Building RFID security gate

What are the components required to build RFID security gate so that if anyone passes through that gate having RFID tag in his/her bag or pocket the system detect it? Will it work for RFID card also? Do I need special RFID tag (long distance RFID tag) or any regular one would do? Really appreciate if you can provide any link of tutorial on building RFID security gates. Thanks in advance.

Would really appreciate it if you didn't post the same question in different parts of the forum.
(I deleted the other one)

Ok, I need to make this clear - STOP CROSS-POSTING.