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Патент USA US2405242

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Aug. 6, 1946.
s. c. SOUTHWORTH
2,405,242
MICROWAVE RADIO TRANSMISSION
Filed Nov. 28, 1941 '
a Sheets-Sheet 1
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INVENTOR
By 6.6‘. SOUTHWORTH
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A TTORNEV
Aug. 6, 1946.
G. c. SOUTHWORTH
2,405,242
MICROWAVE: RADIO TRANSMISSION
Filed Nov. 28, 1941
e Sheets-Sheet 2
M/VENTOR
By GC. SOUTHWORTH
72 M 5
‘
ATTORNEY
Aug. 6, 1946.
s. c. SOUTHWORTH
2,405,242
MICROWAVE RADIO TRANSMISSION
Filed Nov. 28, 1941
8 Sheets-Sheet 3
IN VENTOR
87
sic. SOUTHWORTH
77. m’
ATT ENE?
Aug. 6, 1946.
2,405,242
G. c. SOUTHWORTH
MICROWAVE RADIO TRANSMISSION
Filed Nov. 28, 1941
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8 Sheets-Sheet 4
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F I THU HHHHH I J
INVENTOP
By G.C.SOUTHWORTH
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Aug. 6, 1946.
G. c. SOUTHWORTH
2,405,242
MICROWAVE RADIO TRANSMISSION
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By 6.C.$0UTHWORTH
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Aug. 6, 1946.
s. c. SOUTHWORTH
2,405,242
MICROWAVE RADIO TRANSMISSION
Filed NOV. 28, 1941
8 Sheets-Sheet 6
H6. 24
INVENTOR
By G. C.$OUTHWORTH
77- W Go
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ATTOZNEV
Aug. 6, 1946.
G. c. SOUTHWORTH
2,405,242
IN l/ENTOR
6.6. SOUTHWORTH
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Aug. 6, 1946.
G. c. SOUTHWORTH
2,405,242
MICROWAVE RADIO TRANSMISSION
Filed Nov. 28, 1941
8 Sheets-Sheet 8
FIG. 28
FIG. 29
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6.6 SOUTH WORTH
A TTORNEY
2,405,242
Patented Aug. 6, 1946
UNITED STATES PATENT OFFICE
2,405,242
MICROWAVE RADIO TRANSMISSION
George C. Southworth, Red Bank, N. 1., asslgnor
to Bell Telephone Laboratories, Incorporated,
New York, N. Y., a corporation of New York
Application November 28, 1941, Serial No. 420,747
34 Claims. (Cl. 250-11)
This invention relates to the transmission of
ultra-high frequency electromagnetic waves and
more particularly but not exclusively to appara
tus for the launching of radio waves into space
and for the interception and detection of such
waves.
Objects of the present invention are to improve
the e?iciency with which radio waves are
launched into space or received therefrom, to in
crease the directivity obtainable in the beam
transmission of such waves, and to facilitate con
trol of the direction of radiation or reception.
2
plicity of parallel, elongated apertures or slits.
Other features reside in a. wave collimator adapted
to translate a wave from a guiding passage of re
stricted cross section to one of elongated cross sec
tion, and in the intimate association of such a
collimator with a panel type antenna.
The nature of the present invention and var
ious features, objects and advantages in addition
to those pointed out above will appear more fully
from the following description of the embodi
ments illustrated in the accompanying drawings.
In the drawings:
Figs. 1 to 10 relate to elementary wave guiding
Other objects are to provide radio antennas, that
and radiating structures embodying various fea
is, radio wave Interceptors and radiators, having
tures of the present invention; Figs. 11 to 24 re
special shapes adapting them for use in circum
late to a louver type of radiator and wave colli
stances where space and shape are signi?cant
mators therefor; and Figs. 25 to 29 relate to modi
factors. For example, one object is to provide an
?cations and extensions of structures shown in
antenna that is of substantial expanse and high
preceding ?gures.
ly directive but that is shallow enough for use in
Referring now to Fig. 1 there is illustrated an
the fuselage or wings of aircraft, for example. 20
embodiment of the present invention that is at
Further objects are to permit ready adjustment or
once simple and effective for the purposes in
cyclic variation of the angle of ?re of a directive
tended and that will serve as a basis for the ex
radiator or interceptor apart from control of the
position of certain principles and features that
orientation of the structure, so that, for example,
a ?xed structure may be employed to scan the 25 are involved in other more complex embodiments
hereinafter to be described. This embodiment as
surrounding space as is required in systems for
well as many of the others makes use of the so
the detection and location of aircraft or ships at
called hollow pipe guide, which is a structure
sea.
In accordance with a feature of the invention a
leaky wave guide is employed in a particular man
ner as a, radiator or intercepting device, the leaky
wave guide being de?ned as a wave guide struc
ture that is adapted to permit the escape of guided
wave power substantially continuously along its
adapted for the guided propagation of ultra-high
frequency electromagnetic waves of various ?eld
configurations, and which is characterized at least
in part in that transmission through electrically
long sections of it takes place substantially only
at frequencies exceeding a predetermined critical
length, as for example by reason of a continuous 35 or cut-off frequency that is determined by the
longitudinal aperture in its outer wall or a multi
transverse dimensions of the guide and the index
plicity of discrete apertures the longitudinal
of refraction of the dielectric medium within the
spacing of which is substantially less than the
pipe. In general, the higher the dielectric con
length of the waves within the guiding structure.
stant, or index of refraction of the dielectric me
In accordance with another feature, a leaky wave 40 dium within the hollow pipe guide, the lower are
guide or a wave guiding structure having a multi
the cut-off frequency and the phase velocity. Al
plicity of longitudinally spaced apertures is ta
though in some of its broader aspects the present
pered or otherwise progressively reduced in size,
invention is not limited with respect to the cross
that is, in transverse dimensions, to reduce trans
sectional shape of the guide or the type of wave
mission losses in the guiding structure and to im 45 employed, as will be evident to those skilled in the
prove the e?lciency of coupling with free space.
art, the so-called dominant type of wave in a
A related feature contributing to the same objec
0 guide of rectangular cross section o?ers various
tive has to do with the effect of the total area of
advantages and will be assumed in most of the
the aperture or apertures on impedance match
ing.
