CA2146546C - Antenna array with a continuous transverse stub element - Google Patents

Abstract

A dielectric material is formed into a structure having two parallel broad surfaces with one or more raised integral portions extending transversely across at least one of the broad surfaces. The exterior is uniformly conductively coated resulting in a parallel plate waveguide having a continuous transverse stub element disposed adjacent one plate thereof. Purely reactive elements are formed by leaving the conductive coating on the terminus of the stub element, or by narrowing the terminus of the stub element. Radiating elements are formed when stub elements of moderate height are opened to free space. Radiating, coupling and/or reactive continuous transverse stub elements may be combined in a common parallel plate structure in order to form a variety of microwave, millimeter wave and quasi-optical component including integrated filters, couplers and antenna arrays. Fabrication of the dielectrically-loaded continuous transverse stub element can be efficiently accomplished by machining, extruding or molding the dielectric structure, followed by uniform conductive plating in order to form the parallel plate transmission line. In the case of antenna applications, machining or grinding is performed on the stub terminus to expose the dielectric material at the end of the stub element.

Description

- 2~5~6 ANTENNA ARRAY WITH A CONTINUOUS
TRANSVERSE STUB ELEMENT

BACKGROUND
The present invention relates generally to antennas and transmission lines, and more particularly, to a continuous transverse stub disposed on one or both conductive plates of a parallel-plate waveguide, and antenna arrays, filters and couplers made therefrom.
0 At microwave frequencies, it is conventional to use slotted waveguide arrays, printed patch arrays, and reflector and lens systems. However, as the frequencies in use increase to 20 GHz and above, it becomes more difflcult to use these conventional microwave elements.
The present invention relates to devices useful at frequencies as high as 20 GHz and up known as millimeter-wave and quasi-optical frequencies.
Such devices take on a nature similar to strip line, microstrip or plastic antenna arrays or transmission lines. Such devices are fabricated in much the same way as optical fibers are fabricated.
Conventional slotted planar array antennas are difflcult to use above 2 o 20 GHz because of their complicated design. This, in conjunction with the precision and complexity required in the machining, joining, and assembly of such antennas, further limits their use.
Printed patch array antennas suffer from inferior efflciency due to their high dissipative loses, particularly at higher frequencies and for larger 2 5 arrays. Frequency bandwidths for such antennas are typically less than that which can be reAli~e-l with slotted planar arrays. Sensitivity to dimensional and material tolerances is greater in this type of array due to the dielectric loading and resonant structures inherent to their design.
Reflector and lens antennas are generally employed in applications for 3 o which planar array antennas are undesirable, and for which the additional bulk and weight of a reflector or lens system is deemed to be acceptable. The absence of discrete aperture excitation control in traditional reflector and lens antennas limit their effectiveness in low sidelobe and shaped-beam applications.

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, 4 ~

Filters at millimeter-wave and quasi-optical frequencies suffer from relatively low Q-factors due to high dissipative element and interconnect losses and from relative difflculty in fabrication due to dimensional tolerances.

SUMMARY OF THE INVENTION
A continuous transverse stub element residing in one or both 0 conductive plates of a parallel plate waveguide is employed as a coupling, reactive, or radiating element in microwave, millimeter-wave, and quasi-optical coupler, filter, or antenna. The most general form of the continuous transverse stub element comprises an antenna that includes the following elements: (1) a dielectric element comprising a first portion and a second portion that extends generally transverse to the first portion that forms a transverse stub that protrudes from a first surface of the first portion; (2) a first conductive element disposed coextensive with the dielectric element along a second surface of the first portion; and (3) a second conductive element disposed along the first surface of the dielectric element and 2 o disposed along transversely extending edgewalls formed by the second portion of the dielectric element. The numerous other variations of the transverse stub element are formed by modifying the height, width, length, cross section, and number of stub elements, and by adding additional structures to the basic stub element.
2 5 Other aspects of this invention are as follows:
An antenna array comprising:
a planar sheet of dielectric material having two generally parallel broad surfaces separated by a predetermined distance and having a plurality of elongated, raised, relatively thin, rectangular dielectric members formed 3 o along a broad surface of the sheet of dielectric material that extend across one dimension of the broad surface and that extend away from the broad surface, and wherein the plurality of thin rectangular dielectric members are spaced apart from each other by a predetermined distance; and ~ ~1 4 2a a conductive material disposed on the broad surfaces of the sheet of dielectric material and on transversely extending edgewalls formed by the plurality of thin rectangular dielectric members so as to define a parallel plate waveguide having a plurality of continuous transverse stubs disposed on one plate thereof, and wherein distal ends of the plurality of thin rectangular dielectric members are free of the conductive material so as to define a plurality of radiating elements, and wherein an edge of the sheet of dielectric 1 o material is free of conductive coating so as to define a feed for the antenna array.
A method of making a continuous transverse stub antenna element which comprises the following steps:
processing a sheet of dielectric material to form an integral dielectric member having two generally parallel broad surfaces and at least one elongated raised relatively thin rectangular dielectric portion extending transversely across one of the broad surfaces;
metalizing the exterior surfaces of the dielectric member to define a parallel plate waveguide having at least one continuous transverse stub 2 o disposed on one plate thereof; and removing plating from predetermined surfaces of the exterior of the parallel plate waveguide to permit coupling of energy into and out of the antenna element.
Purely-reactive stub elements are realized through conductively 2 5 terminating (short circuit) or narrowing (open circuit) the terminus of the - stub. Radiating elements are formed when stubs of moderate height are opened to free space. Precise control of element coupling or excitation (amplitude and phase) via coupling of the parallel plate waveguide modes is accomplished through variation of longitudinal stub length, stub height, 3 o parallel plate separation, and the constituent properties of the parallel plate and stub media.
The continuous transverse stub element may be arrayed in order to form a planar aperture or structure of arbitrary area, comprised of a linear array of continuous transverse elements fed by a conventional line-source, or 3 5 sources. Conventional methods of coupler, filter, or antenna array synthesis and analysis may be employed in either thc rl~cr~ or spatial ~omqinC to construa stub cl<~ c and aIrays to mect substqnti~lly any applieatio~
Ille principles of the present invention are applicable to all planar array applica-tions at microwavc, millimeter-wave, and quasi-optical Ç~ encies Shaped-beams, S mllltiple-beams, dual-polarization, dual-~ands, and monopuLce functions are achieved using the prescnt invention. In ~ 1~1iti~n, a planar col~tin~ lc t~nsver e stub array ic a primc candidatc to replace refleaor and lens ~~ennq-c in applieq~i nc fo~ which planar arrays havc ~ol~ been il~ap~ A~ duc to tra~itionql bandwi~l~ and/or cost limi-tations.
~d(1iti- nql advantages in millin~-wave and quasi-optical filter and coupler designs are realized due to the cnhq~e~ plod~ibility and relative low-losc ~igh "Q") of the cor~in~luus transverse stub elemPnt as c~ll-pared to stripline, rnic~strip, and waveguide elem~ntc Fllter and coupler capabilities are fully-integrated with radiator functions in a comrnon structure.
BRIEF DESCRIPTION OF THE DRAWINGS
The various features and advantages of the present invention may be more read ily understood with reference to the following det~iled desclip~ion taken in conjunc~on with the acco-~ing drawings, wherein like reference nurnerals ~siEn~e like struc-tural cl~ ul~ and in which:
Flgs. 1 and la illustrate a con~nuQus transverse stub clçm~nt in accoldance with the principles of *e present invention;
Figs. 2, 3, and 4 depict the continuous transverse stub rlc. ~ nt in short~ircuit, open circuit, and coupler configurations, l~li~ely;
hg. 5 depicts a sirnplified equivalent circuit for the continuous transverse stub el~ment based on simple L~ ...;cs;on-line theory, hg. 6 illustrates a nonAi~lectrically loaded cQntinuous transverse stub element;Flgs. 7a and 7b illustrate slow-wave artificial rliele~ic and inhomogeneous structures employing the continuous transver.se stub elen-ent of the present invention;
Flgs. 8 and 8a illustrate a continUQus transverse stub elen~,nt of the present invention ~Sign~ for oblique in- id~nce Figs. 9 and 9a illustrate two orthogonal continuous transver~se stub ele~-nts ofthe present invention designed for dual pol~i7~tion operation;
Flgs. 10 and 10a ill~lst~e p~u~h b~r vanation in the transverse 11;..~ ns;on;
Flgs. 11 and lla illustrate a firlite width ek-.~-UI, Flg. 12 ill.~ es a multi-stage stub/l~n~...;ss:on section;
Flg. 13 illu~ tes paired~l~ .f nlc cO~ lisulg a ..~ e,1 couplet;

