Transmission Window And Read/Write Distance - Siemens SIMATIC RF 300 System Manual

RF 300 system planning
4.1 Fundamentals of application planning
4.1.1

Transmission window and read/write distance

The reader generates an inductive alternating field. The field is strongest near to the reader.
The strength of the field decreases in proportion to the distance from the reader. The
distribution of the field depends on the structure and geometry of the antennas in the reader
and transponder.
A prerequisite for the function of the transponder is a minimum field strength at the
transponder achieved at a distance S
transmission window between transponder and reader:
Sa
Sg
L
SP
The active field for the transponder consists of a circle (cf. plan view).
The transponder can be used as soon as the intersection (SP) of the transponder enters the
circle of the transmission window.
4-2
Operating distance between transponder and reader
Limit distance (maximum clear distance between upper surface of the reader and the
transponder, at which the transmission can still function under normal conditions)
Length of a transmission window
The length Ld is valid for the calculation. At Sa,min, the field length increases from Ld to Lmax.
Intersection of the axes of symmetry of the transponder
from the reader. The picture below shows the
g
System Manual, 05/2005, (4)J31069 D0166-U001-A1-7618, --
RF 300