www.ti.com
2.4
Differences Between Antennas
2.5
Isofield Diagram
Differences Between Antennas
The performance of the TIRIS system is influenced by the reader antenna selected. Each antenna has its
own specific characteristics.
Figure 2-1. 0
°
Transponder Orientation
Figure 2-2. 30
°
Transponder Orientation
Figure 2-3. 60
°
Transponder Orientation
Figure 2-4. 90
°
Transponder Orientation
A charge-up (Isofield) diagram shows the field strength achieved by a specific antenna voltage against an
axis of length (the distance over which the transponder will be "charged-up" to the required level – the
example given in
is 5 V).
For example: on a G01C antenna, an antenna voltage of 232 V will charge-up a transponder with a 0
°
orientation to 5 V over a distance of up to 0.68 m.
An 'Isofield' diagram and a charge-up diagram are the same and are independent of noise. A readout
diagram includes the effects of noise. Each antenna has its own specific 'Isofield' pattern. The field
strength decreases exponentially with the distance to the readout antenna. For short distances this
exponent differs for various antennas.
In
to
you will see isofield (charge-up) diagrams for the TIRIS antennas. These
patterns show you the charge-up of the transponder to 5 V in 50 ms for the 32.5 mm tube transponder.
The top diagram on each page is the charge-up diagram with a transponder orientation of 0
°
, and the
bottom diagram on each page is the charge-up diagram with a transponder orientation of 90
°
. With this
charge-up voltage, the transponder is able to reset completely. However, the transponder is able to
transmit back its complete ID code with a lower voltage, so the readout distance could be even larger.
10
How the System Works
SCBU025 – November 1996
Summary of Contents for TIRIS SCBU025
Page 1: ...Antenna Reference Guide November 1996 SCBU025...
Page 2: ...Antenna Reference Guide Literature Number SCBU025 November 1996...
Page 6: ...www ti com 6 SCBU025 November 1996 Submit Documentation Feedback...
Page 20: ...www ti com Noise Characteristics 20 SCBU025 November 1996 Submit Documentation Feedback...
Page 30: ...www ti com Mechanical Characteristics 30 SCBU025 November 1996 Submit Documentation Feedback...
Page 34: ...www ti com Theory of Coupled Inductors 34 SCBU025 November 1996 Submit Documentation Feedback...