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Патент USA US2408034

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Sept. 24, 1946.
“A. c. Em
Filed March l7,' 1942
Patented Sept. 24, 1946
Alfred 0. Beck, Red Bank, N. J., assignor to Bell
Telephone Laboratories, Incorporated, New
York, N. 2., a corporation of New York
Application March 17, 19h, Serial No. 435,016
4 Claims.
(Cl. 17s-44)
This invention relates to microwave coupling
devices and more particularly to wave-guide
transmission line coupling arrangements.
In accordance with the preferred embodiment ’
of the invention a coaxial line having an imped
ance Z is coupled to a main quadrilateral wave
As disclosed in the copending application of
H. T. Friis, Serial No. 435,017, ?led concurrently
with the instant application, impedance match
guide having a considerably larger impedance as, ‘
for example, ‘ll-Z, through a rectangular wave
guide having
characteristic impedance of 22
and folded in the plane containing its long trans
ing over a band of frequencies between a coaxial
line or conductive channel and a main wave
verse dimension which plane is perpendicular to
guide, and unilateral wave propagation in the
the plane of polarization of the electric vector.
wave guide, may be effected without the use of a 10 The end apertures of the'folded wave guide sec
piston. re?ector by’ means of a rectangular wave
tion are superimposed so that their short trans?
guide folded or looped in the plane of its short
verse dimensions are aligned. The coaxial line is
transverse dimension, that is, in the plane of
coupled through aimultifrequency matching de
polarization of the propagated electric wave com~
vice of the type disclosed in‘ applicant’s copend
ing application, Serial No. 429,358, ?led February
ponent. In this arrangement the end apertures
of the folded guide are superimposed and joined
to an end ori?ce of the main guide and the co~
axial line is connected to the longitudinal center
point of the looped guide. Also, for multifre
quency operation, each of the two branches of
the folded guide includes a twisted 90 degree po
larity changer for securing colinearly polarized
wave components in the superimposed folded
guide apertures. While the folded guide cou
pling is suitable for use in many microwave sys
tems, the polarity changers aside from being
more or less difficult to manufacture, cause a
certain amount of loss and it now appears desir.
able to employ folded wave guide coupling sec
tions having no quadrature polarity changers of l
the twisted type. In this vconnection applicant
has discovered that, contrary to the teaching of
the prior art, rectangular wave guides may be
equals the combined parallel impedance of the
branches or folded guide sections, and the serially
connected apertures of the loop section have a
bent or curved in the plane of the long transverse
dimensions or, stated differently, in a plane per
pendicular to the polarization plane of the elec
tric component utilized in the wave guide, with
out substantial loss and, in fact, with only slight
ly greater loss than that sustained in guides fold
ed or curved in the plane of polarization.
It is one object of this invention to secure in
single frequency and multifrequency systems,
each comprising a wave guide coupled to a trans
mission line, unilateral propagation in the wave
guide without utilizing a reflecting piston and
with minimum loss.
It is another object of this invention to match
the impedances of a dielectric channel and a line
channel Without using auxiliary adjustable ap
paratus or quadrature polarity changers of the
twisted wave-guide type.
It is still another object of this invention to
obtain a multifrequency folded wave-guide cou
pler which does not include twisted portions and
which is simpler in construction than the cou
plers heretofore utilized.
As used herein the term “quadrilateral” gener
ically includes the terms “rectangular” and
“square,” and the term “rectangular” excludes
1942, to the longitudinal center point of the
rectangular folded wave guide; and the superim
posed end apertures are joined to an end ori?ce
of the main quadrilateral wave guide. In opera
tion, the wave components or wavelets in the two
branches of the loop section have, at the longi
tudinal center point mentioned above, equal
phase angles and are similarly polarized. Since
the end apertures of the loop are equally distant
from the center point and since the folded guide
is not bent in the plane of polarization, the wave
lets at the superimposed apertures are in phase
angle agreement and are similarly polarized,
whereby a wave of maximum intensity is propa
gated unilaterally in the main quadrilateral
guide. Moreover, as explained in the copending'
Friis application, the coaxial line impedance
total impedance equal to‘ that of the quadrilateral ‘
Hence, the folded guide section functions
as a transformer for matching the impedances
of the coaxial line and the main Wave-guide over
a band of microwave carrier frequencies.
The invention will be more fully understood
from a perusal of the following‘speci?cation ta
ken in conjunction with the drawing on which
like reference characters denote elements of sim
‘ilar function and on which:
Fig. 1 is a perspective View of one embodiment
of the invention; and
Fig. 2 is a side or elevational View of the same
Referring to Figs. 1 and 2, reference numeral I
designates a translation device for transmitting
or receiving microwaves and numeral 2 denotes
a conductive channel or coaxial line connected
thereto. The line channel 2 is connected through
a rectangular wave guide section 3 folded or
looped in the plane of its long, transverse dimen
sion b to a quadrilateral main wave guide or di- ‘
electric channel ll and a radiating or receiving
antenna such as a horn 5. The inner conductor
60 6 of coaxial line 2 is attached to the folded guide
section 3 at the longitudinal mid-point ‘I of the
looped guide through a multi-frequency coupling
device of the type disclosed in applicant’s copend
ing application mentioned above and comprising
Although the invention has been explained in
connection with a certain embodiment thereof,
it should be understood that it is not to be limited
to this arrangement inasmuch as other appara
an adjustable sleeve member 8. As explained in Cl tus may be employed in successfully practicing
the invention. More particularly, the folded
my application mentioned above, the sleeve is
adjusted and a particular value for the short
transverse dimension a of the loop 3 selected such
wave-guide coupling section and the main wave
guide may each have a square instead of a rec
tangular cross section. Also, any other type of
conductor 6 has the proper length and impedance 10 line, such as a balanced line, and even a dielectric
wave-guide channel, may be employed in place
for matching over a carrier band of frequencies
of the coaxial line; and the invention may be
the characteristic impedance Z of line 2 to the
utilized for coupling a balanced line to a dielectric
total folded guide impedance comprising the im
channel or for coupling two dielectric channels.
