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Dec- 17, 1946-
2,412,867 '
Filed Nov. 10, 1943
V ‘3 Sheets-Sheet l
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A135!“ A. Mqcdonald.
Dec. 17, 1946.
Filed Nov. 10, 1943
3 Sheets-Sheet 3
[Maynard R
Briggs &
AnyBzés A. Marcdanald.
Patented Dec. 1?, 1946
Maynard R. Briggs and Angus‘ A. Ma‘cdonald,
Catonsvill‘e, Md., assignors to Westinghouse
Electric Corporation, East Pittsburgh, Pa., a
corporation of Pennsylvania
Application November 10, 1943, Serial No. 509,684
8 Claims. (01. 250-11)
Our invention relates to apparatus‘ producing
beams of electromagnetic radiation and, in par
ticular, relates to apparatus of that type suitable
for use in locating objects‘ at a distance by means
of beamsof the electromagnetic energy. ‘Sys
tems of this type which have recently come into
rotates about the focus of the re?ector. The
maximum re?ected energy will be received at the
instant when the central axis of the beam is clos
est to the re?ecting object; and by noting the
position of the antenna at which the maximum
re?ected energy is received, it is possible to de
termine the position of the beam when its axis
wide use are known as radar'syste‘ms.
There has been a considerable development of
is nearest the object, and hence to determine the
arrangements which employ a constricted beam
direction of the object in respect to the central
of ultra-short radio waves to scan distant regions 10 axis‘ of the re?ector.
in which re?ecting objects, such as ships or air
The highest degree of precision in determining
craft, are expected to be present,_ the re?ected
energy of the beam being detected when the beam
_ the instant when the re?ected energy is a max
imum is attained when the beam sent out by the
re?ector is rather narrow; that is to say, when
ing ‘object. By noting the direction in which the 15 the‘
distance it in Fig. 1 is relatively small. On
beam' is’ pointed at the time re?ections of en
the" other hand; if the antenna is maintained‘ al
ergy are received; it‘ is possible to‘ determine the
ways so close to the focus of the reflector as to
direction of the re?ecting‘ ob'jec't'. In most in
give maximum precision in the readings of ‘the
stances, the beam is produced‘by‘locating a short
intensity of the re?ected wave, the angular dis.
is in such a position as to‘ impinge on the re?ect
wave‘ antenna close to‘the focus of a parabolic 20 tance a in Fig. 1 is so small that the total solid
re?ector‘, and‘ the re?ector is then‘rotated and
angle swept over by the beam during one period of
tilted to periodically‘ scan the region in" which
its rotation is relatively small; and consequently
the’ re?ecting‘ objects are expected. In certain
the area searched for re?ecting objects is rela
cases, however, the direction of the expected ob
limited. On this account, it is desirable
je‘cts is known with a'fair degree of ‘accuracy, and
that in searching for the presence of the re?ect
it is then‘ possible to, maintain the re?ector-‘point
ing object the antenna be displaced considerably
edin the general direction and to determine the
from the focus of the re?ector. Then, once the
precise‘ position of the‘ object'by causing'a periodic
object has been picked up and its approximate
displacement of the beam about the central axis
of the re?ector.‘ This latter eifec‘t‘ may be 30 direction been determined, the re?ector can be
turned so that its axis coincides more closely
achieved by displacing the radiating antenna,
usually a small’ di-pole, laterally from the cen
tral axis of the re?ector,and rotating it period
ically about‘ this axis in‘ a circle‘; When the'an;
tenna is displaced laterally from the focus‘ of the
re?ector, the beam‘ of radiant energy is, in effect,
tilted‘ and sent out at an angle‘ relative‘ to the
central axis of the re?ector. Thus; in Figure 1,
with that direction, and the antenna may then be
moved closely enough to the focus of the reflec
tor so as to give the greatest accuracy in deter
mining the time of arrival of the maximum re
?ected energy.
