M-Model: A New Precise Medium-Length Transmission Line Model

Real transmission lines are translated into mathematical models using either the lumped parameter approach or the distributed parameter approach. The first one is used for short- and medium-length transmission lines, while the other is used for long-length transmission lines where the accuracy and precision are required. For medium transmission lines, the lumped parameter approach can be applied using one of four popular circuit representations known as gamma ($\Gamma$), opposite-gamma ┐, tee (T), and pi $\Pi$. This study presents a new circuit representation called em (M). This model is inspired by the sagging phenomenon where, at the sag point, the distributed series impedance of the $\Pi$-model is divided into two equal/unequal parts and the distributed shunt admittance at the center is bigger than that at both ends. For some numerical experiments, the M-model shows a stunning performance in estimating transmission line readings. It wins in most cases and, for the few remaining cases, the M-model shows very competitive results.