In accordance with another feature there is
provided a panel antenna that is shallow but of
substantial expanse, comprising a tapered wave
guiding structure or distribution passage of elon
gated cross section having on one face a multi
50 embodiments to be described.
Whereas, also, it
is found convenient to describe the various em
bodiments in terms of their application to the ra
diation of electromagnetic waves, it is to be under
stood that in each case the structure is adapted
also for the interception or reception of radio
2,405,242
waves, and that the directional properties are sub
stantially the same in the two cases.
Fig. 1 shows a wave guide in the form of a hol
low metal pipe I of rectangular cross section with
air dielectric and an ultra-high frequency source
2 that is connected near one closed end of the
pipe to establish waves of dominant type therein.
4
main guide for impedance match and high gain.
or, more speci?cally, the sum of the slit widths
should be equal to the e dimension or the unslitted
guide portion. This rule does not quite hold true.
however, if extremely narrow slits are employed,
having a width of less than one millimeter for
example, for it appears that such slits radiate
more eiIectively per unit area than wide slits.
vector of the guided waves lies parallel with the
In such cases the slits may be closed 011' progres
shorter transverse dimension of the pipe and at 10 sively from one end of the guide until measure
right angles to the longer dimension. In view
ments indicate minimum re?ection in the guide
of their space relation to the electric and mag
or maximum gain. Some increase in the total
netic ?elds these dimensions will be referred to
eii’ective aperture may be obtained by progres
The wave source 2 is so oriented that the electric
as the e dimension and the h dimension, respec
tively. Along one of the wider or 72 races of the
pipe is a series of closely spaced transverse slits
3 each normal to the length of the pipe. The
other or far end of the pipe is or may be closed
sively increasing the width of the slits towards
the far end of the guide so that more nearly the
same wave power is radiated from each slit.
In the modification of the invention illustrated
in Fig. 2 the radiating structure comprises a hol
to preclude the escape of wave power.
low pipe guide of rectangular cross section as
As the guided waves move toward the far end 20 in Fig. l in which the e dimension, that is, the
of the pipe, wave power escapes through each
dimension parallel to the electric yeotor, is re
of the slits 3 until at the far end of the guide
duced in steps toward the far end of the guide.
little or no wave power is left unradiated. At
At each step as well as at the far end of the guide
each slit the waves issue with the electric vector
a, transverse slit or opening is left. These aper
lying across the slit, that is, substantially parallel _ tures are all normal to and face the direction 01’
with the axis of the guide, hence if the guide is
the axis of the guide, but radiation may take
sdpositioned that the slits are vertical the radi
place at an angle 41 determined as in Fig. 1 by
ated waves are horizontally polarized. With the
the spacing of the apertures and the relative
slits horizontal, as would be the case if the guide
phases of the waves issuing from the several aper
were vertical, the waves radiated are vertically 30 tures. It is to be noted that at each step the
polarized. The radiation from any given slit, as
guided wave is separated by the longitudinal por
suming horizontal polarization for speci?c ex
tion of the step into two portions one of which
ample, would be fairly sharply confined or con
issues through the slit and the other of which
centrated in the vertical plane but fairly wide
proceeds through the forwardly extending por
spread in horizontal planes. In other words, the 35 tion of the guide. This is in accordance with
vertical directivity is much sharper than the hori
principles of wave guide branching with imped
zontal directivity. With respect to the array of
ance match. With the guide in the horizontal
slits, directivity in the horizontal or e plane is
position indicated in Fig. 2 radiation is at an
largely controlled by the spacing of the slits, as
angle upward.
measured in terms of free space wave-length at 40
To facilitate an impedance match between the
the operating frequency, and by the relative
several slits and free space, an outwardly ?aring
phases of the waves issuing from the several slits.
metallic extension may be placed over each slit
If the slits are so closely spaced that there are a
as in Fig. 3 to provide substantially the effect of
large number of them in each wave-length section
of the slitted guide portion, or, in other words, 45 a. small impedance matching horn. This feature
is useful primarily where the interslit spacing is
if this portion constitutes a leaky pipe guide as
comparable with the wave-length in the guide as
hereinbefore de?ned, the radiation will be di
rected principally in the horizontal plane at an
in certain cases to be considered hereinafter.
In lieu of the discrete steps indicated in Figs. 2
angle ,1» from the axis of the guide, as indicated
in Fig. 1. The angle ‘p in this case is such that 50 and 3, the e dimension may be reduced at a linear
rate to form the wedge-like structure oi’ Fig. 4 '
in which the slits lie crosswise in the upper.
sloping face of the wedge as illustrated. It may
be noted that the smooth tapering of the radiat
where Up is the phase velocity of the guided waves
guide portion is calculated to add materially
in the leaky guide portion and c is the velocity 65 ing
to the ?nesse of electrical smoothness.
characteristic of light in the surrounding space.
In the modification of Fig. 4 that is illustrated '
In a typical case in accordance with Fig. l the
in Fig. 5 the slits are somewhat inclined in the
dielectric medium within the pipe was air, di
upper face of the wedge so that the radiation
mension h was 5.8 centimeters, dimension e, 2.5
takes place more nearly continuously along the
centimeters, and the frequency of the wave source 60 length of the wedge. Fig. 5 partakes somewhat
2 was 3,000 megacycles per second corresponding
of the characteristics of the Fig. 6 structure which
to a free space wave-length oi’ 10 centimeters.
is a tapering or wedge-shaped radiator like that
The slits were 2 millimeters wide and spaced 5
in Fig. 4 except that a single longitudinal slit
centimeters apart. The phase velocity up was
found to be approximately 2.75 times 0, which 65 takes the place of the multiplicity of transverse
slits. In Fig. 6 radiation takes place continuous
compares with a phase velocity of 2c in the un
1y throughout the length of the slit and the angle
slitted portion, and the angle 1/ was approxi
of
?re relative to the axis of the guide is sub
mately 68 degrees. If the total area represented
stantially that de?ned in Equation 1 supra.
by the aggregate of slits is not such as to provide
Whereas the wedge-shaped con?guration of the
critical or re?ectionless termination for the guide 70
Fig. 6 structure contributes to eiiicient operation
I, the far end of the guide may be terminated in
cos ¢=£
"I!
