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Патент USA US2403500

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July 9, 1945-
w. L. CARLSON
_ 2,43
SYSTEM FOR AND METHOD OF AIRCRAFT RADIO COMMUNICATION
'
Filed Oct; 22, 1941
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Patented July 9, 1946
2,403,500 >
UNITED STATES PATENT OFFICE‘
2,403,500
SYSTEM FOR AND METHOD OF AIRCRAFT
RADIO COMIWUNICATION
Wendell L. Carlson, Haddon?eld, N. J., assignor
to Radio Corporation of America, a corpora
tion of Delaware
1
Application October 22, 1941, Serial No. 416,022
13 Claims. (01. 250-6)
2
This invention relates to improvements in sys
tems for and methods of aircraft communication,
and particularly to a system for communicating
radiated toward the zenith and vertically polar
between a ?xed radio station and a moving air
craft station so that the radio waves will be effec
tive at all attitudes and all positions of the air
craft.
1y directed paths so that signals will be received
substantially independently of the attitude and
thereby completely shielding the antenna. The
from any direction.
ized waves are radiated horizontally and in which
the waves are received alternately over different
position of the aircraft to which the signals are
directed. An additional object is to provide an
In aircraft radio systems, dif?culties in main_
aircraft radio system in which a pair of antennas
taining communication are often experienced due
are connected through separate ampli?ers to a
to changes in the attitude or position of the air 10 combining circuit whose output includes a single
craft. The changes in attitude may be so pro
communication signal. .A further object is to
nounced that the wings of the aircraft may come
provide a receiving antenna which will normally
between the ground station and the antenna
respond to circularly polarized waves arriving
-
signal waves may be re?ected from the plane 15
The invention will be described by referring to
parts, such as the wings, and may induce signals
the accompanying drawing, in which Fig. 1 is a
into the antenna which oppose the normal signal
block diagram of one embodiment of the aircraft
waves received on the antenna. The changes in
radio receiver of the invention; and Figs. 2 and 3
position of the aircraft may be su?icient to direct
are circuit diagrams of two embodiments of the
the antenna response pattern away from the 20 radio transmitter .of the invention. It should be
ground station instead of toward it, so that the
understood that the ground station of the system
signals, received under conditions of normal an
may include either transmitter and the aircraft
tenna directivity, disappear. Another null signal
station may include the receiver of Fig. 1 or the
position is often found in passing directly over
equivalent thereof.
an antenna which has no vertical response. One 25 Referring to Fig, 2, a radio transmitter I is
example of the effect of the attitude of the air
connected through a transmission line 3 to a loop
craft is found in an aircraft in which the antenna
antenna 5 which radiates along the horizontal a
is installed below the belly of the craft. When
verticallypolarized wave represented .by arrows ‘l.
the craft is banked sharply, so that the antenna
The transmitter i is also connected through the
is shielded by the craft, no signals will bere 30 transmission line 3 and a quarter-wave transmis
ceived from the station from which the antenna
sion line 9 to a second loop antenna II which is
is shielded. If the antenna should be mounted
spaced ‘at 90° with respect to the ?rst ‘loop an
above the belly of the craft, the instant di?iculty
tenna 5. The second loop antenna also radiates
would be overcome only to incur a new difficulty;
along the horizontal vertically polarized waves 1.
namely, the shielding would be effective in the 35 The horizontal portions of the two loops radiate 7
opposite direction. In a similar manner, if the
waves toward the zenith. The waves radiated to
antenna on the aircraft is arranged for receiving
ward the zenith are circularly polarized because
vertically polarized waves in normal ?ight, and
the loop currents are in quadrature phase and
if the craft is banked steeply, the antenna will
theloops are normal to each other. Thus the an
become responsive only to horizontally polarized 40 tenna system provides meansfor radiating circu
waves so that signals will be lost during the bank.
larlypolarized waves traveling toward the zenith
It is one of the objects of the instant invention
and vertically polarized waves traveling toward
to provide improved means for communicating
the horizon.
,
between a ?xed radio station and an aircraft
The aircraft radio receiver is shown in'Fig, l,
radio station so that communication will be effec 45 in which a pair of V-shaped dipoles l3, l5 are
tive at substantially all attitudes and substan
tially all positions of the aircraft. Another ob
ject is to provide an improved method for air
craft communication in which the transmission
includes circularly polarized components and the
reception is directed alternately along two differ
ent paths so that at least one of said ‘paths is
always responsive. Another object is to' provide
an improved method for aircraft radio communi
cation in which circularly polarized waves .are
50
mounted respectively on the tips of the aircraft
wings ll. The antennas are arranged in the ver
tical plane and are differently directed because
of the shielding effect of the Wings [1. The an- .
tennas are separately connected to heterodyne
converters I9, 2| which may include ampli?ers.
