For a nice simple, how it works in layman's terms, go here:
Lots of other good stuff, including ham radio are to be found at the above.
For a simple, but math intense (algebra only needed), go here:
This is a college lab series, but is very good for someone who wants to be self-taught or needs to brush up on old skills.
--- Aeolus v1.2.2b3 (#96101098)
* Origin: The ChatterBox, Justin Texas (1:393/3)