Evening star., 1923-03-25
n COMMANDER STANFORD
HOOPER,, L. =. v.


call the ether nor tho undulatory
movements. or radio waves. set up in
,hy radio transmitters funct ming
ito their antcnna systems. Heavy
gales or unusually high winds change
the normal position Of the overhead
wires of many artcnna systems. how
fvfr, by causing them TO swing
with the wind and any change in the
position OF the overhead antenna
wires with respect to nearby metallic
STRUCTURES or the distance intervening
between the wires and the earth be-
low them. almost Invariably alters the
capaclty" value of the antenna Sys-
TEN.
Any change in either or both the
capacity" or "self-induction" values
of an antenna or other radio circuit
aiters its period or wave length.
hence the period pr fundamental wave
length Of the swinging antenna cir
,ilt CnQerEoes change and this par
tlcuiar circuit becomes out OF reso-
ance with its associated circuits ard
the station as q whole is tlCorn out
o. rune.
In the case OF & transmitting sta
ton, the circuit of the swinging an
tenLa becomes out Of electrical rcSo-
lance with It's associated transmitter
O. some frequency or length other
than the stations normal wave, or
waves of constantly varying fire.
uuencies or lengths are given off.
II waves OF constantly varying fire.
Suencies or lengths are given Of as
tS usually the case with swinging
cransmitter antennas, II becomes i'm
possible to tune that stations signals
III consistently at q distant receiving
station. because with the constantly
varying wave length the signals will
alternately come in and fade out cor
responding to whether the receiving
equipment circuits are in or out OF
electrical resonance with the con-
Stantly varying frequency or icaar- h
OF the incoming wave.
Weakening OF Signals.
Moreover. the strength IF the in
coming signals as whole will be re-
duced because the circuit of the
swinging transmitter antenna will be
out Of electrical resonance most of
the time with its associated transmit
Ter circuits. thereby resulting in de-
creased antenna current at the trans
nlttins station and consequently
Off
In the case Of a receiving station
whose ahteuna is swinging badly
with prevailing high winds. il will
hHswlse he found difficult to consist
~'S'S lAIit III Signals from distant
tFanSmltting station. even though
hish winds 90 not prevail at tire dis
tanL transmitting station and the STA =
tlon is transmitting normally and e.
tectlNely on its prescribed wave and
without any variations in freauency
or length OF wave. Under these CON
oltions the period or Fundamental
wave length pf the receiving anten-
ma circuit will be constantly VARYING
ana It VIII be difficult to keep this
Itrcuit It tuned 70 any desired wave
4enStn or to keep it in electrical reso-
rance with The associated circuits of
the receiver
IEe capacity value Of the ordinary
outdoor antenna circuit is subject
TO quite wide vari. tions from causes
either than high winds. Ice forma-
Tons on the antenna overhead wires
ourlng sieet storms Will cause the
wires to sag considerably thus, alter
ing their normal position and chang
.ig rhe capacity value. If n antenna
tr enveloped by Il heavy fog the ca
Ipactty value of the antenna will also
undergo change due to the change
In the moisture content Of the satmos-
phere. Smoke blown across an an
tenna will also appreciably alter the
electrical characteristic of the anten-
ma circuit.
With the development and inaugu-
r&tion in general service Of contin-
uouS wave equipment and more Sc
and modulated continuous wave ap-
|paratus for radio telephony, includ-
ing the popular radiophone broadcast
Service. and the consequent large in
grease in the number Of tra nsmitting
stations, the antenna systems are
r. pidly assuming q status Of greatly
l. creased Importance. They comprise
an extremely critical feature of mod
e1'n radio stations and their fmpor-
tAnce viii increase rather than de-
crease as time goes on.
Like Jewels of Watch.
Tie relationship which the antcnna
system bears to the electrical func-
Eioning of the modern transmitter or
receiver outfit may be compared to
no relationship that exists between
he jewels of a watch movement and
he mechanical functioning of the
watch mechanism. for example. The
eutenna constitutes the medium on
watch the radio transmitter or re-
eiver is primarily dependent for eff
r. cient and effective functioning in
7piuch the same manner that the
Jewels OF the watch movement con-
stitute the agency on which the
watch mechanism is principally de-
pendent for smooth and reliable
Antenna systems. especially the an
f-nnas of transmitting stations,
should therefore be not only care
hnd the overhead wires effectually In
EuIated, but the overhead part and
Eattail should be guyed or secured IN
Euch manner that its electrical char
Rcteristics will remain constant re-
rardless of gales or high winds which
Prevail from time to time. If spread
- are employed in the construction
pf the overhead part of an antenna.
ro great difficulty will be encountered
h. effectually guying it so that it will
IN
Guy ropes, with a suitable insulator
Inserted in the antenna end, may be
a ttached to, each end of each spreader
Rnd the free ends then secured TO
stakes driven in the earth or to near
by structures. The rattail may be
eutcd in a similar manner by at
.sching an insulated guy rope to it at
he most effective part and likewise
securing the free end.
The collection of ice on antenna
b. Tres can not readily he avoided at
kho ordinary radio station, and II
lsualy will be found necessary to
tcadjust the circuits Of the radio out
ITS to compensate for the changed
electrical characteristics OF the an
rrna circuit during the time the ice
hemains on the wires.
Ice-Melting Facilities.
Il At the high power stations or the
ravy and the radio Corporation OF
Atmerica, the overhead par VI 'he an
kenna system constitute dead
ky eight Of several tons. Such of these
stations that are located within
areas subject to sleet storms are
provided with antenna ice melting
ac;Eties whereby comparatively
igll amperage low voltage current
circulated through the antenna
wires for the purpose of producing
sufficfent heat to prevent the forma-
ion of ice on the wires during storms
br 70 melt 1. off should ice formations
~ anv chance occur This is neces-