21~6541~

Fig. 14 illustrates p~liqtin~ and non-r. ~i-qtinp stub pairs COmrrici~l~ a .I~D;hc~
co~lple~, Fig. lS illustratcs a doublc-sided l~iator/rlltcr, Flgs. 16 and 16a illustrate a radial cl~
S Flg. 17 and 17a illustrate circularly polqri7~ orthogonal ck~ h~
hg. 18 illu~LIdt~s theoredcal cQn~ q~nr!i~ c~.t~,-~ for an x di~d elec~ic field within an àir-filled 6 inch by 15 inch pa~llel platc region fed by a discrete linear a~ay locatcd at y = O and radiating at a L~u~"~y of 60 GHz;
Flgs. 19 and l9a illustratc a typical c~r.l;..~.,s eAl,usion proccss wl~e~eby the 10 stubs of thc cQrltinnQus~ transversc stub array stru~e arc fo~Tne~ etq11i7~d and . ;.-...~d in a c~n~in~QUs sequential operation;
Fig. 20 illuslldtes a discrete process by which individual condnuous transverse stub array structures are molde~Vforrned, met~lli7e~ and tnmm~ in a sequence of dis-crete operations;
Fig. 21 illustrat~s a pencil beam antenna aITay;
Fig. 22 illustrates a complex shaped-bearn ~ntenn~
Fig. 23 illustrat~s relatively wide continuQus transverse conductive troughs formed between indivi~ual continuous transverse stub ele-,~- nt~, Flg. 24 illusll~t~s a slotted waveguide cavity exploitation of the available trough region between adjacent stub elen~n~s;
Flg. 25 illu~llat~s a pair of orthogonally onented continuol~c transverse stub arrays that may be utili~ed to realize a dual-polAn7Ahon rAcliAhon pattem;
Flgs. 26 and 26~ illustrate thick or thin inclined slots ~ in inter~len~nt trough regions;
Figs. 27 and 27a illustrate illustrates the electric field coll~ponenls for TEM and ~01 modes;
Flg. 28 illustrates an intendonal fL~ed or variable beam squint;
Flgs. 29 and 29- illustrate scAnn;ng by l~C~ ni~AI line-feed variadon;
Flgs. 30 and 30- illustrate sc~nning by line-feed phase velocity vasiation;
Flgs. 30b and 3 ~c illustrate scanning and tuning by parallel plate phase velocity variation;
Fig. 31 illustrates sCAnning by frequency;
Flgs. 32 and 32 illustrate a confo~nal array;
Flg. 33 illustrat~s an endfin~ arra~, -Flgs. 34 and 34 illustrate a non scp~able shared a~ray, Figs. 35 and 35- illustrate a conhn-lous transverse stub array co~-fi~l~ed in radial form;

