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Патент USA US2406735

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`Sept. 3, 1946.
Filed Jari. so, 1945
2 Sheets-Sheet l
Sept. 3, 1946. `
Filed Jan. '3o. 1945
.w w
2 Sheets-Sheet 2
Patented Sept. 3, 1946
Andrew Alford, New York, N. Y., assigner to
Federal Telephone and Radio Corporation,
Newark, N. JL, a corporation of Delaware
Application January 30, 1943, Serial No. 474,094
13 Claims.
(Cl. 250---9)
This application is a continuation in part of
my copending application, Serial No. 445,944,
filed June 5, 1942.
The present invention relates to systems for
combining two or more signals and more partic
ularly to such systems wherein at least one of
said signals may be a course determining signal.
It is an object of my invention to provide a
system for interconnecting two modulated radio
frequencysources to a common line or load with
out substantial loss oi radio frequency power.
1t is a further object of my invention to pro
vide an arrangement wherein two separate
sources of modulated radio frequency may be
interconnected to supply modulated energy to a
common load in conjugate relation with a mini
mum oi energy dissipation.
It is a further object of my invention to provide
a system for radiating directively signals defin
ing a course line while at the same time radiat
ing upon the same wavelength further signals
such as signals representing speech and/or sig
no effect at the output of the source of the beacon
signals _and vice versa. 'I'his requires that the
two sources while being both coupled to the single
antenna means must nevertheless not be coupled
to one another. In order to attain such con
jugacy various types of so-called conjugate net
works may be used, such networks including the
well-known “Wheatstone” bridge, the hybrid coil
arrangement commonly used in carrier telephony
and other types of arrangements speciñcally de
Signed for coupling two sources to a load without
intel-coupling the two `sources to each other. One
of the most practical forms of conjugate net
work for use at high radio frequencies is the type
disclosed in my United States Patent No.
2,147,809 issued February 21, 1939, for “High fre
quency bridge circuit and high frequency re
peaters”, wherein there is described a sort of
bridge made up of four lengths of 2-wire trans
mission lines connected together in a square closed
loop with a transposition in one of the four sec
tions so as to prevent the effective transfer of
nals representing a further course line. More
particularly it is an object to provide such a sys»
power from any one corner of the square to the
one common antenna element while one of the
corner diagonally opposite while still permitting
tem wherein both signals shall be radiated from 25 transfer of power from any corner to the adjacent
signals, preferably the course line-defining sig
nal, is additionally radiated from further antenna
A common characteristic of all known types
of conjugate networks, whether of the preferred
type just described or not, is that an impedance
It is a further object to provide such a system 30 simulating the impedance of the useful load must
be connected to the conjugate network and when
wherein voice signals may be radiated from an
element of a directive array used for beacon pur
poses while at the same time insuring that the
mitted to the useful load. Accordingly, when the
voice signals shall not react upon the output stage
conjugate network of the preferred type or any
so connected receives as much power as is trans
delivering the beacon signals or vice versa.
35 other type is employed for coupling to a common
load the energy from a ñrst signal source and
t is a still further object of my invention to
provide a system which shall simultaneously ra
from a second signal source the required balanc
diate directional signals for aiding navigation and
ing resistor or dump which must be connected to
other signals such as speech signals without any
the conjugate network will receive as much energy
interaction between the sources of the two signals 40 as the load thus requiring that the speech signal
sources each generate twice the amount of power
and without requiring that 50% of the power
from each source shall be dissipated in so-called
necessary for the load.
It is an object of the present invention to over
“clumps” or matching resistors.
come the above disadvantage. It is a further
When combining two signals (e. g., directive
beacon signals and speech signals) for applica 45 object of the present invention to provide a sys
tion to a single antenna element (or to a group
tem which may radiate from a common antenna
both speech signals and other signals with rea
of antenna elements connected together so as to
sonable emciency (i. e., without the dumping of
act as a single antenna means) or other load,
large amounts of power) while at the same time
it is necessary that the connections be made so
as to maintain approximate conjugacy between 50 maintaining the essential characteristics of the
signals free from the inñuence of any vacuum
the two sources of signals (i. e., between the
source of the beacon signals and the speech sig
tubes, tuned circuits or other critical equipment
used for supplying them.
