Yellow boxes and yellow nodes on the graph = input.

Blue boxes = output.

SmithMatcher 2.3 is a web-based, non-commercial, non-sniffing freeware to interactively manipulate and calculate Pi-matching networks, whilst displaying the results visually in real-time. It runs in any modern browser, e.g. Firefox.

Besides calculating, it is useful for gaining insight in the workings of a Smith chart. The underlying math was taken from David Knight's impedance matching theory, see G3YNH Impedance Matching. The underlying math applies plane trigonometry. The match is found by finding the appropriate roots of a reactance line on the in/output constant conductivity circles.

For the capacitors an infinite Q is assumed, whilst the inductor Q can be input and is assumed constant. Inductor Q is usually around the 100-200 mark.

Setting one of the minimum C-values to zero yields an L-network. For a symmetrical network, split the coil in two equal parts and ensure both parts do not couple (make 90 degree angles between the coils).

Typical usage for antenna matching:

1) Measure antenna impedance with a VNWA, or find it by an antenna design program such as MMANA or EZNEC.

2) Use this tool to find the required matching network. Note that when matching e.g. Yagis, which are ususally low-impedance, the inductivity can also be achieved by lengthening the radiator slightly e.g. 24+j0 Ohms becomes 24+j20 Ohms. Doing so, you end up with only a single matching capacitor. In any case, make sure you know how to use and calibrate the VNWA you are using!

3) Once a matching network has been implemented, and the resulting impedance is measured, it will likely not deliver the exact match due to part tolerances. In such case, the modes "Tx --> Ant" or "Ant --> Tx" can be used. It shows the impedance at the OTHER side of the network. This is useful for making the final adjustments to e.g. a yagi, usually by changing its reactance by manipulating the length of the radiator (use your design program to determine the ratio Δlength/Δreactance, to make a precise single adjustment. Note that yagi impedance significantly changes with height, so every measurement taken must be at the final position!

No responsibility whatsoever for using this program is assumed. Use at your own risk and peril.

Enjoy, PA2EVR 2016-