FR2546670A1 - Transmission line element for microwave frequencies including one or more incorporated switching units with a view to inserting one or more quadripoles - Google Patents

Abstract

Coaxial switch for microwave frequencies making it possible to insert a quadripole A and whose central conductor comprises two fixed segments 1-3 joined by a movable segment 2 controlled by a switching unit 50. The elastic ends 100-300 of the fixed segments become applied to the contacts 6-7 of the quadripole when they are freed from the movable segment 2, the latter being applied to the earth conductor. Application to the production of variable attenuators.

Description

1 -

  TRANSMISSION LINE ELEMENT FOR MICROWAVE

  HAVING ONE OR MORE INCORPORATED SWITCHING ORGANS

  FOR THE INSERTION OF ONE OR MORE QUADRIPOLES.

  It is often necessary to interpose in a common way

  table, in a microwave transmission line,

  one or more quadrips 8 intended to modify the trans-

mission.

  A particularly interesting application of the invention

  tion concerns the realization of a variable attenuator com-

  carrying several cells of scaled values In other applications, amplifiers, filters or 1.0 frequency changing devices must be

  interchangeably switchable in the line.

  This problem is usually solved by means of switching devices called "coaxial switches", although

  the line element which constitutes them is not necessary

  These switches generally have the disadvantage of using two mobile line segments, which ensure, depending on their position, a transmission

  direct or transmission through the inter-quadrupole

stall.

  They introduce a high insertion loss and have a relatively poor isolation between the two transmission paths. -2- In general, they have a high cost -and a

  notable consumption of electrical energy.

  American patent 3319194 describes a variable attenuator whose switching member is of the aforementioned type, with the particularity that its realization is obtained by means of a

  microstrip line, the central conductor of which forms,

  valleys, two parallel tracks, one of which is transmission

  direct, the other transmission with attenuation, the commu-

  tation between the two channels by means of a segment

  flexible conductor movable from one track to another.

  This embodiment ensures good impedance continuity and low insertion loss, but has the drawback of having a parasitic passageway across the terminals of

  each attenuation cell when this is switched.

  Another disadvantage is that, the contacts being cut for a relatively long time during switching, a significant intermediate attenuation is then obtained,

  which is undesirable for some applications.

  The present invention relates to a switchable transmission line element achievable with the technique of microstrip lines, but free from the disadvantages exposed

  above and particularly economical.

  The transmission line element according to the invention

  includes at least one ground conductor; another conduc-

  naked tor placed near the parallel earth conductor

  Lement thereto, said other conductor having two fixed segments connected by a movable segment; and means for moving the movable segment to bring it from a first position where it connects the fixed segments to a second position in which it allows the connection of the

  fixed segments with conductive or insulating terminations

  tes and is mainly characterized in that said terminations are fixed and positioned so that their respective ends are located opposite -3-

  of a determined surface area of the respective ends

  tives of the fixed segments and that, in the first position, the movable segment comes into contact with said face, while, in the second position, the movable segment is released from the fixed segments and said ends of the segments

  fixed, released by this release, came by deformation-

  elastic tion in contact with said terminations.

  The various features, as well as the advantages of

  the invention will become clear in the light of the

below.

In the attached drawing

  FIG. 1 is a view, in longitudinal section through

  of a common transmission line element

  table according to an embodiment of the invention, shown in the direct passage position;

  Figure 2 shows the element of Figure 1 in posi-

switched tion;

  FIG. 3 is a view in cross section through

  of a switched transmission line element

  ble identical or similar to that of Figures 1 and 2;

  FIG. 4 represents a line element with switching

  multiple positions FIGS. 5 and 6 represent respectively in perspective and views from above, a preferred embodiment of a switching assembly intended to be incorporated in such a line element; and Figure 7 shows a switchable line element

fitted with two coaxial sockets.

