GUI toolkit for RF and MW circuit design that combines S-parameter visualization with synthesis tools for filters, matching networks, attenuators, and power combiners. This is part of the Qucs-S project.
Display S-parameter data in multiple formats:
- Magnitude and phase (Cartesian)
- Smith chart
- Polar plot
- Port impedance
- VSWR
- Group delay
- Read data from Touchstone files and Qucs-S datasets
- Add files by drag-and-drop or via the Add File button
- Manage traces, markers, and limit lines from the data management panel
- Save and restore sessions to a file
- Built-in note-taking widget for annotations
Synthesize schematics for a range of RF building blocks directly inside the tool. Simulation runs internally, no external simulator backend needed. The schematics can be exported to Qucs-S for further analysis.
| Topology | Response |
|---|---|
| Lumped LC — Canonical | LPF / HPF / BPF / BSF |
| Lumped LC — Elliptic | LPF / HPF / BPF / BSF |
| Lumped LC — Direct-coupled | BPF |
| Stepped-Z | LPF |
| Quarter-wavelength | BPF / BSF |
| Capacitively-coupled shunt resonators | BPF |
| Side-coupled | BPF |
| End-coupled | BPF |
| Semilumped | LPF / HPF |
Supports single-port and two-port networks. Complex loads can be entered manually or loaded from a Touchstone file.
| Topology | Elements | Bandwidth | Complex Loads |
|---|---|---|---|
| L-section | 2 lumped | Narrow | Yes |
| Single-stub | 1 TL + stub | Moderate | Yes |
| Double-stub | 1 TL + 2 stubs | Moderate | Yes |
| Multisection λ/4 | N×λ/4 TL | Broad | Real only |
| Cascaded LC | 2N lumped | Moderate | Real only |
| λ/8 + λ/4 | 2 TL sections | Moderate | Yes |
| Tee | 3 lumped | Narrow | Yes |
| Pi | 3 lumped | Narrow | Yes |
| Tapped-C / Tapped-L | 3 lumped | Narrow | No |
| Double Tapped Resonator | 4 lumped | Narrow | No |
Wilkinson, Multistage Wilkinson, T-Junction, Branch-line, Double-box Branch-line, Bagley, Gysel, Lim-Eom, 3-way Improved Isolation, Recombinant 3-way Wilkinson, Wye/Delta/Adams resistive combiners.
Pi, Tee, Bridged-Tee, Reflection, Quarter-wavelength (series/shunt), L-pad (series/shunt), Series resistor, Shunt resistor.
A collection of calculators available from the menu bar:
RF Electronics: reflection coefficient conversions (Γ ↔ Z ↔ VSWR ↔ S11), octaves/decades from bandwidth, frequency-to-wavelength converter, RF power unit converter, free space path loss, image frequency, secondary image frequency.
General Electronics: voltage divider, parallel resistors, parallel inductors, series capacitors.
- Qt 5 or Qt 6
- CMake ≥ 3.x
git clone https://github.com/andresmmera/qucs-s-spar-viewer.git
cd qucs-s-spar-viewer
mkdir build && cd build
cmake ..
make -j$(nproc)GPL-3.0-or-later. See LICENSE for details.