nal source). In other words, the connections
More particularly, it is an object to provide
should be made in such fashion that the varying
voltage from the speech signal source shall have 55 such a system wherein the phase and amplitude
of the beacon signals will be comparatively un
aiTected by the changing of tubes or retuning of
the circuits used for speech radiation and where
0 are the short transmission line sections 8a and
9a whose effective electrical lengths are arranged
to be varied cyclically at the rate of 90 cycles per'
second and 150 cycles per second, respectively,
in such eiîects as shall be produced shall not tend
to alter the directional pattern of the beacon
In brief, the present invention attains the
above and other objects by applying the one set
thus cyclically tuning these line sections to res-~
onance at the frequency of source li and then de~
tuning them again. As a result of such cyclical
tuning and detuning of the coupled sections 8a,
and 0a the transmission of energy along the
of signals and other signals to a common antenna
or other load via a conjugate circuit having a 10 transmission lines 8 and 9 is cyclically varied so
that the currents arriving in the upper portions
dump resistor and by arranging that both the
of these lines 8 and 9 correspond to a` carrier
signals applied to a common load comprise sub
frequency equal to the frequency of source 4
stantial carrier components of roughly the same
modulated with 90 cycles tone and 150 cycles
orders of magnitude and of accurately related
phases, these phases being so regulated that the
amount of power dissipated in the dump is small
compared to the amount of power usefully radi
15.' tone, respectively.
These tone modulated signals are then applied
from lines 8 and 9 to the right and left corners of
a combining bridge lil whose lower corner is con
ated from the common antenna.
The exact nature of >the invention may best
be understood from the annexed sheet of draw
ings in which:
Fig. 1 is a schematic diagram of a system em
bodying my invention and> adapted to radiate di
rective beacon signals and speech signals;
Fig. 2 is a similar diagram of another embodi
ment of my invention wherein the two signals
radiated are both directive beacon signals;
Fig. 3 is a schematic diagram of a portion of a
nected (through circuits more fully described
20 hereafter) to the central antenna element I while
the upper corner of this bridge I9 is connected
to the outer antenna elements 2 and 3. As
shown, the connection from the upper corner of
bridge I0 to antenna element 3 includes the
transposition II while the corresponding con
nection to antenna element 2 includes no such
transposition thus insuring that the antenna ele
ments 2 and 3 are excited in phase opposition to
one another.
circuit which maybe incorporated in the system
It should be noted that because of the transpo
of Fig. 2 in order to render the latter capable of 30
sition Ilia of bridge I0 the energy delivered to
simultaneously radiating two separate beacon sig
the outer antennae 2 and 3 contains no unmodu
nals and one speech signal; and
lated carrier component since this component is
Fig. 4 illustrates two modulated sources con-V
nected to a common load by a circuit incorporat
ing my invention.
Referring more specifically to Fig. 1, I, 2 and 3
balanced out. Thus, the antenna 2, for exam
ple, contains only the side bands corresponding
to the 90 and 150 cycle signals (e. g., c-I-90, c-90,
c-I-150 and c-150 where c is the carrier frequen
cy). The antenna 3 contains the saine four
are three antenna elements horizontally disposed
in a straight line with the outer elements 2 and 3
components in opposite phase. The power de
equally spaced from the center element I. Pref
erably, each element is a loop of the type disclosed 40 livered from the lower corner of bridge I0, on the
other hand, contains a very strong component of
in Henney’s “Radio Engineering Handbook” 1941,
carrier frequency c as well as of the four side
at page 601 and more fully described in my United
bands above described.
