US3038132A - Signal processing arrangement - Google Patents

Description

June 5, 1962 c. E. c. ROMIGUIERE 3,038,132

SIGNAL PROCESSING ARRANGEMENT TRANSMITTER TRAN/SMITTER M x EECE/ TRANSMITTER ll I TRANSMITTER l I ANTENNA 23 2o TO|2OFFlG.2

FROM ANTENNA A OF FIG.2

TO M OF FIGZ INVENTOR:

6, CLAUDE E.G. ROMIGUIERE, I FROM TRANSMITTER z M 4 b E OF H52 BY HIS ATTORNEY.

- TO RECEIVER R OFFIGZ United States Patent 3,038,132 SIGNAL PROCESSING ARRANGEMENT Claude Emile Georges Romiguiere, Paris, France, assign or to Compagnie Frangaise Thomson-Houston, Paris,

The present invention concerns improvements to the vane duplexer, also 'known as a shutter duplexer. Its basic advantage lies in the more efiicient protection of the receiver.

The vane duplexer possesses the advantage over similar previously known devices such as those containing resonant gas cells (known as TR tubes) of being usable at very high transmission powers, i.e., of megawatt power without reduction in performance or destruction. Howeverq, the use of this better duplexer is limited by the fact that the power, which reaches the receiver in stationary transmission operations, called leakage-power is dangerous for the receiver, particularly for its detection crystal.

From the viewpoint of protection of the receiver, the most efficient duplexer has hitherto been the twin TR tube type, more commonly known as the double TR duplexer. FIG. 1 shows its working principle. It consists of two 3 db directional couplers 1 and 2 and two TR tubes 3 and 4. The power P from a source of electromagnetic waves such as a transmitter E is divided by the coupler 1 into two equalparts, P1 and P2 which are reflected into the fired tubes 3 and 4. The two reflected powerstreams P3 and P4 travel towards a first load circuit, such as an antenna A, the streams P5 and P6 entering the transmitter line cancelling one another. The leakage-power fiows P7 and P8 are conveyed, at the coupler 2 output, by reason of the geometry of the system, to a second load circuit such as a power absorption resistance 5. The power-flows entering the line towards a third load circuit, such as a receiver R cancel themselves almost entirely. It is this shunting of the leakage-powers which explains the excellent protection of the receiver which the duplexer can achieve. Unfortunately, this duplexer is not suitable for use at the high powers which can be tolerated by the vane duplexer. The attempt has, therefore, been made to discover devices which incorporate the efficiency of the vane duplexer.

The efiiciency of the vane duplexer could be improved by connecting it to a receiver through a TR tube of known type which fires under the action of the leakage-power of the vane duplexer. The final leakage-power in such a case does not exceed the level to be found in mediumpower transmitter-receiver units equipped with TR tubes only. However, this solution is not always satisfactory since the specific leakageapower of the live TR tube may still be dangerous for the receiver.

Another solution would be to couple in series a TR tube and a vane duplexer. by the association of two single vane duplexers and can tolerate twice the power of a single duplexer. Moreover, it protects the receiver more efiiciently since it incorporates a system of leakage-power shunting similar to that of the twin-TR tube duplexer. But, by asso This duplexer is obtained ciating a duplexer of this model with a TR tube, the protection of the receiver is not necessarily increased. Two possibilities may arise: Either the TR tube may fire under the action of the duplexer leakage-power and deliver its specific leakage power, which is fairly high, to the receiver, or the vane duplexer leakage-power may be too low to fire the TR tube, while still being dangerous to the receiver.

The subject of the present invention is a duplexer which affords highly effective protection to the receiver without any of the disadvantages mentioned above. The new device is obtained by introducing a TR tube into each of two guides located between a 3 db directional coupler and two all-pass couplers. It may also be regarded as resulting from the combination of a duplexer first arrangement and of a second arrangement involving a double TR tube duplexer. This combination is not simply a matter of mere series connection, but results from suitable coupling of the two duplexers in such a way that the two leakagepower fluxes from the double vane duplexer are conveyed to the two TR tubes. The latter thereupon fires correctly, since contrary to the series coupling of the double vane duplexer and a TR tube there is no splitting of the leakage-power between the vane duplexer and the TR tubes. Finally, the new duplexer is a compact and relatively simple structure.

