US2903655A - Transmit-receive device - Google Patents

Description

Sept. 8, 1959 H. c. ALEXANDER f 2,903,655

TRANSMIT-RECEIVE DEVICE Filed March l, 1957 :24 new l l@ d 4A` Y 777 'F`\G.4 Tlc. 2. anni, ,yan

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HERBERT C. ALEXANDER United States Patent O TRANsMrr-RECEIVE DEVICE Herbert C. Alexander, Peabody, Mass., assigner to Bolnac Laboratories Inc., Beverly, Mass., a corporation of Massachusetts Application March 1, 1957, Serial No. 643,390

4 Claims. (Cl. 3133-113) The present invention relates to gaseous discharge switching devices and more particularly to transmitreceive devices employed in microwave frequency radar systems.

The transmit-receive tube or TR as it is commonly referred to in the art comprises a metallic waveguide envelope containing an ionizable atmosphere and a plurality of resonant elements to facilitate both a high power gaseous discharge and low power transmission of microwave signals to the receiver apparatus. Amongst such resonant elements commonly employed are the input 'window with a dielectric covered aperture, paired metallic inductive iris members and capacitive discharge gap electrodes. Recent developments in the art have resulted in multiple-aperture input windows to minimize the heat transfer problem incident on such elements when the intense gaseous discharge occurs. Such structure will `also lower the Q factor of the window to thereby increase the operating bandwidth of the device.

The present invention has for its primary object the provision of a novel capacitive and inductive resonant structure to be incorporated with multiple-aperture input Iwindow structures yto result in a TR device having an overall lower Q factor than prior :art devices.

Another object of the invention is to provide a novel multiple-iris resonant member with discharge gap electrode members for each iris opening in a unitary structure.

Briefly the objects enumerated are achieved by improved flat metallic plate members disposed within a hollow waveguide envelope having the multiple-aperture resonant window members hermetically sealed at the ends thereof. Each plate member comprises a plurality of transverse iris `openings to match the resonant window structure. Conical-tipped members are introduced through opposite sides of the plate member and extend into the openings. A double ended conical-tipped member is supported by the metallic section between the openings with a portion of each tip extending into the opening to thus define with the first members a plurality of resonant discharge gaps in parallel. The resultant structure provides adequate voltage step-up for the radio frequency discharge and is a very low Q structure compared to prototype single iris structure.

Other objects, features and advantages will be evident after consideration of the following detailed speciiication together with the appended drawings in which:

Fig. 1 is a detailed cross-sectional view of the illustrative embodiment;

Fig. 2 is a view partly in section along the line 2-2 in Fig. 1;

Fig. 3 is a perspective view of another embodiment; and

Fig. 4 is a detailed cross-section view `along the line 4-4 in Fig. 3.

Referring now to Figs. 1 and 2 the embodiment shown comprises a section of rectangular hollow pipe waveguide 1 having hermetically sealed `at lthe ends thereof a resonant window element 2 and 3 having a plurality of transverse apertures enclosed by dielectric members 4 and 5 and separated by a metallic portion 6 of the overall window frame. These resonant window elements may be fabricated in accordance with the teachings of U.S. Patent 2,748,351, issued May 29, 1956, and are not claimed as a part of the present disclosure. Flanges 7 and 8 secured to waveguide 1 provide means for securing the device to -other waveguide structure.

In accordance with the teachings of the present invention, I provide a plurality of flat metallic plate members 9 and 10 within the waveguide 1 spaced apart the conventional quarter-wavelength distance. Plates 9 and 10 are provided with a plurality of transverse resonant iris openings 11, 12, and 13, 14 in alignment with the resonant window apertures. With this structure, there is presented in the path of electromagnetic waves propagated through the system two half-height waveguide structures which provide ya substantially lower Q than conventional single iris structure.

Within each plate iris opening I provide the capacitive component of the resonant discharge gap circuit by means of pointed members supported within the plate member. In Fig. 2 wherein plate member 9 is illustrated there is shown a threaded conical-tipped member 15 and 16 introduced through each broad wall of the plate. A double-conical tipped member 17 is supported by the metallic wall portion 18 between the openings with the conical ends 19 and 29 cooperating with threaded members `15 yand 16 to define two resonant gaps 21 yand 22. Adjustment of members 15 and 16 permits tuning of the gaps to the desired resonant frequency. The resultant discharge gaps will be in parallel each within half-height waveguide. This eectively lowers the Q of the resonant circuit while still maintaining an adequate voltage stepup gradient in each gap.

Plate member 10 provides a similar structure, however, the upper threaded member 23 may be hollow to provide for an ignitor electrode 24 to be introduced therein. The tip 25 will be open and permit the introduction of electrons into the discharge gap 41 to `facilitate partial ionization of the gaseous atmosphere. A glass bulb 26 ysupports the electrode 24 and is in turn sealed to a collar 27 secured to the waveguide 1.

