RFdude Smith Chart V2

Free, unsupported software, provided as-is. I do not plan to maintain this project, respond to feedback or support requests, or accept pull requests in general. There may be exceptions....

A new cross-platform implementation of Lance Lascari's RFdude Smith Chart application, built with Qt 6 Widgets and C++20. The legacy application is a read-only behavior reference, not a build dependency.

Acknowledgments

Lance Lascari created the original RFdude Smith Chart application and directed this new V2 project. GitHub Copilot was the principal implementation assistant for this phase and performed most of the implementation work, including substantial code, testing, and documentation contributions, under Lance's direction and review. The V2 project is a new implementation; the original application's source code is not included. Copilot is an AI tool, not a project maintainer or copyright holder.

Status: initial prototype; not full legacy feature parity. The original RFdude Smith Chart V2 code and supplied legacy .lls examples are licensed under the MIT License. The original application's source code and third-party materials are not included in that license. See NOTICE.txt for attribution, scope, and third-party notices.

Build and run

cmake -S . -B build -DCMAKE_BUILD_TYPE=Release
cmake --build build --parallel 2
./build/RFdudeSmithChartV2

Open the supplied legacy example directly:

./build/RFdudeSmithChartV2 examples/legacy-example.lls

Open the included RFdude project example:

./build/RFdudeSmithChartV2 examples/network.rfs_45Mfilter.json

Packaged installs include both examples under share/RFdudeSmithChartV2/examples inside the application install location. Use File -> Open examples... to browse them without finding the install directory yourself. Examples open as templates: Save asks for a filename for your own copy rather than overwriting the bundled file.

Component dialogs use Tab / Shift+Tab to cycle between visible input fields, skipping action buttons. Return / keypad Enter accepts the current valid component, including a selection in an open dropdown. Cancel requires a mouse click; Escape does not discard the component edit.

Build and test

Requirements: CMake 3.21+, a C++20 compiler, Qt 6.5+ Widgets and Test development packages. Use the same compiler/architecture as the installed Qt distribution. On Ubuntu 24.04+, the development dependencies are typically:

sudo apt install build-essential cmake qt6-base-dev qt6-base-dev-tools

Configure and build as above, then:

ctest --test-dir build --output-on-failure

For a Visual Studio multi-configuration build, add --config Release to the build command and -C Release to CTest. Tests use Qt's offscreen platform; they do not launch or manipulate the legacy program or touch its repository.

The GitHub workflow builds, tests, and packages Linux x64, Windows x64, macOS Intel, and macOS Apple Silicon builds using Qt 6.8.3. Each macOS build sets and checks its target architecture explicitly. Download packages from an Actions run's Artifacts section; artifacts are retained for 30 days. Passing builds on main and version tags also publish Linux, Windows, and both macOS installers together as GitHub Release pre-release assets, with checksums and source/build metadata. Pull requests and failed builds never publish releases. The Windows download is a setup .exe; the Linux download is a .deb package that installs into the desktop app menu; macOS downloads are architecture- specific .dmg disk images. The Windows package may still be uploaded if its build succeeds but UI tests fail; its -tests-failed artifact suffix means it has not passed CI tests. The workflow is enabled in repository settings. To run the same installer builds in your own fork, see Build installers with GitHub Actions.

Downloads

Do not install the original v0.1.0 Linux .deb. It installs a shared /usr/bin/qt.conf and Qt runtime files that can break KDE/Dolphin. On affected machines, remove rfdudesmithchartv2, run sudo ldconfig, and reboot. The unsafe release download has been replaced with rfdudesmithchartv2_0.1.0-1_amd64.deb, which uses a private Qt runtime. It was tested successfully on the two affected Kubuntu 26.04 LTS computers and subsequently uninstalled. See the release notes for recovery instructions and validation limits. Discard old installer copies; the Windows installer is unchanged.

Versioned Linux, Windows, and macOS installers are published on the GitHub Releases page. They are unsigned and unsupported, and the macOS DMGs are not notarized; review the release notes before installing.

VS Code: local desktop building and debugging

This is a desktop Qt/C++ CMake project, not an STM32 or embedded firmware project. No board, probe, flashing, or debug server is involved.

