US2659004A - Nonresonant directive antenna - Google Patents

Description

Nov. 10, 1953 UNDENELAD 2,659,004

NONRESONANT DIRECTIVE ANTENNA Filed March 12, 1948 J /a M 3 23 6 0 E lzvamr/v i /V/Y V ,70

6 GP 4 muar/ay /z '//////////////////////////////////////////////fl//////M vENToR ATTORNEY Patented Nov. 10, 195 3 N ONRESONAN T DIRECTIVE ANTENNA .Nils E. Lidenblad, Port Jeferson, N. Y., assignor to Radio Corporation of America, a corporation of Delaware Application March 12, 1948, Serial No. 14,601

`1 The present invention relates to ultra short wave antennas and more particularly to directive non-resonant antennas.

' provision of an antenna system which is usable on supersonic jet propelled missiles.

The foregoing objects and others which may appear from the following detailed description are attained by providing an antenna in the form of a linear conductor having a length compari able with a number of Operating wavelengths.

i The conductor is disposed adjacent the boundary between two dielectrics of differing dielectric i constant whereby a wave tilt is produced thereby coupling the energy carried by the wire to the surrounding space.

The present invention will be more fully understood by reference to the following detailed description which is accompanied by a drawing in which:

Figure 1 illustrates diagrammatically an application of the present invention to a balanced push-pull transmission line, while i Figure 2 illustrates a modification of the invention, and

Figure 3 illustrates the application of the antenna of the present invention to a supersonic jet propelled missile.

Referring now to Figure 1 there is shown a section of balanced, push-pull, two-wire transmission line consisting of conductors l and !2. The conductors are connected to a source of high frequency energy as indicated by the generator G. The other ends of the conductors !0 and l2 are 'connected together by the resistor R having a value of resistance equal to the characteristic impedance of the section of the transmission line. Thus the conductors carry a pure travelling wave v in the direction from G to R.

' found that if a dielectric material such as that 13 Claims. (Cl. 250--33.61)

indicated by reference character !4 is placed in the neutral plane between the conductors, a radiation Component in the direction of the transmission line axis will be obtained as shown by the arrow D. The radiaton which results may be attributed to the so-called wave tilt. Normally the electrostatic field would be perpendicular to the line axis; that is, to the direction of the arrow D. The Wave tilt is a result of the difference in velocity of the waves in the space surrounding the two-wire line and in the dielectric !4. Thus, the electric field enters the dielectric at some angle other than 90. The field also becomes subject to reflection at the boundary between the dielectric and the surrounding space. Further, as the field tilts due to the presence of the dielectric, the magnetic field tilts with it. That is, when considering the transmission line as being in free space, the rings of the magnetic field are in a plane perpendicular to the line axis D. The presence of the dielectric |4 between wires causes the magnetic field around each wire to tilt toe ward the line axis. Since the fields about the two wires correspond to currents in opposite directions, their projections on a plane parallel to the line axis D are additive while the projections on a plane perpendicular to the line axis D are subtractive. The net result of these electrostatic and electromagnetic field tilts is a Component of radiation along the line D.

A single conductor transmission line over conductive ground plane may also be caused to act as an antenna as shown in Figure 2. Here the single wire conductor 20 is disposed over a conductive ground plane GP. The wire 20 is terminated at one end by terminating resistor R and at the other end by generator G as described with reference to Figure 1. Also, as in the case of 'Figure 1, a block of insulating material such as Wood or Bakelite is indicated by reference numeral I4. The manner in which radiation in the direction of arrow D takes place in the form of Construction shown in Figure 2 may be compared with the system in Figure 1 on an image basis; that is, the conductive ground plane GP may be considered as producing a mirror efiect as though a second conductor, carrying current in opposite direction to the current in wire 20, were placed below ground plane GP a distance equal to the distance of wire 20 above the ground plane GP. There will of course be some differences between the two, especially if the dielectric [4 is thick. However, forward radiation in the direction D will still take place.