An ignitor electrode 39 supported by bulb 40 is provided within lower threaded member 38 to ionize the gas in the vicinity of discharge gap 42.

While l have shown a plurality of plate members hav- -ing the discharge gap members positioned therein it will be evident that with changes in the frequency bandwidth, the plate members may be thinner to provide the resonant condition. In such embodiments the teachings of the invention may still be practiced by providing split-conical 'tipped members which when assembled will extend beyond the plane `of said plate-members.

Another application of the present invention resides in a novel multiple-aperture resonant window structure having the plural discharge gap structure incorporated therein. Referring to Figs. 3 and 4 plate 30 of a dielectric or ceramic material is provided with resonant openings 32 and 33 and coated with a metallic paint or covering 31 on both sides. The art of metallizing or painting such materials may be ascertained from U.S. Patent 2,683,863, issued to T. P. Curtis, on July 13, 1954, and U.S. Patent 2,770,784, issued to R. H. Hatch, on November 13, 1956.

Conical-tipped threaded members 34 and 35 are then positioned as shown to extend partly into each resonant opening 32 and 33. The double-tipped member 36 may then be positioned within portion 37 with each end dening with the aforementioned threaded members the plural discharge gaps. The openings 32 and 33 may then'be enclosed'by windows 43 and 44 to define hollow chambers which may be filled with an ionizable atmosphere. The complete window assembly may be sealed to the ends of the waveguide envelope by conventional Vdielectrictometal sealing techniques.

A Vcomplete TR tube structure incorporating resonant elements of the present invention may be exhausted and lled with an ionizable atmosphere under reduced pressure in the manner well known in the art.

With the multiple discharge gap low Q resonant elements described, improved electrical characteristics, ineluding increased bandwidth and lower spike and iiat leakage power values, may be realized. It will be evident that vthe invention will be equally applicable to other multiple iris opening structures and any number of the spaced plate member elements may be employed in waveguide rtransmission systems.

VWhat is claimed is:

Jl. In lcombination with hollow pipe rectangular waveguide structure, a resonant element adapted to be mounted within said waveguide structure comprising a metallic plate member having broad and narrow walls and a pluality of ltransverse resonant iris openings deining therebetween a solid metallic wall, a resonant discharge gap /delined within each resonant iris opening by means of 'single conical-tipped members extending inwardly from the broad walls of said plate member with the ends thereof positioned within said iris openings and a double-conical tipped member supported by said metallic wall with the ends thereof in axial alignment with and spaced from said single conical-tipped members.

2. In combination with hollow pipe rectangular waveguide structure, a resonant element adapted to be mounted within said waveguide structure comprising a metallic plate member having broad and narrow walls and a plurality of transverse resonant iris openings defining therebetween a solid metallic wall, a resonant discharge gap defined within each resonant iris opening by means of threaded conical-tipped members positioned within the broad walls of said plate member with the ends thereof extending into each iris opening, a double conical-tipped member supported within said metallic wall with each end in axial alignment with and spaced from said threaded conical-tipped members, said gap spacings being adjustable by axial movement of said threaded members.

3. In combination with ia section of hollow pipe rectangular waveguide having "multiple-apertured resonant windows sealed `at the ends thereof to define a hermetically sealed envelope, a resonant element spaced within said waveguide section a distance of one quarter of a wavelength away from the ends thereof, said resonant element comprising a metallic plate member having broad and narrow walls and a plurality of 'transverse resonant iris openings defining therebetween a solid metallic wall, said iris openings being inalignment with said window apertures, a resonant discharge gap defined within each iris opening by means of afconical-tipped screw member extending into each broad wall off said plate member with the ends thereof positioned within each iris opening, a double conical-tipped member positioned within said metallic wall with each end in axial alignment with and spaced from said screw members and a iilling of a gaseous atmosphere within said envelope.

4. A resonant window element for gaseous discharge waveguide transmission control devices adapted to be sealed at an end of a section of hollow pipe rectangular waveguide comprising a plate member of a dielectric material lhaving a plurality of'resonant openings therein, a metallic-coating on both faces of said plate member defining a plurality of resonant apertures, a resonant discharge gap dei-ined within each resonant opening Vby means of a single conical-tipped member extending inwardly `from the top and bottom walls of said plate member with the ends thereof'positioned within said resonant openings, a double-conical tipped member positioned within said plate member inthe area between `said resonant openings with the ends thereof in axial alignment with and spaced `from said 4single conical-tipped members, window enclosures sealed at opposite ends of said openings to detine hollow chambers and an ionizable atmosphere within said chambers.

References Cited in the iile of this patent UNITED STATES PATENTS 2,524,268 McCarthy Oct. 3, 1950 2,730,645 Kenty Jan. 10, 1956 2,748,351 Varnerin lMay 29, 1956

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