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    US007817101B2

    1 2 ) Unlted States Patent 1 0 ) P a t e n t N o . : U S 7 , 8 1 7 , 1 0 1 B2Cowles 4 5 ) Date o f P a t e n t : O c t . 1 9 , 2010

    ( 5 4 ) DUALPOLARIZED MULTIFILARANTENNA 6 , 1 5 0 , 9 9 4 A 1 1 / 2 0 0 0 W i n t e r e t a 1 ._ _ _ 6,185,427 B1 2/2001 Krasner t a l .

    ( 7 5 ) I n v e n t o r : PhlhP R- C owles, Cambndge CA) 6 , 2 2 2 , 5 0 5 B1 * 4 / 2 0 0 1 Endo t a l . . . . . . . . . . . . . . . . . 3 4 3 / 8 9 5( 7 3 ) A s s i g n e e : Com ev I n t e r n a t i o n a l L t d . , 6 2 3 6 3 5 4 B l 5 / 2 0 0 1 K r a m e r

    C a m b r i d g e ( C A )* ) N o t i c e : S u b j e c t t o any d i s c l a i m e r , t h e term o f h i s _

    p a t e n t i s e x t e n d e d o r a d j u s t e d u n d e r 3 5 ( C o n t m u e d )U - S - C ~ 1 5 4 ( b ) b y 3 9 5 d a y s - FOREIGN PATENT DOCUMENTS

    ( 2 1 ) A p p l . N o . : 1 1 / 8 7 5 , 5 4 7 Ep 0 6 6 6 6 1 2 9 / 1 9 9 5( 2 2 ) F i l e d : O c t . 1 9 , 2 0 0 7( 6 5 ) P r i o r P u b l i c a t i o n D a t a ( C o n t i n u e d )

    U S 2 0 0 8 / 0 0 9 4 3 0 8 A1 A p r . 2 4 , 2008 OTHER UBLICATIONSRelated US Application Data O f ? c e A c t i o n f r o m t h e r e l a t e d U . S . A p p l . N o . 1 1 / 5 8 5 , 1 4 7 d a t e d M a r .6 3 ) C o n t i n u a t i o n - i n - p a r t o f a p p l i c a t i o n N o . 1 1 / 5 8 5 , 1 4 7 , 1 9 , 2 0 0 3

    ?led o n Oct. 2 4 , 2006, noW bandoned. _( C o n t m u e d )5 1 ) I n t C l P r i m a r y ExamineriHoangAnh T L eH01Q 1 / 3 6 ( 2 0 0 6 9 1 ) ( 7 4 ) A t t o r n e y , A g e n t , o r FirmiBereskin a r r L L P ; l s i s E .

    (52) US. l. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 343/895 Caulder(58) Field of Classi?cation Sea r ch . . . . . . . . . . . . . . . . . . 343/895

    S e e a p p l i c a t i o n ? l e f o r c o m p l e t e s e a r c h h i s t o r y . 5 7 ) ABSTRA CT( 5 6 ) R e f e r e n c e s C i t e d

    U . S . PATENTDOCUMENTS3 , 5 0 3 , 0 7 5 A 3 / 1 9 7 0 G e r s t3 , 9 0 6 , 5 0 9 A 9 / 1 9 7 5 DuHamel3 , 9 1 3 , 1 0 9 A 1 0 / 1 9 7 5 Owen3 , 9 4 0 , 7 7 2 A 2 / 1 9 7 6 Ben-Dov4 , 0 1 1 , 5 6 7 A 3 / 1 9 7 7 Ben-Dov5 , 1 7 0 , 1 7 6 A 1 2 / 1 9 9 2 Y a s u n a g a e t a l .5 , 2 5 5 , 0 0 5 A 1 0 / 1 9 9 3 T e r r e t e t a 1 .5 , 7 0 8 , 4 4 8 A 1 / 1 9 9 8 W a l l a c e5 , 9 0 9 , 1 9 6 A 6 / 1 9 9 9 O N e i l l , J r .5 , 9 8 6 , 6 1 9 A 1 1 / 1 9 9 9 G r y b o s e t a 1 .6 , 0 2 5 , 8 1 6 A 2 / 2 0 0 0 Dent t a 1 .6 , 1 3 7 , 9 9 6 A 1 0 / 2 0 0 0 Baumann

