Evening star., 1922-11-26
ny COMMANDER STANFORD
HOOPER. Il. &. n

ny COMMANDER STANFORD c.
HOOPER, Z. =. n.
Radio fans frequently encounter diff
fculties in designing and installing
their miniature receiving antenna
systems.
The Navy encounters antenna diff
culties, too; usually not for receiving
purposes. but decidedly SO for trans
mitting. 1t has to meet exacting re-
Guirements and contend with most di-
versified and difficult conditions in
this respect.
The construction and installation OF
an antenna system for receiving pur-
poses only is a comparatively simple
necessary to suspend the overhead
part of the receiving antenna at great
heights above the earth. Excellent
results for all ordinary purposes are
obtained with the overhead wire or
wires suspended only 100 feet high,
Or even so feet high.
In fact. antenna systems consisting
of overhead wires and metal buried
IN the earth may be dispensed with
entirely and a closed metallic loop
tntenna utilized If receivers with
vacuum tube detectors and one or
more stages of amplification are used.
without doubt, however, the less
expensive receivers with crystal de-
tectors are the most extensively used
-or receiving the radiophone broad
Sasted programs.
Small Wire May BE Used.
With these sets the ordinary out
f6or antennae, with overhead wire or
wires and ground connection are re-
comparatively small size. No. 12 or
Il copper wire being plenty large
enough. and it may be either tnsu-
I"ted or bare.
At the naval stations where separate
-sceiving antennae are provided bare
seven strands ot No. is or No. IL
wire, is usually employed
The overhead part of the receiving
sutenna need not be extensive. Il
ehort-wave radiophone broadcast re-
ception a single wire approximately
700 feet long will meet the require
1uentS
Likewise the ground" part Of the
ordinary receiving antenna need not
be elaborate. 1t may consist of any
metallic body which makes good cleo
trical contact with permanently wet
CT moist earth.
1t may consist, for example. OF one
Or more bare copper wires of any con-
Eenient length buried two or more
feet in the earth. 4 metallic rod driven
:nto the earth = sufficient distance to
insure its making good electrical
contact with permanently wet or
moist earth. or the piping of the city
connection should be made to the
cold-water piping rathr than the hot
water ping.
Difficult antenna insulation prob
lens are not met with where only
the reception OF the incoming signals
is concerned. because the electro
magnetic energy value in the form of
high frequency oscillations VIII ch
Gow In the circuit is small. The
current value will he some where in
the neighborhood of one-fivet thou
sandth of an ampere only. and the
potential around one one-thousandth
IT J. volt
No Great Strain Imposed.
Insulators of great strength. either
tensile or dielectric. are not required
Imposed on the overhead part of the
Entenna and the impressed voltage is
s. negligible quantity, as compared
with conditions met with at high
power transmitting stations.
Only very small insulators need
therefore be employed. but OF course
itnese should he of good di-iectr c
ruaiity to insure that the feeble cur
rents flow to the earth through the
circuits Of the receiver instead of
The earth through the metal antenna
supports or other conducting paths.
AS no great tensile strain is i'm
posed by the suspension of one or
more small siZ s.ires of -rd
o. one hundred feet in length. anu
no appreciable strain is added by
winds blowing on these wires at
heights of approximately one hun
dred fee. extremely rugged antenna
supports are not required.
The receiving antenna may there
fore be supported by light wood or
iron pipe guyeIl masts, from unguyed
telephone pc. 8. or even from the
Oh hmneys which are in good condi-
tion on the housetops.
At transmitting stations however,
and especially at the high-power sta
ions. all these considerations under
30 a radical change.
The design and Installation of an
nntenna system at transmitting sta
4ons is decidedly other than the
simple and inexpensive problem en-
countered at receiving stations.
Most Expensive Feature.
Bar ring the variable costs Of land
the erection of antenna supports at
a h!gh-power station is by far the