Single Band; Bi-Directional Array; Theory Of Operation - Hy-Gain AV-18HT Instruction Manual

MODEL 14AVQ/WB-S
The 14AVQ/WB-S is a self supporting multi-
band trap vertical for 10 through 40 meters
and is completely factory pre-tuned. It is the
world's most popular ham antenna with an
overall height of 19 feet. The antenna is
thoroughly weatherproofed and has a low
angle DX radiation pattern. It may be ground
mounted or installed on "Roof Top" with a
radial system.
MODEL 12AVQ
The 12AVQ is a self supporting 13 1/2 foot
multi-band trap vertical for 10, 15 and 20
meters. Completely factory pre-tuned with
SWR of 2:1 or less with a low angle DX radia-
tion pattern. The antenna has a new fiberglass
impregnated styron base insulator. It may be
ground mounted with earth acting as the
"image antenna" or installed on the roof using
a radial system.
DESCRIPTION
Increased activity on 80 and 40 meters has
created a need for an antenna with power gain
and directivity. Doublet and long wire
antennas are no longer effective due to
increased QRM. At these low frequencies, the
radiation system must be lengthy and height
above ground is extremely important to obtain
the "low" angle of radiation needed for DX.

BI-DIRECTIONAL ARRAY

(Four Quadrants)
THEORY' OF OPERATION
Two identical vertical antennas can be
installed as a phased array. When excited by
RF energy, gain is achieved by control of the
directional pattern. This direction pattern
control results in added gain by sharpening
lobe patterns and concentrating the radiated
energy at very low angles. Signal flutter is
reduced and reception is vastly improved.
Part 1 - SINGLE BAND
Beams are excellent, but require a large sup-
porting tower and "hefty" rotating system.
Inverted V dipoles and slopers require a large
tower and plenty of property.
The vertical "phased array", the answer for
"DX" on these frequencies combine gain,
directivity and low angle radiation, the three
most important DX factors in a communication
installation. The vertical is well known for its
low angle characteristics. When you combine
two identical verticals, properly spaced and
phased, the resultant is a concentrated low angle
of energy and a power gain. These antennas can
be so arranged to give a definite effect on either
one or two favorite bands or all band coverage
with some pattern compromise and slight loss
of gain.
The following data was experimentally derived
on the Telex/Hy-Gain test range. Due to the
many factors that vary and influence the
performance of an antenna, such as grounding
and close proximity of surrounding objects,
etc., Telex/Hy-Gain cannot guarantee an
installation to perform or exhibit the same
characteristics as outlined in this report.
However, many Amateurs are now successfully
using these arrangements.
broadcast stations have been using a similar
phasing arrangement for years.
Phased arrays will reduce installation height re-
quirements and still maintain low angle
radiation.
Most effective spacing for a bi-directional
array is 1/2 wave length. When two verticals
are excited in phase the radiation is broadside
to the plane of the verticals, offering
substantial gain
characteristics. Side nulls offer excellent signal
cancellation to the undesired direction.
Commercial
and bi-directional