pedances of the two loop branches I0 and I I con
What is claimed is:
nected in parallel. Thus, assuming the line 2 has 15
1. A dielectric channel-transmission line cou
a characteristic impedance Z equal to 100 ohms,
pling device comprising a rectangular wave-guide
each of the loop branches II] and I I has a char
section for conveying wave components polarized
acteristic impedance 22 equal to 200 ohms, and
in the plane of one transverse dimension, said
the two impedances in parallel equal the line im
pedance. The main dielectric channel has a 20 section being looped or curved in the plane of the ‘
other transverse dimension and having superim
characteristic impedance, IIZ, which may be taken
posed apertures, the section being connected at
as the value of its input or send end impedance
since the length of the main guide 4 is great rela
its mid-point to said line and at its super-imposed
tive to the wave-length employed and may be
apertures to said channel.
considered in?nite. Inasmuch as the apertures 25
2. A. quadrilateral dielectric wave channel
l2 and I3 are superimposed with their transverse
transmission line coupling device comprising a
dimensions a aligned, the characteristic im
folded rectangular wave guide having a short
pedances of the apertures are serially associated
transverse dimension equal substantially to one
and their total impedance, GZ, equals the send
half of the short transverse dimension of said
end impedance and the characteristic impedance 30 channel, said folded guide having its end aper
of guide 4.
tures superimposed for junction with said chan
In operation, assuming device I is a transmit
nel and an aperture at an intermediate pointv
ter, while the energies conveyed between the de
for junction with said line, the two paths con
vice I and the horn 5, and propagated in the
necting said intermediate point with said chan
branches I0 and I I, flow relative to point 1 in op 35 nel ibeing electrically equal, said guide being en
ergized with waves polarized in the plane of its
posite or bilateral directions, the combination in
cluding looped section 3 functions to produce only
short transverse dimension and folded in the
unilateral propagation in the dielectric channel
plane of its long transverse dimension.
3. In combination, a quadrilateral wave guide
4. Arrows I4, I5, I6 and I1 denote the directions
of propagation in line 2. branch I0, 'branch I I and 40 having a given impedance and an end ori?ce, a
guide 4. respectively. The wavelets propagated in
transmission line having a di?erent impedance,
and means for matching said impedances and for
directions [5 and I6 have, at center point ‘I, the
same (zero) phase angle and are similarly polar
producing unilateral propagation in said guide
ized as shown by arrows I8 and IS in a'direction
comprising a rectangular wave-guide section hav
aligned with the short transverse dimension a 45 ing an impedance intermediate said impedances
and the exposed exciter 9. that is. in a vertical
and a curvature in the plane'of its long trans
direction in the plane of the drawing. Contrary
verse dimension, said section having superim
to the ‘effect secured in a system of the copending
posed end apertures joined to an end‘ ori?ce of
Friis ‘application, the curvature in the coupling
said quadrilateral guide, said line projecting into
section 3 does not shift the polarity of these wave
said section at its mid-point in a direction coin
lets since the curvature is only in a plane per
cident with the short transverse dimension of
pendicular to the direction of polarization.
said section.
that the exposed. exciter portion 9 of the inner
Moreover. the branches I i) and II are of equal
4. In a system for transmitting transverse elec
length so that in apertures I2 and I3 the wave
tric waves. a quadrilateral wave guide having an
lets are similarly polarized, as shown by arrows 55 end ori?ce. a coaxial line, and means for connect
ing said guide and line and matching their ime
20 and 2!. and combine to form a maximum vec
tor. resultant 23 in the main wave-guide chan
nedances over a band of frequencies several hun
dred megacycles wide, said means comprising a
nel 4.
rectangular wave guide folded in the plane of the
Thus. in accordance with the invention the sys
60 transverse dimension perpendicular to the polar
tem or combination illustrated by Figs. 1 and 2
ization of the transverse electric wave and hav
and comprising a multi-frequency coaxial line
ing superimposed end apertures joined to an end
to-wave guide. coupling device, a wave-guide cou
ori?ce of said quadrilateral guide. the character
pling section folded in the plane perpendicular to
the plane of polarization of the electric vector 65 istic impedance of the rectangular guide being
equal to twice that of said line and to one-half
and a main dielectric channel. functions to match
that of the cuadrilateral guide, a multifreouency
the impedances of a line channel and a dielectric
impedance coupler connecting‘ said line to the
channel. without re?ection losses and without
mid-point of said folded guide. whereby corn-v
losses due to changing the polaritv of the wave
component. over a hand of carrier frequencies in
nonents transferred between said line and said
cluding several hundred megacycles. At the same
time the combination functions to produce ,uni
lateral or one way propagation in the quadrilat
eral wave guide 4.
?rst rectangular guide have the same polarity
endsama phase angle at the iunction of the su
perimposed‘ end apertures with said end ori?ce.
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