A common oscillator 23 supplies the local oscilla
tions for the signal conversion. The ‘outputs of
‘the converters I9,'2l are respectively applied to
.modulators'25, 21 which are alternately keyed by
2,403,500
3
a modulating oscillator 29.
output of the receiver, which is operated as pre
viously described, may be used for controlling the
modulators are combined in a common intermedi
ate frequency ampli?er 3|. The output of the
I.-F. ampli?er is applied through a signal detec
tor and ampli?er 33 to a signal indicator 35.
The mode of operation of the receiver is as fol
lows:
The antennas l5, I‘! respond to the trans
mitted Waves, as hereinafter described. The cur
rents induced in the antennas are ampli?ed sepa
rately in the converters l9 and 21 and are con
4
spond regardless of the attitude of the craft. The
The outputs of the
maneuvers of the craft.
Thus the invention has been described as an
improved radio communication system for air
craft. In one arrangement, the ground trans
mitter is arranged to radiate along the horizon
vertically polarized waves, which are alternately
10 received on V—shaped dipoles located at the wing
tips of the craft. Two receiving antennas might,
if preferred, be located above and below the body
of the plane. The alternately received signals
verted into intermediate frequency currents by
beating with the local oscillations. The I.-F.
currents are alternately applied to the 1-H am
pli?er by means of the modulators and are al
are combined to form a single communication
ternately blocked by the modulating oscillator 15 signal. While the receiver has been described as
a superheterodyne, with the modulator 29 oper
29. The modulating oscillator biases at the same
ating after the conversion, it should be under
instant one modulator tube positively and the
stood that the conversion step may be eliminated
other modulator tube negatively. The modulat
and the circuits operated at radio frequency.
ing oscillator frequency is chosen so that it will
be inaudible (for example, 20 kc.), and may be 20 The modulator 29, which alternately operates the
two channels, may be located ahead of the het
eliminated by ?ltering the detector output cur
erodyne converters l9, 2| or may be combined
rents. After modulation and ampli?cation, the
with the local oscillator. It is possible to elim
currents are combined by the detector and, after
inate the modulator by amplifying separately
ampli?cation, are applied to the signal indicator.
The alternately operated paths produce, after 25 and combining in the audio or output signal chan
nel, While the system has been described in con
combination, a single communication signal so
nection with aircraft communications, it should
that the operator cannot determine from the sig
be understood that the system is not limited to
nals themselves Whether the waves received are
any particular type of communications. ‘
from one dipole or the other, or both.
The dipole radiators of each antenna are pref 30
I claim as my invention:
erably a quarter-wave long and are arranged to
1. The method of communicating between a
form an angle of about 90° with respect to each
?xed station and a moving aircraft station which
includes radiating radio waves including circu
larly polarized components from said ?xed sta
tion, continuously receiving said waves at said
aircraft station, and indicating the reception of
other.
The dipoles are mounted so that a 1on
gitudinal line through the wings will bisect the
angle formed by the radiators.
With the dipoles in this location, and with the
as
plane in normal ?ight, one or the other or both
antennas will be in the direct path of signals
said waves from all directions of arrival and at
substantially all attitudes of said aircraftas a
arriving from the horizon.
single communication signal,
Signals will be in
duced in the antenna from vertical or circularly
polarized waves. When the plane is directly above
the transmitter, a circularly polarized wave will
cause signals to be induced in the antennas.
While the foregoing method operates substan
tially independently of the attitude and position
2. The method of communicating between a
?xed station and a moving aircraft station which
includes radiating circularly polarized waves to
ward the zenith, radiating vertically polarized
waves along the horizontal, continuously receiv
ing said waves on said aircraft, and indicating the
of the aircraft and is entirely satisfactory for
communication employed in commercial air
transportation and in most War operations, a
completely responsive system may be required for
reception of said waves from all directions of
arrival as a single communication signal inde
radio control in which a beam is directed toward
the aircraft to be controlled. In such operation,
a beam of circularly polarized waves may be di
3. The method of communicating between a
?xed station and a moving aircraft station which
includes radiating radio energy in waves includ
rected toward the aircraft by the transmitter of
Fig. 3. In Fig. 3, a transmitter 4| is connected
ing circularly polarized components, separately
pendently of the normalattitude or position of
said aircraft.
,_
_
and continuously receiving said waves at said air
by a transmission line 43 to a quarter-wave line 55 craft along paths differently directed from'said
55 which terminates in a pair of dipoles 41, 49.