21~6546 s hgs. 36, 36a, 37 and 37a illustrate filtcrs employing non~ ~active continuous transverse stub elc .~
Flgs. 38 and 38a illustratc couplers cmploying non-r~ tin~ reactivc continu-ous transverse stub ele~e~
S Fig. 39 is a top view of an em'o41;~ of a continuous transvcrsc stub array in acco~lanoe with thc present inven~iol~, Fig. 40 is a side vicw of thc C~ ;n~ous transvcrse stub array of Flg. 39; and hg. 41 ill~ at~ s a u~.u~l E-planc pattcm for thc c~n~ o.,s tl~ X stub array of Figs. 39 and 40 I~.u~ at a frequency of 17.5 GHz.
;DETAILED DESCRIPTION
Figs. 1 and la illustrate cutaway side and top views of a cQntinuoQs transversc stub element 11 (or stub 11) in its most col.~,~n hornogeneous, dielectrically-loaded, form, that forrns part of a parallel plate waveguide or tr~nsmiCsion line 10, having first andsecondparallelterminusplates 12,13. Thestubelement 11 hasastubradiator 15 exposed at its outer en~, which is a portion of dielectric material that is disl)osed 'oetween the first and s~cond parallel ~ ;nllC plates 12, 13. One of t'ne t~lllinus plates 13 covers the edgewalls of the stub element 11. Incident z-traveling waveguide modes, launched via a pnmary~ line feed of a~ y configuration, have ~cs~at~d with them longin.din~l, z di~cted, electric wall cuIrent co~yonenLc which are il~t~lu~led by the presence of a continuous or quasi-continu~1c y-oriente~, transvcrse stub el~ nt 11, thereby exciting a longtudinal, z dil~t~ displ~remPnt current (electric field) across the stub ele~-n~ 11 - p-~allel plate 12, 13 inl~,Çace. This induced ~icpl~sn.f nl c~rent in turn excites equivalent x-traveling waveguide mode(s) in the stub ~ l 11 which travel to its terminus ar d either radiate into free space (for the l~iialor case shown in Figs. 1 and la), are coLpled to a second parallel plate region (for the coupler case shown in Fig. 4), or ar¢ totally reflected (for the purely-reactive filter case shown in Figs. 2 and 3). For the radiator case, the electric field vector (polanza~on) is linearly-oriented transverse (z-clirected) to the c~tinuou~ transverse stub el~ nl 11. Radiat-ing, coupling, and/or r~active continuo~.s trarLsverse stub ele . ~-nls may be cornbin~
a common parallel plat~ structure in order to foTm a variety of l.~wd~e, millim~wave, and quasi~ptical colnponents inclufling integrated filters, couplers, and antennq arrays.
Figs. 2, 3, and ~ depict the basic COntinuQus transverse stub ele-.~ -l 11 in its short-circuit, open-circuit, and coupler configurations, lcs~li~ely. In Flg. 2, ~e second parallel plate l; bridges acToss dle end of the stub e~ -nt 11 via rr~t~ ti~n 1 3a creating a short cincuit stub ele~w nl l l a In Fig. 3, the second parallel plate 13 is 21g65~6 non-bridging and the cle~ ,nl 1 lb is na,.~... ~ creating an o~en ci~uit stub rlc~
1 lb. In Fig. 4, both cnds of thc stub el~ t 11 are opcn to f~S~li~C first and se~ond parallel plate waveguides 10, lOa, thus creating a coupling stub elc ~ n~ 1 lb'.Back-~U~i energy f~om l~pccli~e ones of the paralld plate waveguide 10 S and shoçt circuit stub elc ~R,nl lla, ~en ci~uit stub ek~ 1 lb and fn~e space, and coupling stub elç~ 1 1 lb' and second waveguide lOa interfaces coh~.ltly interact with in~l~nt energy in thc conve-~ n~ .-ics:on-line scnse as is givcn by thc following e~lua~iol~s.
Sl1 = S22 = (1 ~a) Sl2 = S2l = (1+ a) KI2 1 1 +lal2 where 1 + al2 ~ _ ( h ~ -1 + rsexp-j2~l r = Yo - Ys ~ 2b l rseXp-j2~11 ' s Yo+YS
These interacdons are co..l~hcnsively model~d and exploited using standard tr~nsmission-line theory. Fringing effects at both ;ntC~f~l es are a~uately m~eled 15 using conventional mode-matching t~chri.lcs The variable length (1) and height (h) of the coupling stub element 11 (hg. 1) controls its el~tnc;~l line length (~11) and char-acteristic a~ ncC (Yl) I~,~;ti~dy and in doing so, allows far controlled ~ Çar-mahon of itS termin~ ce (primarily d~nd~nt on b and ~) back to the main parallel plate tr~ncmis~ion line 10, whose char ~enctiC ~Idmi~t~n~ is govemed by its height (b), and in this way allows for a wide range of discrete coupling values (IKI), equal to the coupled power over in~dent power, of -3 dB to less than -35 dB. Varia-tions in the length of the coupling stub elern~nt 11 also allow for straigl~ i phase mod~ tion of the coupled energy, as l~Ui~O~ in shapcd-beam antenna and multi-sugc filter applications.
hg. 5 depicts the simplified equivalent circuit from which are derived sc~t.,.ing parameters (Sll, S22t Sl2~ S2l) and coupling co~.fficiçnt (1~D2) for the continuous transverse stub element 11 based on simple Ll ~n~...;ss~ -line theoly. Note that cou-pling values are chiefly dependçnt upon the l.~ch~ical ratio of the height (h) of the stub elçmcnt 11 relative to the height (b) of the parallel plate waveguide 10, cons;s~ n~
30 with a simple voltage divider rel~tionshir. I~lis ~h~ni~l ratio is independe,~t of thc operating ~uenc~ and dielccll;c c~.~- -t of the sl~uclul." and the c~.~ .o~< trans-verse stub ele-..~ 11 is inh~"e,~ ~dl~d and forgiving of small v~ i~tiQnc in "Y~hAni~ and conc~ enl m~tçri~ a~;nr~ C~n~urn~ YS are set to infinity 2I ~654 6 for a short~rcuit, zero for an open~uit, or Y2 for a coupling configuration without loss of gcner lity.
Fabric~on of the ~1iele~1Ticqlly-loaded c~ntinuQI)s tlansverse stub el~ 11 is effici~ntly ~ r~..plichP~d through IIL'C~ ;n~ or molding of the r~ chic s~c*~e, fol-S lowed by nni~ c4n~cl;~e plaong in order to form the parallel plate trr~ crniss~on-line 10, and, in the cace of qnt~nnq ~plicqtions~ hinin~ or grinding of the t~ sof the stub rle~-~Q~ 11 in order to expose the stub ~diator 15 (hg. 1). l~lere a e null~uus v~ia~ons upon the basic c4~t;~ JouS transverce stub ck~ 11 which may be useful in particular applic~ic~C l~ese v~ri~ti~n~ are described below.
A nort~ e~ lly loaded stub ele-~.c-~l 1 lc is shown in Flg ~ A low density foam 16 (c4rnprising about 99% air), or air 16, may be employed as the tl; Q~ ;SS~n line ~ .n~ for the continuous t~ansver~se stub ck ~ t 1 lc in o~er to ~ali~ an effi-cient elernent for an end-fire array or b~n~stop filter, for example. T~e nondielectrical-ly loaded continuous transverse stub element 1 lc is particularly well-suited in such 15 applications due to its broad pseudo-uniform E-plane element pattern, even at endfire.
Slow-wave and inhomogcneous structures 21, 22 are shown in hgs. 7a and 7b. An ar~ficial dielecLric 23 (co~ugated slow-wave strucnlre 23) or multiple dielectric 24a, 24b (inhomogeneolls structure 24) may be employed between the parallel plates 12, 13 in applications for which minim~l weight, complex frequency d~ndencc, or 20 precise phase velocity cont~l is ~ui~l An oblique incidençe stub element 1 ld is shown in Flgs. 8 and 8a, which show cutaway side and tûp views, ~ ely. Oblique incidence of propa~tin~ waveguide modes are acluc~_d through ~l~cll~n~ or ck~ ;c~l variation of an in~ming phasc front 27 relative to the axis of the c~l;n~ous transverse stub element 1 ld for the pur-25 pose of sl~nning the bearn in the transverse (H-) plane. This variation is normally U11POSed through .. .~-h~nic~l or elw ~ ;~l variation of the primary line feed e~Ccitin~ the parallel plate region. The precise scan angle of this ~c~nned beam is related to the angle of incidence of the waveguide mode phase front 27 via Snell's law. That is, refraction occurs at the stub ele~ent 1 ld - free space interface in such a way as to m-agnify any 30 scan angle ul~yosed by the m~cll~nic~l or electrical variation of the line feed. This phe-no~n~ is exploited in order to allow for relatively large antenna scan angles with only small variations in line feed orient~tioJl and phasing. Coupling values are pseudo-con-stant for small angles of incill~nce.
A longinlrlinql ;nc i~lennc stub el~ nl 1 le is shown in Flgs. 9 and 9a, which 35 show cutaway sidc and top views, .~s~li~ely. A nanow conti"uous transverse stub element lle does not couple ~lo~ nl waveguide modes whose phase fronts are per-penrlicl-lqr to the axis of the stub elen~ent 1 le. This characteristic is e~lc.it~ through implemcntation of orthogonal COntinuollc transversc stub radiator ~ 11, 1 lc in a common pa~llel plate rcgion ccnll~liscd of pa~allel phtes 12, 13. In this way, nvo isolated, olll.ogonally-polarized qntennq modes arc simultaneously ~ t~i in a shared apc.~u,c for thc pul~osc of re-q~ inP dual-polari~ation, dual-band. ordual-beam S capabiliticc.
Pal~c~ vanation in the transverse ~ nSiQn is shown in Flgs. 10 and lOa, which show cu~-. ay side and tx~p vicws, .es~c~i~cly. Slow variadon of thc dimen-sions of thc stub ek-~-f ~ 11 in thc t~ansverse (y~;~n.~nS <!n) may be employed in o~dcr to reali~ tapered c~plin~ in thc transverse plane. 'This c~bility proves useful in 10 q~nt~nnq aTray app~ q~ nc in which non-separable a~ ~ tributi~s are desi~ble and/or for non-reaanglllar array shapes. Such a m~ificd clc .~ is known as a tapered or quasi~ontinuous transverse stub elem~nt 1 lf.
A finite width element 1 lg is shown in Figs. 11 and 114 which show cutaway side and top views, respectively. Although conventionally very wide in the transverse 15 (y) extent, the continuous transverse stub element 11 may be utilized in reduced width configurations down to and including simple rectangular waveguide. The sidewalls of such a truncated or finite width continUouc transverse stub ele ..e~l~ 1 lg rnay be termi-nated in a surface 17 which may be conductive, nonconductive or absorptive usingshort-circuits, open4ircuits, or loads, as ~ict~ted by a particular application.Multi-stage stub elem~n~ 1 lh and tr~ncmicsion ~ionc 27 are shown in Flg.
12. Multiple stages 18 may be employed in the stub elen~nt 11 and/or parallel platec 12, 13 in order to modify coupling and/or broaden frequency bandwidth charact~ cs of the ~llucnl.e as ~ Ared by sp~;irlc electrical and m~hi niA-; l co~sllOints.
Paired~l~ er.l~ 1 li, 1 lj, comprising a mi tche~ couplet, are shown in Flg. 13.Pairc of closely spaced similar continuous transverse stub radiator elements 11 may be employed in order to ~ e co...~ e ~ntenn~ elen~r-t factors (~1;..,;~ for b~dside endfire, or squinted operation) andlor to minimi7~ co.--pos;~e cle---f nt VSWR through destructive ~ ~cncc of individual refl~tion contributions (quar~r-wave spacing). Likewise, b~n~lpcs filter implem~nti tions may be realized in a similar 30 fashion when purely-reactive continuous transrverse stub eleln.ont~A 1 la, 1 lb (Figs. 2 and 3) are employed. Reactive stub ele.,~nls 11 employ the elements 1 la, 1 lb shown in Figs. 2 and 3, for example.
ting and non-r~ ting stub elem~nt pair 1 lk, 1 lm com~ ing a ...; tnl~Cd couplet 19, are shown in Fig. 14. The non-r~ ting purely-reactive cvnl;n~o~s trans-35 verse stub ele--~e-~t 1 lk may be paired with the r di~ting conl;.-uo~Js transver.se stub radiator elem~ont 1 lm as an alterna~ive method for ~u~l~sion of coupler-radiator reflections through desIructive interference of their individual reflection contnbutions, 2 ~

