What does the angle “from boresight” refer to?

What does the angle “from boresight” refer to?

LINKPlanner now displays the angle from boresight below the Subscriber Module Antenna Azimuth (see below).

The images below illustrate how the angles relate to the items on the map. The angle from boresight refers to the angle of the SM in relation to the centre-line of the AP antenna. 


The gain of the AP antenna will usually decrease as the SM moves away from the antenna azimuth. If the angle from boresight is large in relation to the antenna beamwidth then the antenna gain is likely to decrease. The antenna tilt also plays a part, but LINKPlanner automatically allows for the angle from boresight and the elevation when calculating the antenna gain. This is one of the reasons why it is not possible to define custom antennas for an AP, since a 3D representation of the antenna is required to calculate the gain at the chosen frequency, angle from boresight and elevation.

If the angle from boresight is more than half the nominal beamwidth, the subscribers are outside the main beam of the Access Point. In contiguous networks of multiple Access Points, these subscribers may cause or receive interference, as well as having lower gain.