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. sept. 17, 1946.
11m/„PETERSON
2,407,847
R. F. SWITCH
Filed May l, 1945
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Patented Sept. 17, 1946
2,407,847
UNITED STATES PATENT OFFICE
2,407,847
RADIO FREQUENCY SWITCH
Donald W. Peterson, Princeton, N. J., assignor`
to Radio Corporation of America, a corporation
of Delaware
1
Application May 1, 1943, Serial No. 485,388
6 Claims. (Cl. 178-44)
2
This invention relates to radio-frequency
line l is to be selectively short circuited and open
switches, such as are used for making and break
circuited between the inner conductor 3 at a
ing elîectively connections between radio fre
point 5 and the outer conductor l'. A tubular
quency sources and loads, reversing or changing
conductive member 9 is connected to the outer
the phases of the currents flowing in various
conductor l' of the line I and extends substan
parts of radio frequency circuits, and the like.
tially at right angles thereto. A second tubular
Such switching and phasing functions are re
conductive member II is supported concentri
quired for example in the operation of directive
cally within the conductor 9 and connected to
antenna systems when a plurality of directive
the point 5 on the inner conductor 3 of the line
patterns are to be provided selectively. It is 10 I. The space between the walls of the tubular
com-mon practice to employ various combinations
members 9 and I I may be filled With insulating
of variable capacitors and transmission line sec
material it, such as hard rubber, polystyrene,
tions for these purposes. `For example, if two
or the like. The insulator I3 extends beyond
points in a radio frequency circuit are to be
the end of the member I I and is provided `with
alternately connected together and disconnected, 15 a cylindrical bore concentric with and substan
a capacitor capable of being varied between two
tially of the same diameter as that of the mem
values Cmin and Cmax is coupled to the two points
ber II. The length of the member I! is one
through a transmission line. The line is of such
quarter electrical wavelength at the frequency at
length that the reactance o1’ the capacitor atone
which the system is to operate.
of its settings, for example, Cinex is transformed
An iron rod I5, insulated by a coating I1 of
to a short circuit at the end of the line. The
polystyrene or the like, is provided within the
reactance presented at the end of the line by
bore of the member I3 and is adapted to move
Cmin is tuned to parallel resonance by a stub line
longitudinally therein between the positions
or a similar reactive element, so as to produce an
shown in Fig. 1 and Fig. 2. A winding I9 is pro
open circuit. Thus, by changing the capacitance
from Cmax to Cmin or vice versa, a short circuit
or open circuit may be provided. Similar ar
rangements are used for phase shifting or phase
reversal in radio frequency networks.
' Although radio frequency switching systems of
the above described type can be made highly ef
fective by careful design, the variabl-e capacitors
are relatively bulky and expensive. Also, the
transmission line networks necessary to achieve
the desired operations may be somewhat com
pleX.
Accordingly, it is the principal object of
the present invention to provide an improved
method of and means for controlling the ilow of
radio frequency currents.
Another object of the invention is to provide
an improved radio frequency switch structure
comprising a minimum of moving parts and re
quiring no close mechanical tolerances.
A further object is to provide an improved
radio frequency switch structure which is read
ily adaptable to remote control. These and other
objects will become apparent to those skilled in
the art upon consideration of the following de
scription with reference to the accompanying
drawing, in which Figs. l and 2 are sectional
schematic diagrams of switches constructed in
accordance with the invention and Fig. 3 is a
schematic diagram of a typical network includ
\ vided on the outside of the member 9 at the end
adjacent to line l. The winding i9V is connected
through a switch 2l lto an electrical source'23
such as a generator. The rod I5 is substantially
one-half wavelength long so that when itis in
the position shown in Fig. 2 it extends substam
tially one-quarter electrical wavelength beyond
the end of thetubulai` member iI. The opera
tion of the above described structure is as fol
lows:
I
When the parts are in the position illustrated
in Fig. 1 the tubular members 9 and I I cooper
ate to function as a quarter wave line open-cir
cuited at one end and connected across the line
I at the other end.
Owing to the well known
impedance inversion characteristics of quarter
wave lines the open circuit at the far end of this
line is reflected as a short circuit between the
point 5 and the outer conductor l. When switch
2| is closed the solenoid winding i8 is energized,
drawing the iron rod I5 into the position shown l
in dot and dash lines. Since the rod I5 and the
tubular member II overlap for substantially a
quarter wavelength they present the electrical
characteristics of a single conductor one-half
wavelength long. Thus, the members 9, I I and
I5 together constitute a half wavelength line
open-circuited at its far end and present an open
circuit between the point 5 and the outer con
ing the switch of Fig. 2.
ductor 1_ To retract the member `I5 from the
Referring t0v Fig. 1, a concentric transmission 55 member II a second solenoid mayI be provided
v '
.
'
2,407,847
3
4
Although only one application of the inven
at the outer end of the member 9 or the device
` tion has been specifically described it will be
may be mounted in such a position that gravity
will effect a withdrawal when the switch 2| is
opened. If desired, the rod I5 may be magneti
apparent that its utility is not limited thereto.
