Why does my coax feed look disconnected in the EMerge results?

The floating feed point issue almost always comes down to how the simulation anchors the reference plane at the port location. When you put a coax feed right on the edge, the solver needs a definitive ground plane defined immediatly adjacent to that connection point to properly calculate the impedance and S-parameters. Simply tying the shield to a net named ground might be enough for DC analysis, but EMerge needs that spatial relationship defined in the geometry and the port setup. Try adding a small, dedicated ground pad right next to the coax transition, and then assign that pad specifically as the reference for the port definition itself, separate from the global board ground net. This forces the solver to treat that transition as having a known reference. For the phase-shifter states, you cannot just run them one after the other thru the GUI if you want a full matrix of results. EMerge handles parameter sweeping via the configuration script. You need to define the variable you are changing, like the tuning voltage or phase shift angle, as a parameter in the input file. Then, you use a loop structure within the solver settings to iterate over a list of values for that parameter. For instance, you define a list of angles from 0 to 360 degrees, and the solver will run the analysis for every step in that defined range.

It is critical to check the solver input file configuration for the 'parameter sweep' or 'multi-state' section. If that isn't set up correctly, it will treat the shift states as individual components rather than variables in a sweeping analysis. It should be configured as a sweep over a defined range of values, not just a list of static settings. This method of sweeping parameters is standard for all the FEM solvers because it allows the solver to calculate the resulting impedance and phase response across the entire operational range in one pass, which is much more efficient than running a dozen separate simulations.

I don'm really convinced that adding a small dedicated ground pad is a hard requirement just becasue the shield floats.

If the coax shield is allready tied to a net defined as ground, the solver should see that continuity even if the physical proximity isn't perfect. It seems like forcing a seprate reference point just to define the transition is adding unnecessary complexity to a setup that should handle shared ground planes automatically.

I think the floating feed is a nightmare if your physical layout is right but the port definition is missing a small touch. When I was working on a similar setup for a high Q resonator last month, I found that defining the port center only 50 mils from the ground plane boundary made a huge difference in convergence speed. The solver seemed to handle the reference better when that boundary was extremely close.

It also sounds like the phase shifter state sweeping is hitting a boundary condition issue rather than just a missing loop script. Are you defining the sweep variables in the same physical region of the port definition as the initial geometry, or are they far away? That might be key to getting the matrix to populate correctly.

My setup is a bit diferent since I'm modeling a very small patch antenna structure, and I'm starting to worry about the simulation domain size. It seems like the solver gets confused by the boundary conditions when the board is so close to the edge of the simulation box. Is there a standard rule for how much empty space you need around the components to keep the EMerge solver from messing up the field calculations? I tried making the simulation area bigger, but it relly drove up the mesh count. I'm mainly trying to figure out how much of the physical PCB I need to include in the model vs. just using a simple abstraction for the surrounding enviornment. If I leave alot of empty space, does that help with convergence or is it just wasting resources?

I have personally found that the mesh density right where the transmission line transitions into the port aperture can sometimes be a more subtle issue than the overall domain size. If the solver is struggling with the field values, it often suggests the local grid resolution needs to be significantly increased specifically around that transition point, ensuring there aren't any sharp jumps in the field calculation near the feed entry. I wonder if the convergence settings within the input file itself have a specific recommendation for the element size right at the boundary of the extracted port? It feels like a critical detail that is ussually overlooked in initial setup.