Briefly, in accordance with one embodiment of my invention there is provided a combination of first, second, third and fourth waveguides, a source of electromagnetic waves, a first, second, third, fourth, fifth, sixth and seventh load circuits, wherein said third circuit comprises an antenna, said fourth circuit comprises a wave receiver, and said second, fifth, sixth and seventh circuits comprise wave absorbing resistances, a first, second and third 3 db directional couplers, and a first and second TR device, and a first and second directional couplers. Said couplers comprise an ionizable medium which is normally non-ionized. Said source is coupled to one end of said first guide, said first load circuit coupled to the other end of said first guide, and said second and third circuits are coupled to respective ends of said second guide. Said first and second 3 db couplers couple said first and second guides through common waveguide wall connections at respective spaced-apart first and second points along said first and second guides. Said fourth and fifth circuits are coupled to respective ends of said third guide and said sixth and seventh circuits are coupled to respective ends of said fourth guide. Said first and second 100% directional couplers couple said first and third guides and said second and fourth guides, respectively, through common waveguide wall connections at respective third and fourth points located between said first and second points. Said TR devices are mounted within respective ones of said third and fourth guides and positioned between said fourth circuit and said first 100% directional coupler and between said sixth circuit and said second 100% directional coupler respectively. Said third 3 db coupler couples said third and fourth guides through a common waveguide wall connection at a point between said TR devices and said fourth and sixth circuits. In order to propagate waves from said source to said third circuit through said first and second 3 db couplers, said first and second 100% directional couplers are made responsive to the intensity of waves above a predetermined level received from said source by way of propagation through said first and second waveguides and said first 3 db coupler for becoming ionized such that a negligible amount of such waves can reach the fourth circuit. In order to propagate Waves from said third circuit to said fourth circuit, said first and second 100% directional couplers are adapted to be nonionized for coupling said last-named waves through said TR devices, said third and fourth waveguides and said third 3 db coupler to said fourth circuit.

While the novel and distinctive features of the invention are particularly pointed out in the appended claims, a more expository treatment of the invention, in principle and in detail, together with additional objects and advantages thereof, is afforded by the following description and accompanying drawings in which:

FIG, 1 shows a prior art twin TR tube type duplexer;

FIG. 2 shows the basic diagram of the duplexer;

FIG. 3 shows the distribution of the power flux during transmission of electromagnetic waves;

FIG. 4 is the diagram of power distribution when receiving electromagnetic Waves; and

FIG. 5 is a further embodiment of the present invention.

Referring to FIG. 2, it will be seen that the duplexer consists of four guides 6, 7, 8 and 9. Guides 6 and 7 are connected respectively to the transmitter E and the antenna A and terminates in matched resistances 1t and 11. Guide 8 is connected to the receiver R and also terminates at matched resistance 12. Guide 9 likewise terminates at the two matched resistances 13 and 14. TR tubes 15 and 16 are inserted in guides 8 and 9.

Coupling between the guides is efiected as follows: Two 3 db directional couplers 17 and 18 couple guide 6 with guide 7; all-pass directional couplers '19 and 20 located in guides 6 and 7 between couplers 17 and 18 couple guide 6 with guide 8 on one hand and guide 7 with guide 9 on the other. In the slots of the all-pass couplers an ionizable medium in the form of a series of gas tubes 21 and 22 is located. Finally, the 3 db directional coupler couples guide 8 with guide 9 at a place separated from couplers 19 and 20 by tubes 15 and 16.

On stationary transmission operation during the flat stretch of the transmitted pulse when all the gas tubes 15, 16, 21, 22 are live, the transmission power, the path of which is shown by the dotted line 24, is divided by the coupler 17 into two fluxes 25 and 26 as shown in FIG. 3. The latter, reduced by leakage-power and losses occurring at the level of couplers 19 and 20 are both conveyed by coupler 18 towards the antenna A. Fluxes 27 and 28 conveyed towards resistance 10 cancel each other out almost entirely. The leakage-power, entering by 19 and 20 in guides 8 and 9, are for the most part (fluxes 29 and 30) absorbed directly by resistances 12 and 14. The residual power fluxes (31 and 32) travel towards the TR tubes 15 and 16 where they are for the most part (fluxes 33 and 34) reflected towards resistances 12 and 14. Consequently, the TR tubes 15 and 16 are traversed by very low fluxes 35 and 36 which on account of their phase relation are conveyed by coupler 23 toward resistance 13, fluxes 37 and 38 conveyed towards resistance 13 virtually cancelling each other.

