US2441574A

US2441574A - Electromagnetic wave guide

Info

Publication number: US2441574A
Application number: US524418A
Authority: US
Inventors: Edwin T Jaynes
Original assignee: Sperry Corp
Current assignee: Sperry Corp
Priority date: 1944-02-29
Filing date: 1944-02-29
Publication date: 1948-05-18
Anticipated expiration: 1965-05-18

Description

May 18, 1948. E. T. JAYNES ELECTROMAGNETIC WAVE GUIDE Filed Feb. 29, 1944 2 Sheets-Sheet l INVENTOR [DWI/V 72 (/A YNES AZOZE May 18, 1948- E. T. JAYNES ELECTROMAGNETIC WAVE GUIDE Filed Feb; 29 1944 2 Sheets-Sheet 2 INVENTOR 0 WIN 7: 4/4 Y/VES BY Patented May 18, 1948 ELECTROMAGNETIC WAVE GUiDE Edwin T. Jaynes, Garden City, N. Y., assignor to The Sperry Corporation, a corporation of Delaware Application February 29, 1944. Serial No. 524,418

15 Claims. (01.250 11) This invention relates to apparatus for conduction, radiation and reception of electromagnetic energy, particularly for ultra high frequencies.

The technique of guiding electromagnetic waves along a specially shaped and bounded dielectric medium is well known in the art. One type, of waveguide in common use consists of an elongated conductive surface formed as a tube or a pipe with a hollow rectangular crosssection having a major dimension somewhat larger than one-half of the wavelength of the energy to be transmitted therethrough and often having a minor dimension much smaller than one-half the wavelength of the energy to be transmitted therethrough. In such a waveguide, a transverse electric wave may be transmitted with very low attenuation. The electric lines of force then extend between the two wide Walls of the conductive surface.

Air at atmospheric pressure may be employed within the rectangular cross-section, electrically conductive boundary of the above waveguide as the dielectric medium for propagation of. the guided electromagnetic waves. Alternatively, other dielectric material may be used, such as a gas at any desired pressure, a liquid, or a solid dielectric material. A suitable solid dielectric material, for instance, is polystyrene, a commercially available low-loss product.

It is not essential to the waveguide function that a solid dielectric material be bounded by an electrical conductor; a polystyrene rod, for instance, is itself capable of supporting and directing electromagnetic waves. Such a dielectric rod might take aform similar to that of the above discussed rectangular waveguide, with the omission of the electrically conductive skin on the boundary surfaces. The essential condition appears to be a cross-sectional area bounded by a material providing a dielectric discontinuity. The above constructions of electro- '-magnetic wave guides are well known in the art.

' In general, the type of Waveguide employing a rectangular cross-section electrically conductive pipe with the air in the pipe as the dielectric medium has found wide acceptance as a convenient and eflicient structure. Since compactness of the waveguide is highly desirable, such a structure is usually operated at its fundamental transverse electric mode, usually designated as the H01 mode. For this operating condition, the width of the dielectric passage within the pipe must be greater than one-half the wavelength of the electromagnetic energy to be transmitted therethrough. The other internal cross-sectional dimension of the pipe, which may in some cases be as great as the width, usually is only a fraction, such as one-third, of the width. Thus a rectangular pipe or tube for transmission of energy at 3000 megacycles may have 'intemal cross-sectional dimensions of the order of one inch by three inches. The above major dimension is greater than one-half wavelength at the operating frequency of the waveguide, while the minor cross-sectional dimension is smaller than one-half the wavelength. Thus, only one orientation of an H01 wave may be transmitted through'the waveguidethat having the orientation "of lines of electric stress extending from one surface three inches wide to the opposite surface. For guiding horizontally electrically polarized waves along a horizontal axis, therefore the rectangular tube would be extended along the desired horizontal axis of transmission with its cross-section oriented for the three-inch dimension vertical and the oneinch dimension horizontal.

In directive antenna systems for ultra-high frequency radio systems, it is often desirable to guide vertically polarized waves and horizontally polarized waves along a common axis. A paraboloid reflector, for instance, might be used in conjunction with means for such wave guidance extending along the parabola axis to the vicinity of the focal point of the parabola. This combination might be used for guidance from a source and directive transmission of horizontally'polarized waves, and directive reception and guidance to a utilization device of vertically polarized waves. V

It is an object of the present invention to provide novel means for guided or directed transmission such as radiation or conductionof electromagnetic energy. 1

It is a further -object' to provide improved means for independentlyconducting or directing energy of a first polarization and energy of a second polarization along an'axis, either in the same direction or in opposite directions.