resulting in a matched continuous transverse stub coupler 19. Such couplets 19 are particularly useful in continuous transverse stub element array antennas where it is required to scan the beam at (or through) broadside.
A double-sided radiator/filter 28 is shown in Fig. 15. Radiator (Fig.1), coupler (Fig. 4), and/or reactive (Figs. 2 and 3) stub elements 11n may be realized on both sides of the parallel plate structure for the purpose of economizing space or for antenna applications in which radiation from both 0 sides of the parallel-plate is desirable.
A radial element 29 is shown in Figs. 16 and 16a, which show cutaway side and top views, respectively. The continuous transverse stub element 11 may be utilized in cylindrical applications in which cylindrical (radial) waveguide modes 28 are employed in place of plane waveguide modes. The continuous transverse stub element 11 forms closed concentric rings 29a in this radial configuration with coupling mechanisms and characteristics similar to that for the plane wave case. A single or multiple point source(s) 26 serves as a primary feed. Both radiating and non-radiating reactive versions of the continuous transverse stub element 11 may be realized for the 2 o cylindrical case using stub element 11 configurations disclosed above (Figs. 1-4). Such arrays may be particularly useful for antennas requiring high gain 360 degree coverage oriented along the radial (horizon) direction ~ and in one-port filter applications.
Circularly polarized orthogonal elements 11 are shown in Figs. 17 and 2 5 17a, which show cutaway side and top views, respectively. Although the continuous transverse stub radiator element is exclusively a linearly polarized antenna element, left and right hand circular polarization (LHCP, RHCP) is re~li7e~1 in a straightforward fashion either through implementation of a standard quarter-wave plate polarizer (not shown) or 3 o through quadrature coupling 30 of orthogonally-oriented continuous transverse stub radiator elements 11 (orthogonal elements 11) or arrays.
Arraying of continuous transverse stub coupler/radiator elements 11 include the following considerations:

