The Washington herald., 1922-05-21
COIL ANTENNA AID
IN HALTINC STRAYS
DURING SUMMER
Radio Experts Fight to
Overcome Effects of
Hot Weather.

According to the Bureau of Stand
ards, these summer disturbances,
called "strays," static" "atmos-
pheres' and other names. are in evil
dence from about April / to octo-
Der 1. Their seriousness varies
from weak interference for brief
intervals to continuous success
sion of boiler shop noises which
may last throughout the night.
A great deal Of work has been
done by radio engineers and scien-
lists in an effort to reduce the in
terfering noise caused by these
strays. At important government
and commercial stations certain de-
vices and methods are in use by
means of which strays are consid-
erably reduced. and Ii is made DOS
sible to obtain fairly reliable re-
ception during the summer. The ap-
paratus and methods now employed
at such stations are usually too
elaborate to be used at the ordinary
amateur station. One method which
the amateur will find helpful in re-
ducing certain types of strays is
the use instead of the usual ele-
waited antenna, of a coil antenna
and a more sensitive receiving set
A coil antenna may be constructed
by winding a suitable number of
turns of wire with proper spacing
on a square wooden frame about
four feet square. Certain types Of
strays seem to come from a partic-
ular direction. Many strays. how
ever. have no directional properties,
including those due to local cleo
trio storms. The coil antenna has
the property of receiving a stronger
signal when pointed in the direction
from which the signal is approach
ing. and receiving only a weak sig
nal when pointed at right angles
to that direction. Thus by rotating
a coil antenna to the proper posi-
ton the directional types of strays
can be greatly reduced and a better
ratio OF signal to strays will be OBJ
tanned. The ordinary elevated an
rectionl properties. and, therefore.
cannot be used like the coil antenna
for stray elimination. However. the
strength of signal picked up by a
coil antenna Is much smaller than
tie strength of signal picked up by
the ordinary elevated antenna, and
good results should not be expected
from a coil antenna unless three
or more stages of application are
used.
Some relief can also be obtained
by persons having good amplifiers
by using a ground antenna." This
is a long insulated wire run in a
shallow trench or on the surface Of
the ground. The ground wire should
be run in the direction of the sta
ton from which the most signals
are to be received. and should pref
exably be several hundred feet long.
Through strays of given inten-
sity, better results can be obtained
in receiving strong signals than
weak signals. Nearby stations can
be received much better through
the strays than distant stations 1t
is therefore fortunate that broad
casting stations are being estab-
lished at a considerable number OF
different cities located in all parts
of the United States. so that for
most parts of the country there is
a broadcasting station from which
fair reception can be expected even
when strays of moderate intensity
exist. In the summer a person must
be content with weaker signals and
should use less application than in
the winter. since the strays are am
plified as we'll as the signal II
considerable amplifcation is used.
strong stray disturbances will pro-
duce noises in the telephone re-
ceivers which are very unpleasant
and MAXI it almost impossible for an
operator to keep the telephone re-
ceivers on the head for any con-
siderable length of time.