States Patent No. 2,283,897, issued May 26, 1942,`
Temporarily assuming that the lower corner of
for “Antenna system,” being thus adapted to
radiate substantially pure horizontally polarized p bridge I0 is directly connected to antenna I With
out any intervening bridge structure and assum
waves with substantially circular radiation pat
ing that the electrical length of the path from
terns for each individual loop. In order to di
such lower corner of bridge I0 to antenna I is
rectionally radiate beacon signals modulated with
_ 90° longer than that of the path from the upper
150 _and 90 cycles, respectively, the circuit ar
rangement shown in the left hand portion of Fig. 50 corner of bridge I0 to antenna 2, it will then be
clear that the 90 cycle side band components ra
1 is provided, this arrangement being essentially
diated from antenna I will add to the radiation
like that shown in my copending United States
of the corresponding side bands from antennae 2
application, Serial No. 300,166, ñled October 19,
and 3 in that region toV the north side of the
1939, now Patent No. 2,307,184, issued January 5,
55‘ course line WE while tending to oppose such ra
diation on the south side of such line. The rea
Bríeily, this arrangement comprises the com
son for this is that the 90 cycle side bands must
mon source li whose output after passing the
pass through one transposition in traveling from
power amplifier 5 is applied to the lower> corner
transmission line 8 to antenna 2 while encounter
of a bridge (i. This bridgerß is of the type de
scribed in the above-mentioned United States 60 ing noY transpositions but only a 90° greater
length of line when traveling from transmission
patent, No. 2,147,809, the transposition 6a being
line 8 to antenna I. Accordingly, the radiation
arranged in the upper right hand arm thereof
of the 90 cycle side bands from antenna 2 will
and a balancing dissipating impedance -I sub
stantially simulating the loutput impedance of
be 90° retarded with respect to the corresponding
the amplifier 5 being connected to the upper
cornerof the bridge so as to be essentially con
jugate to the amplifier 5. A 2-Wire transmission
line 8 is connected to the right corner of bridge
6 anda similar line 9 is connected to the left
hand corner thereof so that energy is delivered to
each of these lines from the ampliiier 5 although
substantially no energy is delivered from this
radiations from antenna I.
At the same time
the corresponding radiations from antenna 3 will
be 90? advanced compared to those from antenna
I because of transposition II. While the radi
1 ations from antennae 2 and 3 exactly cancel along
70`the course line WE, the vectorial combination of
the> 90 cycle side 'bands from these antennae 2
and 3 will yieid a resultant at any other given
ampliñer to the balancing impedance 'I because
point in space by reason of the difference in path
length from the two antennae to such given point.
of the effect of the transposition 6a.
Loosely coupled to the transmission lines 8 and
North of the course line WE, the radiations from
antenna. 2 will arrive in a shorter time than those
from antenna 3 thus effectively advancing the
phase of the radiations from 2 and retarding the
phase of those from 3 with respect to the phase
of radiations from antenna I. Therefore, the re
panying these speech signals` is dependent upon
sulting radiation from antennae 2 and 3 com
bined will be in phase with the corresponding ra
diation from antenna I at anyv point north of
the course line. Conversely, the 150 cycle radi
ation from the antenna 2 will be 90° advanced in
phase with respect to the corresponding radiation
from antennaV |. The resultant 150 cycle side
band radiation from antennae 2 and 3 will' tend
the characteristics of ampliñer 2| and thus can
be varied due to adjusting the tuned circuits of
this ampliñer or even by virtue of changes in the
tube characteristics thereof.v The phase shifter
22 is. provided to take care of these- variations in
phase andV is intended to be setv so that the phases
of the carrier components in the speech signals
and in the beacon signals are alike at the points
where these signals are applied to the right and
left corners of bridge 23’, respectively. If this
phase relationship is attained and if the magni
tudes of the carrier components of the two sig
to add to the corresponding radiation from an
nals are alike, it will then follow that no carrier
tenna | in the region south of the course line 15 frequency energy will be dissipated in impedance
WE while subtracting therefrom in the region
24> because of the effect of transposition 23a.
north of this course line.
Even if the carrier power from speech ampliñer
The aparatus so far described corresponds to
2| be assumed to be only half as great in ampli
that disclosed in detail in the above-identified
tude as the carrier power from the bottom of
bridge I0 (so that the corresponding voltages are
application, Serial No. 300,166, a detailed under
standing of the operation of such arrangement
in the ratio of .707i to 1) it can readily be seen
being desirable for full appreciation of the pres
that the voltage at the 'upper corner of bridge
ent invention.
23 will correspond to l-I-.707 (i. e., to 1.707) while
The further apparatus 20--25 is associated with
at the lower corner- it will correspond to 1'-.707
the apparatus already described for the purpose 25 (i. e., to .293). rIïhe corresponding powers will
of applying speech signals to antenna I simulta
.be proportional to (1.70.7)2V and (.293)2 respec
neously With the beacon signals heretofore de
tively, being thus in the ratio> of 2.9' to: .086, i». e„
scribed. Such additional apparatus essentially
about 34 to 1. Thus, when the carrier compo
comprises a speech source 20 (illustrated as a
nent from amplifier 2| is only half asV great as
telephone transmitter but preferably comprising 30 the corresponding power from. bridge I0 it still
a microphone and suitable audio amplifier stages)
appears that the power dissipated in dump 241 is
connected to modulate an R-F ampliñer 2| which
less than 3% of the carrier power usefully radi
is excited in parallel with the ampliñer 5 from
ated from antenna I.
