Inductor Approximations

Transmission lines with shorted loads and transmission line segments may be used to approximate inductors. To approximate inductors, a null frequency may be selected such that the impedance of the transmission line is zero or infinity. Frequencies above the null frequency are aliases of frequencies below the null frequency.

Shorted lossless line input impedance may be described mathematically below.

Shorted Load Lossless Input Impedance

 

It may be seen with this equation that the infinite impedance length of the stub is calculated by setting the length of the line such that

Stub Length Inductor Equation

 

At some desired frequency, w, Zo of the line may then be calculated such that

 

Tx Segment Zo

If it is desire to use a transmission line segment to simulate an inductor, the equation for Zo is,

Transmission Line Segment Inductor Equations