RADAC WaveGuide 5 Direction User Manual page 20

The working principle of the WaveGuide Direction is based on the measurement of surface
elevation at three different positions, using an array consisting of three radars. The array
design criteria are:
• The footprints (measurement points) of the three radars on the sea surface must form
a triangle.
• To obtain directional information of the same quality for all wave directions an equi-
lateral triangle is preferable but not critical.
• The measurement of wave directional parameters is optimal for wave lengths that are
3 to 30 times the array size (distance between the center of two radar footprints). For
example, if the dominant wave periods are between 3 and 10 [sec] long (wave lengths
from 15 to 150 [m] long). Then for such waves, a radar array size of 5 [m] is optimal.
To allow the WaveGuide Direction to be installed in various locations it is designed to be
mounted in one of three array configurations. All three configurations allow for the radar
array footprint to form an equilateral triangle on the sea surface at mean water level.
• The point array is the recommended configuration in most situations. Here the three
radars are mounted on a single frame. One radar is looking vertically downwards.
The other two radars are tilted with an angle of 15 [deg] from vertical in the direction
away from the downward looking radar. In this case the size and position of the array
footprints depends on the choice of tilt angle and the vertical position of the radars
(height above actual water level).
• The line array, where the mounting positions of the three radars form a straight line.
The two outside radars are mounted at zero inclination angles and the middle radar
is tilted with an angle between 10 and 15 [deg] in a direction perpendicular to the line
the radars are mounted on. In this case the size and position of the array footprints
depends on the mounting position, the tilt angle and the vertical position of the radars
(height above actual water level).
• The triangle array, where the mounting positions of the three radars form a triangle
and all three radars are mounted at a zero inclination angle (resulting in optimal per-
formance). In this case the size and orientation of the array footprints are determined
only by the horizontal positions of the radars.
11