# Transport Lag Of Polar Plot

**Transport lag of polar plot**

The transport lag

can be written

Fig: 1 Fig: 2

Since the magnitude of G(jω) is always unity and the phase angle varies linearly with ω, the polar plot of the transport lag is a unit circle, as shown in Figure1.

At low frequencies, the transport lag **e ^{-j}**

**and the first-order lag**

^{ωT}**1/(1 j**

**ωT)**behave similarly, as shown in Figure 2. The polar plots of e

^{-j}

^{ωT}and 1/(1 jωT) are tangent to each other at w = 0. This may be seen from the fact that, for

**ω << 1/T**,

For ω >> 1/T, however, an essential difference exists between e^{-j}^{ωT} and 1/(1 jωT), as may also be seen from Figure 2