Here I have a collection of RF and HAM related links.
Ham radio links (some made by hams):
http://www.seed-solutions.com/gregordy/Amateur Radio/W8WWV Experimentation.htm
Ham radio clubs:
Here I have found some antenna related links:
Here I have some links on SDR (Software Defined Radio):
Here are some links on QRP (low power transmitters):
Software for hams:
Here I found an interesting page from minicircuits, the application nots:
The Internet Archive also has a lot of HAM related documents:
PS I noticed that the internet is very volatile.
It can happen that links do not work anymore.
In that case you can have a look at the page in the "internet archive"
When you copy the not working link into the searchbar of this site,
it will produce a page with dates the page still was there.
When you click on the date you get the page of that date.