(1)
an energy absorber. In general the sum of the
areas of the various apertures in a multiple aper
as described with reference to Fig. 4, more nearly
uniform distribution of the wave power radiated
along the slit may be promoted by progressively
tured pipe guide of rectangular cross section
or widening the slit toward the narrow
should be equal to the cross-sectional area 0! the 75 ?aring
edge of the wedge as illustrated in Fig. 7.
2,405,242
5
The structures described with reference to Figs.
1 to 7 may differ somewhat in respect to the
presence and magnitude of secondary lobes in the
directional pattern, that is, in the distribution
of radio wave power in directions other than the
principal or preferred direction of radiation. The
fore where vp=2.75c the spacing that would be
required for equiphasing is 2.75 times the wave
length in air, and for the case where vp=c the
interval between slits would have to be equal to
the free space wave-length. These spacings,
however, would be so large as to give rise to sub
stantial secondary lobes.
A similar effect tends to appear in the multiple
of those obtainable with the structures shown in
apertured leaky pipe guide, that is, secondary
Figs. 1 to 4 and is speci?cally applicable to the
lobes are developed if the apertures are not
Fig. 4 structure. As shown by this diagram the 10 spaced closely enough together in relation to the
radiation is maximum for a value of ‘p of 68
wave-length. In the Fig. 1 system, for example.
degrees. The pattern is highly favorable in that
it was found that whereas the directional pattern
it shows zero radiation in the broadside or 90
was substantially single-lobed when there were
degree direction as well as for larger values of \11,
four or eight slits per wave-length, the subordi
15
and in that no secondary lobes appear. Sub
nate lobes were judged to be excessive for spac
directional pattern represented in Fig. 8 is typical
stantial secondary lobes*are highly undesirable
for many purposes for in any beam transmission
system they represent a waste of power radiated,
impairment of secrecy of transmission, and sus
ings greater than about 0.6 wave-length.
The restriction last discussed is overcome in the
broadside radiator illustrated in Fig. 10 by sur
20 mounting each of the transverse slits with a
ceptibility to interference.
metal horn 6. Each horn is proportioned in ac
Any of the structures hereinbefore described
cordance with principles now known in the art
may be paired to form a balanced structure with
and so aligned as to produce a radiated beam that
the angle between the components adjusted so
is largely con?ned to the broadside direction and
that each radiated beam coincides with the other.
free of secondary lobes. The horns may be of
Fig. 9 illustrates the application of this principle
rectangular cross section and contiguous with
to the Fig. 4 structure. The two wedges are fed
each other at their mouths as shown. Thus
from a common wave guide and are angularly
separated by twice the angle a applicable to the
individual components. The arrangement illus
despite the tendency for the widely spaced slits
to produce a radiation pattern with secondary
lobes, the horns suppress radiation in non-broad
trated in Fig. 9 serves also to reduce the relative 30 side directions from each slit and produce an
intensity of any secondary lobes that may tend
array with a sharply directed broadside charac
to appear in the directional pattern.
teristic.
In lieu of air or other gaseous medium, the
Another device that may be used in lieu of the
radiating pipe guide in any of the examples con
horns in Fig. 10 to reduce secondary lobes is to
sidered may be ?lled or "loaded" with a dielectric 35 fill the radiator section of the guide with a low
material having a dielectric constant greater than
loss insulating material having an effective di
unity. The addition of such a dielectric material
electric constant e that is sensibly greater than
reduces the phase velocity Up and the ratio vp/c.
unity. When this is done the phase velocity with
and it therefore affects the angle of radiation.
in the pipe is reduced so that
40
By properly relating the cross-sectional ‘dimen
sion 71. of the pipe, which affects the phase veloc
ity ‘Up, with the dielectric constant of the medium,
(2)
‘Up can be reduced to equality with 0. Equation 1
indicates then that the angle a is zero, or in other
where ip is the wave-length within the pipe, is
words that the major radiation lobe lies along
is the corresponding free space wave-length, and
the axis of the guide. Radiation in this direc
he is the free space wave-length at transmission
tion may be appropriately termed “end~fire" radi
cut-oil’, viz.,
ation.
With a leaky guide structure such as that de
scribed with reference to Figs. 1 to 4 in which 50
One of the various materials suitable for use as
there are many slits per wave-length, the results
the dielectric is a polystyrene having a dielectric
obtained are much the same as if a single longi
constant e of about 2.6 known as and sold under
tudinal slit were employed. Quite different re
the trade name “Amphenol.” If this material is
sults may be obtained. however, if the space be
used in connection with the example cited here
tween slits is comparable with the operating wave
inbefore where the wave-length in air is ten
length within the guide. More particularly, if
centimeters and the pipe guide has a dimension h
the slits in the Fig. 1 structure, for example,
of 5.8 centimeters then the wave-length within
are spaced 9. wave-length apart so that the waves
the guide is reduced to 7.33 centimeters. This is
issuing from the several slits differ in phase by
360 degrees, or a multiple thereof, the effect is 60 also the proper distance between slits for broad
side radiation. Under these circumstances the
as though the wave traveled through the pipe
elements have an axial spacing of 0.733 times the
with infinite velocity. In accordance with Equa
free space wave-length, which is small enough to
tion 1 the angle of radiation in this case is 90
degrees or, in other words, broadside. It hep» 65 avoid any substantial secondary lobes. It is to be
expected that the radiation will tend to increase
pens, however, that even though the radiating
the phase velocity beyond that otherwise to be
slits are thus equiphased a single highly directive
expected, hence preliminary study with a travel
lobe will not be obtained if the interslit spacing
ing
detector may show that the actual spacing
is too great. The maximum permissible spacing
should be somewhat greater than specified.
