Mounting Options

Discussion of mounting options.

Attachment Points

The sensor has four mounting points intended for UAV attachment. The user must provide appropriate brackets to achieve the desired angle of incidence.

The best way to secure the sensor is by using the four M5 vibration dampers, which are spaced 10 by 5 inches apart and have a 5 mm thread.

Drawing of the antenna, showing the locations of the four vibration dampers.

Choice of Incidence Angle

The following choices for incidence angles are recommended:

1. Nadir-looking (antenna beam pointing straight down):

   • This angle ensures that the soil microwave emission is unpolarized. Any polarized component can be assumed as ambient radio interference.

   • This option also reduces aerodynamic drag, leading to longer flight times.

2. Incidence angle of about 30-40 degrees:

   • At angles greater than 30 degrees, the soil's microwave emission becomes polarized.

   • Both horizontal and vertical brightness temperatures can be used as input parameters to calculate volumetric water content.

Built-in Accelerometer

The antenna is equipped with an accelerometer and gyroscope chip (LSM6DSMTR), which is read out every second and provides de-noised (averaged) values for x, y, and z acceleration, from which the incidence angle can be calculated. The accelerometer and gyro values are stored in the raw data as metadata for each integration.