本文中我們設計一個四埠天線來評估多輸入多輸出(Multiple-Input Multiple-Output；MIMO)系統在室內環境下的效能，並分析探討此系統之分集增益(Diversity Gain)、相關係數與通道容量(Channel Capacity)。因多天線在多輸入多輸出系統，使用選擇式分集(Selection Diversity)增益會變的較不顯著；然而，根據我們所提出的天線架構進行量測分析的結果，顯示在強散射(Rich Scattering)與高Ricean K-factor的環境下，相關係數分別低於0.2與0.5，並且透過量測到的通道容量可達理論值，即非相關性通道容量的82%左右。透過實驗與模擬結果，我們所提出的天線架構有很好的效能且接近於多輸入多輸出系統在室內環境下之理論值。

A 4-port antenna is designed for evaluating the performance of an MIMO system in indoor environment.
Diversity gain, correlation coefficient and channel capacity are calculated and discussed in this paper. The selection diversity becomes more unapparent when using more antennas in MIMO system. Correlation in both rich scattering and high K-factor environment are found below 0.2 and 0.5 respectively. Channel capacity is 82% of the ideal case with uncorrelated channel. The above-mentioned results suggest the effectiveness of the proposed antenna. After experiments and simulations, our proposed 4-port antennas achieve better performance for MIMO systems in indoor environment, close to theoretical bound.