depends on the total number of radiating ele
In any of the embodiments of the invention
ments but in many practical cases it is less than 70
hereinbefore described, the angle a is a function
0.87 of the wave-length in air. The principles
of frequency inasmuch as the velocity of propa
involved are set forth in detail in a paper by ap
gation through the guide, 1. e., the phase velocity,
plicant appearing in the September 1930 issue of
also is a function of frequency. Accordingly, it
the Proceedings of the Institute of Radio En
is possible to operate at various angles ‘[1 merely
76
gineers. For the practical case cited hereinbe
7
9,405,242
by shifting the operating frequency. Alterna
tively, however, the angle ‘0 may be altered with
out changing the frequency by adjusting the h
dimension of the guide and thus adjusting the
velocity of propagation.
Referring now to Figs. 11 and 12 there is illus
trated a panel type of radiating structure, broad
and high but very shallow, that embodies vari
ous important features of the present invention.
8
ary lobes as discussed with reference to Fig. 10.
The relative widths of the several slits have a
bearing on the radiation pattern. Thus, for
example, the elimination of secondary lobes may
be facilitated by making the outermost slits com
paratively narrow and the others progressively
wider to a maximum at the central slit or slits.
Although broadside radiation has been assumed
Excellent broadside gain and directivity have 10 in the description of Figs. 11 and 12, the struc
ture is fairly well adapted for non-broadside ra
been obtained in practice with this structure,
diation within angular limits ?xed by the radia
and it is obvious that its shape adapts it for use
tion patterns of the flaring passages or horns de
?ned by the prisms. The spacing of the slits or
the operating frequency may be adiusted to se
used. In view of its general appearance the radi
cure
the desired angle of radiation.
ator portion proper, represented at III in Fig. 11
The function of collimator I1 is in part to
and shown in cross section in Fig. 12, will be re
reduce re?ection loss in the transition from the
ferred to as the louver. As will appear from these
comparatively small cross-sectional area of the
two ?gures, the louver comprises a multiplicity
pipe guide I to the large cross-sectional area of
of parallel metallic prisms II of triangular cross
section arranged in a row on a metallic base plate 20 distribution passage Hi. In greater part, how
ever, the collimator is intended to induce an ex
I! and spaced apart to leave elongated apertures
pansion of the transmitted waves such that the
or slits I3 between them. The rear faces of the
excitation of the slits I3 is distributed more or
prisms are approximately aligned and, together
less uniformly and in the same phase along their
with a metallic back plate I4, base plate I2 and
a corresponding top plate, de?ne a wave distribu 25 respective lengths. A simple ?aring section of
in many locations where other and bulkier de
vices of comparable performance could not be
wave guide might serve these purposes very well
tion passage I5 that extends across the back of
but even better results can be had with collima
the array of slits.
tors of a type to be described hereinafter with
Distribution passage I6 is tapered from a maxi
reference to Figs. 15 to 18.
mum e dimension at the left-hand end of the
Fig. 13 shows in a cross-sectional view corre
louver to a minimum at the right, in the manner 30
sponding with Fig. 12, a balanced radiator made
and for the purpose described with reference to‘
up of two louver radiators of the kind described
Figs. 2 to 4. It is advantageous to have the rear
connected to a common collimator II. The two
faces of the prisms I I su?lciently misaligned that
louvers 20 and 2| are arranged with their faces
each is substantially parallel to the back plate
It thus making the distribution passage equiva 35 in the same plane to form a unitary array having
an area approximately twice that of either louver
lent in a sense to the stepped guide radiator de
alone. At the junction of the two louvers and
scribed with reference to Fig. 2 and in the same
the collimator II a short Y-branch is interposed
manner contributing to effective operation, At
to facilitate transmission of power from the col
the left, passage I5 continues through an optional
extension I6 of the same elongated cross section 40 llmartor into the two louvers.
Fig. 14 illustrates how a collimator, such as II
and a collimator I‘! to the hollow pipe feed guide
in Fig. 11, may be folded upon itself to reduce
i. The waves supplied through the latter are
its over-all dimensions for instances of practice
polarized in the manner shown so that the elec
where space requirements, for example, make such
tric field in the distribution passage I5 is normal
to the back plate and appears crosswise of the 45 reduction desirable.
In Fig. 15 there is shown a collimator that is
slits I3.
especially well adapted for use in conjunction with
The louver is so proportioned in relation to the
the louver radiator of Fig. 11 and it may be
operating frequency that the distance between
understood that the elements I6—-I1 of the latter
slits is equal to the wave-length within the dis
tribution passage, hence the slits are cophased 50 showing may take the form here illustrated and
now to be described In this case the feed guide
and the radiated beam is broadside or normal to
I is terminated in a pair of branch wave guide
the panel. The length of the individual slits is
sections 24 and 25 of rectangular cross section,
large compared with the free space wave-length
which are angularly separated from each other
as is also the h dimension of the distribution pas
55
by
an amount 2w. Each of the branches 24 and
sage. In one illustrative example of practice, the
25 has on its inner or forward e face a longitu
louver was approximately 100 centimeters square
dinal slit 26. With the parts proportioned in ac
and comprised ten slits I3 each about 5 milli
cordance
with principles discussed with reference
meters wide and spaced 10 centimeters apart for
to Fig. 9, for example, waves received from the
operation at a frequency of 3,000 megacycles per
second. The distribution passage was approxi 60 guide I issue from the two slits 26 to form a
substantially plane wave front normal to the axis
mately 100 centimeters by 5 centimeters at its
of the guide. The waves so issuing are received
input end, the latter dimension being equal to
into the end of a pipe guide 21 of elongated
the sum of the slit widths. Under these condi
tions the phase velocity is substantially equal to 65 rectangular cross section which extends forward
from the slitted faces of the branches 2‘ and 25.
