SmPoint

Plots a point on the chart at a given normalised impedance (resistance + reactance). Renders as an SVG <circle> element, so all native SVG circle attributes work.

Demo

Drag the sliders to move each point.

Point 1

res = 0.00 react = 0.00

Point 2

res = 1.00 react = 0.00

Point 3

res = 0.60 react = 0.80

Usage

<SmithChart>
  <SmPoint :res="0"   :react="0"   fill="red"   />
  <SmPoint :res="1"   :react="0"   fill="blue"  />
  <SmPoint :res="0.6" :react="0.8" fill="green" r="10" />
</SmithChart>

Props

Prop	Type	Default	Description
res	Number | String	—	Normalised resistance. 0 = short circuit, 1 = matched load.
react	Number | String	—	Normalised reactance. Positive = inductive (upper half), negative = capacitive (lower half).
r	Number | String	5	Radius of the plotted circle in pixels.

Any additional attribute you pass (fill, stroke, stroke-width, opacity, etc.) is forwarded directly to the underlying <circle> element.

How coordinates are calculated

The Cartesian coordinates (a, b) of a normalised impedance r + jx on the Smith Chart are:

$$ a = \frac{r^2 - 1 + x^2}{(r+1)^2 + x^2}, \qquad b = \frac{2x}{(r+1)^2 + x^2} $$

These map (a, b) from the [−1, 1] normalised plane to SVG pixel coordinates using the radius provided by the parent <SmithChart>.