the carrier source 4. The speech modulated out
With respect to the side bands of the speech
put of. amplifier 2| which is preferably of the 35 signals and the beacon signals it is true that sub
same order of magnitude as the output of ampliiier
stantially 50% dissipation occurs in impedance 24
5 is transmitted through phase shifter 22 to the
but in most cases the average side band power
right-hand corner of conjugate bridge network
is considerably smaller than the average carrier
23, which is preferably of the type described in
power and therefore the total amount of wastage
the above-mentioned United States Patent No. 40 is a comparatively small percentage of the total
energy usefully radiated from antenna I.
As shown in the drawings, the upper corner of
One great advantage of the arrangement in
the bridge 23 is connected to antenna | and the
Fig. 1 is that phase variations introduced in the
left hand corner thereof receives the proper bea
amplifiers 5 and> 2| (by virtue of the adjusting
con signals from the lower apex of combining
of the associated tuned circuits or variations in
bridge it' earlier described. Thus, both the
speech modulated signals from amplifier 2| and
the combined carrier and four side bands of the
the tube characteristics thereof) do not alter
either ythe position of the course line defined by
the beacon signal or the shape of the radiation
beacon signals from combining bridge I0 are
pattern in respect to relative strengths of the
transmitted via bridge 23 to antenna I. In order 50 150 and 90 cycle signals at. anyY points in space.
to insure conjugacy between the speech signals
It is also true that if .the phases of the carrier
from ampliñer 2! and the beacon signals from
components delivered by the ampliñers 5 and 2|
the lower corner of bridge I0, bridge 23 is bal
vary in opposite sense by a considerable number
anced by means of transposition 23a and a bal
of degrees a substantial dissipation of power in
ancing dissipating impedance 24 whose impedance 55 impedance 24 will result since the carrier com
as viewed from bridge 23 is equal to that of the
ponents arriving at the right and left corners of
antenna element I as viewed from this same
bridge 23 will no longer be in phase. Such a
bridge, A radio frequency voltmeter 25 is con
result, however, is by no means as serious as a
nected across the line between the lower corner of
distortion of a beacon radiation pattern. Fur
bridge 23 and the impedance 24 for a purpose
thermore, the dissipation of energy in the dump
24 is constantly indicated bythe meter 25 and
hereafter to be described.
it should be noted that the signals from mod
therefore any person adjusting the tuned circuits
ulated ampliner 2| and the beacon signals from
associated with either amplifier 5 or 2|A will be
the lower corner of combining bridge I0 are not
immediately apprised of any incorrect phase re
only of the same wavelength but both contain a
It should be observed that even if a very large
substantial component of carrier frequency de
difference in phase exists between the carrier
rived from the common source 4. 1n the case of
components from` amplifiers 2| and 5 the side
the beacon signals this carrier frequency compo
band components of the beacon signal radiated
nent has a phase dependent upon the character
istics of power ampliñer 5 and this phase may 70 from antenna | willstill be properly phased with
respect to the> corresponding side band compo
vary due to adjusting of the tuned circuits of
nents of the beacon signal radiated from anten
this amplifier or even, to some extent, due to
nae 2v and 3. Also, these side bandA components
the two variations in the tube characteristics
will be properly phased with respect. to the por
thereof. In the case of speech signals from am
pliñer 2| also the phase` of the carrier accom 75 tionA ofv the carrier'. component which. is derived
from amplifier 5. If, therefore, the two carrier
beacon signals comprises the power amplifier |05;
the two transmission lines |68 and |09 with their
components supplied by amplifiers 5 and 2| are
modulating equipments |0811 and I09a; the bridge
of equal magnitude, then a phase shift as much
|05 for transmitting the power to these lines |08,
as 60° between the phases of the carrier com
|09 from the ampliñer |05; such bridge being
ponents supplied from the >two Iampliñers will re
provided with a transposition lßEa and a balanc
sult in a phase shift of only 30° between the re
ing impedance |01 in order to prevent the modu
sulting combined carrier radiated from antenna
lator of |00a of channel |09 from reacting on the
I and the beacon side bands. Such a phase shift
channel |08 or vice versa; the combining bridge
will not alter the beacon pattern at all (in viewL of
the fact ythat the side band components in the 102 I I0 with its transposition I Illa and the antennae
|02 and |03. All of this equipment operates es
several antennae are properly phased) but instead
sentially like the correspondingly numbered
will only decrease the efficiency of demodulation
equipment in Fig. l (the number |08 being con
at the receiver by decreasing the amount of use
sidered as corresponding to the number 8, etc.).
