Comparative Study of Mutual Coupling Effects in Microstrip Antenna Arrays Using Array Factor and Simultaneous Excitation Methods

Mutual coupling in microstrip antenna arrays presents a significant challenge, particularly since modern wireless communication systems demand high-performance ar-rays with minimal interference between elements. This study investigates the mutual coupling characteristics of a 2xl linear microstrip antenna array, utilizing both inset-fed and coaxial probe-fed configurations. The analysis is carried out using the array factor method and full-wave simultaneous excitation in CST Microwave Studio 2024, focusing on element spacings of 0.5 <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\lambda$</tex> and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$0.75\lambda$</tex>. Key performance metrics such as 8-parameters, radiation patterns, and E-field distributions are examined. The results reveal that mutual coupling significantly affects array performance, especially at closer spacings, where the inset-fed configuration shows more pronounced coupling effects, including higher 8<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">12</inf> values and greater radiation pattern distortion. However, increasing the element spacing to 0.75λ mitigates these effects, improving impedance matching, and reducing mutual coupling. The coaxial probe-fed configuration consistently demonstrates better performance, particularly at a larger spacing, where mutual coupling is minimized. These findings underscore the importance of carefully selecting feeding methods and element spacings to optimize antenna array performance in practical applications.