Yu. V. Krivosheev - Ph.D. (Eng.), Senior Research Scientist, JSC "Radiofizika"; Lecturer of Moscow Institute of Physics and Technology. E-mail: jscapex@online.ru A. V. Shishlov - Ph.D. (Eng.), Head of Department, JSC "Radiofizika"; Deputy Head of Department of Radio physics and technical cybernetics, Moscow Institute of Physics and Technology

In this paper, antenna noise temperature of a receiving array-fed reflector antenna of focusing type has been calculated. In such an-tennas, a beam inside field-of-view is formed by a cluster of array elements. It is known that as number of array elements in a cluster increases, antenna gain rapidly increases, when number of elements is small. But when number of elements in a cluster is large enough, gain increase significantly slows down. For this reason, when developing a receiving array-fed reflector antenna, a question arises whether increasing number of elements in a cluster is reasonable, because effective noise temperature might increase faster than gain. In this case G/T would decrease as number of elements in a cluster increases. In this paper we derived the analytical expression for effective noise temperature of array-fed reflector, which shows that effective noise temperature does not change as number of elements in a cluster increases. Consequently, G/T increases as number of elements increases. This conclusion has been confirmed by numerical simulation of an array-fed reflector antenna with 10 m reflector operating at 2 GHz with 1 to 37 elements in a cluster.

 

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