The checked-in VS Code launch configuration targets Linux with GDB. Install the dependencies above plus gdb, and open the repository root as a folder in VS Code. Install the recommended CMake Tools and C/C++ extensions if prompted. If CMake Tools asks for a configure preset, select Desktop Debug.

• Build: press Ctrl+Shift+B. This configures and builds the Debug preset.
• Debug: open Run and Debug, select Desktop Qt app (GDB), and press F5. It builds first, then launches the desktop app under GDB.
• Breakpoints: click beside a source line in the editor before pressing F5. For a first test, set one at MainWindow window; in src/main.cpp. When paused, inspect Variables, Watch, and Call Stack; use F10 to step over, F11 to step into, F5 to continue, and Shift+F5 to stop.
• Run without debugging: press Ctrl+F5.
• Test: use Tasks: Run Task from the Command Palette, then select CMake: test Debug. It builds first and runs all five local test suites (GUI tests use the offscreen platform). CMake Tools also exposes the tests in Test Explorer after configuration.

To open a project at startup while debugging, set args in .vscode/launch.json to ["examples/legacy-example.lls"]. By default it opens a new document. The application uses your normal desktop display; only the automated tests use Qt's offscreen platform.

CMake generates the build files; the compiler builds the executable; GDB runs it with breakpoints. The Debug preset includes debug symbols and uses build/debug/, separate from the manual Release build in build/. These same local operations can be run in a terminal:

cmake --preset debug
cmake --build --preset debug
ctest --preset debug
./build/debug/RFdudeSmithChartV2

The presets and VS Code configuration are shared in Git; generated output is ignored. Windows/macOS require a native debugger launch configuration; the checked-in F5 configuration is for Linux. Nothing here enables GitHub Actions or runs remote builds.

First-milestone functionality

• Impedance/admittance Smith chart with resize-safe, antialiased rendering.
• Series/shunt R, L, C and compound series/parallel RLC elements.
• Lossless through transmission lines and open/shorted shunt stubs.
• Ideal transformers, lossless coax with electrical/physical length input, and microstrip elements with a dimension calculator and dielectric loss.
• Frequency-scaled line lengths, highlighted trajectories, endpoint impedances, goal marker, cursor inspection, and sampled maximum-Q overlays.
• VSWR, reflection magnitude, return loss, and mismatch loss relative to the real chart reference impedance.
• Component insertion after selection, editing, deletion, and undo/redo.
• Bottom schematic pane showing the existing RLC, line, and stub networks, with synchronized selection and double-click editing.
• Versioned JSON save/load with atomic writes and unsaved-change protection.
• Read-only import of the supported legacy .lls archive layouts.
• PNG export of the chart, complete schematic, and frequency response with network settings, the ordered circuit description (connections, values, and resulting impedances), and RF metrics.
• Editable LTspice schematic export with ideal components and an AC test source.
• Legacy-style MatchMe and simple Chebyshev filter synthesis wizards, with component previews and undoable network replacement.
• Two-port S11/S21/S22 magnitude response, linear/log frequency sweeps, a linked analysis-frequency marker, and separate frequency-response PNG export.
• Touchstone 1.x .s2p circuit blocks and .s1p frequency-dependent loads, embedded in projects, with complex interpolation and real-reference conversion.

Keyboard and mouse

In the component dialog, the active input has a thick accent-colored border and highlighted text area. Tab and Shift+Tab follow the visible form order: type, connection, values, and OK/Cancel, wrapping around; arrow keys change the focused dropdown selection.

Input	Action
C, L, R	Add capacitor, inductor, resistor; choose series/shunt in dialog
T	Add through line or open/shorted shunt stub
X	Add compound RLC; choose series/parallel type and tuning parameter
I	Add ideal transformer (source-side : load-side turns ratio)
K	Add coaxial cable or coax stub
B	Open microstrip calculator / add microstrip element
Left / Right	Select previous / next component (wraps)
Up / Down	Multiply selected value by 1 +/- tuning step / 100
Mouse wheel over chart	Tune selected value, one step per wheel notch
Ctrl + Up/Down or wheel	Tune frequency
Shift + Up/Down or wheel	Tune real reference impedance
E / double-click	Edit selected component
Delete	Delete selected component
Click chart trajectory / table row / schematic component	Select component
Right-click inside chart	Inspect impedance; use as starting/goal impedance
S	Network setup, starting/goal impedance, title, and frequency presets
W	MatchMe wizard: lumped low-pass/high-pass or quarter-wave transformers
Ctrl+W	Simple Chebyshev low-pass/high-pass filter wizard
Ctrl+J	Open frequency-response window
F, Z, P	Setup focused on frequency, reference impedance, tuning step
F1 / F2 / F3	Recall configured frequency preset
A, G, Q, M, V	Toggle admittance, polar values, Q curves, labels, VSWR circle
Ctrl+N / O / S	New / open / save (platform-standard equivalents on macOS)
Ctrl+Z / Ctrl+Shift+Z	Undo / redo (platform-standard equivalents)

