Note: Descriptions are shown in the official language in which they were submitted.
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Tl~i.5 illv~?ntion relates to a module for the
formatinn o C~!i.y resonance devic~s wherc two or m~re
of such devicos are to be arranged side by side.
By cavity resonance devices are devices for use
at between 25 Megacycles and 1200 Megacycles (from high
frequency by microwave frequencies) comprising an outer
conductor which is a hollow metallic shell with or without
a central conductor. The outer shell may be of many cross-
sectional shapes but this invention is concerned wi~h a
device where the cross-section is rectangular and most
commonly square. Cavity resonance devices fitting the above
description and with which the invention might be used
include : band-pass filters, band stop fil~ers, wave guides,
` cavity resonators and transmission line transformers.
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Since the invention is designed to provide a modular
construction for such devices located side by side it will
`` apply most frequently tos~lch devices as filters, cavity
resonators and transformers which are commonly placed side by
side and infrequently to wave guides which are usually used -r
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!,,, It is an ob~ect of the invention to provide a mo~ule
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for use in the assembly of a plurality of side by side cavity
resonance devices which module is a metallic extrusion in
the shape of rectangular U-shape. (By "longitudinally" in
the specification and claims herein, I mean in the direction
of extrusion). The free edges of the walls forming the
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~ "uprights" of the U are provided with first shaped portions
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~le~igne~ to ~t!~s;:rit witll ~y sliding longitLIdinally a]ong
second s~ s~ons provided adjacent each end of the
~utside of on~ of the walls of the rectangular U-shaped
extrusion. T~lus with the two first shaped portions of one
module interfi~ting with pair of second shaped portions of
another module results in the provision of a square or rect-
angular cavity resonance device having three sides f ~OM the
first mentioned module and a fourth side provided by on~ wall
¦ of the last mentioned module. ~hree sides of another cavity
3 lo resonance device, side by side with the first are provided.
! A number of modules may be assembled in this way if desired
If, with the number of modules assembled, corresponding to the
desired number of side-by-side cavity resonance devices, one
of the modules has only three sides, the fourth wall may be
provided by a separate wall with a pair of second shaped
portions.
Since the module is formed from an extrusion, it
may be cut to any length desired.
Although the extruded modules may be formed fro~ any
¦ 20 extrudable metal with suitable conductivity, the requirements
of economy and ease of fabrication will dictate that the
metal used is aluminium, brass, bronze or copper- and the
preferred one of these is aluminium.
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Prior methods of providing multi-section cavity
resonance devices (most commonly filters) are as follows :
1. Use separate devices joined with sections of
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transmission line or ~oined by welded or brazed waveguide
apértures.
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2. U~e ~ J~ c section devices having common w~lls
containi~ r~-~re~ or loops. The whole ilter section
may be cast l:.on aluminium, bronze or the like.
3~ Use multiple section devices with common walls
,~ fabricated by making a multiple section extrusion.
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4. Use multiple sections formed by providing multiple
four sided square or rec~angular extrusions placed with
side walls of respective sections juxtaposed as clo~ely as
possible and connected by aligned apertures in the juxtaposed
walls with or without common connecting probes or loops.
Separate devices ((1) above) joined by coaxial
,cable or wave guides are expensive and inefficient relative
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,, to the other devices described. Multiple section devices
((2) and (3) above) having co~mon walls formed by casting ' -
or extrusion ~are relatively efficient and may be economical
if the particular shapes chosen are sufficiently in demand
, to be manufactured in sufficiently large quantities. However
these last mentioned multiple section devices have two
principal disadvantages. (a) Such devices are only economical
when manufactured in large quantities to a common pattern.- ~'-`
Thus such devices are not versatile enough to be used for a
large number of different filter (or other resonance device)
configurations each having but a limited yearly sales
potential. (b) The provision of holes or other coupling
mean~ through the common wall between sections of such multiple
section devices is difficult and expensive due to difficulty
of access. The use of multiple sections fonmed by four s~ded
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`~ sections juxt~p~ ed wal] to wall with each other (4) above
suffers rom t~ fact that leakage occurs between adjacent
juxtapos~d ~sa~l~ r.o ~atter how precisely they are made or
aligned. Moreovex such precise manuf~cture or ali~nment is
expensive. A further disadvantage of the last mentioned
method arises from the fact the juxtaposed walls between
connected sections require aligned apertures. Such aligned
apertures require precision forming which is both difficult
1 and expensive due to the difficulty of access once the sections
i 10 are connected and the imprecision of alignment when the
~ apertures a~e separately formed in disconnected sections.
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- The inventive construction using extrusions having
three of the required four walls and forming a rectangular
U~shape in cross-section overcomes the disadvantages of the
prior methods. The production of multiple sections using
the number of such modules corresponding to the number o~
sections, and with the open sides of the U closed (in at least
some cases) by the walls of similar modules, provides
multiple sections which are relatively inexpensive and
electrically efficient. Moreover the three sided modules arë
constructed so that they may be easily assembled into a
variable number of multiple sections or relatively large
vsriety of multiple sections. The production of special
multiple sections in small volume can thus be performed economi-
cally. Because three æided modules are used, the connected
8ections in a multiple 8ection device may always (if desired)
be connected by a single wall. In such case there is no
problem of leakage between or of alignment of apertures in
double walls.