It will be noted that at ultra high frequencies mgoni the overall height of the antenna system shown in Figure 2 is very small. Its overall length is also small since a matter of several wavelengths of centimeter waves still does not result in a large bulky structure. The antenna of Figure 2 is thus well suited for use on high speed airplanes since its projection 'above the surface of the' 'airplane is extrmelysmall. In most' cases the antenna would not project beyond the region of disturbed area surrounding the airplane and would therefore cause no increase in drag V r Another use of the.present invention is`illustrated diagrammatically 33- -HereI ha' ve shown a supersonic speed*`jet-'-pro'el 1ed=ifssil 'as indicated generally by reference numeral 30. This missile may be propelled'by the jetengine 32 within the body of the missile Operating on air received through the nose of the ni's's'ile 'in-'duct 34. The products of ombustion which produce "th* 'l',hrist are discharged throgh "the'tail iofthe ''issne rrm duet 2 6.

appara-tus and an" `"associat'ed 'antenna ?system ***must be carried by 'the missile. 5 The -:a'ntenna sfsfem-pfefMyhDmd hVe a lobe of" maxiini-imres'onse pointing ta-'the rear of the missile. 11 1 normal-*operation the rea-r end of the missile may become extrernely hot. Thus, Te any antenna m'a hg'ee n ar 'the -rear "end of the missile' Will be 'subjectto extrme I inperature rises'while 'the n'if'sile is in operation. Normally; insulators which`--`a`re gobd at-ultra high frequencies will not stand such e high temperatures unless they are made or -'cr'amic material. Hou/ever,- the-'ceramic materials are brittle' and-'easily broken. Furthermore du'e'to the-speedat which 'such mis- "sil`e`s trayeL-normal antennastructures would in- 3 roduce ar'--`excessiveairdrag 'lt w ill beappart tliat it is not practicablet place re'arwardly drrcted hrn antei ias around 'the body* of 'the 3: misile 'Even si'tpe 'd 'fire array; if -it is to #have any 'eff e'ctiveheight; 'will *produc an e xces- *siv drag?-To furthencomplicate fihe p oblen it ay h ec'ess'ary 'to @Wide-*several independntly dpratin aiitehrzs.

y In accordance with -my invention *an ant'e'ina liavng charactristics* suitable for u'smjetprop'elled' in ssil may' beattained byproiiiding an "l'ongted-prs'sibfi along' the length of the *misi one ormere'locatiens aroundits' p'eriphery." Withizf'the depression is' located a block of inulalting material ad whichf if reciu-iredmay be rnade of 'high'tefperature ceramic. Along the i fciut'er surface* ofthe insulator l is provided-' an ""elon`gated 5 c'onductor fi terminatedat"-t-he' "rear endby"trminating resistor R-ancl connected at forward end'tof the radio apparatus srcarried tenna s' 'entirely constructed o'f materials resistant to high Operating temperatures. "Theinaximum lobe of the radiationpattern is `in-the direc- '-tiontoward"the tail -of the missile as required. --A'lso:. quadrantally arranged antennas may be -provided, -theseveral antennas--being substantiany independent in'their operation.

While I have generally described my invention abcve aS though applied'to' transmitting antennas, it is equally as well applicable to receiving 4 antennas if appropriate receiving apparatus is substituted for the generator G.

What is claimed is: l. A directive antenna for use on a conductive surface structure and providing maximum eifec tiveness in a given direction and at an angle sub:- stantilly less than a i i'ght anglewith'respect to said conductivesurface structurer saidconductive V surface structure having -a recess therei n, a body *m ci dielectric material arranged in said recss a conductoarranged on said dielectric body sub"- st'ant i'ally `fiiish with said conductive surface structure; saidwohductor and said body being at le'ast as lon'g as several wavelengths at the oper- 15 ating r' 'e'quency' in said surface along said given direction a resistive element connected between 'said'onductivesurface structure and one end of -said corductor, said element having a resistance Value substantially equal to the characteristc zo impedarce of the transmissior line formed by said conductor: andsad -conductive surface, and means to couple utilization apparatusbetween -said-conductive surfacestructure and- -the other end ofsaid conductor. p A 2. A directive antenna for use at centirneter Waveleng ths on a--vehicle having a conductive -outer surface without producing appreciable aerodynamicdrag andproviding inaximum eectiveness at a small angle with respectto saidsurface including a block-ofdielectric material ar- :ranged"- on' said conductive surface, a -ccnductor arranged on said -dielectric-body -said concluctor and said block being at least as long as several wavelengths :at---the-operating-frequency `in the a 'desired directiorrof -operation ofsaid antenna; a

resistive element connectedbetween said conductive surface and oneendcf said conductor and means to 'comple utilizatior apparatus between saidconductive surface-and the -other end of said 40 conductor. p

