D. N. A. . Zaidel, S. K. A. . Rahim, N. . Seman, R. . Dewan, and B. M. . Sa’ad, “New Ultra-Wideband Phase Shifter Design with Performance Improvement Using a Tapered Line Transmission Line for a Butler Matrix UWB Application”, ACES Journal, vol. 29, no. 08, pp. 611–617, Sep. 2021.