Several quantities are available under Port Characteristics. On the Data Source tab, the Secondary Type group includes the Characteristic Impedance, the Effective Dielectric Constant , and Omega-Beta parameters.
Omega-Beta is the propagation constant, β, as a function of radial frequency, ω. This is the fundamental physical quantity determined by the Analyst FEM simulation.
The Effective Dielectric Constant is a wave port quantity, determined by
where β is the propagation constant at the port and k0 is the propagation constant in free space.
For circuit ports, the Characteristic Impedance is equivalent to the user-defined port impedance. In wave ports, the Characteristic Impedance is the calculated characteristic impedance of the waveguiding structure at the port. The characteristic impedance is calculated according to the selection made in the simulation setup dialog, as described here. The characteristic impedance may be computed using either the Power Current method (P/I2), the Power Voltage method (PV2), the Voltage Current method (V/I), or the Wave impedance method. The first three methods use line integrals to determine the current and/or voltage. The wave impedance method computes the impedance from the electric and magnetic fields directly. This last method is only valid for homogeneous solutions. If you request the wave impedance for a simulation that includes trace ports or inhomogeneous waveguides, RF3p will revert to using the Power Current method for all wave ports. Unlike the impedance parameter matrix Z, the characteristic impedance for one port is independent of any other port.