Values use MHz, ohms, nH, pF, and degrees. A line's electrical length is specified at its own reference frequency, not necessarily the current analysis frequency. The ideal shorted-stub trajectory starts at 90 degrees (an open shunt branch) and moves toward the specified electrical length, matching the legacy concept. Up then Down is deliberately not an exact inverse: the original percentage semantics are preserved.

Component dialogs open with the primary value selected for typing. Press Enter (or keypad Enter) to accept the component, or Esc to cancel. For compound RLC components, the initially selected field is the tuning parameter. The network setup dialog also uses OK as its default action.

Bottom schematic

The schematic shows the source on the left and the starting-impedance load on the right, consistent with LTspice export. Component order is reversed visually because Smith-chart transformations start at the load and work toward the input; component numbers still match the table and chart. The goal is not a termination. The source resistor equals chart Z0; the load box represents the configured complex starting impedance at the current analysis frequency.

The default pane is compact: 140 logical pixels per component and 200 high, leaving more room for the Smith chart. Short value labels omit secondary parameters; hover for the complete description, or use the component table. The same compact layout is used in PNG reports, with full parameters retained in the report's detailed table. A 960-pixel schematic area fits five components plus source/load on one row; a 1200-pixel area fits six.

Drag the horizontal divider to resize the pane, and use its horizontal scrollbar for long networks. A vertical scrollbar is available when the pane is too short to show all labels. Selecting a component in the table or chart, or with the keyboard, scrolls its schematic into view. Click a schematic component to select it, or double-click to edit it. Selection alone does not modify the project. Existing keyboard editing/tuning shortcuts also work with the schematic focused; the schematic's scrollbars/wheel navigate the view rather than tune values.

Compound RLC symbols show their internal series/parallel topology independently of their series/shunt connection. The schematic is a view of the existing network, not a free-form wiring editor. PNG reports include the complete schematic between the chart and circuit description, independent of the pane's scroll position. Long schematics wrap into numbered, left-to-right continuation sections at component boundaries, keeping symbols and values readable rather than shrinking the entire circuit. Exported schematics use black on white without selection highlighting. LTspice export uses the same circuit orientation.

Transformers, coax, and microstrip

Ideal transformer

Use Add -> Ideal transformer... (I). The ratio is explicitly source-side turns / load-side turns, shown as N : 1. The transformation is Zsource = N^2 * Zload, including complex impedances. Thus 2 : 1 transforms a 50-ohm load to 200 ohms; 0.5 : 1 transforms it to 12.5 ohms. The model is lossless, frequency-independent, and has no magnetizing inductance, leakage, or parasitic capacitance. It is a through element only. Up/Down tunes the turns ratio; schematic windings have corresponding polarity dots.

Coaxial cable

Use Add -> Coaxial cable... (K). Set characteristic impedance and select electrical length in degrees at a reference frequency, or physical length in mm. Physical length uses either velocity factor v/c (default 0.66) or a dielectric constant with VF = 1/sqrt(Dk). Propagation is nondispersive and lossless; conductor/dielectric cable attenuation is not modeled.

Through lines and open/shorted shunt stubs are supported. Up/Down tunes whichever length input mode is active. Electrical and physical inputs are stored separately; switching modes uses that mode's stored value, not an automatic conversion. Velocity factor/Dk affects the RF result only in physical-length mode.

Microstrip calculator and elements

Use Network -> Microstrip calculator / add element..., Add -> Microstrip..., or B. All dimensions default to mm. The initial substrate is Dk 4.2, 1.5 mm high with tan(delta) / DF 0.02; strip width defaults to 3 mm and length to 10 mm. Substrate height is the distance from the strip to its ground plane, not necessarily the total thickness of a multilayer PCB. The resizable calculator separates its inputs, calculated results, and model limits; preview values use concise precision without reducing input precision.