    Various embodiments r e described of an antenna i n c l u d i n g ac o m m o n ground l a n e , a ? r s t s e t o fN p p r o x i m a t e l y r e s o n a n te l e m e n t s W i t h a l e n g t h 1 2 and a second s e t o f M p p r o x im a t e l y r e s o n a n t e l e m e n t s W i t h a l e n g t h 1 1 . The ? r s t s e t o f Napproximately r e s o n a n t elements a r e Wound t o f o r m a ? r s th e l i x W i t h an n i t i a l d i a m e t e r d2 and h e i g h t h 2 . The seconds e t ofM p p r o x i m a t e l y r e s o n a n t e l e m e n t s a r e Wound i n t h eo p p o s i t e d i r e c t i o n t o t h e ? r s t s e t o f N p p r o x i m a t e l y r e s o n a n te l e m e n t s t o form s e c o n d h e l i x . The s e c o n d h e l i x i s c e n t r a l l yd i s p o s e d Wi t h i n t h e ? r s t h e l i x , and 1 i s l e s s t h a n d 2 and 1 i sg r e a t e r t h a n h 2 .

    2 0 C l a i m s , 1 5 Drawing S h e e t s

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    US 7 , 8 1 7 , 1 0 1 B2P a g e 2

    6 , 2 7 1 , 8 0 46 , 4 0 0 , 3 3 96 , 4 1 4 , 6 4 86 , 4 2 7 , 1 2 16 , 4 7 6 , 7 7 66 , 5 2 2 , 3 0 16 , 5 3 5 , 1 7 96 , 5 4 5 , 6 4 96 , 5 8 7 , 0 8 16 , 6 1 1 , 7 5 76 , 6 5 8 , 3 4 96 , 7 3 8 , 0 2 66 , 8 1 6 , 1 2 76 , 8 2 3 , 1 7 06 , 9 4 0 , 4 7 17 , 0 4 7 , 1 1 47 , 1 3 3 , 8 1 07 , 2 0 5 , 9 3 3

    2004/01089642004/01933672004/02179002005/01242912006/01996122006/02905902008/00862672008/0088485

    U . S . PATENTDOCUMENTS

    A1A1A1A1A1A1A1

    8 / 2 0 0 16 / 2 0 0 27 / 2 0 0 27 / 2 0 0 2

    1 1 / 2 0 0 22 / 2 0 0 33 / 2 0 0 34 / 2 0 0 37 / 2 0 0 38 / 2 0 0 3

    1 2 / 2 0 0 35 / 2 0 0 4

    1 1 / 2 0 0 41 1 / 2 0 0 49 / 2 0 0 55 / 2 0 0 6

    1 1 / 2 0 0 64 / 2 0 0 76 / 2 0 0 49 / 2 0 0 4

    1 1 / 2 0 0 46 / 2 0 0 59 / 2 0 0 6

    1 2 / 2 0 0 64 / 2 0 0 84 / 2 0 0 8

    Y a n a g i s a W a e t a l .Edvardsson e t a l .Holland t a l .B r o d i eK u r b yTakayama t a 1 .P e t r o sS e a v e yNoro e t a l .B r o d i eC l i n eMcKivergan t a l . . . . . . . . 343/895McKivergan t a l .DentSmithR o g e r sB u t l e r e t a l .S n o d g r a s sMcKivergan t a l . . . . . . . . 343/895C l i n eMartin e t a l .Hart t a l .B e y e r e t a 1 .Takaoka e t a 1 .S t o l t e e t a l .S t o l t e e t a l .

    2008/0094307 A1 4 / 2 0 0 8 CoWlesFOREIGN PATENTDOCUMENTS

    WO WO97/42682 1 1 / 1 9 9 7WO WO9828814 7/1998WO WO0209318 1 / 2 0 0 2WO WO2004010572 1 / 2 0 0 4WO WO2007143478 1 2 / 2 0 0 7

