ETS-Lindgren 3161 Octave Horn Antenna - Manual (Page 25)

Typical Half-Power Beamwidth
Following is a plot of the half-power beamwidth (HPBW) versus frequency. The
information provides the size of the Equipment Under Test (EUT) that can be
illuminated without scanning. The size of the EUT can be obtained as:
EUT = 2
[ ]
Distance · tan
( )
HPBW
2
Distance is the distance between the EUT and the aperture of the antenna
Typical Data | 25