Insertion loss of unbalanced transmission line crossing a rectangular aperture in an infinite backplane

This paper presents the backplane effects for two-wire transmission lines with an unbalanced transmission line crossing the rectangular aperture in a infinite ground backplane. The FDTD method is used to determine the characteristics of the backplane insertion and return losses of the transmission line in accordance with the transmission line spacing and additional wire lengths. The results show that the insertion gain is obtained from the narrow spacing of the transmission lines and the insertion losses appear by the transmission line with the additional wire. The measurements of the return loss is performed to verify the theoretical analysis.