S-parameters and Smith chart

The S-Parameters tab is where you read the simulated response. dB-magnitude plots, the Smith chart, and Touchstone export all live here. It is also where you bring measured traces in for comparison.

dB Magnitude

The default view. S₁₁ is selected on first open. For multi-port projects the toolbar adds S₂₁ and a More Parameters dropdown that lists every cross-term the run captured. Toggle individual parameters from the Sxx / Syy buttons.

Markers

Press M or click Place Marker, then click on the curve to drop a marker. Each marker reads out frequency, magnitude in dB, fractional bandwidth between the nearest -10 dB crossings, and impedance Z. Drag a marker to move it.

The orange Target Resonance marker is automatic. RayRF finds the deepest dip in the swept band and labels it. Turn it off from the right-click menu on the marker.

Smith chart

Click Smith Chart to switch view. The trace shows the impedance trajectory over frequency. A well-matched antenna passes near 50 ohms at the design frequency. Loops indicate resonances and antiresonances. The chart shares markers with the dB view, so dropping one in either reads back in both.

Split view

The Split View button at the left of the toolbar puts dB Magnitude on the left and Smith on the right in a single frame. Markers stay synced across the two panels: drag in either, the other follows.

Multi-port simulations

With more than one active port, the run captures the full S-matrix. The More Parameters dropdown opens a checklist of every S_ij combination. Tick the ones you want plotted and the plot carries one trace per checked parameter, colour-coded in the legend.

Comparing against measured data

Click Import S1P (the label switches to .sNp for higher port counts) to overlay an external Touchstone trace on top of the live result. Use this to compare against a published S-parameter file, a vendor datasheet, or a VNA capture from your bench. Imported traces show up in the Imported Traces panel with an X button to remove individual entries. The legend marks them so you can tell simulated from imported at a glance.

Exporting

• Export Touchstone (.sNp). The primary external format. RayRF writes proper headers (frequency unit, format, Z₀) and one row per swept frequency.
• Export CSV. The same data as Touchstone, in comma-separated form for spreadsheets.
• Export PNG. Saves the current plot view. Use Split View to capture both dB Magnitude and Smith in one image.