Below are some example antenna setups.
Uniform Linear Array (Normal 0,1,2,3 spacing, distance between antennas=lambda/2 on channel 42)
<rosparam param="rx_position"> [0, 0,
0, -0.026,
0, -0.052,
0, -0.078] </rosparam>
0 --X-Axis-->
1
2
3
--
The same array with a more natural antenna placement for the RT-AC86u. It is easier to put the antennas in this order due to the locations of the SMA ports on the physical device. Consider the above image for the scenario (antennas are 1-indexed in this example).
<rosparam param="rx_position"> [0, 0,
0, -0.052,
0, -0.026,
0, -0.078] </rosparam>
0 --X-Axis-->
2
1
3
--
A Square antenna array that can sense the full 360-degree range at the cost of slightly reduced performance. We find that the optimal square side length to avoid aliasing problems is about 3*lambda/8, so to ensure the array works at the highest 5GHz frequencies we set the side length to 19mm.
<rosparam param="rx_position"> [0, 0,
0, 0.019,
-0.019, 0.0,
-0.019, 0.019] </rosparam>
3 1
2 0 --X-Axis-->