Line feed options: As mentioned previously, the continuous transverse stub element 11 may be combined or arrayed in order to form a planar structure fed by an arbitrary line source. This line source may be either a discrete linear array, such as a slotted waveguide, or a continuous linear source, such as a pill-box or sectoral horn. Many conventional line sources may be adapted for use with the present invention, and these are disclosed in the "Antenna Engineering Handbook", edited by Jasik, McGraw-Hill, (1961), particularly chapters 9, 10, 12 and 14.
Two line sources are used in filter and coupler applications in order to form a two-port device. In the case of antenna applications, a single line feed and line source are utilized in order to impose the desired (co~ 3;stribution in the t~ans-verse plane (H-plane) while the p&~t~.~ of individual cQnti~uo ls transverse stub radiator ~k~ 11 are vaned in ord~to control the (CQ~ ) ap~ ctribu~ion in dle longiodin~l plane (E-plane).
Waveguide modes: As an o e ..... ~ structure~ the parallel plate l"~ on line 10 within which the continuo~lC t~ansverse stub ~le ~~ (s) 11 re ide suppon a number of ~. a~l;uide modes which cimlll-a~ol~cly meet the b~ cQ~ itionc i...l~l by the two co~ 3uu1;~g plates 12, 13 of the s~uc~ . The n~ and reladve intensit,v of these prop~g~ting modes ~i,~n~lC acclus;~cly upon the trar.s~ excita-10 tion function ;-~ by the finite line sourcc. Oncc c~te~3 thcsc modc ~r.-ir-.-c are ~,n...od;r~ b,v the presence of the CO~ .VQ~ transverse stub ele-.~t 11 because of its continuous nature in the transverce plane.
In theory, each of these modes has ~Cs~cd with it a unique propagation ve-locity which, given enough distance, cause undesirable di~ /e variation of the line source-imposed excit~tion function in the longitudin~l propagation direcdon. Howev-er, for typical excitation functions, these mode velocities differ from that of the domi-nant TEM mode by much less than one percent and the tTansverse plane eYcit~tion im-posed by the line source is thc,e~.e e~nt~ y tl~nsl~t~A without l.~l;r.~-~;on, over the entire finite longi~lldin~l extent of the c~ntin~lol~c transverse stub array ~llU.
Flg. 18 illusll~tcs the th~let-cdl corlsl~lt ~litud~ colllou~ for the ~t d;l~
ele~ctric field within an air-filled 6 inch by 15 inch parallel plate region fed by a discrete line~r array located at z = O and r~di~ting at a frequency of 60 GHz. A cos.nc-squared arnplitude eXcitqtion was chosen so as to excite a mllltitu~lc of odd modes within the parallel plate region. Note the ~fi' Ct~ Uy of the ihn~d tlansverse eYcit-q-tion over the entire lon~ituflinq~l extent of the cavity.
Edge and end loading effects: The relative ~l~ce of edge effects in the continuous t~ansverse stub array is primarily depen~ent upon the ~osed line-source excitaion function, but these effects are in general small becanse of the strict lor.~,;l..(l;-nal di~cion of propagation in the sllu~-lule. In many cases, especially those employ-30 ing steep eXcitqtion tapers, short circuits may be il~uduced at the edge boun-~-q-nes with little or no effect on internal field ~lic~ibutionc In those applications for which edge effects are not negligible load n~qt~riqlc may be applied as required at the array edges.
In oertain a~licat ons a second line feed may be introduced in order to form a two-port device, such as a coupler or filter, comrr~c~ of c~ntin-lQus ~ansverse stub 35 coupler or reactive el~ ~ - lefi~ For antenna a~pl;c c~nnC dth~ a short circuit, open cir-cuit, or load may be placed at end of the c~ ;n~ O~s transverse stub array, ot)positc the 2146~6 tine source, h o~ter to form a conventjQr~l s~ inp-wavc or travcling-wave fe~
Thcsc wilt be ~ in detait below.
AITay, coupl~, filter synthesis and anatysis: Standard a~y coupler and filter syn~esis and anatysis ~ ues may bc anployect in the s~k~ n of inter el~ rn~
S spacings and elec~ical p~ete-~ for individual c~ntinl~uS trans~cr.sc stub et~n~
11 in c~ ;nuous ~ansverse stub a~ray applications Externat mu~at couplin~ cffects ~et~.~en radiating stub ~ K ~t~ 11 arc ~- o*led using standard d~ c thcory.Nonnqli7~ design ~~es rela~ng thc ph~ l q~ ibu~,s of thc c~ o.Js t~nsvcrsc stub ele~n~n~ l l to c1~1~ ;r~l pa.all~t~l~ arc dcrived, eithcr an-qlyt;cally ~ Cmpi~;Cdlly~ in 10 order to reali~ the desired cor 1;--~O~ trarLsverse stub array ch~- b ~ ;~I;CS
Design r,onl~cul--ng engincering costs and cycle-time: Ihc simple modu1q~
design of the c~ntinuous transverse stub alray concept greatly reduces the design non-recumng engine~nng costs and cycle-time associated with conventional planar arrays.
Typical planar array developments require the individual specification and fabrication of 15 each discrete radiating ~lement along with associated feed c~llponents, such as the angle slots, input slots, and corporate feed, and the like. In contrast the continuous transverse stub planar ~rray requires the spff1fic~qtion of only two linear feeds one com-prised of the array of continuous transverse stub elementc 11 and the other comprised of the requisite line-feed . These feeds may be designed and modified sepO,atelr and 20 concullenlly and are fully spe~ifi~l by a ~ -numba of unique ~h,~t~.~
~rawing counts and d~wing complexities are therefore ,~ll~ced~ ~esign mf~ifi~tionc or iterations are easily nd quickly imp~ .Y ~t~d Fvqb~ ;f ~;on opLonS; Mature f~bric~ti~ n technologies such as extrusion, injection mo1 ling and them~mo'ding are ideally suited to the fabrication of c~ntinllollc tra ls-verse stub arrays 30. ~ many cases the entire continuous transver-ce stub ar.ray, inclu~lin~ all feed details. may be fomled in a single exterior mol linf~ ~peration.
A typical three-step fabrication cycle inc1udes: structure fom~qtiorl, either bycontinuous ~ sion or closed single-step moldin~, unifo~l~ ext~ior met~q1i7~qtir n, either by plating, p~int1ng, Iqminq-tion, or deposition; and planar grinrling to expose input, output and rq~ ing surfaces. Due to the qbse~e of interior details the continu-ous transversc stub arr4y l~uu. s t~t~lli7q-tion only on exterior surfaccs with no stIin-gent ~uil~i~nt on m tq-lli7~q-tion thir~n~ss unifolmity or mq~in~
Figs. 19 and l~a, depict top and side views, l.,s~cLi~ely, of a typical continu-ous extrusion process ~I.ell,by the stubs l l of the corltinuous transverse stub array 30 are fomled or molded 31, rn~tq-lli7~d 32, and 1~-~ed 33 in a cont;i-uous sequential operation. Such an operation results in long sheets of continUolls transverse stub arrays 30 which may subse~uently be diced to form individual c~ntin~louC transverse 21465~6 stub arrays 30. Fig. 20 depicts a similar d;s~ t~ process by which individual continu-ous transverse stub amys 30 are molded or formed 31, metq~ ed 32, and ~ Kd 33 in a sequence of disclct~ operations.
As ~iscuc-~ed pr~iously the relaivc ;~SC~S;I;vity of the non-l~nant continu-S ous transverse stub cl~ - ~ 11 to ~ n5:onql and mq~nql variations g~atly e~lhqnrcs its pr~ducibility relative to co~ r~son''n~ app,uaches. This, in conjllnctic-n with the relative s;~Y~rlic;ly of the design and fa~ication of the c~ c transvc~se stub alIay 30, makc~s it an ideal cq~id,qt~ for low cost/high p~ ,i~.- ratc ~pp!i~l;onc Con~im~oUS l-~r s~_ ~e stub array applic~ioQc: A penc~ beam antenna a~Tay 40 10 is shown in hg. 21. A standard pencil beam qntenn~q array 40 may be constructed using the conhnl~lC ~ sverse stub array ~pt with p, ; ~1~ plane ey~tionc imple..~ntcd through ~p~iat~ selection of line-source 39 and continuous transverse stub elemen~ P~;IA~ Flement spacings are conventionally chosen to be appro~u-mately equal to an inte-~al number of wavelengths (typically one) within the parallel 15 plate region. Monopul~e functions may be realized through a~lv~,iate modl~ on and feeding of the continuous transverse stub array ape. lUI1.
A shaped-beam ~nt~nn~ array 41 is shown in Flg. 22. The variable length of the stub portion of the continUQus transverse stub elem~nt 11 allows for convenient and precise control of individual element phase~s (resulting from varying the ek!~w -l lengths 20 In~ In+l) in continuous Dsverse stub ~ntçnn~ array appli~t1~c This control in COQ-j~lnsti-~n with the c~nti~ uo~ls transverse stub ele ~ent~s conve~l ;on~l capability for dis-crete ~mplin1de variation allows for plecise spe~ifir~tion and re~li7~tiQr~ of complex shaped-beam ~ntenn~ pall. l.ls. Likewise, nonunifoqm spacing of continuous trans-verse stub ele ..~ n~s rnay be employed in order to produce shaped-beam patt~mC Ex-25 arnples include cose~ -squared and non-symmetric sidelobe al,plica~;ons F~ploit~tion of lunused inter ek ~-~t area The c~n~ Jc.us stubs of a continu-ous transverse stub arr4y typically occupy no more than 1(}20 percent of the total planar ~ntenn~ ap~ andlor filter area llle r~ tin~ a~,l~es of the e stubs are attheir termination and a~e therefore raised above the ground-plane forrned by the main 30 parallel-plateL,,.n~ line10. Relativelywide contin~ouC transversecor~ ivetroughs 43 are therefore formed between individual continuous transverse stub ele-ments 11 as is depic~ in Flg. 23. These troughs 43 may be exploited in order to introduce secondary ar-ay Sl uClul~,S.
Other e~rlo~ O~c inc!~lde closing the trough 43 in order to foqm a slotted 35 waveguide cavity 44 is shown in Fig. 24; inter(~i~it~tion of a p~inted patch array; and slotting of the troughs 43 in order to couple alternative modes fr~n the parallel plate 21~65~6 trq~lsmicsion-line 1~, oe intrt)duction of ac~vc cl~ t~ as adjuncls to thc con transverse stub an~y structurc.
Flg. 25 is useful in illustrating throe different ~l~t,Cnn~ arrays 45. A dual-polar-ization qntenna array 45 is shown in Fig. 25. An idcnti~l pair of alrays of o~hog~
nally~iented cQr~tinuo~lc t~Lsverse stubs 11 may bc utilizod in o~der to ~alizc a dual-pol~on (~ Illogon ~1 senses of linear) planar array 45 sharing a cc -.---~ apc.lu.
area. Circular or elliptical pol. rizations may be ~alized tluoi~gh ap~vp~latc co~
tion of thesc two o~hogonal signals ~ ' to signal inpuLc 49a, 49b of the linc so~c 39 using fixed or variablc qUadlalu~; cou~l~. s (not shown) ~ with the .~t~v.h~ of a conventiQnq1 linear-to4ircular po~ AI;On polanza (not shown). Thc purc linear polanzation of individual con~ louS transversc stubs 11 and the natural orthGgonal;lr of the parallel plate waveguide modes provides this apploacll with su~ior broa~n~
polarization isolation.
In a manner si~ilar to the aforementioned dual-polarization ap~lo~ch, two dLC-similar orthogonally-orient~ arrays of con~n~ouC transverse stubs 11 may be employ-ed in order to provide a sim~llt-qneous dual antenna beam capability provided by a dual-beam antenna array 45. As a specific eY-q-ml~le, one contin,~o.ls transverse stub a~ray 11 would provide a vertically-polarized pencil beam for air-~air radar modes, while thc other continuous transverse stub array I le would provide a ho.~onlally-polanzcdcQser~nt-squared be~ for ground l"apping). Dual s luint~ pencil beams for mic~
wave relay ,~;~,l~nts a second application of this dual beam capabili~.
Again utilizing a pair of arrays of olthogonally-~;cnt~d continuous transve~c stubs 11 a dual-band planar array 45 may be consl.u~ duough applvpliatc y~ n of inter ek-~ Y nt ~ac~l~,s and continuous transverse stub e4 ~.~f n~ p~t~.~ for cach a~ray. The two selecte~ frequency bands may be widely Sepa~dt~l due to the disper-si~nless nature of the p~allel plate tr~n~m;ssion line slluclulc and the L~uchc~-indc-pendent orthogonality of the waveguide modes.
A dual-pol~i7- t~or., dual-beam dual-band antenna alTay 46 (~l~le modcs) shown in Flgs. 26 and 26a Periodically-spaced slots 47 may be inll~iuce~ in the previously described troughs 43 between individual continuous transvcrse stub clc-ments 11 in order to couple ~l~n~tive rnode sets from the parallel plate ~ .S~n:c~
line 10. As an exampl~ a TEol mode who~se electric field vector is oriented parallcl to the contluchng plates 12, 13 of the parallel plate L.i~fi~ ;ss;on line may be selectively coupled through the i~ J~Ic!;ol- of thick or thin i-~!in~d slots in the inter-element troughs 43 as depicted in Figs. 26 and 26a, which show culawa~ side and top views, ~cs~ely. These slots 47 rnay protrude slightly from the con~3ucl;~e plate grou~
plane (parallel plate 13) in order to aid in fabrication. Such a mode is not coupled by 21~6546 the contin-lolls transv~lG stub ~ c 11 duc to thc transvcrsc ~nt_tion of its induc~ wall c~.Gnb and the cut-off cor~;t;ons of thc continuo~)s transvG~se stubs to the TEol modc.
Likcwisc the waveguide modcs of thc parallcl platc wavcguide structure, with S i~s elec~ic field vectar ulie~ ..lq. to the c~ducting platcs 12, 13 of thc p~allel plate tn~-~n~isC~n linc lQ arc not coupled to the ~ !incd slots 47 due to thc dispaIity in ope,~ing a~Jd slot l~sonant L~ucQ~ies particulariy fo~ thick (cut-off) slots.
In this w. y a dual-band planar array 46 is fonncd with L~q~.cra,~ band offscts regu latG~ by thc intcr ch,~.ll spaang of thc ~ lo~s tlansvcrsc s~ub and in-~line~d slots 10 .,nd the paralld-platc sp~ing of hc paIallcl plate ll~n~n~;ss o~ linc 10.
Flgs. 27 and 27a depict the electric ficld co~pon~nts for TEM and TEol mvdes.
Dual-beam and dual-polarization ap~.lules may bc realized using intentional m~ Tode operation in a conventi~nal manner.
A squinted-bearn anteMa array 49 is shown in Fig. 2~. An intentional fixed or 15 variable be~m squint, in one or both planes, may be realized with a continuous trans-verse stub array 30 thro~gh applop~iate selection of the spacing ~t~.cen continuous transverse stub ele -~n~ 11, c~nCtihU,~lt material ~ e~c ~!r~ nl and/or l~uisit~ linc feed ch~a~ islics. Such a squinted a~ay 49 may be desirable for applica~,ons in which mounting constraints require deviation beh. ~n the mechanical boresight and tbc 20 electrical boresight of the ~nSelln~
-c~nnin~ by m~h~nic~l line-feed va~iation with respect to an antenna array 50 is shown in Flgs. 29 and 29a, which show top and side views thereof"~ccti~ely.
The requisite line-feed ~9 for a co~t;n~VUc transverse stub antenna a~ray 50 may be mechanically dithered in order to vary the angle of inci~nc~ (phase slope) of the pr~
25 agating parallel plate waveguide mvdes relative to the conn.~ c transverse stub ele-ment axis. In doing so, a lerla~,lion e~ nr~l bearn squint (scan) of the ~ntt'nn~ beam 51 is realized in the tlar sverse (H-plane) of the array 50.
Scqnning by linc-feed phase velocity variation with respect to an antenna ar~ay 50 is shown in Figs. 30 and 30a, which show top and side views thereof, .~s~i~ely.
30 An altemative method for variation of the angle of incidçnce (phase slope) of the pro~
agating parallel plate w~veguide modes relative to the C~ntinuous transverse stub ele-rnent axis is employed. This is âch~ ;xl thrvugh çle~tnc~l or ~ h~ l variation of the phase velocity within the requisite line-feed by mod~ ion of the cQfi>~ enl p~v~
erties andlor 01 Içnt~ti~ of the ~ ~ic mq~iqls within the ~. a~,E,.~ide or through 35 mod~ tior. of its ll~n~e ~e ~1;..~r.~ c Such variation causes sqllinting (~ ,.;ng) of the phase front 51 em~ting from the line source while ~ nil~E a fixed (paIallel)rnechanica~ ;.,nt~;on relative to the continuouc t~nsverse stub element axis.

