I am researching using RFID for a project. I've read a lot about active RFID tags, such as this one. The sites that explain active RFID generally don't say much about the readers. Is a reader for an active RFID tag any different from a Passive RFID reader? Also, do the readers need to be set for the correct frequency? As in, do I need a 433 MHz reader to read a 433 MHz tag?