  4 - In FIGS. 1 and 2, an air triplate line element has been represented, comprising two ground planes 4 and 8 and

  three conductive segments 1-2-3 forming the intermediate plate

  diaire The segments 1 and 3, fixed to the ground plane 4 by dielectric blocks 101-301, are elastic and their respective ends 100-300 are advantageously pre-bent downward The segment 2 is integral with an insulating rod

  which passes through a guide orifice 80 formed in the conduc-

  tor 8 and whose displacement, in a direction perpendicular

  ring to the plans of the line conductors, is controlled by means, known per se, symbolized by a solenoid It is understood that these means can be of a

  any suitable type, manual, mechanical or electro-

mechanical -

  In the position of FIG. 1, the segment 2 is in contact with the lower faces of the ends 100 and 300, which are bent upwards and out of the contact of two contacts 6 and 7 of a quadrupole A The contacts 6 and 7 are themselves introduced, perpendicular to the planes of the conductors of the line, in orifices 40-41 formed in the conductor 4 and placed in a fixed and precise manner relative to the line In the position of Figure 2, the rod 5 having been moved so as to bring the movable segment 2 into contact with the conductor 4, the ends and 300, being freed, come, thanks to their

  elasticity, apply to the ends of the res-

  pective 6 and 7 It is clear that the position of the quadrupole and the orientation of the contacts could vary: for example the quadripole could be placed between the central conductor and the ground conductor, the contacts

  then being inside the structure.

  It is clear that in FIG. 1, the quadrupole A is not connected to the line, a direct transfer of the wave in TEM mode then taking place along the line, which does not have

  no significant discontinuity and has the characteristic impedance

  desired téristique The geometrical arrangement and the dimensions of the elements are determined by a person skilled in the art to obtain the desired characteristics and so that the cut-off frequency of the guide constituted by the conductors

  plans 4 and 8 is clearly greater than the range of

  quences to transmit. In the position of figure 2, the quadrupole A is inserted in the line: it will be for example an attenuator,

  an amplifier, a filter, a changing device

  frequency, or other Note that line segment 2 cannot ensure any spurious transmission, from

  made of its close contact with the ground plane 4.

  When the rod 5 is maneuvered to put the quadrupole out of service, it is clear that the contact between the ends 100-300 and the respective contacts 6 and 7 is not removed until after the segment 2 has come to remove the said ends of said contacts In the reverse operation, the contact between said ends and said contacts takes place before the segment 2 has itself lost contact with said ends.

  no gap in the transmission when switching.

  The displacement of segment 2 is also small

study, of the order of mm for example.

  Figure 3 shows, in cross section, an execution mode

  practical part of the device: ground conductors 4 and

  8 are here connected by side walls 9-10 which are

  run along to form a receptacle suitable for the quadri-

  pole A This is, for example, a holding cell

  nuation of the hybrid circuit type, which is positioned in the receptacle by means of two shoulders 92-102 formed by the extensions of the walls 9-10 The ground contacts of this cell come to connect to the ground of the line

of transmission.

  It will be noted that, as a variant (FIG. 7), the quadrupole A could be connected to the line by means of coaxial sockets, the central conductors 601-701 of which would constitute the contacts 6 and 7. This solution makes it possible, for example, to insert

  a frequency change device in the line.

  In Figure 4, there is shown a transmission line which is incorporated several switching members of the

  type described above The first a constitutes an interrup-

  protective guard: when the ends of the conductive sections 103303 are released by the movable segment 203

  corresponding, they come to rest on isolating stops

  tes 63-73 Alternatively, the stop 63 could be replaced by a contact connected to a load capable of dissipating

the power re-injected.

  We have symbolized by a rectangle 51 an electronic organ of

  cut-off control; this organ will cause displacement

  cement of the rod 53 to cut the transmission in the event of

  detection of accidental power feedback.

  The second and third switching elements b and c per-

  for example activate or deactivate cells

  attenuation, to constitute an attenuator for hyper-

  frequencies In the positions shown, cell b is in

  service, cell c out of service.