2 3;- A directive antenna -for-use at certimeter wavelengths on a vehicle having a conduti-Ve outer u surface x without s -producing appreciable aerodynamic drag -andproyding maximum effectiveness at a small a-ngle With-respectto said-surface, said conductive outer surface having an -elongatedrecess -thereim a--block of dielectricma- -teral arrangepl-onsad conductivesurface; a con- -ductor-arranged -on said dilectric body te locate said conductor substantially fiush with said conductive :surfaceofsaid vehic1e-,-said `cenductor and said block being -atleast i as longas seyeral wavelengths at-theoperating frequency in the desired direction-:of :operation of-'said antennaj a resistive element connected between said conduc- -tive-=surface and-one end of said `-condctor-, and s means to couple i'tiliz'ation .apparatus between said conductive surface and the 'othe end of 'said --cendueton (30 &rA direetive antenna for use at centimeter wavelengths= ona vehicle having a conductive outer surface Without: producing. appreciable aerodynamicclrag and providing maximum 'eifec- ---tiveness at a small angle with respect-to said-surface-;including a-blocl; ofdielectrc material ar- -ranged-on-said conductive surface, a conductor arrangedon said dielectric' body, r said conductor z and-said block--beingat 'least *aslongas several wavelengths at the operating frequencyin the 7 clesired direction :of noperationof -said antenna, a resistive element -CO-lH-Efitdf :between sa-id =conduetivesurface--and one end 'of said `coeluctor, andmeans -to *coupleutilization appar atu between said conductiyesurface and theotherend of said conductor, said 'esistive'element having a resistance value substantially dalto the bha'r'- acteristic impedance of the arrangement of said conductor over said conductive outer surface.

5. A directive antenna for use at centimeter wavelengths on a vehicle having a conductive outer surface without producing appreciable aerodynamic drag and providing maximum effectiveness at a small angle with respect to said surface, including a block of dielectric material arranged on said conductive surface, a conductor arranged on said dielectric block, said conductor and said block being at least as long as several wavelengths at the Operating frequency in the desired direction of operation of said antenna, a resistive element connected between said conductive surface and one end of said conductor, and means to couple utilization apparatus between said conductive surface and the other end of said conductor, said resistive element having a resistance value substantially equal to the characteristic impedance of the arrangement of said conductor over said conductive outer surface, said conductive outer surface being' formed to provide an elongated recess for said dielectric block to locate said conductor substantially flush with said conductive surface of said vehicle.

6. An ultra short wave non-resonant directve antenna for use at -centimeter wavelengths on a metallic aircraft structure without producing appreciable aerodynamic drag and providing maximum eifectiveness in a direction substantially directly astern of the aircraft structure, including a block of dielectric material arranged on said metallic aircraft structure, a conductor arranged on said dielectric body, said conductor and said block being at least as long as several wavelengths at the Operating frequency in the direction of the longitudinal axis of said aircraft structure, a resistive element connected between said metallic structure and the end of said conductor adjacent the stern of said aircraft structure, said element having a resistance Value substantially equal to the characteristic impedance of the transmission line constituted by said conductor and said metallic structure, and means to couple radio frequency utilization apparatus between said metallic structure and the other end of said conductor.

7. An ultra short wave non-resonant directive antenna for use at centimeter wavelengths on a metallic aircraft structure without producing appreciable aerodynamic drag and providing maximum effectiveness in a direction substantially directly astern of the aircraft structure, the metallic aircraft structure having an elongated recess provided therein, a block of dielectric material arranged in said recess, a conductor arranged on said dielectric block substantially flush with the surface of said metallic aircraft structure, said conductor and said block being at least as long as several wavelengths at the Operating frequency in the direction of the longitudinal axis of said aircraft structure,-a resistive element connected between said metallic structure and the end of said conductor adjacent the stern of said aircraft structure, said element having a resistance value substantially equal to the characteristic impedance of the transmission line constituted by said conductor and said metallic structure, and means to couple radio frequency utilization apparatus between said metallic structure and the other end of said conductor.

8. A travelling wave antenna including a conductive surface element disposed in a medium through which radation is eflected, a body of dielectric material having a dielectric constant 'different from that of said medium and arranged several wavelengthsat the Operating frequency', and 'lying for the greater part of the length.

thereof along a region of abrupt' change of dielec-- tric constant, a, terminating resistor having a value of resistance equal to characteristic imped-- ance' of said antenna connected between one end' of said conductor and'said conductive surface' element, and means to couple transducer equipment between the other end of said conductor' and said conductive surface element.