ful carrier component available for demodulating
The side antennae |02 and |03 are fed anti
the signals. This effect is not :at all serious un
less the phase relationship between the carriers
phasally with the four side bands corresponding
becomes as great as 180°, in which case the re
to a 1020-cycle modulation and a 1300-cycle
sultant carrier being 90° to the side bands would
not be useful for producing demodulation in the
modulation, these side bands having the frequen
cies c-l-lOZO, c-1020, c-l~1300, and c-1300. The
receivers. It is clear, however, that the phase
_ central antenna I’ is fed from the lower corner of
shifts of the amplifiers are not likely to equal
180° especially with the constant check provided
bridge I IIla with .appropriate signals having a
strong carrier component and also including the
by meter 25.
With respect to the speech frequencies the
tennae |02 and |03. .The bridge 23’ combines the
shifting of the carrier with reference to the side
bands is also somewhat undesirable since it tends
to'produce harmonic distortion. Such distortion
is unimportant if the percentage modulation is
small. In the system shown, moreover, half the
carrier component isderived from amplifier 2|
and therefore does not shift.
Thus a phase shift of 60° between the two car
rier components would only shift the combined
carrier by 30° with respect to the speech side
bands. YThese two factors (i. e., the effect of low
modulation percentages in preventing distortion
and the fact that only half the phase shift be
tween carriers appears as a phase shift between
the combined carrier and the side bands) both
tend to reduce the amount of distortion encoun
tered in practice. Thus, as a practical matter,
under ordinary conditions with a modulation per
centage around 80% a phase shift as large as
50° between the two carriers will not produce an
intolerable percentage of harmonic distortion in
the speech signal.
>Although the invention has so far been de
scribed as used for radiating speech signals and
beacon signals from one common antenna ele
ment (e. g., antenna element I of the array I, 2,
3), the invention is also capable of other uses.
Thus, for example, it may be used for radiating
two separate beacon signals from a common an
tenna, such an arrangement being illustrated in
Fig. 2.
Referring more particularly to Fig..2 the com
ponents I’, 2', 3', II', 5', 8'., 6a', l', 8', 8a', 9',
9a', I0', Illa' -and II' correspond exactly to the
elements of Fig. 1 having corresponding unprimed
designations. These elements together constitute
same four side bands which are radiated from an
_ signals from the lower corner of bridge ||0 with
those from the lower corner of bridge I0'. Each
of these signals to be combined contains a sub
stantial carrier component and these components
are ofthe same order of magnitude (i. e. the
ratioof the powers is less than 10:1). The phases
of the carrier components arriving at the left
hand and right hand corners of bridge 23’ should
be alike and this condition may be attained by
adjusting the tuned output circuits of amplifiers
5’ and |05 to produce the desired phase relation.
In case a more convenient adjustment is desired,
a phase shifter may be provided just ahead of
amplifier 5' or |55 or immediately following either
or both of these ampliñers. The meter 25’ will
serve to show when the desired phase condition
is reached, since this meter will read Zero or a
minimum when the carrier components arriving
at the left and right corners of bridge 23' are in
phase. In the system of Fig. 2, an east-west
Ul course line is defined by the equality of the 150
cycle modulated signals and the 90 cycle modu
lated signals, while a north-south course line is
defined by the equality of the 1020 cycle modu
lated signals and the 1300 cycle modulated sig
nals. For properly generating the beacon pat
terns to define these course lines, antennae 2' and
3' and |02 and |03 should be fed in phase quadra
ture with respect to the central antenna I’. «Ac
cordingly, the electrical length of the path from
the upper corner of bridge I0’ to antenna 2' may
be 90° shorter than the length of the path from
the lower corner of bridge IIJ' to antenna I'.
Similarly, the length of the electrical path from
the upper corner of bridge III) to antenna |03
may be 90° shorter than the length of the path
a beacon defining a west-east course line exactly 60 from the lower corner of bridge I I0 to antenna I'.
as described in connection with Fig. 1.
