US3560898A - Coaxial reed relay - Google Patents

Abstract

THE RELAY INCLUDES TWO SEALED REED SWITCHES, FOR SELECTIVELY CONNECTING A RADIO ANTENNA TO A RECEIVER OR TO A TRANSMITTER. THE RECEIVER SWITCH, SINCE IT CARRIES MUCH LESS VOLTAGE IS THE SMALLER OF THE TWO AND IS DESIGNED TO MINIMIZE INTRODUCTION OF SIDE EFFECTS IN THE MINUTE SIGNALS THAT IT CARRIES. A PERMANENT MAGNET MAINTAINS THE RECEIVER SWITCH CLOSED. THE SWITCHES ARE INSIDE AN ELECTROMAGNETIC COIL, WHICH WHEN ENERGIZED CLOSES THE LARGER SWITCH, AND BY OPPOSING THE FLUX OF THE PERMANET MAGNET, CAUSES THE SMALLER SWITCH TO OPEN UNER ITS NATURAL BIAS. THIS ASSEMBLY IS MOUNTED IN A METALLIC GROUNDED HOUSING THAT TERMINATES THREE COAXIAL CABLES OR THEIR CONNECTORS.

Description

United States Patent Int. Cl. H01h 53/01 US. Cl. 335-- Claims ABSTRACT OF THE DISCLOSURE The relay includes two sealed reed switches, for selectively connecting a radio antenna to a receiver or to a transmitter. The receiver switch, since it carries much less voltage is the smaller of the two and is designed to minimize introduction of side effects in the minute signals that it carries. A permanent magnet maintains the receiver switch closed. The switches are inside an electromagnetic coil, which when energized closes the larger switch, and by opposing the flux of the permanent magnet, causes the smaller switch to open under its natural bias. This assembly is mounted in a metallic grounded housing that terminates three coaxial cables or their connectors.

This application is a continuation-in-part of my application Ser. No. 816,897, filed Apr. 17, 1969.

This invent-ion relates to relays for radio circuits of high frequency, up to and even in excess of 900 megacycles per second. It is particularly concerned with a relay for switching a radio antenna to a radio receiver or a radio transmitter selectively.

Separate coaxial cables extend from the relay to the antenna, the transmitter and the receiver. It is an object of this invention to provide a relay and cable connecting structure which will have a standing wave ratio as close to unity as is practical at the very high frequencies involved. It is a further object of this invention to produce such a cable connecting structure suitable for use with an automobile radio transmitter-receiver. A further object of this invention is to produce an economical switch having lower insertion losses and better cross talk characteristics.

It is a still further object of the present invention to provide a magnetic reed relay for switching high frequency circuits, oriented in a manner to maintain electrical characteristics conducive with minimum power losses and minimum impedance disturbances introduced thereby in the high frequency circuit to be switched. Two switches are mounted inside an electrically conducted shield in a manner to minimize radio frequency spray. These switches with their shield, are oriented inside a metal enclosure which provides further shielding (confinement) of radio frequencies and also provide mechanical support for electrical connections in the portion of the radio frequency circuits between the reed switches and the coaxial cables.

A transmitter switch and a receiver switch are provided for connecting a radio antenna to a radio transmitte'r or a radio receiver selectively, as in British patent specification 1,074,049. The receiver switch carries an exceedingly small amount of power at a small voltage and the transmitter switch carries a large amount of power at a high voltage. Because of the difference in requirements it is not necessary to use as expensive a switch for the receiver as is required for the transmitter. It is a further object of this invention to provide a relay comprising two switches set forth above, each sealed in its own capsule, and both operated by a single operating coil,

The attainment of the above and further objects of th1s invention will beapparent from the following specification taken in conjunction with the accompanying drawmg.

In the drawing:

FIG. 1 is a longitudinal sectional view through a relay of the present invention, with parts shown in elevation;

FIG. 2 is a sectional view taken along the line of 22 of FIG. 1 with parts in elevation;

FIG. 3 is a sectional view taken along the line 3-3 of FIG. 1; and

FIG. 4 is an enlargement of a part of FIG. 2.

Reference may now be had more particularly to the drawing wherein like reference numerals designate like parts.

