RM310 NXP Semiconductors, RM310 Datasheet - Page 8

• Manufacturer Part Number: RM310
• Description: Ht Rm 310 Hitag Tm Mini Reader Module
• Manufacturer: NXP Semiconductors

02-10-1998
2.4.
The antenna is an important part in the data transmission between the read/write device and the
transponder. Thus, when building the antenna the instructions should be strictly followed in order
to achieve optimum results.
When deciding upon the size of the antenna the ratio between the diameter of the antenna and the
diameter of the transponder´s coil is fundamental. This ratio should be within the limits ranging
from 1 to 4. If the ratio is too big or too small, read/write distances may decrease and difficulties
during data transmission may occur.
2.4.1.
The following block diagram shows the general structure of a proximity antenna and its connec-
tion to the proximity read/write device.
When developing an antenna it is important to take into consideration the limits of the read/write
device, i.e. the maximum antenna current and the maximum voltage at the receiver input (Pin
RxA). With an output voltage Û
the reader module.
Maximum antenna current ( Î )
Maximum input voltage (Pin RxA, Û
The resistance R2 (approx. 600 ... 1000 ) is only needed with cables longer than 50 cm.
How to Design Proximity Antennas
Basics
out
(Pin TxA) of approximately 2.5Vp the following limits apply to
L
)
Page 8 of 41
Rev. 2.3
:
:
100 mAp
32 Vp
Htrm310.doc/HS
HT RM310