New features

• Implemented advanced RF circuit synthesis tool by @andersmmerra #1434 Old filter design tools are candidates for deprecation in the next version.
• RxCalc utility implementing multi-stage receiver calculation by @arhiv6 is integrated with Qucs-S #1463
• Added possibility to select BJT, JFET, MOSFET, and Diode from library using a button in device properties dialog #1478
• Added shortcut manager #1528
• Update Application settings->location UI #1613
• Added SPDT switches and relay #1602
• Added system command component #1606 Library update
• Added Darlington BJT library #1546
• Added SPICE models for USSR opamps #1586 General improvements and bugfixes
• Show line numbers in text editor #1520
• Fixed bug with SPICE netlist generation for multiple Qucs equation blocks #1557
• Fixed environment variables expansion for Xyce #1610
• Fixed SPICE AM sources #1587
• Fixed SPICE netlist generation if schematic contains dangling nets #1594
• Improved graph performance when rendering huge points number #1598 #1600
• Added DIN A6 schematic frame #1554
• Refactoring and bugfixes in schematic editor by @tskaar #1514 #1523 #1559 #1560
• Improved rotation in schematic editor #1488 Localization
• Updated Russian and Italian translation #1464 and #1490 What's Changed
• Update NGspice URL by @andresmmera in #1462
• Russian translation by @antohami in #1464
• fix(WireLabel::mirrorX/Y): Handle axis input by @tskaar in #1473
• Fix Monte Carlo ngspice template by @ivandi69 in #1486
• fix(WireLabel): Handle transformations for detached WireLabels by @tskaar in #1487
• [WIP] New RF tools by @andresmmera in #1434
• feat(Schematic): Add transformations to paste selection by @tskaar in #1488
• Add RxCalc submodule by @ra3xdh in #1471
• RF Design Tools: New features and some class refactor by @andresmmera in #1501
• refactor(MouseActions): extract mouse movement logic and fix tracking bug by @tskaar in #1506
• Add a plus sign on voltage controlled sources to indicate polarity by @mc2285 in #1508
• Fix Issue #1510: Bug with microstrip filter synthesis by @andresmmera in #1511
• Refactor(Schematic): node disconnection and element decoupling logic with doHeal control by @tskaar in #1514
• Update new file icons by @andresmmera in #1521
• Text Editor: Add line numbers widget by @andresmmera in #1520
• S-parameter Viewer: Export feature by @andresmmera in #1519
• Fix crash when pasting zero-length wires in Schematic::installWire() by @andresmmera in #1529
• Fix issue #1518: Open sym files in Qucs-S by @andresmmera in #1530
• refactor(Schematic): move node transformation logic to owner by @tskaar in #1523
• feat(MouseActions): add keyboard driven move and move-and-stretch commands by @tskaar in #1524
• fix(MouseActions): wire stretching by dragging node by @tskaar in #1535
• add port name to spice symbol mapping table by @soldermate in #1531
• Bump fonttools from 4.55.3 to 4.61.0 in /qucs/python by @dependabot[bot] in #1532
• Small fixes by @ra3xdh in #1538
• Shortcut manager by @andresmmera in #1528
• Update QT version and macOS intel fixed by @dsm in #1544
• S-par Viewer: Direct coupled filters improvement by @andresmmera in #1540
• Add Darlington BJT library by @ra3xdh in #1546
• fix missing symbol in NMOSFETs.lib by @Radvall in #1547
• Fix issue #1551: Duplicate and Rename actions disabled in Project view by @andresmmera in #1552
• fix(convertToQucsData): guard against out-of-bounds for extra_vars_dims by @tskaar in #1550
• add rxcalc to macos app bundle by @dsm in #1553
• Add DIN A6 schematic frame by @andresmmera in #1554
• Diagram Dialog: Improvements and fixes by @andresmmera in #1555
• Fixed SPICE netlist for multiple QucsEqn blocks by @ra3xdh in #1557
• fix windeployqt exe naming by @dsm in #1565
• fix(mouseactions): properly deactivate action when releasing keyboard move by @tskaar in #1559
• S-Parameter Viewer documentation (and some fixes) by @andresmmera in #1567
• (fix:qucs-s-spar-viewer) Refactor convert_MA_RI_to_dB to use references, be case-insensitive by @sjgallagher2 in #1571
• fix(ngspice/noise): data duplication in PerPtsSummary by @tskaar in #1560
• Select model from library by @ra3xdh in #1573
• S-Parameter Viewer: Fixes by @andresmmera in #1575
• Migrate S-Parameter Viewer tool to submodule by @andresmmera in #1577
• Bump pillow from 11.1.0 to 12.1.1 in /qucs/python by @dependabot[bot] in #1581
• Update qucs-s-spar-viewer submodule by @andresmmera in #1584
• Small fixes and library update by @ra3xdh in #1586
• Fix SPICE AM sources by @ra3xdh in #1587
• feat(createNetlist): filter out dangling nets by @tskaar in #1594
• Fix GUI freeze when rendering huge simulation dataset by @ra3xdh in #1595
• Don't reload graph data on every interaction by @ra3xdh in #1600
• SPDT switches by @ra3xdh in #1602
• fix(AbstractSpiceKernel/getActiveLabelledNets): iteratively traverse wire nodes by @tskaar in #1604
• Fixed equation parse in equation editor by @ra3xdh in #1608
• System Command Component by @andresmmera in #1606
• feat(Xyce): expand environment variables when using 'include', 'lib' and 'include script' by @tskaar in #1610
• Update QT version and re-enable ARM build for Windows by @dsm in #1614
• Update on the "Application Settings->Location" menu UI by @andresmmera in #1613
• Fix issue #1616 - AC Power Source with ngspice and Xyce by @andresmmera in #1617
• Update qucs-s-spar-viewer submodule to v2026.04.07 by @andresmmera in #1620
• Prepare for v26.1.0 release by @ra3xdh in #1618 New Contributors
• @mc2285 made their first contribution in #1508
• @soldermate made their first contribution in #1531
• @dependabot[bot] made their first contribution in #1532
• @sjgallagher2 made their first contribution in #1571 Full Changelog: 25.2.0...26.1.0