Amit IOG851-0T031, User Manual, Page: 18 / 389

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1.6.3 Install the External RF Cable and Antenna
As illustrated in Section 1.3, there are several SMA antenna Jacks for you to install the required RF cables and
antennas for the RF signal transmission and receiving. You have to purchase required RF cables and antennas
separately for a specific project or installation site to get excellent RF performance.
Since there is limited spacing for allocating all SMA antenna Jacks around the enclosure, the separation among
SMA Jacks (or direct-attached antennas) could be not the optimized arrangement. It is not recommended to
attach the SMA antennas directly to the SMA Jacks. It is very likely to get degraded RF performance at specific
circumstances. It depends heavily on the environment.
However, there are well-known rules of thumb for solving the antenna separation issue.
1: The horizontal distance between antennas should be greater than 1/4 of its wavelength, and there will be
best separation at 1/2 of its wavelength.
2. If multiple frequency antennas are near each other, then use spacing distance of the lower frequency
antenna, or even better try to satisfy the rule for both frequencies.
Wavelength Table for Major RF Category
RF Category Frequency Wavelength
1/2 Wave Length
(Best Separation)
1/4 Wave Length
(Good Separation)
WiFi 802.11 5.8GHz 5.2cm 2.6cm 1.3cm
WiFi 802.11 2.4GHz 12.5cm 6.2cm 3.1cm
Celllular LTE 2600MHz 11.5cm 5.8cm 2.9cm
Cellular LTE 2100MHz 14.3cm 7.1cm 3.7cm
Cellular LTE 900MHz 33.3cm 16.6cm 8.3cm
Cellular LTE 700MHz 42.8cm 21.4cm 10.7cm
GPS 1.57GHz 19.0cm 9.5cm 4.7cm
For example, if you have a 900MHz LTE antenna and a WiFi 2.4GHz antenna, you would want them to be
separated by at least 8.3cm to get good antenna separation.
So, it is recommended to use some external RF cables to extend and separate the adjacent antennas and get
better antenna separation and RF performance, if required.
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