ABSTRACT
This chapter describes the transmitter and receiver sections in an interrogator. The basic structure of the transmitter section in the radiofrequency identification (RFID) interrogator contains an oscillator operating at the frequency of interest, a voltage or power amplifier, and the tuning circuits to match the impedance of the transmitter to the characteristics of the antenna. The basic structure of the receiver in the RFID interrogator also contains a detector, typically an envelope detector, a signal amplifier, filters, and the appropriate pulse-shaping circuits. Phase-shift keying modulation is one of the most effective methods to transmit digital signals. The chapter discusses issues related to extending the read range between transponder and interrogator as well as the requirements for interrogator synchronization when two or more interrogators coexist within the same general area. It provides a description of the structure in different commercial interrogators.
