Hy-Gain AV-18HT, Инструкция по эксплуатации

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OPTIONAL SPACING
SWITCHES & CONNECTORS
Various antenna spacings may be selected
from charts A, B, and C, for single band, duo
band or multi-band arrangements. Associated
radiations patterns for a specific spacing is
shown in Figures 1 through 5 for each band.
If the 3/4 wave length patterns are not
desirable, a single vertical only can be switched
in use to obtain an omnl-directional pattern.
INSTALLATION
The vertical antenna requires a minimum
amount of space. Ground mounted or elevated
arrays are easily installed.
Antenna placement and orientation is a most
important factor when planning maximum ef-
fectiveness is desired directions. Each vertical
should be installed in the clear relatively free of
surrounding objects in order to maintain its
design 50 Ohm terminal impedance.
Each antenna must be mounted at the same
height on or above ground and be so arranged
according to their radiation pattern to offer
desired directivity.
The phased array is primarily designed for long
range and DX communications. In cases where
close and medium distance contacts are
hampered by the array's low angle characteris-
tics and a higher angle is required, switching
arrangements can select one vertical for this
coverage.
Low loss constant impedance type coaxial
switches and connectors should be used when
splicing phasing lines. B&W multi-position,
single or multi-gang coaxial switches with Am-
phenol coaxial cable and "T' connectors are
recommended.
FIELD TESTS
Actual field tests comparing one vertical to the
phased array results in doubling the receivers
sensitivity and offering up to 12 dB of signal
increase. An attenuation of up to 30 dB is
noticeable on the phased verticals with half
wave spacing. With quarter wave spacing, up
to 20 dB cardioid, and 30 dB front-to-back at-
tenuation can be obtained.
"End Fire" directivity offers a larger area of
radiation at slightly reduced gain as compared
to the broadside arrangement. The "broad-
side" arrangement is recommended for
communications at greater distances whereas
the "endfire" arrangement would be so ar-
ranged to cover a larger area of
communications. Special attention to the coax
phasing line lengths and their proper
placement is of utmost importance.