7.2.2 Radiated Measurements in the 2.4 GHz band
For the transmitter antenna, the on-board printed inverted-F antenna of the BRD4174B Radio Board was used (the R1 resistor was
mounted). The supply for the RF section (RFVDD) was 1.8 V provided by the on-chip DCDC converter, the supply for the 2.4 GHz
power amplifier (PAVDD) was 3.3 V provided by the mainboard; for details, see the schematic of the BRD4174B. The transceiver was
operated in continuous carrier transmission mode. The output power of the radio was set to 19 dBm based on the conducted measure-
ment. During the measurement the sub-GHz antenna (P/N: EXH-170-SM (Laird Technologies)) was attached to the SMA connector.
The radiated performance was measured with and without mounted shielding can.
The results are shown in the tables below.
Table 7.2. Maximums of the Measured Radiated Powers in EIRP [dBm]
Frequency
EIRP [dBm]
Orientation
Margin [dB]
Limit in EIRP [dBm]
Fund
20.7
XZ/H
9.3
30
2nd
-48.2
XZ/V
10.6
-37.6
3rd
<-50
*
-/-
>10
-37.6
4th
<-50
*
-/-
>10
-30
5th
<-50
*
-/-
>10
-37.6
* Signal level is below the Spectrum Analyzer noise floor.
Table 7.3. Maximums of the Measured Radiated Powers in EIRP [dBm]
Frequency
EIRP [dBm]
Orientation
Margin [dB]
Limit in EIRP [dBm]
Fund
20.9
XZ/H
9.1
30
2nd
-47.6
XZ/V
10
-37.6
3rd
<-50
*
-/-
>10
-37.6
4th
<-50
*
-/-
>10
-30
5th
<-50
*
-/-
>10
-37.6
* Signal level is below the Spectrum Analyzer noise floor.
As shown in the table, due to the high gain of the inverted-F antenna, the level of the fundamental is higher than 19 dBm. The harmon-
ics are compliant with the applied limits with or without shielding.
BRD4174B Reference Manual
RF Performance
silabs.com
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