Optimization of a Subarray Structure to Improve the $G/T$ of an Active Array Antenna

In this letter, a subarray optimization to improve <inline-formula><tex-math notation="LaTeX">$G/T$</tex-math></inline-formula> of an active array antenna is presented. To optimize <inline-formula><tex-math notation="LaTeX">$G/T$</tex-math></inline-formula>, an equation for <inline-formula><tex-math notation="LaTeX">$G/T$</tex-math></inline-formula> is derived by calculating the formulas of the gain and noise temperature in the active array antenna. By using <inline-formula><tex-math notation="LaTeX">$G/T$</tex-math></inline-formula> and the peak sidelobe level of a scanned beam, the cost function is defined. Applying this cost function to the subarray optimization, a <inline-formula><tex-math notation="LaTeX">$G/T$</tex-math></inline-formula> value of 5.68 dB/K is obtained. To demonstrate the improved <inline-formula><tex-math notation="LaTeX">$G/T$</tex-math></inline-formula>, the subarray optimization without considering <inline-formula><tex-math notation="LaTeX">$G/T$</tex-math></inline-formula> is also conducted. Because <inline-formula><tex-math notation="LaTeX">$G/T$</tex-math></inline-formula> is not considered, some cases having low <inline-formula><tex-math notation="LaTeX">$G/T$</tex-math></inline-formula> is occurred. Compared to the worst case from these results, the proposed subarray optimization strategy improves <inline-formula><tex-math notation="LaTeX">$G/T$</tex-math></inline-formula> by 1.01 dB/K.