ETS-Lindgren 3148B Log Periodic Dipole Array - Manual (Page 7)

Introduction | 7
1.0 Introduction
The ETS-Lindgren Model 3148B Log Periodic Dipole Array is a
linearly-polarized broadband antenna designed to operate over the frequency
range of 200 MHz to 2 GHz. 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 29). The precise design of the feed and the positioning of the elements on
the boom together 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 Model 3148B antenna fully satisfies the CISPR-16 cross-polarization
rejection requirement, and has better than 20 dB cross-polarization rejection
below 1000 MHz. The constant gain of the antenna yields an antenna factor
which varies linearly with frequency as shown in Typical Data on page 27. The
variation is smooth; therefore, accurate interpolation of performance between
specified frequency points is simple.
The Model 3148B is constructed of lightweight, corrosion-resistant aluminum,
providing years of trouble-free indoor and outdoor service.
The Model 3148B includes an integral mount and the necessary attachments to
mount the antenna to either a tripod with a 1/4–20 threaded mount or an
ETS-Lindgren antenna mast. Individual antenna calibration data is included with
each antenna.
The Model 93148B is a non-characterized version of the Model 3148B. Should
calibration/characterization be desired please contact our calibration department.
A variety of mounting options are available for the Model 3148B. For information,
see Mounting Instructions on page 15.