    OTHER PUBLICATIONSComments t o t h e N a t i o n a l Telecommunications and I n f o r m a t i o nA d m i n i s t r a t i o n p u b l i s h e d D e c . 1 , 2 0 0 6 .Hoye t a l . , S p a c e - b a s e d A I S f o r g l o b a l m a r i t i m e t r a f ? c m o n i t o r i n g ,A c t a A s t r o n a u t i c a 6 2 ( 2 0 0 8 ) , p p . 2 4 0 - 2 4 5 , a v a i l a b l e o n l i n e S e p . 1 7 ,2 0 0 7 .U . K . S e a r c h R e p o r t d a t e d J a n . 1 , 2 0 0 8 .L o W d e l l e t a l . , D u a l Band Q u a d r i ? l a r H e l i x A n t e n n a s f o r U HF/VHFBand O p e r a t i o n , A n t e n n a s a n d P r o p a g a t i o n , T w e l f t h I n t e r n a t i o n a lC o n f e r e n c e o n ; v o l . 1 , M a r . 3 1 - A p r . 3 , 2 0 0 3 , p p . 1 8 0 - 1 8 5 , e n t i r ed o c u m e n t .PCT I n t e r n a t i o n a l S e a r c h R e p o r t and W r i t t e n O p i n i o n m a i l e d o nA u g . 4 , 2 0 0 8 .PR. C o W l e s , S t u d i e s o f m i l l i m e t e r Wave a e r i a l s , U n i v e r s i t y o fK e n t , PhD h e s i s , 1 9 7 3 .I n t e r n a t i o n a l P r e l i m i n a r y R e p o r t o n P a t e n t a b i l i t y , I n t e r n a t i o n a lA p p l i c a t i o n N o . P C T / C A 2 0 0 8 / 0 0 0 7 3 6 , d a t e d A p r . 2 0 , 2 0 1 0 .* c i t e d by examiner

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    DUALPOLARIZEDMULTIFILARANTENNACROSS-REFERENCE TO RELATED

    APPLICATIONT h i s a p p l i c a t i o n i s a c o n t i n u a t i o n - i n - p a r t a p p l i c a t i o n a n d

    c l a i m s p r i o r i t y f r o m US. a t e n t a p p l i c a t i o n S e r . N o . 1 1 / 5 8 5 ,147 ? l e d on O c t . 2 4 , 2 0 0 6 .

    FIELDThe embodiments d e s c r i b e d h e r e i n r e l a t e t o h e l i c a l a n t e n

    n a s and i n p a r t i c u l a r an a n t e n n a comprised o f m u l t i ? l a r h e l ic a l e l e m e n t s o p e r a b l e a t t h e same f r e q u e n c y s i m u l t a n e o u s l y .BACKGROUND

    When e c e i v i n g r a d i o s i g n a l s , i t i s n e c e s s a r y t o u s e ana n t e n n a t h a t n o t o n l y o p e r a t e s o v e r t h e f r e q u e n c y r a n g e t h a tt h e s i g n a l s o c c u p y , b u t t h a t a l s o m a t c h e s t h e n a t u r e o f t h ep o l a r i z a t i o n o f t h o s e s i g n a l s . As s knoWn o t h o s e s k i l l e d i nt h e a r t , p o l a r i z a t i o n d e s c r i b e s t h e d i r e c t i o n o f t h e e l e c t r i c a l? e l d component o f a n e l e c t r o m a g n e t i c (EM) W a v e , a s i ta r r i v e s a t t h e r e c e i v i n g a n t e n n a . The e l e c t r i c a l ? e l d c o m p onent of an EM ave can be subdivided i n t o a horizontalcomponent and a v e r t i c a l component.