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Irl ~irawin~s which illus~rate preferred embodimellts
of the invention :
~igure l shows the cross-section of an extrusion in
accord with the invention;
, Figure 2 shows the cross-section of a number of
connected modules each formed of the cross-section of Fi~ure l;
Figure 3 shows a member for use with modules formed
from the extrusion of Figure l;
Figure 4 shows a multi sectional c~vity resonance
device formed from the extrusions of Figure l;
Figure 5 shows the coupling of members of the type
shown in Figure 4;
Figure 6 shows a cross-section of another extrusion
in accord with the invention; and
`1 Figure 7 shows the connection of four extrusions of
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the type shown in Figure 6 in the formation of a four section
cavity resonance device.
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In the drawings, Figure 1 shows an extrusion 10 of -
~3 generally rectangular U cross-section. At each corner w~e~ --
the wall 12 forming the cross-bar of the U joins a wall 14
forming the upright of the U, the extrusion is shaped to form
an outwardly open circular groove 16 with the defining ex-
;~ trusion material 18 and 19 extending approximately 3/4 of the ~ -
way about of the circle of the groove and with the opening
directed outwardly at about 25 to the side walls of the
'extrusion. It will be noted that the shaped portions are pre-
ferably arranged so that the side walls 14 of the extrusion
are of smooth contour and the shaped portions only interrupt-
~ the end wall 12 or cross-bar of the U-shaped extrusion. The
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The free cd~es ~f the w~lls 14 are provided with shi~rted
po~tion3i 2G, ~ rJed to complemen~ the circular grooves 16,
at the e~ r-utirt~ corncrs as hereinafter described. The shaped
portions 20 on one module are arranged to abut against the
outer lip l~ deining the circular groove 16 of another
module. The shaped portion 20 is shaped to conform to the
I curvature of the circular groove adjacent it's lip 19. The
I extensions 20 or "male members" of one module are slid
` longitudinally into the circular grooves ~ or "female members"
~- 10 o the other member to form the arrangement described and
- best shown in Figure 2. It wIll be obvious that with the
embodiment shown the modular fvrm allows the assembly, in a
; line, of as many sections as desired. The end section will
have only three walls and the fourth wall is provided by a
plate 26 (shown in Figure 3) shaped to define at each edge
the two circular grooves 18, similar to those on a module so
that the plate may be slid longitudinally over and relative
to ~he portions 20 of the open-~nded module. The circular
shape of the grooves 18, (and the conforming shape of the
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~ 20 male member 20 are not essential to the invention). For most
J applications however it is important that the groove defining
surfaces define opposed faces on one of which the male member
will lie and further def~ne inwardly curved surfaces on each
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side of the opposed surfaces. This is so that a screw
(pre~erably "thread forming" as distLnct from "thread cutting"
~ msy be inserted into the passage remainLng between the male
¦ member and the defining surface of the female member spaced
therefrom. The pressure exerted by the screw moves the male
member ol-twardly clamping it firmly against the adjacent surface
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of the ~r~v~Je defining member thus clamplng the two
~ module~ flrm!,~ t~gethex. A similar screw attachment is
m used to fi~ily fa~ten the end plate in place. The action af
a screw 24, as above described is shown in Figure 5. The
clamping not only gives good mechanical connectiDn but good
electrical connection to properly ensure the electrical
qualities of the device. The screw of course is used, not
only for clamping but fox attachment of the end cap of the
device, which will be provided with whatevex electrical
elements (~e.g. probe, loop, central conductor or s~mple
closure) are required for the sections of the multisection
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device.
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~ Although the modules may be constructed where the
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male members 20 at the free edges of one module are spaced to
-~ confonm to the spacing of the female members (grooves 16 ~-
~ deined by extents 18 and 19) so that they may be simply slid
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longitudinally there into. However it is preferred to shape
the extrusion so that the side walls 14 are slightly toed in
and hence male members 20 are more narrowly spaced relative to
the female members of the module to which the former are to
be attached. The 'toe in' of walls 14 is shown in Figure l.
To connect the male members 20 of one module into the female
members o~ another the male members are spread to obtain the
proper spacing before being slid longitudinally therealong.
The extrusion must therefore be designed to be sufficiently
-~e~ilient for bending of the side walls 16 about lines running
longitudinally therealong ~ufficient to allow the necessary
sp~reaa~ng of the male members. The result of "spreading" the
male member~ to enter the female members is that the fonmer -
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bea~ inw.~r(li.y nn the la~ter creating a better electrical
conrlectlon. The mDdular shape of Figure l is a single extrusion
as is th~ d ~lember of Figure 3. Such extrusions may
obviolsly be simply out to any length desired.
The embodiment of Figure 1 to 5 is designed to provide
any plurality of sections arranged in a line.
A multi-section device comprising four modular sections
is shown in perspective in Figure 4. The end module which
would otherwise define only three side walls of a cavity
resonance device is closed by an end member 26 of the type
shown in Figure 3. The four section multi^section device?is
closed at each end by end caps 28 held in place by screws 30.
