ESCO Technologies ETS-Lindgren 3147, User Manual, Page: 27 / 49

Typical Data | 27
The antenna factor of the Model 3147 (triangles) measured at the distance of
three meters as per ANSI C63.5. The standard states that
the spacing R
between log-periodic array antennas is measured from the projection onto the
ground plane of the midpoint of the longitudinal axis of each antenna
. This
midpoint has been marked on the radome and labeled Reference Point
Per ANSI C63.5 . The line shown in the figure is a linear fit to the antenna factor
data. The second curve shows the gain of the antenna as computed from the
antenna factor by:
G(dB) = 20 log(F
MHz
) – 29.79 – AF
dB(m
-1
)