The bounding box of the picked end face will then exactly define the dimension of the port. If the interior of the waveguide is modeled by a dielectric material block, you can simply pick the end face of the waveguide as shown in the picture below: The port dimensions will then automatically adjust to the bounding box of the picked elements. The easiest way to define a port’s face is to pick structure elements such as points / edges / faces before opening the port definition dialog box. However, it is important to make sure that the port covers the entire waveguide cross-section. The port assignment for this type of waveguide is quite simple. The most frequently used waveguide type of this category is the rectangular waveguide shown below: Microstrip Lines / Coplanar Lines (QTEM Modes)ĭielectrically Loaded Waveguides (Hybrid Modes) Inhomogeneous Waveguide Ports (Special Treatment in the hexahedral Time Domain Solver) Please note that the input signal of an excited waveguide port is normalized to 1 sqrt(Watt) peak power. The strategies to properly define waveguide ports depend a bit on the type of the transmission line. In the following we focus on the most commonly used applications. The number of modes to be considered in the solver calculation can be defined in the waveguide port dialog box. The eigenmode solver can then calculate the exact port modes within these boundaries. In general, the definition of a waveguide port requires enclosing the entire field filled domain in the cross section of the transmission line with the port area. This procedure can provide very low levels of reflection below -100dB in some cases. CST Microwave Studio uses a 2D eigenmode solver to calculate the waveguide port modes.
Very low reflections can be achieved when the waveguide mode patterns in the port match perfectly with the mode patterns from the waveguides inside the structure. The waveguide modes travel out of the structure toward the boundary planes thus leaving the computation domain with very low levels of reflections. This kind of port simulates an infinitely long waveguide connected to the structure.
Waveguide Port Overview Waveguide Port Overview Waveguide ports represent a special kind of boundary condition of the calculation domain, enabling the stimulation as well as the absorption of energy.