aerial elements (31), (34) are arranged at the centres of the long sides of said rectangle, the spacing between adjacent elements being # #/4. Outputs from the elements (31), (34) are taken through respective power splitters, and inputs are provided to four first subtractors (24), (25), (28), (29) from respective pairs of elements (30), (31); (31), (32); (33), (34); (34), (35), a delay element being provided in one input connection to each subtracter. Outputs from the pairs of first subtracters (24), (25); (28), (29) are taken to the inputs of respective second subtracters (26), (23), a delay element being provided in one input connection of each. Outputs from the subtracters (26), (23) are taken to the inputs of a third subtracter (27), a delay element being provided in one input connection thereof. Output from the subtracter (27) is taken to a receiver (45). In a third embodiment, four vertical loop elements 51-54, Fig. 6, are coupled in pairs, and the two resulting sub-outputs are coupled to provide a system output on a lead 61.