the velocity of light. The restriction of the max
The forward end of the guide 21 may be con
imum e dimension to a half wave-length sup
nected as in Fig. 11 to the distribution passage
presses wave types of higher modes and is for
of a louver radiator or it may be used directly as
that reason a desirable feature. In the forward
a radiating ori?ce.
direction, that is, normal to the panel and in 70
The normal intensity distribution of a wave of
the direction of radiation, the prisms II de?ne
dominant type in a pipe guide of rectangular cross
outwardly ?aring passages extending from the
section is represented by the solid line curve in Fig.
respective slits I3 and constituting short but ex
16 which shows how the electric intensity varies
tremely wide electromagnetic horns which con
tribute to the substantial elimination of second 75 along the h dimension of the guide. It is evident
that the field intensity drops o? markedly from
2,405,249
10
sage and connects with collimator section 24-25
and the wave guide I which extends up into the
chamber 32 to the terminal apparatus 33. The
latter is represented schematically as being the
first stage of a double-detection wave receiver,
the output of which is delivered through a coaxial
conductor line 34 to subsequent receiving ap
a maximum value at the central e plane of the
guide, and it will be appreciated that ii’ the same
distribution obtained in the distribution passage
of the louver radiator the excitation of each slit
would be quite non-uniform over its length. The
branch guides 2| and 25 of Fig. 15, however, force
in the guide 21 an initial intensity distribution
paratus.
that is not normal but more nearly uniform along
Another convenient structural arrangement is
the h, dimension, as indicated by the dotted line
illustrated in Fig. 21 where two coplanar louver
l0
curve in Fig. 16. Whereas this favorable distri
radiators Ill are integrally and rotatably mounted
bution would not be maintained and normal dis
with an apparatus chamber 35 between them.
rtribution would appear, if the waves were to be
One of the louvers it may be a radiator and the
transmitted any considerable distance through
other a receiver, or both may be either radiators
the guide 21. the latter is or can be made so
receivers.
short that no substantial degeneration of the in 15 or The
louver radiator may comprise a dielectric
tensity distribution appears at the feed end of
material having a dielectric constant substan
the louver distribution passage. Accordingly, by
tially greater than that of air. Where a solid di
thus intimately associating the collimator with
electric material, such as polystyrene, is employed,
the distribution passage of Fig. 11 each slit l3
the louver may take the form illustrated in Fig.
may be supplied with power more or less uni 20 22. In this case the distribution passage is ?lled
formly throughout its length.
with the solid dielectric 36, a metallic back plate
As a further or alternative feature the Fig. 15
M is provided as before and on the front face
collimator may include a longitudinal metallic
metallic plates 31 are spaced apart to de?ne the
baffle plate 28 which extends forward from the
multiplicity of parallel transverse slits. To fa
Junction of the forward faces of branch guides 25 cilitate radiation of wave power through the slits
24 and 25 and which lies parallel with the e
the solid dielectric material may be extended out
faces of the guide 21. The baffle 28 separates
in the form of protuberances 43. These may be,
guide 21 into two subguides of equal widths, and
as shown, wedge—like and in some cases may ex
the latter may be further subdivided by additional
tend out as much as a wave-length. Since the di
ba?les as shown. If each subguide receives sub 30 electric material 36 operates to reduce the velocity
stantially the same amount of wave power from
of wave propagation through the distribution pas
the feed guide I, the ?eld intensity at the forward
sage, the slits may be spaced closer together than
end of guide 21 and at the entrance to the louver
would be true if the dielectric material were air
distribution passage will be more nearly equally
and still produce a broadside directional pattern.
35
distributed along the h dimension than would
The Fig. 22 structure is well adapted for non
otherwise be the case. Fig. 1'1 shows the normal
broadside radiation or reception and with a given
distribution of electric intensity across a guide
installation it is only necessary to change the op
with three equally spaced baffles, but does not take
erating frequency to alter the angle of fire. The
into account the improvement due to the manner
collimator connection 21 may also comprise a
in which the subguides are excited. Preferably 40 solid dielectric material and be fed from any of
the central baffle 28 is extended through the dis
the collimators hereinbefore described.
tribution passage 05 of the louver to inhibit or
Figs. 23 and 24 show an arrangement of three
retard degeneration of the transmitted wave into
louver radiators combined as a, single panel but
a wave with normal distribution, thus preserving
provided with three independent outputs or feed
approximately uniform excitation for the slits I3 45 guides. The central unit 40 is essentially that
that are farthest from the collimator. It will be
shown in Fig. 13 while the two louvers ID on the
understood that the h dimensions of the subguides
outside are each of the form described with refer
should not be so small as to produce transmission
ence to Figs. 11 and 12. The respective outputs
cult-oil‘ at a frequency higher than the operating
taken off through the collimators 21‘ may be
60 combined in various ways as may be needed. It
frequency.
In the collimator illustrated in Fig. 18, the guide
will be noted that the collimators of the two
section 21 forms with the feed guide I an L
outside units can be made to overlap the central
shaped structure with the end of guide 21 closed
louver All in view of the tapering of the distribu
over a longitudinal slit 30 in one of the e faces of
tion passages, thereby making the three louvers
55
the guide I. The slit 30 is discontinuous with
appear as one continuous array. This leads to a
the separate portions thereof spaced about a
considerable saving of space and such structural
wave-length apart so that the waves issuing there
simplicity that a rigid unit can readily be ob
from into the guide section 21 are cophased. Be
tained. Although the three louvers may be used
tween the slit portions are short triangular prisms
as a unit for transmitting or receiving they may
3| which form ?aring passages connecting the re
alternatively be used separately. For example,
spective slits with the main body of the guide
the central unit may be used as a transmitter in
section 21. Bailles may be extended through guide
an object locating system while the two outer
21 from the forward edges of the prisms 3| in the
units are used as receivers for intercepting the
manner and for the purpose described with refer
waves re?ected back from the distant object.