• Enter width, substrate height, and Dk to calculate characteristic impedance and effective Dk immediately.
• Enter a target impedance and click Calculate width from target impedance to synthesize width. Invalid or unattainable geometries report an error.
• Set physical length, or electrical length at the reference frequency. The preview reports electrical length and matched dielectric loss in dB at that reference frequency. The target impedance is a calculator input; the element's actual impedance always comes from its stored geometry.
• Select through, open stub, or shorted stub; OK inserts/applies the element, while Cancel leaves the network unchanged. Up/Down tunes the active length.
• Geometry, substrate Dk/DF, and both length inputs survive save/reopen.

The impedance/effective-Dk calculation is the Hammerstad-Jensen quasi-static, zero-thickness model for a single strip above an infinite ground plane. Supported width/height ratios are 0.01-100 and Dk is 1-128. Width synthesis uses bounded bisection over this range, not a guessed impedance-to-width conversion.

Microstrip includes a weak dielectric-loss, quasi-TEM propagation model with real characteristic impedance. For q = (effectiveDk - 1)/(Dk - 1), beta = 2*pi*f*sqrt(effectiveDk)/c and alpha = beta*Dk*q*DF/(2*effectiveDk) in Np/m. The implementation uses the equivalent filling factor directly, including the finite limiting case at Dk=1. The distributed line uses complex propagation alpha + j*beta; this affects both through lines and stubs, rather than adding an arbitrary lumped resistor. DF must be 0-0.1; zero recovers the lossless model. Matched line attenuation is 8.68589*alpha*length dB, not the chart's input mismatch-loss metric.

Limits: no copper-thickness correction or conductor/roughness loss, solder mask, radiation, discontinuity, open-end extension, or frequency dispersion. Dk and DF are treated as frequency-independent. Use an EM solver or more complete line model when the quasi-static/weak-loss assumptions are inappropriate.

Matching and filter synthesis

Both wizards are available in the Network menu and on the toolbar. They follow the original Windows program's MatchMe and simple-filter workflows, not a general-purpose optimizer. Change the controls to preview the complete component list and endpoint. Replace network explicitly applies the preview; Cancel/Esc leaves the document unchanged. Replacement is one undoable operation, including start/goal, title, frequency, and display changes.

MatchMe (W)

• Choose Lumped low-pass, Lumped high-pass, or Quarter-wave transformer.
• Specify 1-10 sections, complex starting and goal impedances, and the design frequency. Defaults come from network setup, not the selected component or current endpoint. The existing components will be replaced, not appended.
• Intermediate resistances follow equal-ratio steps. Low-pass sections use series L/shunt C; high-pass sections use series C/shunt L. Step-down networks reverse the ladder order. Quarter-wave sections use 90-degree lossless lines referenced to the design frequency.
• Series elements cancel the starting reactance and add the goal reactance. Both resistances must be positive. The preview reports unsupported component values or numerical limits and disables replacement.
• Like the original, synthesis enables Q curves and the chart-Z0 VSWR circle.

Unlike the old equal-resistance example fallback, this wizard never changes the requested starting resistance to invent a match. Already identical impedances need no components; equal resistances with differing reactances need only reactance compensation. All nonzero reactances are accounted for, rather than using the old 2%-of-resistance compensation threshold.

Simple filter (Ctrl+W)

• Choose Chebyshev low-pass or high-pass, shunt-first or series-first, ripple cutoff in MHz, passband ripple in dB, order, and termination resistance.
• As in the original, requested orders are 3-15; even values round up to the next odd order, visibly shown in the preview. Ripple range is 0.0001-10 dB, defaulting to 0.1 dB. The default is a third-order, shunt-first low-pass.
• Synthesis sets real starting/goal impedances and chart Z0 to the specified resistance. Elements alternate series/shunt starting at the starting impedance; the odd-order equal-termination ladder is symmetric.
• The analysis frequency is explicitly set to the ripple cutoff, and the title records the effective order, response, cutoff, and ripple. The original left analysis frequency unchanged when a different cutoff was entered.
• The calculation uses the legacy Chebyshev prototype recurrence with an exact dB conversion instead of its rounded 17.37 constant.

