7.2.1 Radiated Measurements in the 169.4 MHz Band
For the 169.4 MHz radiated power measurements, an external whip antenna (P/N: EXH-170-SM (Laird Technologies)) was used as a
transmitter antenna. It was connected to the SMA connector of the BRD4174B Radio Board. The supply for the RF section (RFVDD)
was 1.8 V provided by the on-chip DCDC converter. The supply for the sub-GHz power amplifier (SUBGRF_ON, SUBGRF_OP) was
3.3 V provided by the mainboard (VBIAS through the discrete balun); 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.
The measured radiated powers are shown in the table below.
Table 7.1. Maximums of the Measured Radiated Powers in EIRP [dBm]
Frequency
EIRP [dBm]
Orientation
Margin [dB]
Limit in EIRP [dBm]
Fund
5.7
YZ/H
23.4
29.1
2nd
-49.3
XY/H
15.4
-33.9
3rd
-63.9
YZ/H
12.1
-51.8
4th
-55.6
XZ/V
3.8
-51.8
5th
-65.4
YZ/H
13.6
-51.8
6th
-57.6
YZ/V
29.7
-27.9
7th
-56.4
YZ/H
28.5
-27.9
8th
-51.4
XZ/V
23.5
-27.9
9th
-66.6
YZ/V
38.7
-27.9
10th
-66.9
YZ/V
39
-27.9
* Signal level is below the Spectrum Analyzer noise floor.
As shown in the table, with mounted shielding can, the fundamental and all of the harmonics are compliant with the limits. Unfortunate-
ly, the antenna together with the relatively small ground area (compared to the wavelength), provided by the BRD4174B Radio Board
and the Wireless Starter Kit Mainboard, results very poor antenna gain, thus the radiated power of the fundamental is relatively low. The
harmonic emissions are compliant with the limits.
BRD4174B Reference Manual
RF Performance
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