It is, accordingly, one object of our invention
to provide an arrangement in which a radiating
as the double dot-and-d'ash line I’ represents the
antenna may be subjected to periodic motion
bythe polar curve 2' shown in heavy’lines‘. It
moved relative to said focus in such a way as to
to the focus of a re?ector in such a way
central axis of the‘re?e‘ctor, the intensity of the 40 relative
a relatively wide solid angle in order
beam with the antenna displaced laterally in the
to pick up re?ecting objects, and thereafter be
plane of the paper from the’ focus is represented
will be ‘seen from the curve 2‘ that theline of
greatest intensity of the beam is‘ tilted at an
angle a‘ to‘ the re?ector-axis I. If now the an‘
I tenna is rotated in' a circle about the focus, the
curve 2“ will‘ rotate likewiseabout the’ axis I‘,
the angle a remaining constant; v
If a beam having the con?guration of‘ that
just described‘strikes a distant object which is
located at’ a point other than’ on“ the‘ axis I of
the re?ectonthe intensity’_ of energy striking the
object, and hence the intensity of the received
reflection’, will vary periodically- as the antenna
insure a high degree of precision indetermining
the‘ direction of the re?ecting object.
Another object of our invention is to provide
an arrangement in which a radiating antenna
may be rotated about a curve of varying radius
relative to the focus of a re?ector.
Another object of our invention‘ is to provide
an arrangement in which the beam of radiation
sent out by a re?ector energized by a source of
short-wave radio may be periodically varied in
effective width while at the same time it rotates
periodically about‘ the central axis of the re?ector.
Still another object of our invention is to pro;
vide an arrangement in which an antenna may
be moved about the focus of a re?ector periodi
cally in a curve of varying radius.
Other objects of our invention will become ap
arrangement adapted to the short radio. waves
being utilized to produce the beam.
' The central core 32 which cooperates with the
line-portion It has a slightly ?ared end-portion
33 having a central hole 34 concentric with its
parent upon reading the following description,
axis into which extends a cylindrical extension '
‘taken in connection with the drawings, in which:
35 from the core-portion 25. The width, of the
Figure 1 is an explanatory diagram represent
annular space 34 is made sufficient so that the
ing the energy intensity plotted in polar coordi
extension 35 will not come within sparking dis
nates sent out by a re?ector system embodying
tance of the bell-portion 33, when the line sec:
the principles or our invention;
tion 24, 25 is. rotated in the gimbals 2I, 22, 23
Fig. 2 is a view in elevation showing a re?ector
through the maximum angle in which the arprovided ‘with a radiating antenna which is
rangement is intended to operate.
caused to move about the focus of the re?ector,
The line-portion I5 is provided with an exten
in accordance with our invention;
35 having a turned-back cuff portion 3'!
Fig. 3 is a sectional view through the central
axis of the antenna and the concentric line sup
plying it, and showing details of a ?exible cou
pling making it possible to rotate the antenna
while, at the same time, displacing it at a variable
which is spaced away far enough from the walls
of the end-bell 23, so that it will never come with
in sparking distance thereof when the gimbals
2!, 22, 23 are turned through their maximum
range of operation. The ?ared end of the end
bell 23 is provided with a screw-cap 4!) which is
tion of the transmission line;
adapted to hold in place a ?exible diaphragm 38
Fig. 4 is a view, partly in section and partly in
which may, for example, be of rubber, and which
elevation, of the mechanism for producing the
has its inner edge attached to the extension 36
desired movement of the antenna relative to the
by a suitable collar 39 and a nut III. The length
focus of the re?ector, in accordance with our in 25 of the annular channels separating the extension
35 from the ?ared end 33, and separating cuff 3'!