Ripple/cutoff describe matched-source/load insertion loss, not the chart's mismatch-loss metric. These are ideal LC ladders: there is no finite-Q loss model, band-pass/band-stop transform, Butterworth/Bessel selection, or automatic value rounding. Generated components remain editable and can be saved, tuned, or exported to LTspice like manually entered networks.

Frequency response

Open Network -> Frequency response... (Ctrl+J), the toolbar action, or View -> Frequency response.... The nonmodal window stays open while editing the circuit. S11 is red, S21 blue, and S22 dashed green; coincident traces overlap. All existing elements, including transformer ratios and microstrip dielectric loss, are included.

• Set start/stop in MHz, 2-2001 points, linear/log frequency scale, and a real reference impedance shared by both ports; click Apply sweep.
• Port 1 is the source/input end; port 2 is the load end. The component order matches the source-to-load schematic, not the load-to-input table ordering.
• The starting impedance, goal impedance, and schematic source resistor are external terminations, not included in the plotted two-port.
• S11 assumes port 2 is terminated in the selected port reference. It equals the Smith chart's endpoint reflection only when the chart's starting load and chart reference both match that port reference. S22 similarly assumes port 1 is matched. S21 is transmission under these matched-port conditions, not the chart's mismatch-loss metric.
• The port reference initially copies chart Z0, then remains independent. Editing chart Z0 does not silently change the response reference.
• Click the plot to set the main analysis frequency. The Smith chart, table, and metrics update through the normal undoable document operation. Conversely, tuning or recalling the main frequency moves the response marker. Marker values are computed at the exact frequency, not interpolated from sweep samples; an out-of-range marker is reported explicitly without moving the sweep limits.
• Circuit edits, undo/redo, and new/open update an open response window. Selecting a component or changing plot controls does not modify the circuit. Closing/reopening the window retains controls during this application session; sweep settings are not saved in project JSON.
• Export plot PNG... writes the plot, title, applied range/port settings, and marker readout. Pending, unapplied controls do not appear in the report. File -> Export chart / schematic / response PNG... combines the Smith chart, full schematic, response plot, complete component table, and metrics in one image. It uses the same applied response settings, including when the response window is hidden. Before the first response view/export, a default sweep is created. Invalid response settings report an export error rather than silently omitting the plot; apply a valid sweep in the response window.
• Terminated input: S11 only includes the starting/measured load and plots the circuit's input reflection. S21/S22 are not defined in this view and are hidden, not fabricated. This is the default when importing a one-port load. Select Two-port circuit: S11/S21/S22 to exclude that load again.

The plot shows 20*log10(|S|) with a -100 dB floor, clipping deeper nulls only visually. Its upper limit is normally 0 dB and expands for measured gain. Exact zero is shown as -inf dB in the marker readout. The engine retains complex S11/S21/S12/S22 internally, but this first UI shows magnitude only, not phase or group delay. Invalid sweeps clear stale traces and display an error. A finite sample grid may miss narrow resonances; increase point count or narrow the range as needed.

The engine cascades element scattering matrices rather than multiplying raw ABCD matrices, avoiding overflow for long attenuating cascades and supporting exactly blocking stubs. Numerical tests compare known transformer/line results, matched-line dielectric attenuation, analytic Chebyshev insertion loss, reciprocity/passivity, and the existing terminated-impedance calculation.

Touchstone measurements

Use File -> Import Touchstone... or Network -> Import Touchstone block / load.... The import is undoable and opens the frequency-response view.

