| 摘要 |
<p>An array antenna for receiving microwave-band signals. The array antenna comprises radiating elements (1), power feed circuits A (2) in subarrays, LNAs (3) (low noise amplifiers), a frequency converter (4), and a power feed circuit B (5) for combining the outputs of the subarrays. In the case of this configure, in the equation expressing the noise temperature of the whole of the array antenna, which is the noise temperature observed from the side of the elements (1), the gain of the LNAs (3) is the denominator of the term representing the loss of the power feed circuit (B) (5) for combining the outputs of the subarrays. Therefore, when the gain of the LNAs (3) is large enough, the effects given to the noise temperature by the losses of the power feed circuits (A, B (2, 5) for combining the outputs of the subarrays, can be ignored. Also, when each subarray comprises the plural elements (1) and the power feed circuit A (2), the higher the number of the subarrays is, the less the losses of the power feed circuits A (2) can be. As a result, the G/T is improved. Also, since an optimum number of the subarrays can be selected, the improvement of the G/T can be realized with an irreducible minimum increase in cost. <IMAGE></p> |
