Qorvo
MatchCalc
Qorvo MatchCalc is a free downloadable RF/microwave matching calculator with ideal tunable passive components. It displays the impedance of the input and output match in a 50Ω test environment as measured on a network analyzer. Some of its key features are; displays insertion loss/gain of S1P and S2P files, real-time optimization and tuning, plot markers, snap-shot feature to hold static plots, on-tool transmission-line calculator, return loss plots to all input and output ports, ability to create a match report in word and thru-line function that displays input source impedance and output load.
RF Impedance Matching Calculator
The L match circuit gets its name due to the circuit topology – resembling the letter “L”. This tool will help you create a matching circuit so optimal power transfer occurs between unmatched loads at a specific frequency. The calculator provides output data for circuit topology and component values.
3D Smith Chart
Andrei A. Muller (PhD), Alin Moldoveanu (PhD), Victor Asavei (PhD), Cristian Fleischer
The 3D Smith Chart is the first commercially available software tool that enables new capabilities for RF/microwave designers that were not available using the original Smith chart introduced in 1939. First proposed in 2011, the 3D Smith Chart can represent both active and passive microwave circuits on a spherical plot. Using the mathematical concept of the Riemann sphere, the extended reflection coefficient plane is transformed into the surface of the unit sphere. Since the 3D Smith Chart compiles the whole complex plane, all possible loads can be plotted on the chart, which is not possible on the traditional Smith chart. Lossy lines with complex characteristic impedances can also be represented.
Purchase Required
Microwave Impedance Calculator 
Rogers Corporation
This software is intended to assist with microwave circuit design in predicting the impedance of a circuit made with Rogers High Frequency circuit materials. The software also has some capabilities for predicting transmission line losses as well. The user will select the circuit materials and the circuit construction, after which the software will determine the predicted impedance and other electrical information.
The calculator uses well known closed form equations to determine impedance and loss of a given circuit model. The loss calculation is divided into conductor loss and dielectric loss. With specific circuit designs, the calculator also predicts other properties such as wavelength in the circuit, skin depth and thermal rise above ambient.
Free (Requires Registration)
RSplot
RS Microwave Company
RSplot simulator plots and analyses S-parameter files. It is a simple to use application that does not require installation (application is in exe form). RSplot is suitable to plot multiport S-parameter files in rectangular formats.
Free Download
Smith Chart Matching Web App
Besser Associates
Use this handy Smith Chart web app to create matching networks. Easiest tool to use: drag elements right on the chart! Supports multiple frequencies, transmission line elements, etc.
Free Online (Registration Recommended)
SParamViewer
Teledyne Lecroy
SParamViewer is a tool for plotting S-parameters
Features
- Reads standard Touchstone format S-parameter files
- Zoom in for more detail
- Copy and Paste S-parameter data as images, text or Microsoft Excel® format
Free Download
Z-S-Y-A Parameter Conversion Calculator
Daycounter, Inc
This calculator converts between Z-, Y- and S-parameters. S-parameters are a function of the characteristic impedance. All impedances are expressed in rectangular form (R+Xj).
Free Online
VSWR/Return Loss Calculator
Pasternack
Pasternack's VSWR/Return Loss Calculator finds VSWR, Return Loss, Mismatch Loss, and the Reflection Coefficient given any one of the listed input types.
Free Online
The Smith Chart
Pegasus Technologies
This site comprises a comprehensive array of tutorials and related tools, including explanations, examples, references and charting applications.
Free
COMSOL Multiphysics®
COMSOL 
S-parameters, transmission and reflection coefficient, impedance matching properties make up the core information of RF and microwave components. With the COMSOL RF Module, an add-on product to the COMSOL Multiphysics® simulation software, you can virtually tweak your device design to extract the required information and plot with various formats such as the Smith plot. COMSOL Multiphysics® allows you to use traditional mathematical expressions as well as your own user defined equations to further postprocess and extend the results of your analysis.
For more information visit: www.comsol.com/rf-module
General-Purpose Scientific and Engineering Plotting Library
SiberSci, LLC/DISLIN
DISLIN is a FREE general-purpose scientific and engineering plotting library for visualizing engineering and scientific data in numerous 2D and 3D graphical formats. This plotting library permits users to work in both 32-bit and 64-bit environments to write programs for visualizing data that was measured in a laboratory environment, or calculated by commercial or privately developed CAE programs. The DISLIN library is available for Unix, Linux, FreeBSD, Windows, Mac OSX, and MS-DOS systems. Download informational pdf here