antenna circuit design for rfid applications(microchip)_AN710 Antenna Circuit Design for RFID Applications Author: Youbok Lee, Ph.D. Microchip Technology Inc. REVIEW OF A BASIC THEORY FOR RFID ANTENNA DESIGN Current and Magnetic Fields Ampere’s law states that current flowing in a conductor produces a magnetic field around the conductor. The magnetic field produced by a current element, as shown in Figure 1, on a round conductor (wire) with a finite length is given by: INTRODUCTION Passive RFID tags utilize an induced antenna coil voltage for operation. This induced AC voltage is rectified to provide a voltage source for the device. As the DC voltage reaches a certain level, the device starts operating. By providing an energizing RF signal, a reader can communicate with a remotely located device that has no external power source such as a bat……