    I f t h e e l e c t r i c a l ? e l d component of h e Wave h a s o n l y onesubcomponent, e i t h e r a h o r iz o n t a l component o r a v e r t i c a lc o m p o n e n t , t h e n t h e Wave s s a i d t o h a v e l i n e a r p o l a r i z a t i o n .I f t h e Wave a s b o t h subcomponents h e s i g n a l i s s a i d t o h a v ee l l i p t i c a l p o l a r i z a t i o n . I f t h e h o r i z o n t a l a n d v e r t i c a l comp on e n t s a r e e q u a l i n m a g n i t u d e a n d d i f f e r i n p h a s e b y 9 0 , t h eWave s s a i d t o b e c i r c u l a r l y p o l a r i z e d . E i t h e r t y p e o f p o l a ri z a t i o n , l i n e a r o r e l l i p t i c a l , c a n p r o v i d e t W o o r t h o g o n a l s i gn a l s a t t h e same f r e q u e n c y . F o r e x a m p l e , a l i n e a r p o l a r i z e ds i g n a l c a n e i t h e r p r o p a g a t e W i t h i t s p o l a r i z a t i o n i n t h e h o r iz o n t a l d i r e c t i o n o r t h e v e r t i c a l d i r e c t i o n ; and a c i r c u l a r l yp o l a r i z e d s i g n a l c a n e i t h e r b e r i g h t - h a n d e d o r l e f t - h a n d e d ,depending on h e d i r e c t i o n t h e e l e c t r i c a l ? e l d v e c t o r r o t a t e s .An a n t e n n a t h a t i s s i m u l t a n e o u s l y o p e r a b l e i n b o t ho r t h o g o n a l p o l a r i z a t i o n s i s a d v a n t a g e o u s b e c a u s e u s i n g e a c ho r t h o g o n a l p o l a r i z a t i o n t o i n d e p e n d e n t l y c a r r y d a t a mayd o u b l e t h e c a p a c i t y o f a communications c h a n n e l . I n a d d i t i o nt o i n c r e a s i n g t h e c a p a c i t y o f a c o m m u n i c a t i o n s c h a n n e l ,p o l a r i z a t i o n o f a r a d i o s i g n a l can be used t o maximize t h es t r e n g t h o f a r e c e i v e d s i g n a l by m a t c h i n g t h e a n t e n n a t o t h eincoming p o l a r i z a t i o n . I t can a l s o be used t o e l i m i n a t e anu n W a n t e d s i g n a l b y s e t t i n g t h e r e c e i v e a n t e n n a t o b e o r t h o g on a l t o t h e unWanted i g n a l .

    D u a l p o l a r i z e d a n t e n n a s h a v e been r e a l i z e d i n s e v e r a l d i ff e r e n t f u n d a m e n t a l a n t e n n a f o r m s s u c h a s d i p o l e t y p e a n t e nn a s , W a v e g u i d e - t y p e a n t e n n a s , r e ? e c t o r - t y p e o r l e n s a n t e n n a sand e l i c a l a n t e n n a s . H e l ic a l a n t e n n a s , i n p a r t i c u l a r , a r e W e l ls u i t e d f o r s a t e l l i t e a p p l i c a t i o n s b e c a u s e t h e y h a v e a r e l a t i v e l yl a r g e bandWidth and s i n c e i t i s p o s s i b l e t o s t o W them i n as m a l l volume. A e l i c a l antenna t y p i c a l l y c o n s i s t s of cond u c t i n g W i r e Wound i n t h e form of h e l i x and mounted o v e ra ground p l a n e . The h e l i c a l a n t e n n a c a n o p e r a t e i n e i t h e rnormal o r a x i a l mode. I n a x i a l mode, t h e h e l i c a l antenna s an a t u r a l r a d i a t o r o f c i r c u l a r l y p o l a r i z e d r a d i a t i o n a n d c a n b ec o n ? g u r e d t o p r o vi d e b o t h h a n d s o f o p e r a t i o n . F I G . 1 i l l u st r a t e s an i s o m e t r i c vieW of a t y p i c a l a x i a l mode h e l i c a lantenna 5 .A ommon o r m of u a l - p o l a r i z e d h e l i c a l a n t e n n a i s a d u a l

    p o l a r i z e d s i n g l e - W i r e h e l i x a n t e n n a . F I G . 2 i l l u s t r a t e s a s i d ev i e W o f a t y p i c a l d u a l p o l a r i z e d s i n g l e - W i r e h e l i x a n t e n n a .The a n t e n n a 1 0 i s comprised o f a s i n g l e W i r e h e l i x 1 2 , a

    20

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    2r e ? e c t o r o r ground l a n e 1 4 , a l o W e r end c o a x i a l f e e d 1 6 anda f a r end f e e d 1 8 . When h e a n t e n n a 10 s f e d from h e loWere n d 1 6 t h e p o l a r i z a t i o n i s de?ned b y t h e h a n d e d n e s s o f t h es i n g l e - W i r e h e l i x 1 2 . When h e a n t e n n a 1 0 i s f e d a t t h e f a r end1 8 , t h e h e l i x 1 2 r a d i a t e s i t s oWn a r t i c u l a r hand o f p o l a r i z at i o n , b u t t h i s i s r e v e r s e d When r e ? e c t e d b y t h e g r o u n d p l a n e1 4 .

