GB1351146A - Electronic-scan antenna - Google Patents

Abstract

1351146 Aerials THOMSON-CSF 1 Sept 1971 [11 Sept 1970] 40844/71 Heading H4A An electronic scan aerial system comprises n active aerial modules which do not incorporate phase shift devices, and a circuit supplying said modules with n reference signals of frequency F 1 . Said circuit comprises means supplying at first and second outputs respective orthogonally phased component signals of frequency f= F 1 /p, where p is an integer greater than one, and a controllable amplitude modifying device receiving the signal from said first output, and a signal from a control means, and supplying a signal from a third output. The circuit also comprises n amplitude modifying devices having different fixed gains, whose inputs are all coupled in parallel to one of the said second and third outputs, n adders each having a first input coupled to a respective one of said n amplitude modifying devices and a second input coupled to the other one of said second and third outputs. The circuit further comprises n devices producing frequency multiplication by p, each of which is coupled to the output of a respective adder, and each of which provides one of said reference signals of frequency F 1 . As described a stable oscillator O of frequency F 1 /p feeds a phase splitter MD which provides two output signals V 1 , V 2 in quadrature with each other. The output signal V 1 is coupled to the paralleled first inputs of n adders AD 1 to AD n . The output signal V 2 is coupled through a variable attenuator AV 3 to the paralleled inputs of n non-variable attenuators AT 1 to AT n , whose outputs are coupled to respective second inputs of the adders AD 1 to AD n . A computer C a2 in association with a control device CG 2 sets the valve of the attenuator AV 3 according to the angle of scan required. This attenuator has two balanced outputs, + K 2 V 2 and - K 2 V 2 , each of which is connected to half of the attenuators AT 1 to AT n . The valves of these attenuators are gradated, so that proportional amounts of the outputs ŒK 2 V 2 are fed to the adders AD 1 to AD n . The outputs of the adders are taken to respective frequency multipliers X 1 to X n , of factor p, and outputs of frequency F 1 , stepped in phase, are available at terminals S 1 , and are used as reference signals for the n active modules of an aerial array. In a second embodiment (Fig. 4, not shown) the input signal to the n non-variable attenuators is derived from both of the output signals, which are in quadrature, of the stable oscillator or signal generator. Each of said output signals is coupled through a variable attenuator to a respective input of a further adder. The values of the variable attenuators are set by respective control devices operated by a computer, and the output signal of the further adder is coupled to the non-variable attenuators. The circuits may be duplicated, and each active aerial module may be fed with two reference signals, of respective frequencies F 1 and F 2 , thereby allowing simultaneous transmission and reception with the array (Fig. 7, not shown). If the frequencies F 1 and F 2 are close, and if simultaneous operation is not required, two oscillators of respective frequencies F 1 /p and F 2 /p may be selectively switched through common equipment to supply the modules (Fig. 8, not shown).