For example, it will be clear without further
illustration that switches of the described type
cally polarized, and the coil I9 energized from
may be employed to insert or remove line sec
a D.-C. source through a reversing switch.
tions of undesired length in a transmision line
Fig. 2 showga modification of the switch of
circuit for providing different phase shifts be
Fig. 1 arranged to short circuit and open circuit
tween
predetermined points. It should also be
selectively two transmission lines I and I’. The
outer conductor 9 is connected between the outer 10 noted that although the illustrated embodiment
is arranged to be operated electro-magnetically,
conductors I and I’. The inner tubular con
the outer conductor 9 may be slotted to provide
ductor I I is duplicated with a conductor II ’ con
for mechanical operation by means of a pin
nected to the inner conductor of the line> I’. A
or the like' extending radially from the mem
solenoid I9' surrounds the outer conductor 9 at
the end adjacent the line I’. The windings I9 15 ber I5. In the case of a single ended structure
such as that of Fig. 'l the member I5 may be
and I9’ are connected through a double throw
provided with an extension rod of insulating
switch 2|’ to the source 23. A single rod mem
material for mechanical operation through the
ber I5 is provided as in the structure of Fig. 1.
outer
end of the switch structure.
When the switch 2|’ is thrown to ~the left, the
The invention covered herein may be manu
rod I5 is drawn into the tubular member |I, 20
factured and used by or for the Government
short circuiting the line I at the point 5. When
of the United States for governmental, military,
the switch 2|' is thrown to the right, ythe rod I5
naval and national defense purposes without pay
is drawn into the tubular member Il', short cir
ment to me or assigns of any royalty thereon.
cuiting the line I’ at the point 5’ and presenting
an open circuit across the line I.
25
I claim as my invention:
l. A system for selectively presenting an open
circuit and a short circuit between two prede
termined points in a radio frequency transmis
sion system, comprising a tubular member of
anced with respect to ground. Juxtaposed points 30 conductive material connected to one of said
Fig. 3 Vshows the above described switch ar
ranged >to reverse the phase on a balanced radio
Afrequency line. Conductors 25 and 2'! consti
tute a parallel open-wire transmission line, bal
29 and 3| on the lines 25 -and 2'! respectively are
interconnected by a concentric line S5 one-half
electrical wavelength long. A point 3l one-quar
ter wavelength to the left of point 29 is con
nected to the point 39 one-quarter wavelength
to the right of the point 3| by a half-wave line
4|. The point 43 one-quarter wavelength to the
left of the point 3| is similarly connected to the
points, a second tubular conductive member con
nected to the other of said points and positioned.
within and coaxial with said first tubular mem
ber, and an insulated rod of conductive material
adapted to move longitudinally within said sec
ond tubular member.
>
2. A system for selectively presenting an open
circuit and a short circuit between two pre
determined points in a radio frequency trans
point 45 one-quarter wavelength to the right of
the line 29 by a half wave line 41. The mid points 40 mission system, comprising a tubular member
of conductive material connected to one of said
5| and 53 of the lines 4| and 4'! respectively are
points, a second tubular conductive member con
connected together by a half-wave line 49. A
nected to the other of said points and positioned
switch 55A is -connected between the points 29 and
within and coaxial with said first tubular mem
5I. The switch 55 may comprise a structure
similar to that of Fig. 2 arranged to provide a 45 ber, an insulated rod of conductive magnetic
material adapted to move longitudinally within
short circuit at one end at the same time as an
said second tubular member, and solenoid means
open circuit is presented at the other end. The
supported on the outer surface of said first tu
operation of the system of Fig. 3 is as follows:
bular member.
VAssume that the switch 55 is actuated so that
the point 29 is short-circuited while the point 5i 50 -»3. The invention as set forth in claim 1, in- v
cluding a body of insulated material positioned
is open-circuited. The short circuit at the point
29 is reñected as an open circuit at the points
31 and
The open circuit at the point 5I has
no effect upon the performance of the line 4I.
between the inner wall of said first tubular mem- '
ber and the outer wall of said second tubular
member,
4. The invention as set forth in claim 1 where
in said second tubular member is substantially 1A,
29 reflects a short circuit at the point 3| through
electrical wave length long and said rod mem
the half wave line 35. The short circuit at the
ber is substantially 1/2 electrical wave length
point 3| is reiiected at the points 39 and 43 as
long.
'
open circuits. Energy applied to the line 25
5. A radio frequency distributioncircuit, in
flows from the point 31 through the line 4I to the 60
cluding an open wire, transmission line com
point 39 and energy applied to the line 2ï lflows
prising two conductors, a concentric line 1/2 wave
through the line ‘4l to the point 45. Thus the
length long connected between juxtaposed points
polarities of the points 39 and 45 are reverse
on said conductors, second and third concentric
with respect to the corresponding points 43 and.
31. When the switch 55 is actuated so as to 65 lines each 1/2 wave length long cross-connected
between points on said first and second con
provide a short circuit at the point 5Il and an
ductors 1/4 wave length to each side of said
open circuit at the point 29, open circuits are
juxtaposed points, a fourth concentric line 1/2
presented at the points 31 and 39 by the line
wave length long connected between the mid
4| and at points 43 and 45 by the line 4'I. En
points of said second and third lines, means for
ergy applied through the lines 25 and 21 to the
Thus, the short circuit presented at the point 55
points 45 and 39 directly through points 29 and
3| and the polarity of the point 45 with re
alternately providing a short circuit and an open
circuit at one of said midpoints, and means for
spect to that of point 39 is the same as the
simultaneously providing respectively an ope-n
polarity of the point 3'I with respect to that of
circuit and a short circuit at one of saidjuxta
posed points, said last named means comprising Y
`point 43.
5
2,407,847
tubular conductive members each connected to
6. The invention as set forth in claim 5 Where
in said rod member is made of magnetic mate
rial and said outer tubular member is surrounded
bular members and positioned c'oaän'ally with
by electro magnet means comprising at least
respect thereto, and a, conductive rod adapted to 5 one solenoid Winding.
be moved from a. position Within one of said
inner tubular conductive members to a position
DONALD W. PETERSON.
Within the other of said inner tubular conduc
tive members.
one of said last mentioned points, a further tu
bular conductive member surrounding said tu
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