    The m o s t s i g n i ?c a n t o p e r a t i o n a l c o n s t r a i n t o f t h e d u a lp o l a r i z e d s i n g l e - W i r e h e l i x a n t e n n a 1 0 i s i t s s i z e . The n t e n n a1 0 W i l l o n l y r a d i a t e c i r c u l a r p o l a r i z a t i o n i n t h e a x i a l modeWhen t s c i r c u m f e r e n c e i s a b o u t o n e w a v e l e n g t h 7 ) . F u r t h e rm o r e , t h e g r o u n d p l a n e 1 4 m u s t b e s u f ? c i e n t l y l a r g e t o s u pp o r t s u c c e s s f u l Wave r o p a g a t i o n on h e s i n g l e - W i r e h e l i x 1 2 ,and h i s c a n t y p i c a l l y b e l a r g e r t h a n a w a v e l e n g t h 7 ) a c r o s s .

    A t t e m p t s t o d e s i g n d u a l p o l a r i z e d f o r m s o f h e l i c a l a n t e nn a s h a v e f a i l e d g e n e r a l l y b e c a u s e t h e c o u p l i n g betWeen t h etWo s t r u c t u r e s d e s t r o y s t h e p e r f o r m a n c e o f b o t h , o r i n t r od u c e s a v e r y h i g h d e g r e e o f e l e c t r i c a l c o u p l i n g b e t W e e n t h etWo antennas o r antenna elements.

    SUMMARYI n one a s p e c t , a t l e a s t one embodiment d e s c r i b e d h e r e i np r o v i d e s an antenna com pri sing a common r s h a r e d ground

    p l a n e ; a ? r s t s e t ofN p p r o x i m a t e l y r e s o n a n t e l e m e n t s a s s oc i a t e d W i t h t h e c o m m on ground l a n e , e a c h o f s a i d ? r s t s e t o fa p p r o x i m a t e l y r e s o n a n t e l e m e n t s h a v i n g a l e n g t h 1 2 a n dWound o f o r m a ? r s t h e l i x With an n i t i a l diameter d2 and ah e i g h t h 2 ; and a s e c o n d s e t o f N p p r o x i m a t e l y r e s o n a n te l e m e n t s a s s o c i a t e d W i t h t h e c o m m on r o u n d p l a n e . Each o fs a i d second s e t of a p p r o x i m a t e l y r e s o n a n t e l e m e n t s have al e n g t h 1 1 a n d a r e Wound i n t h e o p p o s i t e d i r e c t i o n t o t h e ? r s ts e t of pproximately e s o n a n t e l e m e n t s t o form second e l i xt h a t i s c e n t r a l l y d i s p o s e d W i t h i n t h e ? r s t h e l i x , a n d h a s a ni n i t i a l d i a m e t e r d 1 and h e i g h t h1 Where 1 i s l e s s t h a n d2 andh 1 i s g r e a t e r t h a n h 2 .

    I n a n o t h e r a s p e c t , a t l e a s t one embodiment d e s c r i b e dh e r e i n p r o v i d e s a d u a l p o l a r i z e d m u l t i ? l a r a n t e n n a c o mp r i si n g a g r o u n d p l a n e ; a ? r s t s e t o f N e s o n a n t e l e m e n t s c o u p l e dt o t h e ground l a n e and Wound o form ? r s t h e l i c a l a n t e n n a ;and a second s e t of M e s o n a n t e l e m e n t s coupled t o t h eg r o u n d p l a n e a n d Wound i n a n o p p o s i t e d i r e c t i o n t o t h e ? r s ts e t of e s o n a n t elements o f o r m second e l i c a l a n t e n n a . The? r s t and second h e l i c a l a n t e n n a s a r e c o n c e n t r i c , have d i f f e re n t h e i g h t s a n d d i a m e t e r s , t h e r e s o n a n t e l e m e n t s o f b o t hh e l i c a l e l e m e n t s h a v e s i m i l a r l e n g t h s , and t h e h e l i c a l a n t e nn a s a r e o p e r a b l e a t s u b s t a n t i a l l y s i m i l a r f r e q u e n c i e s s i m u l t an e o u s l y .