A further object is to provide means for directing energies of different polarizations along a common axis to or from an electromagnetic energy director'.

A further. object is to provide methods for supplying energy to the novel waveguide mentioned above.

A furtherobject is'to'direct electromagnetic energies having diiferent polarizations along a 3 common axis to or from the focal point of a parabolic reflector.

A further object is to provide an electroma netic waveguide system for transition between separate waveguide channels and the novel waveguide of the present invention.

Further objects will be apparent from a study of the following specification in conjunction with the drawings, of which,

Fig. 1 is a cross-sectional view of a dielectric waveguide formed according to the present invention, showing the lines of electric force schematically represented therein; 1

Fig. 2 is a perspective view and an end view of a waveguide structure according to the present invention, showing one type of exciting means therefor;

Fig. 4 is an end view of an embodiment ofthe present invention showing a modified system of excitation for the waveguide;

Fig. 5 is a perspective View of a waveguide embodiment of the present invention recombination with a paraboloidrefiector; l" v Fig.6 is a perspective view of a modified combination of t he cro'ss shaped waveguide with a parabolic reflector, wherein an auxiliary reflector is employed to permit'extension of the waveguide through the araboloid reflector; w 7 f Fig. 7Visa side view of a specially developed form of waveguide structure for transfer from separate electromagnetic waveguide channels to the cross-shaped waveguide of the present inventi z Fi 8 is a pl n View ofthestructure of Fig. 7

Fig. 9 is a side elevation .of the structure of Fig. 7; V

Figs- 9A, 9B. 90, 9D. 9 1 F. 96 H 9; K are sectional views, talgen on lineshh, 3 -13, 0-0, DD, EE, FF, JJ, and K-K of Fig.

9;and. V

Fig. 10 is azperspective .ViGWI Qf the waveguide structure of Figs..7 to ,9,.inclusive, m V

The waveguide 9 represented by ;the cross-sec- 4 while the width of surface It would correspond to the other or minor cross-sectional dimension of a rectangular waveguide substantially equivalent to leg 25 of the cross-shaped waveguide shown in Fig. 1.

As an example of dimensions suitable for a waveguide in which copper skin surfaces l2 to 19, inclusive, and 2| to 24, inclusive, form an electrically conductive tube employing air dielectric suit-able widths of planar conductive strips l3, l6, |9 and 23 might be three-fourths inch,

J while the widths of the remaining planar surtional view of Fi 1 'comprises a dielectric medi- 2| to '24, inclusive... Thisifigure may .be considered to represent any of several alternative waveguide structures, such as ,an air. dielectric waveguide arrangement .in which the aboveplanar surfaces representv electrically. conductive areas,

or a solid. dielectric waveguidehaving .sucha material as polystyrenewith ;orv without, electrically conductive boundary surfaces. This cross section maybe. described: as of'theform of a cross electric lines of force,qindicated by lines 28, may,

be generated in waveguide .leg 25. Each leg of the cross-shaped. waveguide is thus substantially equivalent to a rectangularcross-sectioned waveguide of a well known type,-havin'g a major crosssectional dimension larger than half of the wavelength of the energy to be transmitted therethroug'h. i r I In the cross section illustration of Fig. 1, the

sum of the widthsof surfaces", |9Zand 22 is two to three inches. Such dimensions would be suitable for Hui-mode transmission of energy at 3099 to 4090 megacycles per second, for example.

Electric lines of stress 21 could then be produced by excitation of leg 25 of waveguide 9 with electromagnetic energy having a frequency of the order of 3000pmegacycles per second. Electric lines of stress 28 similarly could be produced by excitationof leg ;26 of waveguide 9 with electromagnetic energy of a similar frequency not necessarily equal to the first frequency.

In Figs. '2 and 3 fi's'seen a waveguide 9 having a cross-sectional configuration substantially equivalent to that of Fig. 1. Mutually perpendicular conductors 3| and 32 are provided for transverse electric excitation of

legs

25 and 26, respectively, of the cross-shaped waveguide system, These conductors may be spaced from a conductive reflectorplate 29, by dimensions corresponding to one-fourth, three-fourths, fivefourths, of the respective wave lengths in the "guide of energies to be transferred between the conductors and the waveguide legs. Thus, conductor 3| inight bes'p'aced from reflector plate 29 approximately one-fourth of the guide wave length or the energy to be transferred therethrough, whereas conductor 32 might be spaced approximately three-fourths of the guide wave length of the energy to be transferred therethrough In Figs. 25nd 3, conductor 32 is noted to be in front of conductor 3|, as seen by an observer looking in'tothe open end l'Oof the waveguide syst m. surfaces |2 t o l9 and 2| to 24,

