Optimum number of antenna elements in a sub-array for highest G/T

There are a number of different parallel arm feed topologies which give the same radiation pattern characteristics. On the other hand, noise temperature and efficiency of those feed structures will, possibly, be not the same. In this work, parallel arm feed structures are studied for their noise and efficiency performance using the noise equivalent line length method and an optimum number of antenna elements for a sub-array is obtained by comparing noise temperature and efficiencies of the structures.