Fig. 5 is a view in elevation at right angles to
from end-bell ‘23, are preferably approximately
the view in Fig. 4 of the same mechanism; and
one-quarter of the wave length of the radiation
Fig. 6 is a detailed view of one of the com
sent out by antenna 26, 21. Cult 3? is made elec
ponent parts of the mechanism of Figs. 4 and 5.
trically one-quarter wave length long by addition
radial distance from the central axis of one por
. Referring in detail to Figure 2, a re?ector Ii
which may be of any suitable conductive mate-'
rial well known in the art, and which is preferably
of an insulating material v3'1’ inserted between
the folded back portion 3'! and 36. ~
Fastened to the line-portion I5 is a gear 'wheel
of substantially, parabolic section, is mounted 35 42 which meshes with a second gearfwheel 43
in a framework I2 which is suitably supported to
which is supported in a bearing 44 on, frame I2.
be turned in any desired direction at will, by
Attached to the‘ same, shaft as the gear 43 is-a
arrangements well known in the art, and forming
third gear 45 which meshes with gear teeth on a .
no part of our present invention. The re?ector
drum 4'! which is supported, in turn, on ball
I I. has a central axis I3 on which is positioned its 40 bearings 48 surrounding line-portion I5. The
focal point l4. Positioned with its axis concen
ratio of the respective gears 42 to 45 is such that
trio with the axis I3 is a transmission line of the
the drum 41 rotates relative to the line-portion
concentric type shown in more detail in Fig. 3.
I5, preferably at a relatively slow rate. The drum
One ‘portion I5 of the transmission line is sup
'41 extends over a portion of the end-bell I9, and
ported in suitable bearings It on the framework
has its annular end-face which is nearest to the
'I2, so that it may be rotated about its central
antenna 26, 21 shaped so that it does not fall in
axis. " Such rotation may be imparted to the por
a plane perpendicular to the axis I3. Extending
tion I5 by a set of bevel gears I'I transmitting
radially from the external face of the end-'bell23
motion from a suitable motor I1’ which is sup~
is a stud which supportsa roller 49 positioned so
vported on the frame I2. The transmission line , that it can traverse the annular .path along the
portion I5 passes through the interior of a cham
end-face of the member 4?. A spring 5| extend
ing between the end-bell I9 and a stud 52 which
ber I8 which is attached to the re?ector II, and
which is shown in section in more detail in Fig. 4.
projects from the end-bell- v23 biases the roller 49
As is shown in more detail in Fig. 3, the trans
into. contact with the, end-face of drum 41.
It will be remembered that the drum 41 rotates
mission line portion I5 terminates in what may
relative to the line-section I5 to which the end
be termed an end-bell ‘9 having two projecting
bell I9 and the gimbals 2|, 22, 23 are attached.
arms 2| containing set screws 22 which form gim
The drum 41, accordingly, rotates relative to the
bals in which is supported an end-bell 23 which
end-bell 23; and as it does so, ‘the roller 49, mak
is connected to a second concentric transmission
ing contact continually under the stress of spring
vline-portion 24. The portion 24 has a core-por
5| with the end-face of drum 41, traverses an
tion 25 concentric with its axis which terminates
annular path on the latter the Plane of which
at the focus I4 of re?ectoriII in an extension 26,
.is not normal to the axis I3. In view of the latter
forming one branch of the radiating antenna.
fact, it will be seen that the end-bell 23 will be
The other branch 21 of the radiating antenna is
moved by the roller 49 about the axisof set-screws
attached to the line-portion 24. The line-por
22, and caused to periodically tilt in varying an
tion 24 is likewise surrounded by an annular ring
glesrelative to the axis I3. In consequence of the
28 of conducting material which supports a con
continual‘ periodic tilting of the end-bell 23-, the
ducting sleeve 29, leaving an annular space be;
line-portion 24 and the antenna 26, 21 attached
tween the sleeve 29 and the line-portion 24 which
thereto will be periodically tilted, to varying
is approximately one-quarter wave length long.
angles relative to, the axis I3, and hence-a pe
There is likewise supported on the line-portion
riodic radial movement will beimparted to the
24, and in front of the antenna halves 26, 27, a
conducting dummy-element 3 I. It may be noted
antenna 26, 21, relative to the focus I4 ,of the
that the antenna portions 26'through 3| may be - .
