S-parameters are one of the most important information regarding any passive or active component for RF design, simulation and analysis. To ensure the accuracy and quality of the complex system, RF engineers often deals with S-parameters of many devices and components.

**1. ** **AppCad Design Assistant**

**Supported formats**

- Rectangular Plot / Logarithmic magnitude
- Smith Chart
- Polar format
- Smith Chart: Gain/Noise Circle
- Tabular listing (frequency and gain)

**Options**

- Support multiple files for comparison
- Lumped Balun design and tuning
- Voltage biased circuits
- Current biased circuits
- Small signal and large signal detector
- FET and transistor bias source resistor
- Amplifier efficiency
- Transmission line impedance calculation
- Reflection, Noise, Spurs and Intercept point calculations
- Device thermal calculations
- Engineering constants and Complex Math calculations for RF circuits
- Print plots and results

**Limitations**

- Only support 2 port S-parameters

**2. RFSim99**

RFSim99 is a powerful tool to simulate and analyze simple circuits and plot S-parameter files. It can simulate one port and two port measurements with basic passive elements and it is suitable for simple impedance matching and plotting.

**Supported formats**

- Linear magnitude
- Logarithmic magnitude
- Smith Chart
- Polar format
- Phase
- Group delay

**Options**

- Simulate 2 port circuits
- Analyze S-parameter
- Impedance matching

**Limitation**

- Only support 2 port measurements

**3. **** ****RSplot**

**Supported formats**

- Logarithmic magnitude
- Phase format
- Delay

**Options**

- Support multiport S-parameter
- Support multiple files for comparison
- Adjust view
- Adjust Frequency /Span
- Markers and Legends
- Print plots

**Limitations**

- Only support rectangular plots

**4. ****SPview**

**Supported formats**

- Logarithmic magnitude
- Smith chart
- Admittance chart (Y smith)
- Polar format
- VSWR (only for full version)
- Group delay (only for full version)
- Phase (only for full version)

**Options**

- Support multiport S-parameter files
- Script support for more functions (full version)
- Schematic analysis (only for full version)
- Remote communicator for instrument connectivity
- Mix mode analysis

**Limitation**

- Full functions only available with licensed version

## 5. QUCS Simulator

Quite Universal Circuit Simulator is another powerful tool to simulate basic electronic circuits and S-parameters. QUCS is free software under GPL (General Public License) available for all operating systems.

QUCS supports Verilog-A compact model standardization for electronic circuit design and macromodelling.

### Supported formats

- Linear magnitude
- Logarithmic magnitude
- Smith Chart
- Polar format
- Phase
- Tabular
- Smith – Polar Combination
- 3D-cartesian

### Options

- Simulation of electronic circuits with component library and macro modeling
- S-parameter simulation
- DC simulation
- AC simulation
- RF Simulation
- Low Pass, High Pass and Band Pass filter design
- Impedance matching

## 6. S-View S-parameter Viewer

S-View is a simple S-parameter viewer; It allow you to plot the s-parameter data which is used to characterize RF/Microwave components and systems. The S-View supports the touchstone format which has file extensions such as .s1p, .s2p, .s3p, .s4p etc

Download it from Microsoft store: S-view s-parameter viewer

**Conclusion**

RF system complexity has been increasing and thus the challenges in design and implementation also huge. RF engineers are using sophisticated tools for design, simulation and analysis. I hope the above mentioned software can be used for better understanding of S-parameters, simple analysis and as a handy tool for personal use.

Andy says

I need this program

Pine Pienaar says

Maybe slightly off context, but I recently started using QUCS, a free network simulator in the public domain. Not quite as user friendly but it can take over where RFSim99 ends and has a lot to recommend it for those who cannot afford simulators costing the price of a farm. It could therefore profitably be included in this overview.

I need to produce overlay graphs of work on RF networks. Your excellent overviews gave me exactly what I was looking for. Thank you very kindly!

Pine Pienaar says

Thank you for a blog that introduced me to graphing software with the exact features needed to compliment

the RF network analysis I am doing.

To simulate RF networks, I recently upgraded from RFSim99 to Quite Universal Circuit Simulator (Qucs) which is a free-software electronics circuit simulator released under GPL.

It has a graphical user interface that features; schematic capture and data visualization and is able to support all kinds of circuit simulation types, e.g. DC, AC, S-parameter, Transient, Noise and Harmonic Balance analysis as well as pure digital simulations.

It aims to be much simpler to use and handle than other circuit simulators like gEDA or PSPICE and in my opinion it deserves mention in this blog.

Rajiv says

Thanks for your suggestion. We haven’t tried this program (Qucs) yet.

Wiwyam says

I use a really nice free Smith chart tool, it’s great for interactive RF matching and is free and is online!

http://www.will-kelsey.com/smith_chart/

John Rogers says

Very interested in these free SWs but I need recommended choice for my particular need. I measure passive components with complex parasitic elements. Even after compensation the high frequency S21 S11 results become noisy. I would like to build lumped lumped element models which can be tweaked to cleanly emulate the overall measurement results. Then use the lumped element model to create the S parameters. In other words I want to filter the data with theoretical model.

Rajiv says

Thanks for your comment. Free software has lot of limitation for detailed analysis of S-parameter characteristics. You may need to consider AWR microwave office or ADS for design and analysis.

Ro man says

This program is powerful and free. I like it https://www.ag-rf-engineering.de/products/software/s-parameter-viewer/

Istvan Nagy says

None of these support displaying the X axis frequency in logarithmic scale. Why??