On stationary receiving operation, where no gas tube is live, the power from antenna A is divided by coupler 18 into two fluxes 40 and 41 as shown in FIG. 4. The latter almost entirely enter the guides 8 and 9 respectively, pass through TR tubes 15 and 16 and are conveyed by coupler 23 almost in their entirety towards the receiver R.

FIG. 2 represents a particular arrangement in which the guide axes are all in the same plane. Other arrangements are possible with a different geometry from FIG. 2 without departing from the spirit of the invention.

FIG. 5 shows a partly cut-away perspective view of such a duplexer, the structure of which consists of four guides assembled in pairs, either narrow side to narrow side or broad side to broad side. The coupling slots of the 3 db duplexers 17, 18, 23 are cut into the broader sides while the through couplers 19 and 20 which are equipped with gas tubes are located along the narrow sides. In the structure at FIG. 5, guides 6 and 7 have the broader sidewalls in common, likewise guides 8 and 9, while guides 6 and 8 together with guides 7 and 9 have their narrow sidewalls in common. This structure also makes possible simplification of construction and maintenance. The apertures of all- pass couplers 19 and 20 can be arranged one beside the other, which then enables only one set of gas tubes 42 to be used for these two apertures.

While the principles of the invention have now been made clear, there will be immediately obvious to those skilled in the art many modifications in structure, arrangement, proportions, the elements and components used in the practice of the invention, and otherwise, which are particularly adapted for specific environments and operating requirements without departing from those principles. The appended claims are therefore intended to cover and embrace any such modifications within the limits of the true spirit and scope of the invention.

What I claim and desire to secure by Letters Patent of the United States is:

1. A duplexer comprising first, second, third and fourth rectangular waveguides, a source of electromagnetic waves coupled to one end and a first wave absorbing means coupled to the other end of said first guide, a receiver coupled to one end and a second wave absorbing means coupled to the other end of said second guide, an antenna coupled to one end and a third wave absorbing means coupled to the other end of said fourth guide, fourth and fifth wave absorbing means coupled, respectively, to opposing ends of said third guide, said first and second guide being contiguous and having a first common wall portion, said third and fourth guide being contiguous and having a second common wall portion, said first common wall portion including a first long slot directional coupler, said second common wall portion including a second long slot 100% directional coupler, said first and second directional coupler each comprising a plurality of ionizable gas tubes oriented in the plane of the wall portion and extending transversely to the longitudinal axis of the guide, a first and a second 3 db coupler coupling said first and fourth guides on opposite sides of said directional coupler, respectively, said second and third guides being contiguous and having a third common wall portion, a third 3 db directional coupler located in said third common wall portion at a point in said second waveguide intermediate said end coupled to the receiver and the directional coupler, a first TR tube in said second guide and a second TR tube in said third guide, each of said TR tubes located at a point along the longitudinal guide axis intermediate said third 3 db coupler and said directional couplers.

2. A duplexer comprising first, second, third and fourth rectangular waveguides, a source of electromagnetic waves coupled to one end and a first Wave absorbing means coupled to the other end of said first guide, a receiver coupled to one end and a second wave absorbing means coupled to the other end of said second guide, an antenna coupled to one end and a third wave absorbing means coupled to the other end of said fourth guide, fourth and fifth wave absorbing means coupled, respectively, to opposing ends of said third guides, respectively, said first and second guide being contiguous and having a first common narrow wall portion, said third and fourth guide being contiguous and having a second common narrow wall portion, said first common narrow wall portion including a first long slot 100% directional coupler, said second narrow common wall portion including a second long slot 100% directional coupler, said first and second directional coupler each comprising a plurality of ionizable gas tubes oriented in the plane of the wall portion and extending transversely to the longitudinal axis of the coupled to the receiver and the directional coupler, a first 10 2,945,194

TR tube in said second guide and a second TR tube in said third guide, each of said TR tubes located at a point along the longitudinal guide axis intermediate said third 3 db coupler and said directional couplers.

References Cited in the file of this patent UNITED STATES PATENTS Sanner Oct. 20, 1959 Reverdin July 12, 1960

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