ETS-Lindgren 3147 Log Periodic Dipole Array Antenna - Manual (Page 7)

1.0 Introduction
The ETS-Lindgren
Model 3147 Log Periodic
Dipole Antenna is a
linearly-polarized broadband
antenna designed to operate
over the frequency range of
200 MHz to 5 GHz. The
antenna was designed with
the latest revision to Part 15
of FCC Rules and
Regulations in mind. See
page 13 for specifications.
The Model 3147 is constructed from 30 elements mounted on two 6.35-mm by
12.7-mm booms. The choice of scaling factors, the various diameters of each
element, and the center-to-center spacing of the booms yield excellent VSWR
characteristics throughout the operating frequency range (see VSWR on
page 23). The precise design of the feed and the positioning of the elements on
the boom yield an optimum phase relationship. This causes the active region, at
any given frequency, to propagate RF energy towards the smaller elements,
leaving the elements behind it electrically dead.
The constant gain of the Model 3147 yields an antenna factor which varies
linearly with frequency, as shown in Typical Data on page 23. The variation is
smooth; therefore, accurate interpolation of performance between specified
frequency points is simple.
Due to the relatively high upper frequency limit, the small elements on the
Model 3147 are very thin. The antenna is equipped with an integral, low
dielectric-constant radome to protect the elements from possible damage.
Do not disassemble or drop the antenna or the
thin elements may be damaged.
Introduction | 7