• A .s2p file inserts a measured two-port after the selected table component. The schematic shows a box with port 1 toward source/input and port 2 toward the load, plus its filename. S12 is retained separately from S21; active and nonreciprocal data are not forced to be passive or reciprocal. Cascading and terminated Smith-chart calculations use the measured matrix. Active impedances may lie outside the Smith-chart unit circle; VSWR/mismatch loss and sampled-Q values are marked undefined where their passive definitions do not apply. This is not a stability analysis.
• A .s1p file replaces the starting load with its measured S11. Existing circuit components are retained. The load appears as S1P in the schematic. Use Network -> Use constant starting load, or uncheck Use imported one-port load in Setup, to return to the stored constant start impedance. Using a chart point as the starting impedance also removes the measured load.
• Accepted files use Touchstone 1.x S data, RI, MA, or DB pairs, Hz/kHz/MHz/GHz, and one equal, real positive reference resistance. Comments and wrapped records are supported; two-port order is S11, S21, S12, S22. Standard omitted-option defaults are GHz/S/MA/R50. Version-2 keyword blocks, mixed-mode/multiport data, noise data, and non-S formats are rejected explicitly rather than guessed. Limits: 16 MiB per file, 100,000 samples, strictly increasing positive frequencies.
• Interpolation is linear in complex Cartesian S values versus frequency, before conversion to the chosen real port reference. There is no extrapolation. Import adjusts analysis frequency into the datasets' common range; disjoint ranges fail without changing the document. Existing sweep limits are narrowed to the common range when datasets change. Unapplied controls do not override the applied sweep.
• Single-frequency data is supported: it displays one measured point, not an extrapolated curve. A dashed Smith-chart connector joins a measured block's input/output impedance endpoints; it is not a fractional physical trajectory.
• Dataset name, reference, range, and sample count are shown in full in tooltips and report descriptions. All complex samples are embedded in saved projects; the original files are not needed to reopen them. Measured values are read-only and not component-tunable; delete/reimport to replace a block. Synthesis replacement removes the measured load along with the old network.
• LTspice export of measured blocks/loads is deliberately rejected; there is no silent ideal-element substitution. PNG export supports them. There is no separate measured-data overlay mode, port reversal, phase/group-delay UI, or broadband rational fitting in this implementation.

Project files and legacy compatibility

Save new projects as .rfs.json. Format version 2 contains explicit component types, connections, units in field names, display settings, frequency presets, transformer ratio, cable input modes, and microstrip geometry/substrate/loss. Version 1 files still load with the original element behavior; saving upgrades them to version 2, which older builds cannot open. Projects containing measured blocks or loads use version 3, embedding their samples; version 1/2 projects remain readable. Projects without measured data continue to write version 2. Older builds cannot read version 3. Unknown versions and invalid values are rejected with an error; failed opens do not replace the current document. Saves use a temporary file and atomic commit.

Legacy .lls files are import-only. The importer supports the 2003-era layout with reserved fields and the 2006/2007 extension with three frequency presets. It supports ANSI/UTF-16 MFC strings and ignores unused uninitialized component fields. The supplied original example is exercised by automated tests. Other historical layouts are rejected rather than guessed; Mathcad .mcd files are not RFdude project files. Imported files always require Save As in the new format.

LTspice export

Choose File -> Export LTspice schematic... to save an editable .asc file, then open that file in LTspice if it is installed. Export does not launch LTspice, save the project, or clear its modified state. LTspice is not required to build the application or export a schematic, and no LTspice binaries or symbol files are bundled.

The schematic uses standard LTspice resistor, capacitor, inductor, voltage-source, and ideal transmission-line symbols. Series/shunt connections and compound RLC topologies are preserved. Component instance numbers match the chart's list; compound elements become individually editable R/L/C parts with the same number. Transmission-line delay is calculated from each line's own length/reference frequency. Zero-length through lines become wires, open stubs are omitted, and shorted stubs become ground connections.

Ideal transformers export as a standard dependent-voltage/current-source pair, enforcing both the voltage ratio and the inverse current ratio without an approximate magnetizing inductance. Coax exports using its derived impedance and delay. Microstrip exports as a transmission line plus a matched symmetric resistive T attenuator whose ABCD matrix matches the dielectric-loss model at the exported analysis frequency only. Geometry/material settings remain in annotations. A zero-DF microstrip exports without the loss pad.

The diagram runs from the source on the left to the starting-impedance load on the right. Thus component order is reversed visually: the chart starts at the load and applies components outward toward the source. The 1 V AC source has a series resistance equal to chart Z0. The goal impedance is an annotation only. A complex starting impedance becomes a series R/L or R/C termination that matches at the exported analysis frequency; its behavior away from that frequency is not a constant complex impedance.