One of the dipoles 41 is disposed vertically; the
other dipole 49 is arranged horizontally. The
aircraft, and indicating the received waves from
all directions of arrival substantially independ
ently of the direction of said paths as a single
waves radiated toward the east and west horizons
communication.
are circularly polarized as indicated by the ref
erence marks 5|, 53. The waves radiated toward
the north and south horizons are vertically po
larized as indicated by the arrows 55, 51. The
7
p
_
'
a. The method of communicating between a
?xed station and a moving aircraft station which
includes radiating radio energy toward the zenith
in circularly polarized waves, radiating radio en
waves radiated toward the zenith are horizontally
ergy along the horizontal‘ in vertically polarized
65 Waves, receiving said circularly polarized Waves
polarized as indicated by the arrow 59.
on said aircraft when said aircraft is at zenithal
In operating the transmitter of Fig. 3, the cir
positions and said vertically polarized‘ waves on
cularly polarized waves, which for convenience
have been described with respect to radiation
toward the east-west horizon, are directed toward
the aircraft to be controlled. It should be under
stood that the beam must be directed in both
azimuth and elevation to obtain complete control
without regard to the attitude of the aircraft.
If the waves are thus directed to the aircraft, the
dipole antennas I3, [5, or one of them, will re- p
said aircraft when said aircraft is at horizontal
positions along differently directed paths alter
natively e?ective, and indicating the, alternately
received waves substantially independently of the
direction of said paths as a single communication.
5. The method 'ofcommunicating between ‘a
?xed station and a'moving vehicle station includ
ing a pair of antennas having different direc'l
2,403,500.
5
6
tional response which includes the steps of ra
amplifying alternately said waves, means for com
diating radio waves including circularly polarized
bining said alternately ampli?ed Waves, and
components, receiving said waves separately on
said antennas, separately amplifying said sepa
rately received waves, and combining the thus
ampli?ed signals to form a single communica
tion signal.
means for indicating said combined waves as a
said waves on said moving aircraft station along
said alternately ampli?ed ‘waves, and means for
differently directed paths, separately amplifying
indicating said combined waves as a single com
single communication signal.
10. A communication system for aircraft in
cluding means for radiating circularly polarized
waves toward the zenith, means for radiating
6. The method of communicating between a
vertically polarized waves toward the horizontal,
?xed station and a moving aircraft station which
a pair of antennas located on said aircraft and
includes the steps of radiating circularly polarized 10 differently directed and responsive to said waves,
waves toward the zenith, radiating vertically
means connected to said antennas for amplify
polarized waves along the horizontal, receiving
ing alternately said waves, means for combining
said separately received waves, and combining 15 munication signal.
the thus ampli?ed signals to form a single com
11. An aircraft receiving system including a
pair of antennas differently directed and respon
munication signal.
sive to radio waves including circularly‘ polarized
'7. The method of communication between a
components and vertically polarized components,
?xed station and a moving aircraft station by
means of radio energy which includes the steps 20 means connected to said antennas for amplify
of radiating circularly polarized waves toward
ing separately the received waves, means for
combining said separately ampli?ed waves, and
the zenith, radiating vertically polarized waves
along the horizontal, receiving said circularly
means responsive to said combined waves for in
dicating said reception as a single communica
polarized Waves on said aircraft at zenithal po
sitions, receiving said vertically polarized waves 25 tion signal.
12. A communication system including in com
on said aircraft at horizontal positions, and indi
bination means for transmitting circularly po
cating the reception of said waves substantially
independently of the attitude or position of said
larized waves, an obstruction movable with re
spect to the earth and located in the path of said
aircraft.
8. The method of communicating between a 30 waves, and means including two ?xedly related
antennas disposed in different ?xed positions with
?xed station and a moving aircraft station in
respect to said obstruction for continuously and
cluding a ?xed antenna array which includes ra
cooperatively receiving said waves arriving in
diating radio waves including circularly polarized
any plane of orientation.
components from said ?xed station, receiving
13. A communication system including in com
said waves on said ?xed antenna array, and indi 35
bination means for transmitting circularly po
cating the reception of said waves from substan
tially all directions of arrival and at substantially
larized Waves, an obstruction movable’with respect
to the earth and located in the path of said
all attitudes of said craft as a single communi
waves, and means including a pair of -V shaped
cation signal.
9. A communication system for aircraft in ~10 antennas disposed in different ?xed position
with respect to said obstruction for continuously
cluding means for radiating from a ground sta
receiving said waves from all directions of arrival
tion radio waves including circularly polarized
at said antenna irrespective of the attitude of
components, a pair of differently directive an
said antenna.
'
tennas located on said aircraft and responsive to
WENDELL L. CARLSQN.
said waves, means connected to said antennas for
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