At 1 there is indicated a coaxial cable relay and connector for switching a radio antenna to a transmitter or to a receiver selectively. The connector comprises a housing that includes a cast metal body 2 having a longitudinally extending cavity 3 closed by a cover 4 that is bolted or otherwise secured in place as by bolts 4'. The body 2 has holes 5 extending theretbrough, which do not open into the cavity 3, and are in alignment with corresponding holes in the cover 4 for receiving mounting bolts for mounting the unit 1. The cavity 3 has three aligned chambers, namely a longitudinally extending central relay receiving chamber 6 which opens at the opposite ends into a first connector chamber 7 and a second connector chamber 8. Identical coaxial cable terminations 11, 11a and 11b secure corresponding coaxial cables to the housing. The cables connect, respectively, to an antenna, a radio receiver, and a radio transmitter. Each termination comprises a coaxial cable 12 having a central inner conductor 13 surrounded by a conducting shield 14 which is insulated from the inner conductor 13 by solid insulation 16. The cables may be those used on high frequency circuits, for instance up to and even exceeding 900 megacycles per second. The end of the shield 14 is turned back and clinched between a metal cable bushing 17 and a sleeve 18 that is cast as an integral part with the body 2 of the housing, thereby to establish electrical connections between the shield 14 and the housing. A lead bushing 19 and a lead washer 21 surround the insulation 16, the washer 21 pressing against the shield 14. The center cable conductor 13 projects through a mounting terminal arrangement in the housing wall, and into the chamber 7. The mounting termination arrangement comprises an outer ring 22 threaded into the wall of the body 2 and separated from an inner conducive tube 23 by a dielectric ring 26 of glass or the like compressed between the two. The top of the tube 23 is cut away for about half the length thereof and constitutes a conducive termination for the cable conductor 13. It is the means for establishing substantially in-line electrical connections to the coaxial cable conductor 13, which is electrically and mechanically secured to the tube 23.

Within the central chamber 6, there is mounted a relay 30. The relay comprises two separately sealed dry reed type switches 31 and 32 surrounded by a shield 35 which in turn is surrounded by an actuating electro-magnetic coil 33 on a bobbin 34. The shield may be of any desired non-magnetic material that is or has been rendered electrically conducting. In the present instance it comprises an oval shaped non-magnetic metal tube that closely surrounds the switches. Between the shielding tube 35 and the interior bore of the bobbin is a permanent magnet 36. The shield 35 permits the magnetic flux of the magnet and any magnetic fiux of the coil 33 to pass freely therethrough. At its left and right hand ends the shield 35 is electrically connected to the metal body 2 in any desired manner as for instance by tack welding, soldering, compression or the like, indicated at 39 to maintain the potential of the tube the same as that of the body 2 which is that of the conducting shields 14 of the coaxial cables.

The reed switch 31 is the radio receiver switch in that it connects a radio receiver to the antenna. The switch 32 is the transmitter switch in that it connects the antenna to a radio transmitter. The switch 31 is much smaller than the switch 32 because the maximum power and voltage carried by it is much smaller than that carried by the switch '32. The switch 31 includes first and second cooperating contact members 41 and 42 respectively, sealed in a non-magnetic capsule, in this instance of glass. The switch 32 includes contact members 41' and 42 also sealed in a glass capsule. The members 41-42 and 41' and 42 are made of an alloy of about 52% nickel and the rest iron, which is magnetic. Within the capsules the ends of the respective contact members that make contact with one another may be of a rhodium silver alloy. In each switch the longer one of the two members (42 and 42' respectively) is a reed that is mechanically biased to its switch open position and is flexible for movement to its closed position by the action of suflicient magnetic flux penetrating the glass capsule. In the case of the switch 31 the magnet 36 biases the reed 42 to a position where it makes contact with the contact 41 as illustrated in FIG. 1. The magnet is ineffective to actuate the switch 32. That switch remains in its normal switch open position as illustrated in FIG. 1.

The current carried by the transmitter switch 32 is very large in comparison to the minute current carried by the receiver switch 31. The contact members 41'-42' are copper clad. Since the current carried by this switch is at a high frequency the skin effect forces the current to flow almost entirely through the copper clad film. Because the switch 31 carries minute currents it is not necessary to copper clad its members 41-42.

The direction of the flow of direct current through the coil 33 when it is energized is such that in the region of the switch 31 the flux of the coil is in opposition to the flux of the magnet. As the magnetic flux of the coil builds up from zero, when the coil is energized, it progressively reduces the value of the permanent magnet flux penetrating the switch 31. The switch 31 opens when the resulting flux is insufficient to hold its contacts closed. As the flux produced by the coil builds up further, the switch 32 closes. The flux produced by the coil never reaches a value such that the resulting flux is sufficient to reclose the contacts of the switch 31. The switch 31 remains open so long as the coil remains energized. Upon deenergization of the coil the switch 42 opens. Also the magnet 36 again takes over and closes the contacts of the switch 32.

If desired the exterior surfaces of the capsules 31-32 may be coated with an electrically conducting material. The conducting shield or its equivalent maintains these coatings at the potential of the shields 14, thereby further enhancing the shielding of each of those two switches. The extensions of the contact members 4142 and 41- 42' that project out of the capsules are of sufficient stiffness to support the switches 31-32 even in the absence of the shield 35. Those from the switch 32 are copper clad, for skin effects as previously stated.