reflector II; The frequency-of the, periodic mo.
replaced by any other suitable radiating-antenna
tion will, of course, be equal to the difference in
number of revolutions per second of the drum
41 relative to the line-portion l5. Since the line
by the rotation of the transmission line 15-24
portion I 5 is rotating on its axis relative to the
and all their connected parts within the frame
work l2, as previously described. The end of the
shaft 69 is provided with suitable means, such as
re?ector II, the antenna 25, 21 will rotate rela
tive to the re?ector H at a frequency relative to
the number of revolutions per second imparted
by the motor H’ to the line-section Hi. The an
tenna 26, 21 will, accordingly, rotate about the
focus of re?ector II in ‘a periodic curve having a
a motor 14, so that it may be rotated when de
sired. When it is desired to stop the periodic
tilting of the antenna 26, 21 relative to the focus
I4, after the approximate position of an ap
radius which periodically varies between limits 10 proaching object has been determined, the shaft
69 is rotated; thereby imparting a rotary move
which are determined by the contour of the end
ment to the member 61 and causing the slot ‘65
face of the drum 1S1. The last-mentioned con
tour may, for example, lie in a plane which is
other than normal to the axis l3 or, instead of
to move relative to and along the stud 62. Move
ment of the roller 65 in the slot as will ‘obviously
being plane, this end-surface may be warped in 15 move the member 61 toward focus M (i. e., move
it farther to the right in Fig. 4); thereby dis
ways obvious to those skilled in the art, to pro
placing the annular ledge 13 into contact with
vide for the description by the antenna 26, 21
roller 6|, and thereby preventing roller 49 from
of any desired curve about the focus It.
thereafter following the contour of the end-face
The arrangement thus far described represents
of drum 41. Since the annular ledge 13 lies in
the condition in which the apparatus is intended
to operate during the search period in which the 20 a plane normal to the axis IS, the progress of
the roller 8| about this ledge will cause no tilting
‘approximate position of an approaching object
of the end-bell 23 and its attached antenna 26,
is to be determined. By suitable oscillographic
21 upon the set-screws 22, but will maintain the
well known in the art, by
which the position versus time curve represent
ing the rotation of line-portion l5 and the inten
sity versus time curve for the received re?ected
energy can be correlated, the azimuth of the an
tenna 26, 21 about the axis l3 at the time when
the object is closest to the center of greatest in
tensity in the beam from re?ector H can be de
termined. The frame I2 can then be displaced
by suitable arrangements well known in the art,
but not shown here, to move the axis 13 of the
re?ector ll close to the direction of the object.
It then becomes desirable to stop the periodic 35
radial movement of the antenna 26, 21 relative
to the focus l4, and to rotate it in a circle of
relatively small diameter about that focus.
In order to eifect the result just described, we 4.0
mount on the end-bell 23 a second roller 6| on
a radially projecting stud. We further provide
the sleeve l8 with three projecting studs 62 which
support rollers 65 and extend radially inward
from the sleeve l8. The rollers 65 engage a slot
66 in an annular member 61 having a projecting
rim 68 provided with suitable gear teeth. A shaft
69 is supported in suitable bearings 10 on the in
ner face of the sleeve l8 in a position parallel to
the axis l3, and is provided with a pinion 1|
adapted to mesh with the gear teeth on rim 68.
The annular member 61 is formed with a ledge
13 lying in a plane normal to axis l3 and adapted
to form an annular path to be traversed by roller
BI. The slot 66 is so cut that the distance of its
center line from the rim 6B varies with circum
antenna 26, 21 at a ?xed radial distance from
the focus M of the re?ector H. The antenna
26, 21 will thereafter describe a circle of small
radius about the focus Hi, this radius being de
termined by the number of times shaft 69 is
turned, and the apparatus will be in the condition
for most accurate determination of the direction
of the re?ecting object relative to axis l3.
