Evening star., 1922-11-26
HUGE ANTENNA SYSTEMS
WITHSTAND TYPHOONS
Those at Annapolis and Arlington Also
Survive Severe Atlantic Wind
and Sleet Storms.

most difficult and expensive feature
of the station. They usually exceed
n cost all other items combined.
such as buildings electric power
equipment radio transmitting appa-
ratus. antenna system. etc.
Likewise the antenna-ground sys-
TEN is the most important feature OF
transmitting station. On Its design
; largely depends the efficient and eco
nomical operation of the station. The
mltter is dependent entirely on the
correctness Of design Of the antenna-
ground system into which 1t func-
tions to produce ether waves.
The energy contained in an electro
magnetic or ether wave at any point
distant from the station which created
the wave is dependent on the height
above the earth Of the overhead part
OF the antenna and the value Of the
current delivered by the transmitter
to the antenna system.
Transmitting antennas of great
height are therefore desirable, espe.
cially for long distance work. They
must be of large dimensions to ac-
commodate the heavy current values
delivered to them. and the overhead
wires must be well insulated to with
stand the very high voltages i'm
pressed on the antenna circuit.
, At the naval high-power stations.
ranging in power from 100 kilowatts
F; to 500 kilowatts. self-supporting steel
towers weighing several hundred tons
and from $50 to 500 feet in height
nave been erected to support these
extensive wire systems. AT the La
fayette 1.000-kilowatt station in
france. which was erected by the
Navy as war measure, the towers
are $40 feet in height.
Three Steel Towers Built.
The overhead part Of these an
tennas. consisting OF heavy copper
wires. supporting steel cables and
gate dead weight of from two to
more than fifteen tons suspended from
the tops of these towers high above
the earth.
The steel towers themselves are
each designed to Withstand a hori-
to ten tons. Three such towers. rang
Ing in height from $50 to 500 feet.
have been erected at eight Of the
Nays high-power stations, six 6oe-
foot towers having been erected at
Annapolis, while eight S20-foot tow
ers stand as monuments at Lafayette,
near Bordeaux, France.
Porcelain insulators having an ulti-
mate tensile strength of as high as
ten tons and Il dielectric strength in
| excess of 100000 volts at the wave
lengths employed, insulate the an
..
trio currents Of from $50 to $50 am
| peres flow in the antenna wires when
the transmttters arc tunctioning into
, the antenna.
I The to,al length of copper wire
comprising the overhead part Of these
| antennas range from three miles in
length at the smaller stations to
| more than sixteen miles at the La
tayette station. approximately three
tines these lengths Of wire have been
buried to an average of two and one
half feet in the earth at these sta
| tions to fern the ground part OF
the antenna systems.
These antenna systems are subject
to the varying climatic conditions
which prevail in the areas In which
he stations are located.
stand Up Under Typhoons.
The existing antenna and towers at
Cavite In the Philippines have with
stood the force of four severe ty-
phoons which swept over that area
within as many years. Those at
Cayey In Por.o Rico nave wItns,oud
a Slight earthquake shock and the
force of several hurricanes which
have visited that area within the past
three years. The antenpas at An
napolis, Arlington and Sayville are
subject to the severe wind and sleet
storms which occur In the winter
months along our Atlantic seaboard.
At the latter named three stations
it has been found necessary to so de-
sign the antenna systems that cleo
trio currents of comparatively low
voltage and high amperage can be
circulated through the wires to pro-
duce sufficient heat in the wires to
melt the ice which forms thereon
during the progress of these storms.
At the Annapolis station 900 kilo-
watts OF electrical energy is dissi-
pated in the antenna wires to create
sufficient heat for this purpose there
by Transforming this antenna into a
huge electric heater for the time be-
ing.
Copyright. 1921