21465~6 s ~ C3nning and t,uning by pa~lld platc phasc vdocity variation as shown in Flgs 30b, 3ûc. Variation of ~e phase velocity within the parallel plate t~ncmicsion-linc 10 scans the beam (~ 2) for ~ntenn~ applic~tions in the longitudinal (E-) planc. Such a variation may be induc~d through ap~ ialc el~tlical and/or n~h~nic~ )dubti~n 5 of the cQncnn)ent ~.. ~ ~.cs of the diel~l,;c material (~r) cont~ined within the pamllel plate regio L Sc~ning ~y this t~rhnique in the h n~ ~;n~l planc may be C~m~
with previously mcntioncd scanninP I~Lniques in the transverse planc in ord~ to achieve simultaneous b~am se~ ng in two ~ n~;ol~s Ihi ..~d~ in phasc velocity within the para lel plate t~ ;s~ -line 10 may also be employed in continu-10 ous transverse stub array filter and couplcr sLlu~ùfes in order to ~ uency tune theirres~c~ive l~nse5, i~ cluding p~Csb~n~1s~ stopbands, and the like.
Sc~nnin~ by frequency is shown in Fig. 31. When utilizcd as a traveling wave antenna array 50, the position (squint) of the ~ntenn~ m~inbe~m varies with frequency.
In applications wher~ t~is phenomena is desirable inter-element spacings and material 15 dielectric conct~nt values may be chosen in order to enhance this frequency-dependent effect. As a particular example, a contim]Qus transverse stub array 50 fabricated from a high dielectric n~t~n~ = 12) exhibits apl,~" ;. . .~tely a 2 degree beam scan for a 1 percent variation in operating frequency.
A conformal a~ay 53 is shown in Figs. 32 and 32a, which show side and top 20 views thereof, ~;s~ ively. The absen~e of intemal details within the continuo~ls transverse stub ~ll Uclu~e allows for convenient defo~nation of it~s shape in order to con-fonn it to curved rnoun ing surfaces, such as wing leading edges, missile and aircraft fuselages, and aulo~obile bodyworlc, and the like. The ovem~oded nature of the con-tinuous t~ansverse stub array 50 allows such defolllla~ion for large radii of curvature 25 without ~.lul~tion of its planar coupling charaaeristics.
The inter ele .. ~ I tr~ughs 43 in the con~ .ol~s transver~se stub a,lay 53 may provide a rneans for ~u ~ression of undesirable surface wave phenomenâ ncnmally associated with oonf~ll lal arrays. Dcf~ulalion or cuIvature of the radiated phase f~ont em~n~ting from such a curved cont~nuous transverse stub array, such as the confol,~
30 array 53, may bc cc~-~t~d to planar through app,~pliate selection of line feed 39 and individual continuous thnsverse stub cl.~ 11 phase values.
An endfire arra~ 54 is shown in Fig. 33. The continuous transverse stub array may be oplilniLed for ehdfire operation (illù~ t~d by arrows 54a) through a~l~pliate selection of inter~lç~ nt spar1n~; and constihlent mqt~l characteristics. The elevat-35 ed loca~ o~, relative to -he inter-stub ground plane, of the top ~ f~s of the individual COntinuQus t~nsverse ~tub radiator el~ c~ 11 affords a broad ~ f n~ factor and therefore yields a distinct advantage to d e continuous transvcrse stub CL _-~ nt 11 in cndfirc applications.
Top, side, and end views, ~ ely, of a non~cpq~able shared array 55 are shown in hgs. 34, 34a, and 34b. Variation of con~inllo~.c transvcrse stub ck-. ~ n~
S pO~cte.~ in the transve~e plane yieldc a quasi~ontinuo.~s tTansversc stub el<..~
1 lf which may be utili~ed in quasi~-~ o-)s transverse stub arrays f~ which non-separable ape.lu e Aictributionc and/or non-recr-ng~ apc.lul~- shapes, such as ci~ular or cllipticaL or the like, are desi~d. For c~l;n~o~s c~n~othly-valying ~nlq i~!n of quasi~ontin~ous t.~ .se stub cl~ nt pa-~t~ the e~ ;on propagation and 10 coupling of higher ord~r modes within the quasi-conl;n~o.,s transversc stub aTray ~lluclu~ can be ~Csu~ to be locally similar to that of the standard c~inuous trans-verse stub array 50 and hence the ~Il~inuous transverse stub array design c~lualions may be applied locally across the transve~ie plane in quasi-continuous t~nsverse stub applications.
Low radar cros$ section pot~nLial: The absence of variation in the transve~e plane for continuous transverse stub arrays 50 elimin~te~ scattering contributions (Bragg lobes) which would otherwise be pr~sent in traditional two~im~nsi~l arrays comprised of discrete r~ ting elen ~ r~ In addition the dielec~ic loading in thc con-tinuous transversc stub array 50 allows for tighter (smaller) inter cl~-n ~ spacing in the 20 longit~ldin~l plane and herefore provides a means fvr sup~,lcssivn or m~nipulation of Bragg lobec in this plane. The c~d~ility to intentionally squint the ...~ ... in con-tinuous transverse stub array appli-~tionc also affords to it an ~ o~l design advan-tage in terms of radar cross section p~.rv....~-cc A radial array 56 is shown in Figs. 35 and 35a, which show top and side views thereof, l~ s~;~ively. n the radial array 56 the continuous transverse (transverse to radially proFr~gPting modes) stubs form CQntinUou~ con~ntnc rings 29. A single or multiple (mlllhm~e) point source 24 replaces the ~rlitjon~l line svurce 39 in such applications. Radial w veguide modes are utilized in a similar manner ~ plane wave-guide modes in order to derive design equations for the radial array 56.
Dual-polarization dual-band and dual-beam capabilities may be realized with the radial array 56 throug} app~ iate s~lP~l;ol) of feed(s), radial c~-~;. "o~s transverse stub elçm~on~c 29, and r uxiliary elc-~.f .~l ch~ac~ ics in a manner that directly parallels that for the planar continuous transverse stub array 50. Similar pe.rO. . .-~nce applica-tion and producibility xdvantages apply. Both endfire (~o~izon) and ~ c (zenith)nuin~m pal~ l.C may be realized with the radial array 56.
A filter 57 is il~ustrated in Figs. 36, 36a, and 37, and the ~ll~sp~nAing electn-cal s~ucture is shown in Fig. 37a. Nonr~ ting reactive cl~ntinuQus t~nsverse stub .