The relay of the present invention maintains a high impedance-match at the switching point, with low or no tendency for sustained standing waves whether the system is transmitting or receiving.

The cover 4 has two coil terminals 5050 to which the respective lead wires from the electro-magnetic coil 33 are connected for establishing circuit connections to the coil. The lead wires 51-51 are of an excess length so that they may be connected to the underside of the respective terminals 50-50 while the cover 4 is not secured to the body 2. When the cover is positioned in place, the excess lead wire length is in a pocket 54 that is separated from the chamber 7 by a wall 56 of the cast metal body 2.

I claim:

1. A coaxial cable connector and switch for high frequency coaxial circuits comprising a current conducting housing, a cover closing an opening into the cavity of the housing, coaxial terminators each of which is mounted on the housing, each terminator having an outer conductor grounded to the housing and inner conductor means projected into said cavity; a relay assembly comprising first switch unit and a second switch unit, each of which includes a sealed non-magnetic capsule containing first and second relatively movable cooperating contact members formed at least in part of magnetic material and at least one of which is biased to a first position and movable to the alternate position by the action of magnetic flux, one position being a switch closed position and the other an open position, a permanent magnet providing an effective field in the space occupied by the first switch unit to move its movable contact member to its alternate position and ineffective to operate the contact members of the second switch unit, and coil means for establishing a magnetic field in the region of both switches by which the movable contact member of the second switch units is operated to its alternate position, the arrangement being such that upon energization of the coil means the effect of the permanent magnet field upon the first unit is reduced and the movable contact member of the first contact unit returns to the mechanically biased position; said assembly being located within the cavity of the housing and the first and second switch units being connected within the housing to the inner conductor means of the terminators, and circuit connections for the coil means extending from the housing.

2. A relay as defined in claim 1 wherein each switch unit comprises a reed switch.

3. A relay as defined in claim 1 wherein said permanent magnet is outside of the capsule of the first switch unit.

4. A relay as defined in claim 1 wherein the first switch unit is between the permanent magnet and the second switch unit.

5. A relay as defined in claim 1 wherein a non-magnetic electrically conducting shield surrounds both switch units, and the coil means surrounds the shield.

6. A relay as defined in claim 1 wherein the switch units with their surrounding shield are mounted in a housing that is electrically connected to the shield.

7. A relay as defined in claim 1 wherein first, second, and third coaxial cables are connected to and extend electrical connections into the housing, each said cable having an inner conductor surrounded by but insulated from an outer shielding conductor, and wherein the first con tact member of each switch unit is connected to the inner conductor of the first coaxial cable and the two second contact members of the two switch units are connected respectively to the inner conductors of the second coaxial cable and the third coaxial cable, and the shield around the switch units is electrically connected to the shielding conductor on at least one of the coaxial cables.

8. A relay as defined in claim 7 wherein the three coaxial cables are adapted to be connected respectively to a radio antenna, a radio receiver and a radio transmitter, and wherein the first switch unit is physically smaller than the second unit.

9. A relay as defined in claim 7 wherein the three coaxial cables are adapted to be connected respectively to a radio antenna, a radio receiver ad a radio transmitter, and wherein one of the switches connects the receiver to the antenna and the other switch connects the transmitter to the antenna, the transmitter switch being of substantially higher current carrying capacity than is the receiver switch.

10. A coaxial cable connector and switch comprising an electrically conductive housing including a body having a longitudinally extending cavity, first, second and third coaxial cable terminations each including an inner conductor surrounded by a conductive shield insulated therefrom, each termination conductor extending into the housing but insulated therefrom, means for establishing an electrical connection between said housing and the shielding conductors, a cover closing an opening into the cavity, the terminations being secured to the housing independently of the cover, a relay assembly within the housing including two reed switches for extending electrical connections from the inner conductor of the first termination selectively to the inner conductors of the other terminations, each switch comprising a sealed capsule having a longitudinally extending electrically conducting switching reed on the inside thereof, each said reed of the respective switches having a magnetic flux-responsive portion on the inside of the capsule, each reed being mechanically biased to a certain position and being movable to another position by magnetic flux penetrating its capsule, and a single energizing magnetizing coil within the body cavity for producing a magnetic field penetrating the capsules to move each reed of both capsules from one position to its alternate position.

References Cited UNITED STATES PATENTS 2,897,313 7/ 1959 Burgess 335-5 3,202,784 8/1965 Santangeli 3355 3,264,425 8/ 1966 Hosokawa 335153 3,320,559 5/1967 Morrison 335-151 3,439,303 4/1969 Purzycki 335-154 HAROLD BROOME, Primary Examiner

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