The screws 30 clamp the extensions 20 against the groove de-
fining members 19 as best indicated in Figure 5. Since there
~ are no male members 20 in the grooves 16 in the section at
- the left of Figure 4 compressible fillers 32 will be used if
- the screws 30 are to be the same size as the others. It may
also be necessary to slightly off set the end holes for screws
; 30 since these will be concentric with their grooves 16 while
the others will not. Ang necessary apertures or connections
through the common walls between the sections (i.e. walls 12)
are made and any connecting equipment is installed before the
individual modules are assembled to each other. The end cap
may be provided with whatever equipment e.g. probes, loops,
central conductors etc are required for the particular sections.
These are not shown as they are conventional and well known
4 to those skille~ in the art as are the criteria for their design
and performance.
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The en-l~o~ilr~nt of Figure 6 sl-ows a module 38 de~igned
not only to pro~?ide e:lt~ t:U end multisections as shown iLI Figure
6, but also al~ows t~e assembly of multi-section cavity resonance
devices with its U-shaped members arranged in differing orienta-
tions .
- In Figure 6 a rectangular U-shaped extrusion is
shown. In this embodiment circular grooves 40 whose inner
defining surface encompasses about 270 of a complete circle
axe located, nol: only at each end of the cross bar or end
~- 10 wall 44 of the U but also at the free edges of the "uprights"
of the U o~ side walls 42. The gap in the shaped poxtions
de~ining the circular grooves is at substantially 45 to the
side walls 42 and end wall 44 of the module (when the side
walls 42 are biased to be perpendicular to the end walls). As
in the embod~ment of Figure 1 to 5 the shaped portions defining
the circular grooves are arranged so that they do not interrupt
;i the outer contour of the side walls 42.
At the free edges of the side walls 42 the inner
lip 46 of the shaped portion defining inner exeent is provi~ `
20 with a lip 48 extending to curve (oppositely from the lip
curvature) over the ends of the lips defining portions of circular
grooves 40 and to provide an extent which will rest against the - -
corresponding surface defining the circular groove of another
similar module. It will be noted that the two lips 48 or male
members may be inserted into pairs of grooves 40 or ~emale members
with the modules in the same orientation in the same manner as
in the embodiment of Figures 1-5 with (and using an fitting end
r~ember not shown but analogous to that of FLgure 3~. However it
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wili also i:)e ~ d th~t the male meMbers 48 on one m~ldule
may be inser.ed in th~ female members at each edge of a side
wall 42 oL ane~!ler module so that the side wall 42 of the
second module forms the fourth wall of the first module, and
the modules are relatively oriented at 90 to each o~her. Thus
an I. shaped arrangement of three or more modules may be
provided with an end plate on the open end of one of the modules,
or four modules may be arranged in a square as shown in
Figure 7. Modules are again connected bg longitudinal sliding 10 of the male members of one module into the female members of
another.
With the embodiment of Figures 6 and ~ it is
still considered advantages to have the side walls 22
resllient and slightly toed in (as shown in Figure 6~ to be
biassed outwardly to fit in to the female members for good
electrical connection.
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Again the module 38 is a single extrusion.
Also as with the embodiment of Figures 1-5 the
second embodiment does not have to define circul~ contours
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~t~ 20 and circular male members to conform thereto. It is necessary
~ that the inner surface of the female groove enconrass a
^~ sufficient part of a completed ring that when the male member
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is inserted therein the outward pressure of a screw will bear
in one direction on the male member clamping it on a portion
of the defining surface of a female member, while bearing on an
opposed female member defining surface to exert the clamping
pressure. Also if it i9 desired to have connected modules
oriented at 90 to one another than the female member must have
symmetry about a plane at 45 to the end and side walls 42 and
.
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'~ 44 of a mo~lc~ wh2r l)e end and side walls are mutually per-
pendI.cula~: .
~ re a mod~lle is sufficiently large in dimensions
perpendicu~ tO ~L~e iongitudinal direction, it mag be desirable
to have screws to hold down the end cap other than at the
corners. Provision for extra screws may be provided by the `
small grovves ~8 defined in the extrusion of Figure 6, such
grooves may also be provided in the embodiment of Figur~ l-S.
End caps may be applied to the embodiment of Figures
6 and 7 in a similar manner to the way they are applied to the
embodiment of Figures 1-5, The end caps will be pr~vided with
equipment conforming to the character of the sections to which
they are attached. Before assembly the side walls of the modules
may be provided with any needed connecting apertures, probes
or the like.
The male and female members described are the best
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~' way known to me of connecting the modules. However in its
- broadest aspect of the invention relates to a module for a
'~ cavity resonance device which is generally a rectangular or
square U-shaped metal extrusion of conducting metal with first
r~ shaped portions adjacent the free edges and at least one pair
second shaped portions respectively adjacent the opposite end
of the outside of a side or end wall shaped to receive the
first shaped portions when longitudinally slid thereinto. Thus
~3 the module allows the formation of multiple sections when the two
~3 first shaped portions of one module are slid longitudinally into
the second shaped portions of another module.
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