inclusive, 'as shown in Figs. 2 and 3, constitute conductor-3| ofcoaxial li'ne 3|, 33 is bonded as substantially equivalent to the greater cross-sec-- tional dimension of leg 26 as referred to above,

by asold'er d 'joint, 'to'con'ductive wall 23, while outer conductor'3'3 is bonded, again as by a soldered joint, to conductive surface l fi Center conductor3 2 gn line'32, 34 is similarly connected to wall 9, while the outer conductor 341s bonded tow l With a source 3 connectedto coaxial line 3|, 33. the currents -;i lowing through conductor 3| to electrically conductive surface 23, and thence .1. Similarly, ultrahigh frequency generator 36, connected to

coaxial line

32, 34 serves to excite leg-2'6 of the cross-shaped waveguide, as shown by lines 23'in Fig.1. With the type of excitation thus providedino coupling exists between the electromagneticenergy induced in the waveguide by source35 and :that induced in'the waveguide by s'ource 33. This fact, together with the capability of independently transmitting energy from -source ''35 and energy from source 3!? along 'a common axis, is a feature 'of the present inyenti'on. Furthermore, either source- 35' or source '36 maybe replaced 'by'an energy utilization device such as a radio detector, so that waveguide 9 may be used for independenttransmission and reception of perpendicularly. polarized electroinag'netic waves p 7 An alternative system for feeding 'energy to,-or extracting energy from waveguide '9' is shown in Fig. 4. In this figure,

coaxial line

32,34, conhected to source 36, is 'coupledto 'leg 26 of the cross-shaped waveguide 9 through coaxial line sections 31 and 38' and the electromagnetic coupling loops "39 and "4|. These loops emerge as the center conductors of coaxial sections :31 and 38, respectively, and 'are bonded asby soldering to walls 23 and "f6, respectively of leg 26. C70- ajxial line section '38 from junction 42 to conductive'surface i1 "is made equal to-or an integral number of wavelengths longer than, the length of "section 31 from junction 42 to wall '2 2,-as indicated by the-dimensions shown inFig. -4-so that the voltages applied to the loops 39 and'41 are in phase. The resulting induced fields will be 180 out of phase due to the fact that-loops 39 and M are turned in opposite directions. Similarly, 301116835 is connected through coaxial line '31, '33 andjunction'fi

tocoaxial line sections

44 and 45, which, in turn, are connected to

electromagnetic coupling loops

46 and 41, respectively. Coaxial line section 45 extending from junction "43 to waveguide surface I2 is made "equal to, oran integral number of wavelengths longer than section '44 extending from junction 33 to surface 2|, whereby currents through

conductor loops

46 and 41 are in phase. I

The wavelength used s a basis for computing the difference of lengths of coaxial line sections 4'4 and E5 is determined by the frequency of source 35 while the wavelength used as a basis for computing the' differenoe of lengths of coaxial lines -3-l and '38 is based 'on the frequency of source 36.

maybe replacedby'a high frequency utilization device or devices.

In Fig. 5-is shown an electrically'conductive paraboloid reflector 48 having an aids 49 and a focal p'oint 5i. Fixe'd-alorig axis Hand-extending substantially to focal point 5| is a cross-shaped waveguide-'9 similar'to thatdes'cribed-above. The cross-shaped waveguide 9 of Fig. 5 is shown broken at 52, beyond which point maybe-at- 'tached a feeder system such asthatof Fig. 2*or 55 th V i ii. as described above, or that fiFi 7 1 0 130 be described.

Waveguide in Fig. '6 is shown inserted from 'the rear of electrically conductive paraboloid reflector 4-8, "and adapted to cooperate with auxiliary reflector 53fpositioned substantially at focal point 5l"of-reflector 48. Waveguide 9 is again shown broken as at point 52,-beyond which feeding or utilization coupling means may be provided. I p

"As an' example ofthe'applications towhich the waveguide and reflector combinations of Figs. 5 and 6'may be adapteda source of high frequency energymay be u'sedto "excite leg of waveguide 9, thus providing horizontal-1y polarized electromagnetic energy at fo'carpoint 'S l "or 51', whereby such energy is radiated by reflector or 48 serving as anelectroma'gneti'c energy director. A utilization device's'uchasa' ra'dioreceiver, may

vertically polarized electromagnetic "energy reflected by-reflector ta r n to focal point-51 6i -5'l"-. Reflector '48 or 48 and waveguide -9 may thus form part of a radioconimunication systern, or of an object locating system, as -iswell 5 known in the art.

l0 directive radiating systems.