ele..~ , t~ ;n~t~ in an open or short a~it, may bc arraycd in adcr to convcnicnt-ly fonn filter ~l~ucl~. Such ~ S fmlction indG~x~-dcr.lly as filters or may bc combined with r~ ng el~ nls in orda~o form an integrated filtcr-multiple~c~-an-tenna structurc. Conventional ~ 5 of filter analysis and synthesis may be cmploy-5 ed with the connnuou- transverse stub ar~y filter willloul loss of gcnerality.The continuous transverse stub ar~ cnjoys advantages over conv~ ;o~l filtcr re~li7~io~s particularly at millimPt~-wa~e and quasi~ptical L~ ;c s where its inichtd ~ tfs losses and reduced mcchanical tole~ncc scnsidvitics a~ow f~
the rrr~cic -l f~l~ic~io ~ of high p~ ion high-Q devices. Notc that the ll~.,t;cal 10 ~ s;pal;~e losses for the continuous L d.. ._.~ stub a~ray's paralld platc lli r.~...;cS~n line ~l,uct~ are a~p~ lely one-half d'dlose ~ss~:~tl~ with a ~d~i I~E;ular waveguide ope~ g at the i~enn~l freque~cy and C~ 1J~ of identic~1 d;~k~Q;~ and conductive materials.
A coupler 59 is illustrated in Figs. 38, which shows a side view thereof and its15 corresponding electrical structure, lesp~..ely. In a manner sirnilar to filters precisic~
couplers may also be ealized and intc~d using the cor l;...~oll~ transverse stub array 59 with individual continuous transverse s~b e4-~ ~.t~ 11 filn~i~ning as brancb-guide su~ogates. In the co~pler 59, energy is coopled from the lower parallel plate region the upper parallel platé region as is indica~d by the arrows in Fig. 38. Oncc again 20 conven~ion~ e~l~odc of coupler analysis and synthesis may be employed without loss of generality.
Extrusions or nulti-layer ~ ~Iding~phting t~niques are ideally suited to the re-qli7-q-tion of continuolls transverse stub alray couplers 59. Such couplers 59 ue par-ticularly useful at hig~ er o~,dting frequçr~s, inelu.~;-)g m~ wave _nd quasi-25 optical, where conventional couplers based on discrete l~ ant el. . .u".-~ are ~
~1iffi''..1t to fa~i~qt~
Fig. 39 shows a top view of a~n Ç...l~;...~nt of a c~ntinuouC transverse stub antenna ~ray 50 made in accor~ance with tbe l,lhlei~les of the present invention that was built and tested. Fig. 40 shows a side view of the array 50 of Fig. 39. A 12 by 24 by 0.25 inch sheet of Rexolite (er = 2.35, L.t = 0.0003) was m~hine~ to forrn a 6 by 10.5 inch continuous transverse stub anlenna alray 50 comE~ ed of twenty contin-uous transverse stub ~lements 21 decign~ for operation in the Ku (12.5-18 GHz) fre-quency band. A moderate qmrlihlde excita~ion taper was hl~d in the lon~ inql plane through apl,lop iate vanation of cont;nnouC transverse stub widths whose indi-vidual heights were constrained to be cons~ nt. An inter el~ ~.c .l spacing of 0500 inch and a parallel plate spacing of 0.150 inch were anployed. A sil~er-based paunt was used as a con~llctive coating and was unifamly applied over all e~posc i arcas (front - 21~6546 and back) of the co"l;h~lQus transversc stub ~t~nq array 50. Input and stub radiator surfaces were C~E~o~ after plating using a mild abrasivc.
A line sourcc ~9 compnsing an H-plane scctoral hom 39a (a = 6.00 inch, b =
0.150 inch) was ~esi~ed and fabncated as a slmple Ku-band line source providing a 5 cQCinuso~ tud~ and a 90 dcgree (peak-to-peak) pA~ phase distribution at the input of the contin~lo~c transversc stub array 50. A quar~r-wave llar.aro...Jcr 52 was built into the c~-l~nuous trans~erse s~b array 50 in ord~ to match t'ne intc.r~cc . oen it and the sec ~1 horn linc sourec.
E-plane (loln~ qntennq p&l~ S were ~as.l,.,d far the c~ntinuo~ trans-verse stub anteMa arr~y 50 over the L ~r.~;r band of 13 to 17.5 GHz, ~Yhi~iti~ awell-fonned mqin~qrA (<-13.5 dB s:d~l~ level) over this entire rl~u~r~y rangc.
Cross-pola-~ti~n lev~ls were .n~un~d and found to be better than -50 dB. H-plane(tnqAnsverse) artenna p ttems exhibited characteristics identic-q-l to that of the sectoral horn, a fact which is consistent with the separable nature of the ape.lu~e distribution 15 used for this configur~tion. Flg. 41 depicts a ll~asul~d E-plane pattern for this contin-uous transverse stub a-ray 50 of Figs 39 and 40 measuled at a frequency of 17.5 GHz Thus, it rnay be seen that, for the case of qnten~AqC a c~ ntin~lous transverse stub a~ray realized as a conductively-plated didectric has many ~r~ qnc~ p~ducih;lity, and apFliration advantages over co,.~ ;onql slotted waveguide a~ay, p*nted patch ar-20 ray, and reflector and ens antenna apl)loaches. Some distinct advantagcs in intee~t. Afilter and coupl~ ylpl r~q~tionC are realized as well.
Perfo~nce advantages ~ le: au~iOr apc.lu~e effiriency and e--hqnc41 filter "Q", achieving l~ss than -0.5 dB/foot ~;sC;l~al;~e losses st 60 GHz; superior fre-quency bandwidth, having up to one octave per axis, with no ~~SO~ cc....ponenls or 25 structures; superi~r broadh~ pol~i~l~n purity, with -50 dB cross-polarization; su-perior b~o~h~ ck~ eYrit~ion range and control, having covpling values from -3 dB to -35 dB per e~ ;t, supaior shaped beam c~p~ility, wlle.e;n the non-ullil'u.~
exçit~ion phase is ;- .~ nt~ through m~ tion of stub length and/or ~s;lion; and supenor E-plane elen~c ~t factor using a 1~ 5s~i ground-plane allows for wide scan-30 ning capability, even tp endfire.
P~ducihility aivantages include: superior ince~ ity to ~;...~n~;on~l and m a-terial variations with l~-ss than 0.50 dB coupling variation for 20% change in tliel~ic const~nt, no ~.,son~ t ~tructures; totally "e~t rn~ ed" cons~ ction, ~vith absolutcly no intemal details .~uil~l; simplified f~ic~tion p.~lu.. s and plO~SSCS, wherein the 35 structures m ay be tL. ~-I-~d, eAI. uded, or injected in a single mo!~ling pnxess.
~,vith no 3~ on~1 joir ing or ~ . -bly ~~ui~ and reduced design no.~cu~ing engi- ' .

necring costs and cycle-time due to a modulqr, scqla~k design, simplc and rcliable RF
theo~y and analysis, and two~ .sional co,ll~lacity reduced to one ~im~ncirm App~ ion advantages inclllde a very thin profilc (planar, diel~1~ically load-cd); lightwaght (1/3 th~ density of q~ --"); c~lf~l~ in that the array may be S cwed/bent without im~act on internal c~lpling m~hq~ rnc; ~u~.ior dlurability (no cavities or me~l skin to crush or dent); dual-polarization, dual-band, ~and dual beam capable (ut~li7ing ~ll.ogo~al stubs); L~u~nc~-s~qnnqblc (2 deglees scan per 1%
L~ue.-~;~ delta for hig~ ~:rk~1~ ;c matcrials); decll~lly~ q-nnq~e using an clo~l,on-ically- or ti~~ ch~ k~lly-sc~ncd line feed; n~lu~xl radar c~ss sec~ion providing a 10 one ~ n~ c~" latticc; it is ~plir-qble at milli~-wavc and quasi-optical frequen~iec, vnth e~,c~ly low ~3iCs;p~ e losses, and enhq~e~ tol-.~nces, and it provides for inte~at~ filter, coupler, and radiator fu~ionc, wherein the filter, coupler and ~diator elen~ntc ~ay be fully integrated in c~-----~n structures.
Ihus there has been described a new and improved continuous transverse stub 15 elernent It is to be und~rstood that the above-descnbed embolirn~nt is merely illustra-tive of some of the many specific embo~ entc which ~ senl appli~ti~c of the prin-ciples of the present invention. Clearly, nume~,us and other arran~n~ can be ~adi-ly devised by those skiL:ed in the art without dep~ing from the scope of the invention.

