Altium Designer might be a bit more popular than QUCS. We know about 1 link to it since March 2021 and only 1 link to QUCS. We are tracking product recommendations and mentions on various public social media platforms and blogs. They can help you identify which product is more popular and what people think of it.
If you can get s parameter model you can use that. There are also generic transformer and coupled line models so long as you've got a way of characterising it you should be able to model it. https://sourceforge.net/projects/qucs/. Source: over 1 year ago
Check out Altium’s website (altium.com. A lot of free resources that might help. They also have a YouTube channel. Good luck. Source: about 1 year ago
LTspice - LTspice® is a high performance SPICE simulation software, schematic capture and waveform viewer with enhancements and models for easing the simulation of analog circuits.
KiCad - A Cross Platform and Open Source Electronics Design Automation Suite
Autodesk EAGLE - Autodesk EAGLE is an electronic design automation (EDA) software.
Proteus PCB design - Proteus PCB design combines the schematic capture and ARES PCB layout programs to provide a...
EasyEDA - EasyEDA - Web-based EDA suite; runs in browser.
Ngspice - Ngspice is a mixed-level/mixed-signal circuit simulator.