A developed waveguide system characterized by transition from two separate rectangular waveguides to a single waveguide of cross shaped "cross-section is shown in Figs. '7 to 10, inclusive.

1 In this form of the invention, one'w'avegu-ide 5 6 is enlarged from a major cross-sectional dimensionfi'l greater than one-half of the wave length "of energy to -be transmitted thereth-rough, to a cross-sectional dimension 58 appreciably greater 0 than said wavelength at section C or Fig. 9, b'eyond which two divergent septa 59 and 6! are introduced within guideifi to separate waveguide -56 into two substantially parallel channels 6-2 and '63, extending through sections D, E, and F 5 tosec'ti'on Waveguide 64 is 'twisted from vertical orientation of its major cross sectional dimension at section A to horizontal orientation of its cross-sectional dimension at section D of Fig. '9, beyond which waveguide -64 is causedto $0 converge to a position intermediate between channels 6 2 and '53 of waveguide This is clearly shown by sectional'view 9E,'9E', and 9G. The energy produced in waveguide- 56 by current transmitted through coaxial line 31 '33, 'dividedb'y septa/59 and'GI and'transmitted*inequal Here, also, source 35 or source'35 leaving 'the interior'of the -waveguidestructure parts throughjcha'n'nels 6"2'and 63 is reunited in vertical leg 25 of the cross-shaped "Waveguide formed at the termination "atsection 9G ofsepta 59 and 6 I. The'energy produced in waveguide fi l '40 by coaxial line 32, His led-along twisted-waveguide 54 and thence along the path of convergence with channels 62 and 6 3. At section 9G of the waveguide "structure shown in the Figs. 7't0 10, inclusive, se'pta59 andfil are terminated,

substantially as shown in section 9H. "Thereafter, the majorcross-sectional dimension of the waveguide system is reduced'until thisdimension is substantially equal 'to the 7 vertical cross-sec- 'tional dimension'o'f waveguide'fifias indicated at fill "in sectional view "9A. Thus, the "cross-sectional waveguide Bis developed a'sshown in sectional view 9K, with excitationinvertical leg'2-5 provided by the ultra high fre'quency current throughconductor 3 I ,and with excitation of leg 26 -produced by'the ultra high frequency currentthrough' conductor 32.

V t'will be seen thatthedeveloped'structure of "Figs. 7 to 10 inclusive is suitable for'use inter- 'chan'geably with eith'erthe's'tructum ofFig. 4 or that-of Figsy2 and 3. Furthermore,the-waveguide structure of Figsf'l to -10, inclusive, is suitedfor usewith a director, such as the parabolic reflector shown inFigfe or Fig. '6.

The structure of Figsl'l'to l0,-inclusive,'is particula'rly useful as'an adapter for coupling to cross-shaped waveguide 9 oscillators and/or -uti- 'lization devices provided with hollow- 'pipe'wave guide fittings, to which separate'waveguides 56 and 64 may be connected.

Since many changes could be made inthe "above construction an'd m'an'y apparently widely different-embodiments of this invefit-ion could be made without departing -from the-scope thereof,

"it is i intended "that an m'att'er=contalned in the drawings shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. Electrical apparatus for operation at a given operating frequency comprising a dielectric waveguide bounded by twelve consecutively adjacent and intersecting substantially planar surfaces so positioned as to define a cross-shaped dielectric cross section having a medial portion dimensioned below cutoff at the operating frequency.

2. Apparatus for conducting both electromagnetic waves of a first polarization and electromagnetic waves of a second polarization comprising a dielectric waveguide of substantially rectilinear internal contour having a longitudinal extension of length greater than the wavelength of said waves and two transversely extending leg portions, means disposed parallel to one of said leg portions for exciting said waveguide for transverse electric polarization therein, and means disposed parallel to the other of said leg portions for exciting said waveguide for transverse electric polarization perpendicular to said first polarization.

3. Apparatus for conducting electromagnetic energy between an ultra high frequency device and a predetermined point spaced therefrom by a distance long relative to one wavelength of said energy and for conducting electromagnetic energy between a second ultra high frequency device and said point, comprising a waveguide extending fromsaid point along an axis and including a tube of conductive material substantially coextensive with said guide and having an internal cross-sectional outline of substantially cross shape, means for coupling said waveguide to said first device, and means for coupling said waveguide to said second device.