These relationships may be satisfied by suitably
The bridge 23’ with its transposition 23a and
choosing the lengths of the transmission lines. If
desired, however, phase-shifter equipment can be
its dump 2li' and its meter 25' serve, as in thev
case of Fig. 1, to transmit to the central antenna 65 inserted between Vthe upperl corner of bridge I0'
I’ not only the appropriate beacon signals (con
and the antenna array and other phase-shifting
sisting of a carrier component and four side band
equipment may be inserted between the upper
components having the frequencies c+ 150, c-150,
corner of bridge | I0 and the antenna array. Such
c+90 and 0_90, respectively), but also an ad
phasing equipment, if provided, would be adjusted
ditional independent set of signals based upon 70 for initially aligning up the courses and would
the same carrier frequency. In the case of Fig. 2A
thereafter not be disturbed.
such additional independent Set of signals is as
lfit is desired to combine more than two signals
sumed to be another set of beacon signals rather y
upon >a common antenna, this may be done by
than a speech channel as in Fig. 1.
extending the principle of the present invention.
The equipment _for providing the additional. 75 Fig. 3 illustrates how Fig. 2 could be modified to
-embody such a system, the circuit of Fig. 3 being
intended to be substituted for the rectangle 5D
age incurred with the ordinary conjugate circuit
arrangements, without controlling the phases of
in Fig. 2. As will be shown by comparing Fig. 3
with the right hand portion of Fig. l, the ampli
the carriers). In respect to phasing, also a ‘con
siderable latitude is permissible. Thus if the
vfier 22! which is modulated by speech source 220 5 two carrier components to be combined are equal
feeds its speech modulated output to bridge 223
in power, a phase divergence Of as much as 30%
in essentially the same way that amplifier 2l
causes the dissipation of only .about 61/2% of the
fed its output to bridge 23 in Fig. l. In the sys
total power while even a phase divergence as
tem of Fig. 2 as modified by Fig. 3, the additional
large as 60° >causes the dissipation of only about
input which is combined with the speech signals 10 25% of the total power.
in bridge 223, arrives from the lower corner of
Although the invention has been particularly
bridge I I0 and in order to minimize losses in the
described for combining two signals one of which
dump 224, the phases of the arriving carrier com
is a beacon signal, it can also be used for com
ponents may be adiusted by adjusting the tuned
bining two signals of any type, for example,
output tank of amplifier HB5 of modulated ampli
-iier 221, or both. If desired, however, a phase
shi‘fter'may be included before or after either or
both of these amplifiers. The output from bridge
223 'is applied to the right hand corner of bridge
23’ where it is combined with output from the
lower corner of bridge l0’. Preferably, the ampli
tudes of the carrier components arriving at the
upper and lower corners of bridge 223 (from
amplifier 22K! and the lower corner of bridge I I0)
should be approximately equal in magnitude and
should each be approximately half the amplitude
of the carrier components delivered from _ the
lower corner of bridge lil’. Thus, the combined
carrier delivered from the left corner of bridge 223
-will be of substantially the same amplitude as the
carrier delivered from the lower corner of bridge
l0’ and therefore substantially no dissipation of
vcarrier energy will occur in the dump 24’.
In the circuits of Figs. 1, 2 and 3 a circuit ac
cording to my invention has been shown for com
bining beacon signals and speech signals. The
circuit is useful, however, for combining modu
lated radio frequency energy from any two
In Fig. 4 is shown a ñrst source of carrier modu
lated signal '60H and a second source of modu
lated signal 402. These sources are of the same
radio frequency but carry thereon different signal
The modulations may be of any de
15 phase and amplitude modulated signals vemploy
ing the same carrier or telegraph and telephone
signalsY based' on the same carrier.
For` convenience, the illustrated embodiments
of the invention show the modulation as effected
at audio-frequencies (i. c. by audible -frequency
tone modulators producing ‘power tones of 90
cycles, 150 cycles, 1020 cycles or 1300 cycles, or
by speech frequency >modulating equipment. It
should be understood, however, that the modu
lation may be performed at `super-'audible or sub
audible frequencies and may lconsist of or include
the process of 'keying in A-N rhythm >or other
rhythm. Thus, the expression “modulation” as
used in the appended claims should `be inter
preted in its broader sense to include `all modifi
cations of the amplitude, phase, or frequency of
the carrier by any of the commonly used proc
esses ordinarily referred to >as modulation or
Although certain >embodiments of the inven
tion have been shown and described for purposes
of illustration, it will be understood that varia
tions, adaptations and modifications thereof oc
curring to one skilled in the art may be made
without departing from the scope of `the inven
tion as defined bythe appended claims.
