I would appreciate any information regarding the topic, and/or suggestions concerning recommended tutorials and/or COMSOL models already available, as a starting point to my study (I am new to COMSOL). Thanks in advance!
1. You can view and download models with their supplementary explanations files(you just need to be registered) from the link below https://www.comsol.com/models?q=rf
2. Also you can find a lot of useful tutorials (webinars as well) in video gallery section https://www.comsol.com/videos?type%5B%5D=videotype-tutorial&sortOrder=&s=
RF modelling is quite a well researched topic in Comsol, Also, I believe the developed RF interface is strong. An appropriate starting point is to understand the underlining physics, the rest is just finding the correct parameter to represent the propagating material. My favorite book on the subject is "Microwave/RF Applicators and probes for material heating sensing and plasma generation" by "Mehrdad Mehdizadeh". The book was introduced brilliantly and I am sure it will help you as it did to me.
Concerning the RF modeling, i advise you to follow the Comsol Blog entries provided by Walter Frei, which are nicely and informatively written and include a lot of RF modeling.
https://www.comsol.com/blogs/author/walter-frei/
Keep looking through the pages, you will reach RF modeling then.