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Operating the Reader Using the ReaderStart Software
14.7.1
Port Power
In Europe, the radiated power is limited in accordance with ETSI 302208 to 2 W ERP. In the FCC/IC region, max. 1 W
connected RF power applies with an antenna gain of 6 dBi. If the antenna gain is greater than 6 dBi, it is necessary to
reduce the RF power accordingly. While the European standard refers to a half-wave dipole, FCC part 15/RSS 210 refers
to an isotropic radiator.
To set the port power, it is necessary to include the length-dependent cable attenuation and the antenna gain into the
calculation of the port power. An example for the calculation of the port power for Europe and FCC/IC is given below.
The following applies to the European approval region:
P
port
= P
ERP
+ D
cable
– G
HW
,
where P
port
is the port power of the reader in dBm; P
ERP
is the port power based on a half-wave dipole in dBm; D
cable
is the
cable attenuation in dB; G
HW
is the antenna gain based on a half-wave dipole.
The cable attenuation is the length-dependent attenuation of the cable at the related frequency:
D
cable
= l*D
dB/m
,
where D
cable
is the cable attenuation in dB; I is the length in m; D
dB/m
is the attenuation in dB/m at frequency.
The antenna gain is stated in various different units. These units include dBi and dBic. The units dBi and dBic refer to an
isotropic (spherical) radiator, where dBic refers to a circularly polarised isotropic radiator and dBi to a linearly polarised
isotropic radiator.
In the European approval area, the radiated power must not exceed 2 W ERP. This figure refers to a half-wave dipole. The
relationship shown below exists between an isotropic radiator (dBi) and a half-wave dipole.
G
HW
= G
isot
– 2.14 dB,
where G
HW
is gain-based on a half-wave dipole and G
isot
is gain-based on an isotropic radiator in dBi
If the gain of the antenna is referred to the polarisation of a circular isotropic antenna (dBic), the linear gain of the
antenna is 3 dB lower. As a result ,the port power can be increased by 3 dB.
G
HW
= G
isot
– 2.14 dB – 3dB,
where G
HW
is gain-based on a half-wave dipole and G
isot
is gain-based on an isotropic radiator in dBi
In the FCC/IC approval region, the RF power connected at the antenna input must not exceed 1 W. If the gain of the
antenna is higher than 6 dBi, it is necessary to reduce the RF power correspondingly. The reader's port power is then:
P
port
= P
cond
+ D
Kabel
with P
cond
≤ 1W and G
isot
≤ 6dB,
where P
port
is the port power of the reader in dBm; P
cond
is the power on antenna output in dBm; D
cable
is the cable atten-
uation in dBm; G
HW
is the antenna gain in dBi.
If the antenna gain is stated in dBic, the reader's transmission power can be increased by 3 dB.
The port power for the European variant can be set in 0.25-dB steps from 6 dBm to 33 dBm.
Summary of Contents for ARU4 Series
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