Claims (34)

What is claimed is:

1. Antenna means comprising:
a dielectric element comprising a first portion and a second portion that extends generally transverse to the first portion that forms a transverse stub that protrudes from a first surface of the first portion;
a first conductive element disposed coextensive with the dielectric element along a second surface of the first portion; and a second conductive element disposed along the first surface of the dielectric element and disposed along transversely extending edgewalls formed by the secondportion of the dielectric element.

2. The antenna means of Claim 1 wherein the second conductive element extends across an end of the dielectric element, thus enclosing it to form an shorted waveguide.

3. The antenna means of Claim 1 wherein the second portion of the dielectric element extends substantially along the length of the dielectric element.

4. The antenna means of Claim 1 wherein the length and width of the second portion are substantially the same, thus forming a coupler.

5. The antenna means of Claim 1 wherein the dielectric element further comprises:
a third portion having a length, width, and cross section that are substantiallythe same as the first portion that is coupled to the end of the second portion, and wherein the second conductive coating extends along a first surface of the third portion that is proximal to the first portion; and a third conductive element disposed along a second surface of the third portion of the dielectric element that is distal from the first conductive predetermined, thus forming a coupler.

6. The antenna means of Claim 1 wherein the dielectric element comprises air and which further comprises a slow wave structure disposed along an inner surface of the first conductive coating adjacent the second portion of the transverse stub.

7. The antenna means of Claim 1 wherein the dielectric element comprises a plurality of dielectric layers having different dielectric coefficients.

8. The antenna means of Claim 1 wherein the dielectric element comprises a fourth portion disposed on the same side of the first portion as the second portion that extends generally transverse to the first portion and that is oriented orthogonal to the second portion, which fourth portion forms a second transverse stub that is orthogonally oriented with respect to the transverse stub.

9. The antenna means of Claim 1 which further comprises first and second terminating surfaces disposed along opposite lateral edges of the first and second portions of the dielectric member, thus forming a finite width stub element.

10. The antenna means of Claim 9 wherein the first and second terminating surfaces comprise conductive surfaces.

11. The antenna means of Claim 9 wherein the first and second terminating surfaces comprise nonconductive surfaces.

12. The antenna means of Claim 9 wherein the first and second terminating surfaces comprise absorptive surfaces.

13. The antenna means of Claim 1 wherein the second portion of the dielectric element has a tapered cross section.

14. The antenna means of Claim 1 wherein the second portion of the dielectric element has a stepped configuration.

15. The antenna means of Claim 1 wherein the first portion of the dielectric element has a stepped configuration.

16. The antenna means of Claim 14 wherein the first portion of the dielectric element has a stepped configuration.

17. The antenna means of Claim 1 wherein the second portion of the dielectric element has a circular shape forming a circular transverse stub.

18. The antenna means of Claim 1 wherein the dielectric element comprises a plurality of second portions that protrude transversely from the first surface of the first portion and that are separated from each other by a predetermined distance.

19. The antenna means of Claim 18 wherein each of the respective transverse stubs have distinct widths that become progressively smaller relative to their positions across the antenna means.

20. The antenna means of Claim 18 which further comprises a conductive element disposed between adjacent transverse stubs, which form a plurality of transverse cavities.

21. The antenna means of Claim 8 which further comprises a plurality of line sources individually coupled to selected adjacent edges of the dielectric element.

22. The antenna means of Claim 18 wherein the dielectric element further comprises an additional plurality of transversely extending portions disposed between adjacent ones of the plurality of second portions that are individually rotated with respect to the second portions.

23. The antenna means of Claim 18 wherein the dielectric element has a contoured cross section adapted to conform to a predetermined nonplanar shape, and wherein the plurality of second portions individually extend along a plurality of radial lines determined by the shape of the contour.

24. The antenna means of Claim 18 wherein each of the plurality of second portions has substantially the same height.

25. The antenna means of Claim 18 wherein selected ones of the plurality of second portions have different heights relative to the remainder of the second portions.

26. The antenna means of Claim 18 wherein the dielectric element has a semicircular shape.

27. An antenna array comprising:
a planar sheet of dielectric material having two generally parallel broad surfaces separated by a predetermined distance and having a plurality of elongated, raised, relatively thin, rectangular dielectric members formed along a broad surface of the sheet of dielectric material that extend across one dimension of the broad surface and that extend away from the broad surface, and wherein the plurality of thin rectangular di-electric members are spaced apart from each other by a predetermined distance; and a conductive material disposed on the broad surfaces of the sheet of dielectric material and on transversely extending edgewalls formed by the plurality of thin rectangular dielectric members so as to define a parallel plate waveguide having a plurality of continuous transverse stubs disposed on one plate thereof, and wherein distal ends of the plurality of thin rectangular dielectric members are free of the conductive material so as to define a plurality of radiating elements, and wherein an edge of the sheet of dielectric material is free of conductive coating so as to define a feed for the antenna array.

28. The antenna array of Claim 27 wherein each of the respective dielectric members have distinct widths that become progressively smaller relative to their position in the antenna array.

29. The antenna array of Claim 27 wherein the conductive material is disposed over the distal ends of the thin rectangular dielectric members to define a short circuited radiating elements, the apparatus thus comprising a short circuit stub antenna array.

30. The antenna array of Claim 27 further comprising:
a second planar rectangular sheet of dielectric material having two generally parallel broad surfaces separated by a predetermined distance and wherein one of the surfaces is integrally connected to the plurality of elongated, raised, relatively thin, rectangular dielectric members; and wherein the conductive material is disposed on the other of the surfaces of the second sheets of dielectric material to define a pair of parallel plate waveguides having a plurality of continuous transverse coupling stubs coupled therebetween.

31. A method of making a continuous transverse stub antenna element which comprises the following steps:
processing a sheet of dielectric material to form an integral dielectric member having two generally parallel broad surfaces and at least one elongated raised relatively thin rectangular dielectric portion extending transversely across one of the broad surfaces;

metalizing the exterior surfaces of the dielectric member to define a parallel plate waveguide having at least one continuous transverse stub disposed on one plate thereof; and removing plating from predetermined surfaces of the exterior of the parallel plate waveguide to permit coupling of energy into and out of the antenna element.

32. The method of making a continuous transverse stub antenna element of Claim 31 wherein the step of processing a sheet of dielectric material comprises the step of:
machining a sheet of dielectric material to form a dielectric member having two generally parallel broad surfaces and at least one elongated raised relatively thin rectangular dielectric portion extending transversely across one of the broad surfaces.

33. The method of making a continuous transverse stub antenna element of Claim 31 wherein the step of processing a sheet of dielectric material comprises the step of:
extruding a sheet of dielectric material in the form of a dielectric member having two generally parallel broad surfaces and at least one elongated raised relatively thin rectangular dielectric portion extending transversely across one of the broad surfaces.

34. The method of making a continuous transverse stub element of Claim 31 wherein the step of processing a sheet of dielectric material comprises the step of:
molding a sheet of dielectric material to form a dielectric member having two generally parallel broad surfaces and at least one elongated raised relatively thin rectangular dielectric portion extending transversely across one of the broad surfaces.