9. An antenna including a conductive ground plane element, an elongated body of dielectric material having a dielectric constant differing from that of 'surrounding space, an elongated conductor having a length at least as long as several wavelengths at the Operating frequency disposed on said body of dielectric material along a direction of desired maximum response and eectively for substantially the entire length thereof along a region of substantial change of dielectric constant, means to couple transducer apparatus between one end of said conductor and said ground plane element, and a' resistance device connected between the other end of said conductor and said conductive ground plane element to terminate the' antenna in the characteristic impedance thereof;`

10. An antenna including a highly conductive ground plane element, a body of dielectric material having a dielectric constant difiering from that of surrounding space arranged on said conductive ground plane element, an elongated con'- ductor having a length, at least as long as several wavelengths at the .Operating frequencydisposed on said body of dielectric material substantially parallel to said ground plane element along a direction of desired maximum response whereby said conductor lies for the effective part of the length thereof in a region of substantially abrupt change of dielectric constant, means to couple transducer apparatus between one end of said conductor and said ground plane element, and a terminating resistor having a value of resistance equal to the characteristic impedance of said antenna connected between the other end of said conductor and said ground plane element.

11. A directive traveling wave antenna system for radio apparatus installed in close proximity to a semi-infinite conductive surface element, including an elongated block of dielectric material having a dielectric constant different from that of the medium in which the antenna is eifective arranged on said conductive surface element, an elongated conductor arranged on said block of dielectric material to lie for the greater part of the length thereof along a boundary of an abrupt change of dielectric constant, said block of dielectric material and said elongated conductor having lengths at least several wavelengths at the Operating frequency, a resistor having a resistance value substantially equal to the characteristic impedance of the transmission line effected by said elongated conductor and said conductive surface element connected between one end of said conductor and said conductive surface element, and means to connect said radio apparatus between the other end of said elongated conductor and said conductive surface element, thereby to provide maximum effectiveness of saidentenna srst m insthedir ctiotowam said roneenst` oi said elon ated onduct. ndatssubstantially less than a ,rightgang-le yvthrespect :to saidconductive :surface element,

.12. AV directive :traveling: wave antenna system for-;radio apparatus installed: in :avehicle havin an external porton thereqf constituting ;a-conductive :surface element, saidccnductye surface element *having an-elongated-depression external.- ly of :said vehicle, including. ganelonga-tedblock of dielectric material havin -ga. delectric constant 'difierent from that of air arra-ngedin the depressionsof said conductive :surf-aceelement, an elongated conductor arranged; on ;sa-id blOCkz of dielectric material above said: depressior tor lie 'for the greater :part of :the-.length thereof along a `boundary 4 of an abrupt change of -die1ectrc constant; said block 'of .dielectrc-material and said elongated.conductor having lengthsat least sev.- eral wave-length& at the Operating frequency a resistor having a resistance -Value substantally equalto the characteristicimpdance of the -transmisson line efiected by said elon-gated-.conductor and saidiconductive surface element connected between one (endet said conductor and 'said .conductive surface element; and means to connect said. radio ;apparatus between the ,other 'end pflsaid elon ated conductor andrsaid .conduc- .tive ;surface ;element thereby ..to ;provide maximum effectiveness of sad antenna .system in :the direction ;toward said ;oneend of said .elongated conductor and atsubstantially less thana right angle with respect tocsaid conductiv'e surface element;

- 13. ;A;-drective tra-veling wave zantenna system r iiorradio rapparatusinstalled in' close proximity -tua semi-infinit& highly conductive surface element; including an- `'elongateol :block of r substantially solid dielectrc material having a diele'ctric constant different from that: of the medium in 8 `whichdahe; arterma risefiecti-ve :arranged on: said 'conductive surface; element r ans-elongated .conductor. ;arranged onisaid 'ble ck :of dielectric ma- -terialwherebysaid-elongated conductorv lies for substantially the entire length thereof along a boundaryof an .abrupt change -of delectric: constant, sa-id block odielectric material and said 'elongated conductorhaving :lengths of at 'least several wavelengthsxat the operatng -frequency, aresistor, havingaresstance value substantially equa-lto thecharacterstc- -impedance of the transmssion line-formed by said elongated conductor andsaid conductive surface element connected between; .one end of said conductor` and said conductive surface element,` and means to connect said radio apparatus between the other end of 'saidelongated-ccnductorand said conductive-surface: element, therehy to provide maximum effectiveness 'of said antenna system in the direction toward theone end of said elongated conductor and-at substantially less than a right angle-Wth respect-'to said conductive surface element..

Nlls E; -LINDENBLAD References-.Ciklin the file of this patent UNITED"STATES PATENTS Number Name Date 1533936 Martin 'Harvey Apr. 14, 1925 1,562`,961 Heising Nov; 24, 1925 1,602,085 Rice et al. Oct. 5, 1926 2,418,084 Montgcmery Mar. 25, 1947 2,431,124 Kees et' al; Nov; 18, 1947 OTHER REFERENCES The A. RL R; LL" Antenna Book, published 1946 bythe American Rado'Relay League, West Hartford,`Cohn., pages '46 and 47'.- Copy in Division 51';

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