Simatic Rf600 - Siemens SIMATIC RF600 System Manual

Antennas
6.4 Guidelines for selecting RFID UHF antennas
As a result of the principle used, no special requirements need be observed to suppress the
orthogonal components (cross-polarization).
①
②
③
Figure 6-19
Front-to-back ratio
Definition
As a result of their design, directional antennas not only transmit electromagnetic waves in the
main beam direction but also in other directions, particularly in the reverse direction. The largest
possible suppression of these spurious lobes is expected in order to reduce faults and to keep
the influence on other radio fields low. This attenuation of spurious lobes in the opposite
direction to the main beam is called the front-to-back ratio.
Specifications
Requirement: The front-to-back ratio must be ≥ 10 dB. This requirement also applies to
spurious lobes illustrated by the following graphics in Section Half-value width (Page 193).
192
Transmitter antenna, vertical polarization
Receiver antenna, vertical polarization
Transponder dipole
Homogenous vertical polarization of antenna system and transponder
Draft Version 02.06.2010
System Manual, 06/2010, J31069-D0171-U001-A10-7618

SIMATIC RF600