    I n b o t h c a s e s , N ndM r e i n t e g e r s W i t h v a l u e s g r e a t e r t h a no r e q u a l t o t h r e e .

    F u r t h e r a s p e c t s and e a t u r e s o f t h e embodiments d e s c r i b e dh e r e i n W i l l a p p e a r f r o m t h e f o l l o W i n g d e s c r i p t i o n t a k e nt o g e t h e r W i t h t h e a c c o m p a n y i n g d r a W i n g s .

    BRIEF DESCRIPTION OFTHE DRAWINGSF o r a b e t t e r u n d e r s t a n d i n g o f t h e embodiments d e s c r i b e d

    h e r e i n and o shoW more c l e a r l y hoW h e y m a y be a r r i e d i n t oe f f e c t , r e f e r e n c e W i l l noW e m a d e , b y Way o f e x a m p l e o n l y ,t o t h e accompanying draWings Which shoW t l e a s t one exemp l a r y e m b o d i m e n t , a n d i n W h i c h :

    F I G . 1 i s an i s o m e t r i c vieW o f a t y p i c a l p r i o r a r t a x i a l modes i n g l e - W i r e h e l i c a l a n t e n n a ;

    F I G . 2 i s a s i d e vieW o f a t y p i c a l p r i o r a r t d u a l p o l a r i z e ds i n g l e - W i r e h e l i c a l a n t e n n a ;

    FIG. 3 i s a s i d e vieW of an exemplary embodiment of d u a lp o l a r i z e d q u a d r i ? l a r a n t e n n a ;

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    FIG. 4 i s a t o p vieW of an exemplary embodiment of d u a lp o l a r i z e d q u a d r i ? l a r a n t e n n a ;F I G . 5 i s an s o m e t r i c vieW o f a t y p i c a l q u a d r i ? l a r a n t e n n a e

    f e d b y b a l a n c e d t r a n s m i s s i o n l i n e s ;F I G . 6 i s an i s o m e t r i c vieW of a t y p i c a l p r i o r a r t s h o r tc i r c u i t e d q u a d r i ? l a r h e l i x ;F I G . 7 i s a g r a p h s h o w i n g t h e r a d i a t i o n p a t t e r n ( r e f e r e n c e dt o c i r c u l a r p o l a r i z a t i o n ) o f t h e d u a l p o l a r i z e d m u l t i ? l a r

    a n t e n n a shoWn i n F I G . 3 ;FIG. 8 i s a s i d e vieW of d u a l p o l a r i z e d m u l t i ? l a r a n t e n n a

    Where t h e o u t e r h e l i x h a s a v a r i a b l e d i a m e t e r ;F I G . 9 i s a s i d e vieW o f a s i n g l e - W i re h e l i x , showing t h e

    b a s i c d i m e n s i o n s of h e l i x ;FIG. 10 i s a s i d e vieW of a s a t e l l i t e system comprising a

    d u a l p o l a r i z e d m u l t i ? l a r a n t e n n a a s shoWn i n F I G . 3 ;F I G . 1 1 i s a s i d e vieW of h e s a t e l l i t e system shoWn n F I G .

    1 0 W i t h t h e d u a l p o l a r i z e d m u l t i ? l a r a n t e n n a compressed o rs t o W e d ;FIG. 12 i s a s i d e vieW of an exemplary embodiment of ad u a l p o l a r i z e d t r i ? l a r a n t e n n a ;

    FIG. 13 s a t o p vieW of an exemplary embodiment of d u a lp o l a r i z e d t r i ? l a r a n t e n n a ;

    F I G . 1 4 i l l u s t r a t e s s i m u l a t i o n r e s u l t s s h o W i n g t h e r a d i a t i o np a t t e r n f o r q u a d r i ? l a r a n d t r i ? l a r h e l i c a l a n t e n n a s h a v i n gs i m i l a r W i r e g e o m e t r y ;

    FIG. 15 s a s i d e vieW of d u a l p o l a r i z e d m u l t i ? l a r a n t e n n aWhere t h e i n n e r h e l i x h a s a v a r i a b l e d i a m e t e r ; and

    FIG. 16 s a s i d e vieW of d u a l p o l a r i z e d m u l t i ? l a r a n t e n n aWhere b o t h t h e i n n e r h e l i x and o u t e r h e l i x have a v a r i a b l ed i a m e t e r .

