##### Explicit Ground Reference

The following image shows use of a lumped port to apply a voltage to the end of a thick conducting trace. In this geometry, the trace is metal and the lumped port patch connects the trace to the ground plane, where the ground plane is defined by a PEC impedance boundary condition on the bottom face of the geometry. Note that in this example the port happens to lie on the interior of the structure but this is not required.

To define the explicit ground reference, create a lumped port patch by drawing a rectangle that touches both the trace and the ground (see Surface Rectangle for details on drawing rectangles) and applying the port attribute to the rectangle. In the following geometry, the port attribute is also applied to the end of the trace to allow for control of the port's polarity as described in Polarity.

By default, RF3p will define 10 integration paths connecting the trace to the ground. This value is usually sufficient, but if you have a very fine mesh in the vicinity of the lumped port you may wish to increase this number by changing the value in Lumped Only/Integration Path Count in the port properties. To see the integration paths, create a port mesh annotation for the lumped port as follows:

The 10 paths are evenly distributed across the patch.

Lumped ports can also be used with zero thickness conductors. The following image shows a lumped port that has been applied to the edge at the end of a 2D rectangle, as well as to the port patch. Note that in this example the port happens to lie on the exterior of the structure but this is not required.

The geometry may have any number of lumped ports, and those ports may have any relation to each other in space. The three ports in the following image are completely independent sources, as explained in Port Indices.

If two ports are given the same port attribute, they are sourced together. In the following image, the two ports will be at the same voltage with respect to ground.

In every previous example with a lumped port patch, the patch has connected the trace to a ground plane. In practice, the patch may lie between the port trace and any other conductor in the geometry. In the following figure, the patch goes between two of the traces, so that the left trace is considered ground for the purposes of the port calculation.