4. Apparatus for conducting electromagnetic energy between a source and a first device, and between said source and a second device, comprising a waveguide extending along an axis from said source and including a dielectric medium having substantially cross-shaped internal cross section, means for coupling said waveguide to said first device for utilization of electromagnetic energy polarized substantially parallel to a plane including said axis at said source, and means for coupling said waveguide to said second device for utilization of electromagnetic energy polarized substantially perpendicularly to said plane at said source.

5. In a radio system including a source of electromagnetic energy and a utilization device for received energy, directive radiation and reception apparatus conjointly operable from a pretion apparatus conjointl operable from a pre determined focal point comprising waveguide means extending from said focal point and including a dielectric medium having an internal cross section characterized by two mutually perpendicular legs, means for coupling said source to said waveguide means at one of said legs to supply energy of a predetermined polarization at said focal point, and means for coupling said utilization device to said waveguide means at the other of said legs for acceptance of a component of energy polarized perpendicularly to said predetermined polarization at said focal point.

' 7. In a radio system including a source of electromagnetic energy and a utilization device, apparatus comprising an electromagnetic energy director means for transmission and reception of electromagnetic wave energy along an axis,

waveguide means coupled thereto for transfer of .energy to and from said director including a dielectric medium having substantially crossshaped internal cross section, means coupling said source to said waveguide means for transmission of energy of a first polarization to said director, and means coupling said waveguide means to said utilization device to render the latter responsive to energy of a second polarization received by said director.

8. Waveguide apparatus for connecting a first waveguide element, having a cross shaped continuous dielectric cross section of two perpendicular legs, to two ultimate waveguide elements having rectangular dielectric cross-sections, comprising a second waveguide element adjoining said first element and having a cross shaped cross section with two electrically conductive septa introduced therein separating said element into two separated waveguide channels and a third waveguide channel intervening between and perpendicular to said two channels; and a third waveguide element connecting said second element to said ultimate elements for high frequency energy transmission therethrough, said third element having two sections respectively connected to said two channels and a third section connected to said third waveguide channel and emergent from between said two sections at a point along said two sections, said two sections being convergent to form a single waveguide channel beyond the point of emergence of said third section and being adjoinecl to a first of said ultimate elements, and said third section being adjoined to the second of said ultimate elements.

9. Apparatus comprising two rectangular waveguides conjoined to terminate in a single wavea guide having a cross-shaped dielectric cross-section, characterized by two divergent septa introduced into a first of said wave guides separating said first waveguide along a finite length thereof into two electromagnetic energy transmission channels, and further characterized by convergence of the second of said two waveguides to contiguity with said septa, within said I finite length.

' 10. Apparatus comprising two rectangular waveguides conjoined to terminate in a single 7 waveguide having a cross-shaped dielectric crossh with said septa, within said finite length.

11. Apparatus comprising a waveguide elemritfwherein three rectangular waveguides having. initially distinct hollow electrical'conductors converge to form common electrically conductive boundary surfaces along the areas of contact separating the respective interior zones of said waveguides, said common conductive boundary surfaces being terminated Within said conductors to render said interior zones intercommunicating.

12. Electromagnetic energy transmission apparatus comprising three rectangular waveguides having initially distinct electrically conductive surfaces converging to adjacent positions to form common electrically conductive boundary surfaces, said common conductive surfaces being terminated within said apparatus to form a single electromagnetic energy conductive structure terminating said apparatus and having a single continuous dielectric cross-section.

13. A waveguide for operation at a given operating frequency having a longitudinal axis and adapted for transmission of electromagnetic signals along said axis, comprising means defining a bounded dielectric medium having in cross-section a pair of mutually perpendicular medially intersecting legs each formed between cooperating pairs of parallel bounding surfaces, the spacing between said bounding surfaces defining crossed wave guides above cutoif and a central intersection space dimensioned below cutoif at the operating frequency.

14. Apparatus for conducting both electromagnetic waves of a first polarization and electromagnetic waves of a second polarization comprising a dielectric wave guide of substantially rectilinear internal contour and having a longitudinal extension of length greater than the wavelength of said waves and two transversely extending leg portions, means coupled to one of wavelength of said Waves and two transversely extending leg portions, and means coupled to said leg portions for exciting said waveguide in mutually perpendicular transverse electric polarizations therein.

EDWIN T. JAYNES.

REFEBENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,197,122 Bowen Apr. 16, 1940 2,206,923 Southworth July 9, 1940 2,283,935 King May 26, 1942 2,395,560 Llewellyn Feb. 26, 1946 FOREIGN PATENTS Number Country Date 495,977 Great Britain Nov. 23, 1938 OTHER REFERENCES Proceedings of the I. R. E., Oct. 1936, vol. 24, No. 10, pp. 1326 and 1328.