65
ence to Fig. 15.
Binaural reception may be practiced in this con
In Fig. 19 a louver radiator is shown set up for
nection and by phasing or angular displacement
convenient adjustment of its angular orientation.
the outer units may be used to project the over
The rectangular chamber 32 in which the louver
lapping beams sometimes employed for accurate
proper is mounted rotates therewith and may
object location. or by frequency wobbling and
house the transmitting oscillator or receiver and
proper phasing of the waves supplied to the two
associated equipment. One convenient structural
louvers the two radiated beams can be made to
arrangement is shown in cross section in Fig. 20.
variably diverge or converge.
In this case the chamber 32 is high enough to ac
The radiator illustrated in Fig. 25 comprises at
commodate the collimator section 21 which curves
the end of the feed guide I, a pair of branched
75
from the lower end of the louver distribution pas
11
2,405, 242
tapering guides 4| disposed at an angle to each
other and provided with spaced transverse slits
as described with reference to Fig. 9. Fed from
each slit is a pair of diverging guide sections 42
which have respective longitudinal slits on their
inner faces and which are angularly separated
to concentrate a beam in a direction parallel with
the guide i. The pairs of branch guides 42 are
of different lengths and more particularly their
12
so that wave power supplied through any one
of the latter can escape only into the pair of
slitted guides constituting the corresponding
louver.
What is claimed is:
1. A hollow pipe guide for ultra-high frequency
electromagnetic waves a section of which con
stituting an antenna has a plurality of apertures
lengths are progressively reduced toward the 10 longitudinally spaced therein, the total eifective
area of said apertures being substantially equal
outer ends of the guide sections 4|. Further
to the cross-sectional area of said guide at one
more, the slits in the branch guides 41 that are
end thereof, whereby the impedance of said an
associated with the longer branch guides 42, are
tenna section is matched to that of the guide.
made wider so as to permit more wave power to
2. A louver antenna comprising a hollow pipe
escape through them. By proper proportioning 15
guide one cross dimension of which is many times
of the various parts a fairly large plane wave
the other. said other dimension being tapered,
front may be fabricated thereby producing high
one
face of said guide comprising means de?ning
directivity. Some of the pairs of guide sections
a multiplicity of longitudinally spaced slits each
42 may be omitted, if desired, so that radiation
takes place directly from the transverse slits, and 20 substantially coextensive with the larger cross
dimension. and conductive surface means at said
in one embodiment only the central or axial pair
slits de?ning respective flaring passages normal
of guide sections 42 is retained.
to and external of said face.
The structure illustrated in Figs. 26 and 27
3. A combination in accordance with claim 2
may be regarded as an intimate combination of
in which said de?ning means comprises a multi
a modi?ed form of the Fig. 15 collimator and a 25 plicity of conductive triangular prisms.
modi?ed form of louver radiator. The collimator
4. A combination in accordance with claim 2
connected to the feed guide i comprises two
comprising an unslitted wave guide extension
wedge-like branch guides 45 which have respec
from the end of said guide and translating
tive longitudinal slits 46 along the upper edge
means connected thereto.
of their inner or e faces and which are arranged 30
5. .A pair of oppositely extending coplanar
at an angle of 90 degrees with reference to each
louvers in accordance with claim 2 and a feed
other. The branches 45 are so proportioned that
connection at their Junction.
_
the phase velocity Up=C cos 45"=l.414 c, or in
6. In combination with a hollow pipe guide,
other words so that the slits yield a substantially
plane wave front normal to the axis of guide I. 35 a wave collimator connected thereto comprising
a pair of divergent leaky pipe guides and a wave
The waves issuing from these slits enter a tri
guiding structure of elongated cross section con
angular chamber that is bounded in part by a
nected to receive waves emanating from said
triangular metallic base plate 41 and that is
leaky guides or to deliver waves thereto.
closed at the top by a plurality of triangular
'7. A combination in accordance with claim 6
metallic prisms 48 which are of different lengths 40
comprising at least one conductive baille sub
and spaced apart to form a triangular louver.
dividing said wave guiding structure into a plu
To secure substantially uniform distribution of
rality of wave guiding passages.
wave power over the face of the louver. the longi
tudinal slits 46 may be tapered so that more
power escapes in the vicinity of the shorter
radiating slits of the louver. Radiation normal
to the face of the louver is Secured by proportion
ing the parts in accordance with the principles
hereinbefore discussed.
8. As an antenna, a wave guiding passage of
elongated cross section comprising a conductive
plate as one wide face thereof and a plurality
of parallel conductive prisms spaced apart as the
other face, said prisms being disposed with one
plane face parallel to said conductive plate and
set back progressively from said back plate
In Fig. 28 is illustrated schematically a unitary 50 whereby said passage is tapered in discrete steps.
array made up of four of the Fig. 27 triangular
9. A microwave antenna system comprising as
louvers arranged as a. square. The four feed
the
wave radiating or intercepting element a ho]
guides 49, here shown as of trapezoidal cross sec
low
pipe guide of substantially rectangular cross
tion. are brought out together in one direction
section having in one face thereof a multiplicity
or the other normal to the plane of the array. 55
of longitudinally spaced transverse slits, means
It will be noted that one pair of the triangular
at one end of said guide for launching there
louvers is adapted for the radiation or reception
in
or receiving therefrom guided waves of domi
of horizontally polarized waves El while the other
nant type with electric ?eld normal to the said
pair is adapted for vertically polarized waves E2.
face, the dimension of said guide normal to
One pair may be used for transmission and the 00 one
the said face being tapered from the said one
other for reception in a two-way communication
end.
system, for example.
