ETS-Lindgren 2171B Boresight Antenna Tower - Manual (Page 10)

10 | Introduction
ETS-Lindgren Patented Boresight System
The Model 2171B provides the ETS-Lindgren patented boresight system to
provide direct antenna aim on EUT during scanning. This boresight meets the
requirements of ANSI C63.4 2003 and 2009 for compliance with
FCC measurements above 1 GHz.
During scans, the boresight system maintains constant directional antenna
positioning while varying the angle between the antenna and the mast. This is
particularly important when using higher gain antennas of more than 3 dBi. As
the antenna is raised above the ground, the tilt of the antenna will maintain the
EUT within the half power (-3 dB) beamwidth.
The following drawings use a generic positioning tower to illustrate boresight
and non-boresight function.
B ORESIGHT F UNCTION (2171B O NLY )