New-York tribune., 1922-04-02
Produced as Protection
From German Intcrfer-
cncc With Wireless Com.
nlunicatien Of Allies,
Efforts Were Ne,,lralizcd
Will Have lmpo ortant Bear
ing on Commercial Work.
Especially Across Sea

sigrals f5or diatsnt station upon
rece:vinG apparatus located ve.y close
70 hich power traasni,sti station.
This receiver viii have IN important
Bearing upon the appl CO ion Of COM
mercial wireless telcohone work. cspe-
cialiy IN transoceanic cos "rsion
The receiver had jts -ption as
resalt OF the activities n' the Germans
during the late war. Th~ iatte- es.ab-
t;shed certain stations. which they en-
ployed solely for the purpose of send
ing out electro. magnetic waves in such
e manner sc % make Allied intercom-
uunication hy means % radio almost
impossible because Of The Interference
Their efforts we're cat rely neatralized
by the barragc receiver
The action of this receiver was ex-
piained IN recent paper delivered by
Ernst +. w Alexanderson, the we'll
',Eown radio engineer, whose high fire.
4ueney a'.erna,oY greatly improved
trans At!arti. wireless communication.
In It he said:
he object Of this development was.
briefly to provide means for neutraiiz-
lng the overwhelming intensity OF the
transmitted signal SO IS 20 make The
receiving Sc. sensitive 10 the faint i'm
pulses Of the distant signal. Popularity
speaking. the corresponding equivalent
IN sound waves would be to have an ear
which could be so adjusted that per
son could stand close to a steam whistle
put listen 20 person speaking from
distance Of few hundred feet
During the war the same problem
presented itself again III a form which
called for new solution. Distances
are only relative. and steam whistle
'ocated in GERMANY sht make such
noise that it would completely drown
ou. both in England and France the
sound Of the voice calling from Amer
lca
To find way TO c3unteract sueh
contingency was seriously considered
by the inter Alhad conference in Feb
ruary. 1918. and appeals for solution
were conveyed to the author by the
French representative in this country
Lieutenant Paternot.
The solution Ct this problem, which
Voas adopted by the American as well
- the French government after the
hrst demonstration, has become known
q. the barrags receiver This name
appears appropriate because the word
harrage has not only the military
meaning which has become so familiar,
but also the original meaning of toll
or stoppage prevention. Thus the bar
rag receiver may be used not only in
time OF war 20 counteract the offensive
barrage Of an enemy radio station, but
= may be used to multiply the number
Of peaceful communication that may
be carried on simultaneously without
disturbing each other.
The receiving set proper when used
With the barrsge receiver has all the
normal characteristics of a standard
receiving set.
Undergoes Difficult Test
"An experimental barrage receiving
set was operated for several months
about three miles from the New Bruins
wick. n. j.. radio station Records
1vere kept on the reception OF Euro
yean stations during the operation Of
The New Brunswick station. As tic
New Brunswick wave is 1860 meters,
ard the Carnarvon, Wales, wave is
14,200 meters, the reception Of Car
narvon was the hardest test to which
the set could be put
"It was found that in spite of the
overwhelming intensity of the New
Brunswick signals on an unbalanced
receiver the barrage receiver could be
adjus, led so that the transmitted wave
rot only did not interfere with the
Carnarvon signals. but the New Bruins
wick signals could be made entirely
lnaudible
OuTiiE IttSG Jesus IL WAS iOu1lu tHdl
the directive characteristics of the bar
rage receiver were material help in
reduction of interference by static and
strays, as il WAS found very frequent
Is that solid copv could be obtained by
= proper directive adjustment. while the
gnals were practically unreadable
with ordinary methods.
"A rather surprising characteristic
was discovered by the use of the bar
fa1 hot.
this receiver could be used to neutral
ize signals from all directions except
the direction close to the signal to be
received AS a matter Of fact, it was
found that interference could be neu-
tralized originating in the same direc-
tion as the signal
This was first discovered in the
New Brunswick installation. Signals
from San DIEGO. Calf, right in line
with the transmitting station, could
be received without great reduction
n intensity while the set was ad
justed SO as to neutralize the trans
lnitting station three mics away.
Difference in Radiation
The explanation for this is the
fact that in the case Of the nearby
station the wave front is curved and
the radiation diverging. whereas in the
case of the far-away station the radi
Gtion is parallel. The receiving an
tenna covers q space Of four miles,
end in this space there is sufficient
divergence of the radiation from the
nearby station so that an adjustment
can be made whereby the diverging
ard parallel radations have different
effect upon the receiving set.
The phenomenon is comparable to
.the focusing of field glass on near
sby and distant objects. In this case
we have a radio field glass of fouc
miles in diameter. and, for such di-
smeusions. the foeusiA~ effect is suf-
fcient. even al considerable distance,
TO produce an effective discrimination.
While the barrage receiver was
worked out primarily to avoid interfer-
scncc in transoceanic communication, it
a3nay be found useful also for the pur
poses for which the bridge receiver was
developed that is. simultaneous send
iuq and receiving from small shore sta
ticns and ship stations.
,.-v.'Jn such cases it has the advantage
over the bridge receiver in that it can be
s1sed not only to neutralize the transmit-
tting station 10 which il belongs, but can
ereutralize interference from any other
ship or shore station. 1t is thus hoped
that this development will open up new
possibilities in dealing with problem