10. A combination in accordance with claim 9
Fig. 29 is similar to Fig. 28 in that it comprises
in which the total effective width of said slits
four of the Fig. 27 QO-degree louvers arranged to
is substantially equal to the said dimension of
form a square panel but it differs therefrom prin
the guide at the said one end thereof.
cipally in regard to the manner and means oi’
11. A combination in accordance with claim 9
excitation. The four feed guides in this embodi~
in which the said one dimension at the said one
ment comprise quadrantal subdivisions ill of a
end is not substantially greater than one half
cylindrical pipe 5i that are formed by radial
the length of the waves being transmitted.
baflles 52. The four pairs of branching wedge
12. In combination, a pair of elements in ac
shaped guides that comprise the louver array are
cordance with claim 9 disposed to form a V with
arranged radially around one end of the pipe 5!
the faces bearing the said slits forming the re
with each pair connected laterally to one of the
spective inner faces of the V.
feed guides 50. A metallic disc 53 to which the
13. In combination, a radio antenna compris
bellies 52 extend closes the end of the feed guides
ing a pair of intersecting, angularly related. uni
2,405,242
13
conductor pipe guides, said guides having respec
tive walls that face each other, the said facing
walls each having a multiplicity of apertures
spaced apart along the length of the respective
guide, and means for‘ exciting radio frequency
electromagnetic waves in said pair of guides or
receiving such waves therefrom.
14. In combination, a pair of conductive-walled
electromagnetic wave guides, each having a wall
14
conductive means de?ning a hollow pipe guide
of elongated cross section the end of which is
disposed to receive waves issuing through said
leaky faces or to deliver waves to said faces.
22. An antenna for ultra-high frequency waves
comprising a hollow pipe guide of elongated
cross section having a multiplicity of longitudi
nally spaced apertures in a wider face thereof.
said apertures extending substantially complete
with a multiplicity of apertures spaced apart 10 1y across the guide. an antenna transmission line
comprising a hollow pipe guide and a wave
therein along the length of the respective guide.
collimator
coupling the ends of the two guides
and exciting or receiving means common to said
and forming a continuation of each, said colli
guides for exciting electromagnetic waves in both
mator comprising a pair of leaky pipe guides
01' said guides for transmission out through said
multiplicity of apertures or for receiving from 15 divergent from the end of said transmission line.
23. An antenna structure comprising conduc
said guides electromagnetic waves entering
tive means defining a hollow pipe guide of elon
through said multiplicity of apertures, said guides
gated rectangular cross section having a multi
being disposed, with reference to three mutually
Dli?ity of longitudinally Spaced transverse slits
perpendicular planes, substantially in a ?rst of
said planes, substantially symmetrically on op 20 in one of the wider faces for the radiation or
interception of radio waves, the smaller cross
posite sides of a second plane passing between
sectional dimension of said guide being tapered
them, and with the said apertures in each of
with discrete steps at the successive slits.
said guides spaced at progressively greater dis
24. An antenna structure in accordance with
tances from both said second plane and the third
claim 23 in which the said conductive means de
25 ?ning the said wider face comprises a multi
of said planes.
15. An antenna system comprising conductive
plicity of conductive prisms of at least approxi
means de?ning a hollow pipe guide of elongated
mately triangular cross section disposed with
and substantially rectangular cross section hav
one plane face parallel to the other of the wider
ing a multiplicity of longitudinally spaced slits
disposed transversely of the axis of the guide in 30 faces of the guide ‘and spaced apart to form slits
between them.
and substantially coextensive with one of the
25. A directive radio antenna system compris
wider faces of the said guide, collimating wave
ing, in combination, a uniconductcr pipe guide
guide means adjacent one end of said guide for
having a plurality of distinct faces, one of said
launching therein or receiving therefrom guided
faces having therein a multiplicity of longitudi
35
waves of dominant type polarized with the elec
nally spaced transverse apertures affording a di
tric field normal to said wider face. and means
electric connection between the interlor of said
for substantially equalizing the ?eld intensity
guide and free space, the successive portions of
across the said wider face.
said one face that de?ne said apertures being in
16. A combination in accordance with claim 15
stepped relation to each other, and means for
comprising baffle means disposed in said slitted 40 exciting in said guide or receiving therefrom elec
guide for inhibiting degeneration of the ?eld in
tromagnetic waves having lines of electric force
tensity distribution ln collimated waves supplied
that are substantially normal to said one face.
thereto.
26. In combination, a radio antenna compris
17. A combination in accordance with claim 15
ing a hollow conductive-walled passage of sub
comprising a conductive ba?le disposed longi—
stantially rectangular cross section, one of the
tudinally in said slitted guide and normal to
walls of said passage comprising longitudinally
the said wider face.
successive portions that are substantially paral
18. An antenna system for ultra-high fre
lel to the opposite wall of said passage and that
quency waves comprising means de?ning a ?rst
50 are disposed, in stepped relation to each other,
hollow pipe guide of elongated cross section
successively closer to said opposite wall, said one
having a multiplicity of longitudinally spaced
wall having a multiplicity of elongated trans
transverse slits in one of the wider faces thereof
for the radiation or interception of radio waves,
an antenna transmission line comprising a second
verse apertures each formed between a pair of
said wall portions, and means for exciting in said
55 passage or receiving therefrom electromagnetic
hollow pipe guide, and a wave collimator coupling
waves having lines of electric force that extend
said ?rst and second guides, said collimator com
between said one wall and said opposite wall.
prising a pair of leaky pipe guides divergent
2'1. A radio antenna system comprising a uni
from the end of the second hollow pipe guide.
conductor pipe guide for electromagnetic waves,
19. A combination in accordance with claim
said guide having a multiplicity of apertures
18 comprising a conductive ba?le extending longi 60 spaced along its length for the radiation or ad
tudinally from the point of divergence of said
mission of radio waves, the size of said guide
leaky pipe guides through said ?rst hollow pipe
guide.