What is claimed is:
1. A `system for simultaneously applying two
Vsignals on the same carrier lfrequency wavelength
sired type, for example, they may be intermediate 45 to a common useful load which comprises a 'first
carriers modulated with signals to be applied to a
signaling means for producing 'a iirst side band
component and a first carrier component, second
signaling means for producing a second side band
transposition 405. A balancing dissipating net
component and a second carrier component,
work 406 is coupled to the bridge terminal opposed `50 common load means, a balancing dissipating ele
to load line 403 and is proportioned to match the
ment simulating the impedance of said common
’impedance of the load. Thus, two sources are
load means, a balanced network connected to
interconnected so as to have no reaction one on
transfer energy from said first and secon-d sig
the other, and yet relatively wide variations in
naling means to said common load means and
amplitude and phasing of the signals may be per .55 with a relative phase reversal to said balancing
multiplex line 423. Sources Ml, 402 are applied
to the opposed d'iagonals of bridge 404, having a
mitted without destroying the substantial advan
element while maintaining substantial conjugacy
tages of the system.
between said first and second signaling means,
If desired, 450|, 402 or both, may include `arn
and carrier synchronizing means for maintain
plitude and phase adjusting means so that ad
ing said first and second carrier -components at
justment may be made until minimum lcurrent 60 the same frequency and in a predetermined
is applied to dissipating network 4835 as indi
phase relation such as to minimize the absorption
cated in meter li111.
of carrier energy in said balancing element.
Although it is preferred that the two carrier
2. A system for simultaneously applying two
components to be combined ‘in any one of the
signals on the same given carrier frequency
bridges (e. g. 23. 23', 223 or 404) are preferably
wavelength to a common useful load which com
oophas‘ial and oi’ equal magnitudes, very wide
prises a iirst signaling means for producing a
departures from this condition may be tolerated
first side band component and `a first carrier
while still giving surprisingly'small losses in the
component of said given wavelength, second sig
dum-p balancing resistor. Thus, for example, a
naling means for producing a second side band
4:1 power ratio will result in a dissipation of
component and a second carrier component of
only 10% of the total power; 90% of this `power
said given wavelength, common useful loa-d
being transmitted to the useful load. Even a
means, a balancing element simulating the im
10:1 power ratio results in wasting only about
pedance of said load means, a, balanced network
21% of the total power (which is a very sub
connected to transfer energy from said iirst and
stantial improvement over the 50% power Wast 75 second signaling means to said common useful
Y 2,406,735
load connection, means in said bridge for Yproduc
load> and with a relative phase reversal to said
ing a phase reversal of energy from one of said
sources intermediate the connection points of said
source and said dissipating network to the said
balancing element while maintaining substantial
conjugacy between said iirst Iand second signaling
means, and means for adjusting the phases of
said first and second carrier components thereof y5 bridge and means for maintaining energy sup
plied from said sources to said bridge substan
as measured at the input to said balancing'ele
ment substantially into opposition.
tially in phase coincidence whereby carrier fre
quency energy is substantially balanced out at
3. A system for simultaneously applying to a
common useful load two signals on the same car
the input of said dissipating'network and substan
rier frequency wavelength which comprises ñrst 10 tially only side band energy is dissipated in said
signaling means for producing a ñrst side band
8. A system in accordance with claim 7 wherein
each of said sources comprise independent ampli
fier arrangements and said means for maintain
nent, said carrier components being of the same 15 ing energyY applied from said sources to said bridge
substantially in the same phase comprising a
radio frequency, a dissipating balancingelernent
phase shifting network for adjusting ’in phase
simulating the impedance of said common load,
energy from one of said modulated sources with
a balanced network connected to transfer energy
respect to energy from the other of said sources.