  In Figures 5 and 6, there is shown a movable segment 204

  provided at each end with a notch, advantageously semi

  circular, through which the fixed contacts 604 and 704 pass. The engagement of these fixed contacts with the blades 104 and 304 takes place practically at the edge of said blades, as the

  shows figure 6: this avoids creating disconti-

  overnight stays in the line; which would increase the wave rate

  stationary in direct transmission.

  It will be noted that in the devices described, the contact is always made, whether one is in one position or the other, on the same face of the elastic segments 1-3; 104-304, which significantly reduces the discontinuities that occur

at the time of switching.

-7-

  It goes without saying that the invention is not limited to the provisions

  tions described and represented It will be noted that a line element comprising a switching member, such as that of FIG. 7, could be provided with a coaxial input and output allowing its connection to coaxial transmission lines The device thus produced will fulfill the role of the classic "transfer relay" while having a number of advantages over it:

  direct passage position, no short circuit of the quadri-

  pole; reduced number of successive contacts in a report

  of them; one moving element instead of four.

Claims (11)

Patent claims   1 Transmission line element for microwave   quences comprising at least one ground conductor (4); another bare conductor (1-2-3) arranged near the ground conductor parallel to the latter, said other conductor comprising two fixed segments (1-3) connected by a movable segment (2); and means (5-50) of moving the movable segment to bring it from a first position where it connects the fixed segments to a second position in which it allows the connection of the fixed segments with conductive or insulating terminations, characterized in what said terminations (6-7) are   fixed and positioned so that their ends respect   tives are located opposite a determined surface portion of the respective ends (100-200) * of the fixed segments and that, in the first position, the movable segment (2) comes into contact with said face, while, in the second position, the movable segment is released from the fixed segments (1-3) and said ends of the segments   fixed, released by this release, came by deformation-   elastic tion in contact with said terminations.   2 Transmission line element as claimed   cation 1, characterized in that, in the second position, the segment   mobile (2) is in contact with the ground conductor (4).   3 Transmission line element as claimed   cation 1 or 2, characterized in that said fixed (1-3) and mobile segments   (2) -are flexible conductive strips.   4 Transmission line element according to one of claims 1 to 3,   characterized in that said terminations are external contacts (6-7, figure 1) which penetrate through the ground conductor (4) substantially perpendicularly to this one. 25466 Y O   -9 _ Transmission line element according to claim 1, characterized in that said terminations are insulating stops (63-73, FIG. 4) and that the means (53) for moving the movable segment are controlled by a device   (51) detection of an overload in the line.   6 Transmission line element as claimed   cation 3, characterized in that the blade (204) which constitutes the movable segment has at its ends notches or cutouts through which the terminations (604-704) pass, the ends of which end in the immediate vicinity of the respective extreme edges of the blades ( 104-304) which constitute the mobile contacts.   7 Transmission line element according to one of claims 1 to 6,   characterized by a second ground conductor (8) present   both a geometrical configuration suitable for maintaining   the impedance of the constant line in the two said positions tions.   8 Transmission line element as claimed   cations 1 or 4 and 7, characterized in that the two ground conductors (4, 8) are connected by side walls (9-10) extended by   legs shaped to constitute a receptacle for posi-   operation of a quadrip 6 the (A) which will be provided with said external contacts (92-102).   9 Transmission line element as claimed   cation 8, characterized in that it comprises a plurality of assemblies (FIG. 4) each comprising two fixed segments and an intermediate mobile segment, the quadrupole associated with each   of these sets being an attenuation cell. -   Transmission line element as claimed   cation 1 or 4, characterized in that said external conductors consist of the central conductors (60 A 70 A) of coaxial parts engaged in orifices provided in the ground conductor.   11 transmission line element according to claim 10, characterized by a coaxial input and output linked to the fixed conductors, allowing it to play the role of a transfer relay.   12 Transmission line element as claimed   cation 1, characterized in that one of the terminations is an insulating stop, the other a contact, linked to a load and that the means (53) for moving the movable segment are controlled by a device (51) for detecting 'an overload in the line.