Summary
International Symposium on Antennas and Propagation
2008
Session Number:2SS01A
Session:
Number:2SS01A-3
Impedance Control and Radiation Properties of a 2.45 GHz ISM Band Wave Guide Antenna for Embedded Transponders in Metallic Objects
E. B. Kaldjob, M. Gamal El Din, B. Geck, H. Eul,
pp.-
Publication Date:2008/10/27
Online ISSN:2188-5079
Summary:
The recent development of low cost field-powered transponders has significantly increased the demand on identification of goods in industrial areas. Especially in factories where machines and metallic work pieces should be identified and monitored, the use of commercial tags fails because of the reflecting properties of metallic surfaces; an approach to solve this problem is presented in [1] where the transponder is not placed on the object to identify, but under its surface. The signal transmission between the transponder chip and the air interface occurs through a cavity working as cylindrical wave guide antenna, as shown in Fig. 1a). A planar wave guide-to-planar transition achieves the field coupling between the wave guide and the chip. To maximize the communication range, the chip should be matched to the wave guide antenna. Also optimal alignment of the reader and the transponder antennas is required [2]. This paper presents a method to tune the input impedance of the wave guide antenna by varying the transition geometry. Furthermore the radiation properties of the antenna excited by the transition are analyzed.