Press Run in LTspice, then open View -> SPICE Error Log to see ZinRe and ZinIm, the real and imaginary endpoint impedance in ohms, excluding the source resistance. GammaRe and GammaIm give the reflection coefficient relative to chart Z0. For an ideal-open endpoint, the schematic omits the undefined finite-impedance measurements and reports reflection instead. The included AC analysis runs at the current chart frequency. You can edit it into a sweep, but update the measurement frequency as appropriate. For microstrip, the fixed loss pad will not track the model's frequency-dependent dielectric attenuation away from the exported frequency. Inductors explicitly use zero series resistance to match the ideal RF model. These are editable simulation schematics, not PCB netlists or finite-Q models.

Local integration checks have been run with LTspice 26.1.1 and XVII under Wine. Normal tests do not require Wine or LTspice. To opt into the numerical comparison tests on Linux after building the Debug preset:

RFDUDE_LTSPICE_EXE="/path/to/LTspice.exe" ./build/debug/tests/ltspice_tests

Deliberate limits and differences

• No network reversal or printing yet. Touchstone support is limited as above. Lumped components remain ideal, with no finite-Q model; line loss is currently limited to microstrip dielectric loss.
• Only a real, positive chart Z0 is supported. Start may be a finite passive impedance (including a short); goal must have positive resistance. Component R/L/C values must be positive. Unsupported legacy values report an error.
• The VSWR circle and metrics use chart Z0, not the old goal-centered circle approximation. The goal is displayed separately as a purple cross.
• Mismatch loss is reflection loss, not insertion loss.
• Maximum |X|/R is sampled along trajectories; it is not an exact optimizer, a component quality factor, or a bandwidth prediction. Display curves cap at Q=10.
• Ideal opens/shorts are handled in calculations without dividing by infinity. Trajectory samples are bounded (256 to 8192 segments per component); very long lines or extreme values may require further rendering refinement.
• Undo history is bounded to 200 changes. There is no autosave recovery yet.

Packaging

For a step-by-step explanation of Qt deployment, per-platform package creation, public downloads through GitHub Releases, signing/notarization, and open-source readiness, see the Deployment and public-release guide. It distinguishes existing development packaging from release work still needed.

Normal cmake --install build --prefix <directory> installs the executable and notices; Qt must already be available on that machine. To bundle Qt:

cmake -S . -B build -DCMAKE_BUILD_TYPE=Release -DRFDUDE_BUNDLE_QT=ON
cmake --build build --parallel 2
cpack --config build/CPackConfig.cmake -C Release -B build/packages

Bundling on Linux additionally requires patchelf. Prefer an official Qt kit for portable packages; distro Qt can pull in many system libraries. Linux portability is constrained by the build machine's glibc baseline; building on Ubuntu 22.04 is intended to support that baseline and newer systems, not every Linux distribution.

Bundled Linux installs keep the executable, qt.conf, Qt libraries, plugins, and translations under lib/rfdudesmithchartv2 relative to the install prefix. Only a shell launcher is installed in bin; no shared bin/qt.conf or global Qt libraries/plugins are installed. Debian revision 0.1.0-1 supersedes the unsafe original 0.1.0 package. Validate the finished package without installing it using python3 tools/check_linux_package.py build/packages/*.deb (requires xvfb-run, xauth, and the package's host library dependencies).

Windows downloads are setup .exe installers with Start Menu and desktop shortcuts; Linux downloads are .deb packages that add the application to the desktop menu. macOS packages are unsigned DMGs. These remain development artifacts: Windows signing, macOS signing/notarization, clean-machine validation, and complete dependency-license review remain release work.

Layout

• src/RfModel.*: portable RF model and calculations, no Qt dependency.
• src/FrequencyResponse.*: portable complex two-port analysis and frequency sweeps.
• src/FrequencyResponseDialog.*, src/ResponsePlotWidget.*: response controls, linked frequency marker, dB plotting, and response PNG export.
• src/Synthesis.*: portable legacy-style matching and filter calculations.
• src/SynthesisDialogs.*: synthesis controls, previews, and validation.
• src/DocumentIO.*: JSON persistence and bounded legacy archive reader.
• src/LtspiceExport.*: editable LTspice schematic generation and atomic export.
• src/SmithChartWidget.*: chart rendering and mouse interaction.
• src/SchematicWidget.*: scrollable circuit rendering and synchronized selection.
• src/Editors.*, src/MainWindow.*: desktop UI and document workflow.
• tests/: calculation, archive, and Qt interaction/rendering tests.
• .github/workflows/: native platform builds and installer packages.