Trace to pad and pad to component mount discontinuity taken into account. Extra metal can be de-embedded. If you need to use a waveguide port because of a ...
Multipin Waveguide Ports A multipin waveguide port is characterized by having more than two conductors in the port region (incl. shielding). The main application is given by homogeneous multiple coaxial or connector ports. The multipin port can also be applied to inhomogeneous ports if the propagation constants of the modes differ only slightly. Shielding
Multipin Waveguide Ports Labeling of Multipin ports
‘Set’= mode number 1(2,+) = port number (mode number, potential)
A ‘Set‘ corresponds to a particular definition of a mode via the potential distribution for the conductors. Therefore, a ‘Set‘ represents a given superposition of the port‘s eigenmodes. Pins without a potential definition are treated as a ground conductor, and potential definitions on pins for another ‘Set‘ are set to zero. CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com | Jan-17
Multipin Waveguide Ports Homogeneous multipin modes The occurring TEM modes are degenerated (having the same propagation constant). The TEM modes are orthogonal to each other, so that they can be superimposed to new (desired) mode patterns. The definition of multipin modes allows you to define exactly the mode pattern that you want to excite.
Example: Differential / Common Mode Port number (mode number, potential)
“Set”=mode number Resulting Modes
Mode 2
Mode 1
“odd mode” / differential mode
“even mode” / common mode
Ethernet standards nomenclature S2(1)1(1) = SDD21 (Differential transmission from port 1 to port 2) S1(2)1(1) = SCD11 (Reflected differential to common mode at port 1) CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com | Jan-17
Multipin Waveguide Ports Inhomogeneous multipin modes The occurring QTEM modes are not degenerated and cannot simply be superimposed. However, for slightly inhomogeneous ports it might be suitable to superpose the resulting QTEM modes using a Multipin port. When the inhomogenity error is not negligible all ports should be defined as single-ended. After the simulation the singleended S-parameters are calculated as a post-processing step and can be recombined in CST DESIGN STUDIO™.
Example for inhomogeneous multipin port defined as single-ended CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com | Jan-17
Multipin Waveguide Ports Single-ended multipin ports The ports are described with respect to every single pin, taking into account individual conductor to ground voltages & currents. The modes describe the coupling of one pin with the other and are non-orthogonal. Single-ended results can be used in CST DESIGN STUDIO™ to obtain arbitrary common or differential S-parameters.
Port Definition on Component Pins Pins cannot always be excited using a waveguide port. In such cases, discrete ports need to be used.
SIG
GND
Horizontal Discrete Port
or Vertical Discrete Port
Consider the current return path. Choose the one closest to measurement setup. Can be easily created within the EDA imports. CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com | Jan-17
Port Definition on Component Pins If you need to use a waveguide port because of a special kind of excitation: Vertical Waveguide Port
1-
1+
Horizontal Waveguide Port
1-
1-
1+
1-
Extra metal can be de-embedded. Note: Mesh needs to be homogeneous for 3 mesh steps in the transient solver. Trace to pad and pad to component mount discontinuity taken into account. CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com | Jan-17