    I t W i l l b e a p p r e c i a t e d t h a t f o r s i m p l i c i t y a n d c l a r i t y o fi l l u s t r a t i o n , e l e m e n t s shoWn i n t h e ? g u r e s h a v e n o t n e c e s s a ri l y been draWn o s c a l e . F o r e x a m p l e , t h e d i m e n s i o n s o f someo f h e e l e m e n t s m a y e e x a g g e r a t e d r e l a t i v e t o o t h e r e l e m e n t sf o r c l a r i t y .

    DETAILEDDESCRIPTIONI t W i l l b e a p p r e c i a t e d t h a t f o r s i m p l i c i t y a n d c l a r i t y o f

    i l l u s t r a t i o n , Where c o n s i d e r e d a p p r o p r i a t e , r e f e r e n c e numera l s may e r e p e a t e d among h e ? g u r e s t o i n d i c a t e c o r r e s p o n di n g o r a n a l o g o u s e l e m e n t s o r s t e p s . I n a d d i t i o n , numerouss p e c i ? c d e t a i l s a r e s e t f o r t h i n o r d e r t o p r o v i d e a t h o r o u g hu n d e r s t a n d i n g o f t h e e x e m p l a r y e m b o d i m e n t s d e s c r i b e dh e r e i n . H o W e v e r , i t W i l l b e u n d e r s t o o d b y t h o s e o f o r d i n a r ys k i l l i n t h e a r t t h a t t h e embodiments d e s c r i b e d h e r e i n m a y bep r a c t i c e d W i t h o u t t h e s e s p e c i ? c d e t a i l s . I n o t h e r i n s t a n c e s ,W e l l - k n o w n m e t h o d s , p r o c e d u r e s a n d c o m p o n e n t s h a v e n o tbeen described n d e t a i l s o a s n o t t o obscure h e embodimentsd e s c r i b e d h e r e i n . F u r t h e r m o r e , t h i s d e s c r i p t i o n i s n o t t o b ec o n s i d e r e d a s l i m i t i n g t h e s c o p e o f t h e embodimentsd e s c r i b e d h e r e i n i n a n y W a y , b u t r a t h e r a s m e r e l y d e s c r i b i n gt h e i m p l e m e n t a t i o n o f t h e v a r i o u s e m b o d i m e n t s d e s c r i b e dh e r e i n .

    Reference s ? r s t made t o FIGS. 3 and 4 t h a t shoW a s i d evieW and a t o p vieW of an exemplary embodiment of d u a lp o l a r i z e d m u l t i ? l a r a n t e n n a 1 0 0 , r e s p e c t i v e l y . The a n t e n n a100 i n c l u d e s an i n n e r m u l t i ? l a r h e l i x 1 0 2 , an o u t e r m u l t i ? l a rh e l i x 104 and a c o m m o n ground p l a n e 1 0 6 . The i n n e r h e l i x102 s p l a c e d c o n c e n t r i c a l l y W i t h i n t h e o u t e r h e l i x 104 o v e rt h e c o m m on ground p l a n e 1 0 6 . The i n n e r and o u t e r h e l i c e s1 0 2 a n d 1 0 4 f o r m i n d e p e n d e n t o p p o s i t e l y p o l a r i z e d a n t e n n a st h a t a r e s i m u l t a n e o u s l y o p e r a b l e a t t h e same f r e q u e n c y f ) .

    I t should be understood t h a t While a common r sharedr e ? e c t o r i s u t i l i z e d i n t h e p r e s e n t embodiment i n p l a c e o f t h ec o m m on r o u n d p l a n e 1 0 6 , v a r i o u s o t h e r d e v i c e s c a n b e u s e di n p l a c e o f t h e c o m m on g r o u n d p l a n e 1 0 6 . F o r e x a m p l e , a

