The drawback of polar plots is that impedance values cannot be read directly from the display. The magnitude of the vector is the distance from the center of the display, and phase is displayed as the angle of vector referenced to a flat line from the center to the rightmost edge. But instead of actually plotting impedance, we display the reflection coefficient in vector form. The polar plot is very useful since the entire impedance plane is covered. Unfortunately, the open circuit (quite a common impedance value) appears at infinity on the x-axis. Since any impedance can be represented as a real and imaginary part (R+jX or G+jB), we can easily see how these quantities can be plotted on a rectilinear grid known as the complex impedance plane. Let's review how complex reflection and impedance values are displayed. 2 o Rectilinear impedance plane -90 o Constant X Z = Zo L Constant R G = Smith Chart maps rectilinear impedance plane onto polar plane The amount of reflection that occurs when characterizing a device depends on the impedance the incident signal sees.
