The Salitronic Antenna Tuner is a free online antenna matching tool. It needs JavaScript and runs entirely in your browser, so your files are never uploaded.
It reads Touchstone, CITIfile and CSV S11 data, plots it on a Smith chart with return loss, VSWR, impedance and delivered power, and designs matching networks by hand or automatically with real component losses and self-resonance.
Read more about the Antenna Tuner or ask about RF design services.