Antenna wire
is a copper (at some references the wire made from a special brass)
cord in thick strong plastic insulation. The length of this wire
is 60 meter.The wire is strengthening with a steel core inside the copper cord. The
antenna wire is going through plastic triangular insulators,
which help keep it is isolated from the earth. The insulators
placed at distance near 1.5 meter apart each other. The plastic
triangles may be inserted into the ground by one end therefore
they were made from a strong plastic.
The two-wire ladder line in strong plastic insulation is connected
to the antenna wire and the counterpoise. The two wire line connected
the antenna and counterpoise is going to transmitter. The length
of this two wire line is 5 meter. The length of the counterpoise
is 15 meter. Termination Load has 300 Ohm value. Load is protected
from mechanical damage, water and atmospheric influences. The
length of the counterpoise after termination load is 15 meter.
Both counterpoises made from the same antenna wire. Counterpoises
were connected to steel pins in 70 cm long, which were hammered
into the ground. The antenna was operated in the frequency range
from 1 to 50 MHz. The maximum power going into the antenna was depend
on dissipative power of the termination load. There was antenna
option for 5 kW RF power ever.
In the internet I found description one more very interesting Russian
Spreading Antenna. The antenna is mentioned to be produced in
70s. Antenna is named SA- 60-2M-PK (CA-60-2M-PK, in Russian
letter). Figure
5 shows design of the antenna.
The outer sheath of the antenna is made of
from strong foam insulating material that could be floated on
the surface of both fresh and salt water. The diameter of the
plastic body is 16 cm. The surface of the plastic was special
and it repelled water and dirt. The plastic insulation of this
antenna was non-flammable. According to technical parameters,
this antenna can withstand being run over by a tank weighting
up to 100 tons. It does not fail even with close explosions of
a nuclear bomb and direct hits by shells or mines.
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Antenna wire in part B made
from copper cord in diameter of 4 mm. The counterpoise of part
A is made from a wire, similar to the antenna wire. Counterpoise
of part C is made from a cord having a pure dc resistance of 100
ohms at its ends. This counterpoise is artificial termination
load of the antenna. It allows the use to the antenna without
grounding pins and on any type of the ground- sand, stone, permanent
ice, etc. Special design of the artificial termination load allows
match the antenna in the wide frequencies range.
A two-wire line by length
of 5 meters is connected to the antenna. According to technical
parameters the antenna works in frequencies range of 1-50 MHz
and could stand up to 5 kW RF Power. This antenna is still workable
if it is buried at a small depth in the ground.
Design of Underground
Short Wave Radio Site
The underground radio sites
were arranged for navigation and for emergency purposes, as a
commander radio site. The commander underground communication
sites were designed for operation on LW, MW and HF ranges. Figure
6 shows design of a commander communication site for
operation on HF bands.
The underground radio site
consists of Equipment Room (1) located at depth of 15-30 meters
underground. The room contained transmitting/ receiving equipment
and place for personnel. The transmitting/ receiving equipment
is connected by feeders (2) to the matching devices (3). Matching
devices is placed at depth of 2-4 meters from the surface of the
ground. The 4- 8 aperiodic loaded antennas (4) are
connected to matching devices. The length of each of the antenna
may be in range of 20 to 50 meter.
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