How Radio Frequency(RF) System Works

Swept-RF uses a transmitter to create a detection zone where tags are detected. The transmitter sends a signal that varies between 7.4 and 8.8 MHz (millions of cycles per second), which is why it is called swept; it sweeps over a range of frequencies.
The transmitter signal energizes the swept-RF tag, which is composed of a circuit containing a capacitor and a coil, both of which store electrical energy. When connected together in a loop, the components can pass energy back and forth or "resonate."

The tag responds by emitting a signal that is detected by a wideband receiver, meaning a receiver that monitors for signals over a wide frequency range; for swept-rf systems the bandwidth is typically about 1,400,000 Hz. By detecting a phase difference between these two signals,the receiver recognizes the presence of a tag, and it alarms.

More advanced RF Systems, emit a low-energy RF pulse, which "listens" for the tag. This technology, known as Digital Signal Processing (DSP), pulse based systems are meant to be more accurate and less susceptible to false alarms.