calcTLPort
==========
```{function}  calcTLPort( port, SimDir, f, varargin)
```
Full definition:
```{code-block} matlab
[port] = calcTLPort( port, SimDir, f, varargin)
```

Calculate voltages and currents, the propagation constant beta
and the characteristic impedance ZL of the given transmission line port.

The port has to be created by e.g. AddMSLPort().

input:
- port:       return value of e.g. AddMSLPort()
- SimDir:     directory, where the simulation files are
- f:          frequency vector for DFT

variable input:
- 'RefImpedance':  - use a given reference impedance to calculate inc and
                     ref voltages and currents
                   - default is given port or calculated line impedance
- 'RefPlaneShift': - use a given reference plane shift from port beginning
                     for a desired phase correction
                   - default is the measurement plane
                   - the plane shift has to be given in drawing units!
- 'SwitchDirection': 0/1, switch assumed direction of propagation

output:

- output signals/values in time domain (TD):
  - port.ut.tot     total voltage (time-domain)
  - port.ut.time    voltage time vector
  - port.it.tot     total current (time-domain)
  - port.it.time    current time vector

- output signals/values in frequency domain (FD):
  - port.f                  the given frequency fector
  - port.uf.tot/inc/ref     total, incoming and reflected voltage
  - port.if.tot/inc/ref     total, incoming and reflected current
  - port.beta:              propagation constant
  - port.ZL:                characteristic line impedance
  - port.ZL_ref             used reference impedance

example:

    port{1} = calcTLPort( port{1}, Sim_Path, f, 'RefImpedance', 50);

reference:

= W. K. Gwarek, "A Differential Method of Reflection Coefficient Extraction From FDTD Simulations",
  IEEE Microwave and Guided Wave Letters, Vol. 6, No. 5, May 1996



-----------------------
(C) 2010 Sebastian Held <sebastian.held@uni-due.de>

See also AddMSLPort, calcPort