Thank you all for your replys! 
About the EMP yeah, that's pretty much what I read about, and was really disappointed 
About the jamming technique I do believe it's legal here, not sure, I'm not from US and here laws are pretty loose about pretty much everything, in fact it was ruled 2 year ago that there is no such thing as illegal download so we can download whatever we want! 
About the signal jammer I do believe I need more information (once again Hollywood in my head blocking all the signals not just 1 band).
Apparently the voice scrambler being reversible is a real thing (Hollywood being truthful!!)
When I said Radio Scanner I actually meant to read the cards that operate on I believe it's Radio frequency, might be InfraRed or bluetooth though, I meant the credit cards that can make purchases without code and you don't even have to put it in a machine. But yeah Police scanner would also be nice! Added!!
EDIT: Do you know of any papers good for reading about these subjects? If not I'll just Google 
multi-band jamming is a LOT more involved, and depending who/what your using it on useless. ie a naval war vessel is just about impossible to jam. (boosting transmission power, frequency hopping etc. and when you start getting into jamming that does that....not just money intensive but knowledge intensive too). if its more of a "lark" ie you cant get your cellphone to work!(and police force jammers are very much along these lines) its rather cheap/simple to make or buy them. As for more knowledge on the area of transmissions i would suggest picking up a book on it(we probably have something in the ebook library) or a lot of google searching. Far to much info for me to give even a "basic" rundown of it here, and even then i dont know a lot, and dont remember a good bit as well as i havent used most of in in over a decade.
As for the cards/passports etc your talking about that is RFID technology, and their is just a ASSTON of info out their about it.
As for building your own jammer..if i remember right now it wasnt a defcon presentation but a HOPE presentation that i watched talking about it/showing how to make one. That being said their are a lot of tutorials on it out their. Their are also websites that sell that(and most of what else you are looking for) pre-made. As for why i suggested amateur radio for scanning police bands is that "commercial" products have lockouts preventing it/are designed to not get them, but ham radio will allow you access to it and so much more(with the correct atmospheric conditions you can talk to people across the world! Yeah not a big deal now..but it used to be! Also necessary to have the right antenna/enough juice but still!)
Really though if you want to get to know this stuff, the same way you would a "program" i would suggest getting yourself a good to high end (100-300$+) variable temperature soldering iron, get a book on electronics(basic electronics course by norman h crowhurst) , get a book on radio(i cant recommend a good one here, mine is technically classified/what i used in IT "A" school), then look up what you want to build and build it! Bright side to this is not just the satisfaction angle, but that considering a 2.4ghz jammer should cost you 20-30 in parts but would probably be 50+ buying from another source means that if you built most of the devices you want you would probably break even, if not make money from it. On top of it you gain lots of knowledge. Aside from books though you can always just google and wiki for the basics, but its generally helpful to have a book to go off of.
