CHAPTER E
Antenna Selection
The Vision-RTK2’s GNSS receivers require signals located at the L1 and L2 bands for
adequate operation. Based on our internal testing, we recommend using helical antennas
with a gain of around 35 dB. For reference, our evaluation kit ships with two Hi-Target AH-
3232 antennas. The frequency response of the GNSS antennas should be approximately
located at the [1195 - 1280] MHz and [1560 - 1610] MHz bands. On top of that, for helical
antennas, we recommend a noise figure lower than 1.5 dB.
Other antenna types (e.g., patch, short helical) should be evaluated carefully depend-
ing on their placement with respect to other electrical components and the shape of the
ground plane provided for them. Thus, besides using a suitable and good antenna (and
appropriate cabling), the placement of the antenna is important. See below and for ex-
ample the following u-blox document: https://content.u-blox.com/sites/default/
files/ZED-F9P_IntegrationManual_UBX-18010802.pdf
Antenna assemblies that combine multiple antennas (such as, GNSS, Wi-Fi and cel-
lular) in once casing are not recommended at all. While such antennas work fine for
autonomous standard (C/A only) GNSS, they are likely to have bad performance for high-
precision GNSS that require phase measurements, such as RTK. Also, the GNSS perfor-
mance may depend on activity of the other antennas (Wi-Fi signal strength, cellular band
used, etc.).
For further analysis, besides analyzing the position estimate performance of the sensor,
one can look at the "Receiver RF AGC" value located at the advanced "GNSS status"
tab in the web interface. The expected values should ideally be located between 20 and
80 percent. For additional information, see also the following U-Blox document: https://
www.u-blox.com/sites/default/files/products/documents/GNSS-Antennas_AppNote_
%28UBX-15030289%29.pdf.
Only active antennas (with a built-in LNA) are suitable for the VRTK2 sensor.
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