from said ñrst and second signaling means to
9. A system for simultaneously applying car
said common load and with a relative phase re 20
rier energy of the same frequency but modulated
versal to said balancing element while main
component and a first carrier component, a sec
ond signaling means for producing a second side
band component and a second carrier compo
with different characteristic signals to a common
taining substantial conjugacy between said ñrst
radiating means, said signals each comprising a
and second signaling means, carrier synchro
carrier frequency component and respective side
nizing means controlling said ñrst and further
signaling means to maintain the phases of said 25 band components comprisingV a balanced four
arm bridge circuit, means for coupling saidV radi
carrier components substantially opposite as
ating means to a ñrst point on said bridge, a dis
measured at the terminals of said balancing
sipating network means for coupling said Ydissi
pating network to a second point diagonally oppo
4. A system according to claim 3 wherein said
ñrst and second signaling means are adjusted to 30 site said first point, means Yfor applying carrier
and said band components from each of said
transmit to said balanced network carrier com
sources to ’respectively opposite terminal points
ponents of substantially the same Iorder of power.
of said bridge to supply carrier frequency energy
5. A system according toY claim 3 wherein said
first and second signaling means are adjusted to
transmit to said balanced network carrier com
ponents, the ratio of whose powers _is less >than
and side band frequency energy from both sources
35 to said common radiating means, and means for
maintaining energy from both said sources 'over
said network to said dissipating network in such
phase relationship that said carrier components
6. A system for simultaneously applying to> a
from the respective sources are substantially in
phase opposition whereby substantially no car
rier frequency energy Vis dissipated in said net
common load two signals on the same carrier fre
quency wavelength which comprises ñrst signal
ing means for producing a ñrst side band com
ponent and a first carrier component, second sig
work, said side band components both being ap
plied to said network for dissipation.
10. The method for simultaneously applying
naling means for producing a second side band
component and a second carrier component, a
dissipating balancing element simulating the im
45 two signals on the same‘wavelength to a common
useful load over a’balancing network designed to
pedance of said common load, a balanced network
connected to transfer energy from said first and
second signaling means to said common load and
maintain conjugate relation between said signals -
which comprises producing a first carrier compo
nent at said wavelength and an associated ñrst
with a relative phase reversal to said balancing
element while maintaining substantial' conjugacy »
side band component, producing a second carrier
between said first and second signaling means,
carrier synchronizing means controlling said first
and second signaling means to maintain the fre
quency of the carrier components identical and
the phases of said carrier components within 60°
component at said wavelength and a second asso
of being opposite.
ciated carriercomponent, applying said ñrst car
rier component, said first side band component,
said second carrier component and said second
carrier side band component to said load over
said network in such phase relation that said car
riers are substantially in phase coincidence in
said load and applying said components over said
network to said dissipating network in such phase
'7. A system for simultaneously applying two
signals on the same common carrier frequency to
a common load comprising a ñrst source of modu
lated energy having a carrier componentof said
common frequency and side band components, a
second source of modulated energy having a s'ec
ond carrier component of said common frequency
relation that the ñrst and second carrier com
ponents are substantially in phase opposition at
the inputin said dissipating network whereby
substantially only side band energy is dissipate
in said dissipating'network.
and other side band energy, a dissipating ele- Y
1l. The method in accordance with claim 10
ment simulating the impedance of said common 65
the further step comprising adjusting the rela
load, a balanced bridge having four diagonally
arranged points, >means for applying energy from
tive phase in said first and second carrier com
ponents to maintain the desired phase relationship
said ñrst modulated energy source and said sec
ond modulated energy source to opposite diagonal
therebetween atV said load and said balancing
points of said'bridge, means for coupling said
load to another of said diagonal points to receive
carrier frequency energy and side band frequency
' energy from both said sources, means for cou
` `
l2. A system for simultaneously radiating
course indicating signals and voice signals simul
taneously from the same antenna system on the
pling said dissipating network to the other'Y said
same carrier frequency comprising a ñrst’car
point on said bridge diagonally opposite to. said 75 rier frequency source, means for modulating en
ergy from said carrier frequency source with
and means in said balancing networks for main
beacon signals, means for applying said signal
modulated energy only to certain of said antenna
taining carrier frequency energy from both of
said sources substantially in phase coincidence at
units, a second carrier frequency source, means
said common antenna and substantially in phase
for voice modulating said second carrier fre
opposition at said dissipating network.
quency, a balancing network, a common antenna
13. An arrangement in accordance with claim
12 further comprising means for shifting the
phase of said voice modulated carrier energy be
fore application to said balancing network to
unit cooperatively arranged with respect to said
certain antenna units, means for applying modu
lated energy from said course indicating source
and from said voice modulated source over said 10 assure proper phase relation of said carrier energy
at said antenna and at said dissípating network.
balancing network to said common antenna and
for supplying energy from said sources over said
balancing network to said dissipating network
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