IDENTIFICATION
ID ISC.LRU3000 / LRU3500
5 Operating and Display
Elements
Page 24 of 30
If a linear polarized antenna is used which gain is less then 6 dBi (factor 4), or if a circular polarized antenna
is used which gain is less then 9dBic the reader can always be configured to an output power of 1W.
Antenna Gain < 6dBi
→
P
out
= 1 W
This would be the case if the FEIG standard antennas ANT.U170/170 -FCC (4dBic) or ANT.U270/270 -FCC
(8,7dBic) are used.
If an antenna is used which gain is more then 6dBi (9dBic) it is necessary to consider the antenna gain and
the attenuation of the antenna cable to calculate the right output power. If a circular polarized antenna is used
the antenna gain [G]=dBic can be reduced by 3dB. This is the case if the FEIG standard antenna
ANT.U600/270 -FCC is used. In this configuration the maximum output power of the reader can be calculated
in the following way.
P
Out
= 36 dBm (4 W e.i.r.p)
– Antenna Gain (in dBi) + Cable Loss (in dB)
P
Out
= 36 dBm (4 W e.i.r.p)
– Antenna Gain (in dBic) – 3 dB + Cable Loss (in dB)
The antenna gain of the circular polarized standard antenna ANT.U600/270 is 10,5 dBic. This could be
compared with a gain of 7,5 dBi of a linear polarized antenna (10,5 dBic
– 3 dB).
Example 1:
Antenna ANT.U600/270 and 2 m Belden H155 Coaxial Cable:
P
out
= 36 dBm
– 10,5 dBic + 3 dB + 0,6 dB
P
out
= 36 dBm
– 7,5 dBi + 0,6 dB
P
out
= 29,1 dBm
Reader Configuration = 0,8 Watt
Example 2:
Antenna ANT.U600/270 and 6m Belden H155 Coaxial Cable:
P
out
= 36 dBm
– 10,5 dBic + 3 dB + 1,8 dB
P
out
= 36 dBm
– 7,5 dBi + 1,8 dB
P
out
= 30,3 dBm
Reader Configuration = 1,0 Watt
According to Example 2 it will only be necessary to adapt the output power of the reader when the antenna
ANT.U600/270 is used if the length of the antenna cable is less then 6m.