20. In a system for the transmission of ultra
high frequency electric waves, a wave collimator
being reduced gradually between successive aper
tures, and means for exciting said guide with
radio frequency waves or receiving such waves
comprising a. pair of leaky pipe guides divergent
therefrom.
from a. common point, wave translating means
ing a, uniconductor guide enclosing a dielectric
medium, said guide having at least one substan
tially flat side wall and said side wall having a
coupled to both of said guides at said point, and
wave guiding means connected laterally of both
of said leaky guides in wave transfer relation
therewith.
21. In combination. a pair of shielded electric
transmission lines divergent from a, common
point in the form of a V, said lines being elec
trically leaky along the inner faces thereof, and
. 28. In combination. a radio antenna compris
multiplicity of openings therein spaced apart
along the length of said guide, said guide having
a transverse dimension normal to said side wall
that tapers substantially continuously, and
means for exciting said antenna with electromag
15
2,405,242
16
netic waves oi’ radio frequency or receiving such
said guide radio waves intercepted thereby, said
waves therefrom.
guide having a transverse dimension that tapers
29. In combination, a radio antenna compris
substantially
continuously along said guide from
ing a conductive-walled electromagnetic wave
a larger value adjacent said exciting or receiving
guiding passage of substantially rectangular cross 6 means.
section that tapers smoothly from one end of said
32. In a combination, a leaky wave guide and
passage to the other, one of the tour conductive
means for exciting in said guide or receiving
walls of said passage having therein a multiplictherefrom guided electromagnetic waves of a type
ity of elongated transversely disposed openings
in which the lines or electromotive force are sub
spaced apart along the length 01' said passage for 10 stantially parallel to a transverse dimension of
the emission or admission of radio frequency
the guide, the said transverse dimension varying
waves, and means for exciting radio frequency
substantially continuously from point to point
waves in said passage or receiving them there-
along said guide.
from.
33. In combination, a leaky uniconductor pipe
30. In combination, a radio antenna compris- 15 guide for electromagnetic waves, said guide hav
ing a leaky uniconductor pipe guide for electroing a substantially continuous taper. and radio
magnetic waves, said guide having a face that
frequency wave exciting or receiving means con
contains a multiplicity of apertures spaced apart
nected to the larger end of the tapered guide.
along the length of said guide, the spacing of
34. A radio antenna system comprising a mul
Said apertures being small compared with the 20 tipiicity of panel antennas arranged to form a
operating wave-length and the said guide being
substantially continuous active forward surface,
tapered in size from one aperture to the next.
each panel antenna having a multiplicity oi’
and radio frequency wave exciting or receiving
apertures in its forward surface and an individual
means connected to said guide.
tapered distribution passage that extends across
31. A radio antenna system comprising a iealur 25 its back surface, and at least one or said distribu
wave guide and exciting or receiving means contion passages being extended in overlapping rela
nected thereto for exciting waves in said guide
tion along the back surface oi‘ a contiguous panel.
for radiation therefrom or for receiving from
GEORGE C. SOUTHWORTH.
Disclaimer
2,405,242.—Ge0rgc C’. Soutliworth,
Bank, N. J. MICROWAVE RADIO TRANSMIS
SION. Patent dated Aug Red
6, 1946.
Disclaimer ?led
assignee, Bell Telephone Laboratories, Incorporated.
Dec. 21, 1948, by the
Hereby enters this disclaimer in claims 13, I4, and 20 of said patent.
[O?icial Gazette January 25, 1949.]
15
2,405,242
16
netic waves oi’ radio frequency or receiving such
said guide radio waves intercepted thereby, said
waves therefrom.
guide having a transverse dimension that tapers
29. In combination, a radio antenna compris
substantially
continuously along said guide from
ing a conductive-walled electromagnetic wave
a larger value adjacent said exciting or receiving
guiding passage of substantially rectangular cross 6 means.
section that tapers smoothly from one end of said
32. In a combination, a leaky wave guide and
passage to the other, one of the tour conductive
means for exciting in said guide or receiving
walls of said passage having therein a multiplictherefrom guided electromagnetic waves of a type
ity of elongated transversely disposed openings
in which the lines or electromotive force are sub
spaced apart along the length 01' said passage for 10 stantially parallel to a transverse dimension of
the emission or admission of radio frequency
the guide, the said transverse dimension varying
waves, and means for exciting radio frequency
substantially continuously from point to point
waves in said passage or receiving them there-
along said guide.
from.
33. In combination, a leaky uniconductor pipe
30. In combination, a radio antenna compris- 15 guide for electromagnetic waves, said guide hav
ing a leaky uniconductor pipe guide for electroing a substantially continuous taper. and radio
magnetic waves, said guide having a face that
frequency wave exciting or receiving means con
contains a multiplicity of apertures spaced apart
nected to the larger end of the tapered guide.
along the length of said guide, the spacing of
34. A radio antenna system comprising a mul
Said apertures being small compared with the 20 tipiicity of panel antennas arranged to form a
operating wave-length and the said guide being
substantially continuous active forward surface,
tapered in size from one aperture to the next.
each panel antenna having a multiplicity oi’
and radio frequency wave exciting or receiving
apertures in its forward surface and an individual
means connected to said guide.
tapered distribution passage that extends across
31. A radio antenna system comprising a iealur 25 its back surface, and at least one or said distribu
wave guide and exciting or receiving means contion passages being extended in overlapping rela
nected thereto for exciting waves in said guide
tion along the back surface oi‘ a contiguous panel.
for radiation therefrom or for receiving from
GEORGE C. SOUTHWORTH.
Disclaimer
2,405,242.—Ge0rgc C’. Soutliworth,
Bank, N. J. MICROWAVE RADIO TRANSMIS
SION. Patent dated Aug Red
6, 1946.
Disclaimer ?led
assignee, Bell Telephone Laboratories, Incorporated.
Dec. 21, 1948, by the
Hereby enters this disclaimer in claims 13, I4, and 20 of said patent.
[O?icial Gazette January 25, 1949.]
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