Obviously, when it is desired to return the
apparatus to
curve of periodically
varying radius about the focus M, the shaft
69 may be turned so as to move the pivot 62 to
the position in slot 66 initially described.
While we have described, as required by the
patent statutes, a specific mechanism for pro-1
ducing the desired movement of the antenna 25,.
21 relative to the focus
This particular mechanism is, accordingly, only
a particular embodiment of our broader inven
tion which is the possibility inherent in provid
ing for movement of the antenna in a periodic
curve of varying radius while searching, and in
following a curve of substantially constant radius
about the focus while making more accurate de
of the direction of the re?ecting
We claim as our invention:
1. In a system of ultra-high frequency beam
transmission, means for projecting a beam into
ferential distance about the rim 68. The posi
tion of the stud 52 on the sleeve I8 is so deter
mined that when the stud 62 engages those por
tions of the slot 66 which ‘are least distant from
the rim 68, the ledge 13 is displaced so far away 60
from focus M (i. e.,
in Fig. 4)
that it can not engage the roller Bl even when, in
2. In a system of
course of rotation of the end-bell 23 about the
axis l3, the roller 49 engages the portion of the 65 transmission, means
end-face of drum 41 which is most distant from
focus I 4 (i. e., when it engages the portion of
the end-face of drum 41 which is farthest to the
left in Fig. 4). Under such circumstances, the
roller 49 is able to follow in engagement of the 70
pared with that at
end-face of drum 41 during the entire revolution
ried out.
of antenna 26, 21 about focus l4.
3. In a system of ultra-high frequency beam
However, it will be observed that the member
61 stands stationary relative to the sleeve l8,
transmission, means for projecting a beam into
framework I 2 and re?ector l I, and is unmoved 75 space, means for rotating said beam at a fixed
angular displacement with respect to the normal
axis of rotation thereof, andrmeans for gradu
ally increasing said angular displacement at re
current intervals'which have a periodicity small
compared with that at which said rotating is
carried out.
4. In a system of ultra-high frequency beam
transmission, means for projecting a beam into
space, means for rotating said beam at a ?xed
tatably disposed near the axis of a parabolic re
flector, said wave guide being displaced at ;an
angle from the axis of said parabola, means for
varying the width of the radiated beamqcom
prising means for changing the angle of displace
ment of said wave guide from said angle to an
other angle while said wave guide is being ro
'7. The method of locating an object by means
minimum angular displacement with respect to 10 of a beam of ultra-high frequency energy for the
the normal axis of rotation'thereof, and means
purpose of range ?nding which comprises, ir
for gradually increasing said angular displace
radiating space having the form of a hollow, coniment from said minimum position to another
position of maximum displacement and gradu
ally decreasing from said maximum displacement
to said minimum displacement at recurrent in
tervals of ?xed periodicity which is small com
pared with that at which said rotating is car
ried out.
5. In an ultra-high frequency radio locator
cal pattern, sweeping the ?eld of search by said ’
pattern, enlarging the effective base of said coni
15 cal pattern for rough location of said object at
will during sweeping said ?eld of search, and
narrowing said effective base upon location of the
object for accurate determination of range.
8. The method of locating an object by means
of a beam of ultra-high frequency energy for
system, means radiating a beam of ultra-high
the purpose of range ?nding which comprises,
frequency energy comprising an antenna rotat
irradiating space having the form of a hollow
ably disposed near the axis of a parabolic re
conical pattern sweeping the ?eld of search by
?ector, said antenna being displaced at an angle
said pattern, enlarging the effective base of said
from the axis of said parabola, means for vary
conical pattern for rough location of said object
ing the effective width of the radiated beam com 25 at recurrent intervals of ?xed periodicity dur
prising means for changing the angle of dis
ing sweeping said ?eld of search, and narrow
placement of said antenna from said angle to
ing said effective base upon location of the ob
another angle while said antenna is being ro
ject for accurate determination of range.
6. In an ultra-high frequency radio locator 30
system, means radiating a beam of ultra-high
frequency energy comprising a wave guide 1'0
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