    20

    25

    30

    35

    40

    45

    50

    55

    60

    6 5

    4balanced f e e d netWork such a s a quad-balanced r a n s m i s s i o nl i n e con?gured s o t h a t t h e i n n e r m u l t i ? l a r h e l i x 102 and h eo u t e r m u l t i ? l a r h e l i x 1 04 a r e p r o p e r l y f e d can be used n s t e a d .G e n e r a l l y s p e a k i n g , u s e o f a g r o u n d p l a n e i s b e n e ? c i a l i n t h ec a s e W h e r e m a x i mu m o r W a r d g a i n i s r e q u i r e d (eg n s p a c ec r a f t a p p l i c a t i o n s ) . H o W e v e r , f o r e x a m p l e , i n m o b i l e a p p l i c at i o n s i t i s m o r e d e s i r a b l e t o have a W i d e r , more omni-direct i o n a l c o v e r a g e p a t t e r n a n d a c c o r d i n g l y a n o t h e r d e v i c e s u c ha s t h e quad-balanced t r a n s m i s s i o n l i n e d i s c u s s e d above canbe s e d . F I G . 5 shoWs an i s o m e t r i c vieW o f a t y p i c a l q u a d r i ?l a r a n t e n n a 1 2 1 f e d by a l a n c e d t r a n s m i s s i o n l i n e s Where h ed i r e c t i o n o f ? r e i s i n d i c a t e d a l o n g i t s a x i s a s s h o W n .

    A l s o , i n some a p p l i c a t i o n s , i t s h o u l d b e u n d e r s t o o d t h a t i tmay e c o n v e n i e n t t o f e e d e i t h e r t h e i n n e r o r o u t e r m u l t i ? l a rh e l i x 102 o r 104 i n one manner, and h e o t h e r of h e i n n e r o ro u t e r m u l t i ? l a r h e l i x 102 o r 104 i n another manner. Fori n s t a n c e , i f t h e r e Was t i g h t l y re s t r i c t e d s p a c e a r o u n d t h e b a s eof h e o u t e r m u l t i ? l a r h e l i x 1 0 4 , i t can be f e d u s i n g a 4 - W i r equad e e d , W h i l e t h e i n n e r m u l t i ? l a r h e l i x 1 0 2 c a n b e f e d W i t ha c o n v e n t i o n a l ground l a n e . Of o u r s e , t h e r e v e r s e can a l s oa p p l y .

    The u l t i ? l a r h e l i c e s 102 a nd 104 r e e a c h comprised o fNi d e n t i c a l r e s o n a n t e l e m e n t s o r ? l a r s Where N s g r e a t e r t h a no r equal t o f o u r . While t h e ? l a r s a r e r e f e r r e d t o a s resonante l e m e n t s i t i s n o t e s s e n t i a l t h a t t h e e l e m e n t s be t r i c t l y r e s on a n t , i t i s s u f ? c i e n t i f t h e y a r e a p p r o x i m a t e l y r e s o n a n t o rW i t h i n 1 2 0 o f r e s o n a n c e . I n t h e exemplary embodimentshoWn i n FIGS. 3 and 4 t h e h e l i c e s 102 and 104 a r e eachc o m p r i s e d o f f o u r r e s o n a n t e l e m e n t s 1 0 8 , 1 1 0 , 1 1 2 , 1 1 4 a n d1 1 6 , 1 1 8 , 1 2 0 , 1 2 2 r e s p e c t i v e l y . Each e s o n a n t e l e m e n t h a s a? r s t e n d 1 0 8 a , 1 1 0 a , 1 1 2 a , 1 1 4 a , 1 1 6 a , 1 1 8 a , 1 2 0 a , 1 2 2 a a n da s e c o n d e n d 1 0 8 b , 1 1 0 b , 1 1 2 b , 1 1 4 b , 1 1 6 b , 1 1 8 b , 1 2 0 b ,1 2 2 1 ) . T h e r e s o n a n t e l e m e n t s 1 0 8 , 1 1 0 , 1 1 2 , 1 1 4 , 1 1 6 , 1 1 8 ,1 2 0 , and 122 m a y be implemented a s W i r e s made o u t o fe l e c t r i c a l l y c o n d u c t i v e m a t e r i a l s u c h a s c o p p e r , c o p p e rp l a t e d s t e e l , b e r y l l i u m - c o p p e r , p l a t e d p l a s t i c o f c o m p o s i t em a t e r i a l , o r c o n d u c t i v e p o l y m e r s , a n d t h e l i k e .

    The g a u g e o f t h e r e s o n a n t e l e m e n t s 1 0 8 , 1 1 0 , 1 1 2 , 1 1 4 ,1 1 6 , 1 1 8 , 1 2 0 , a n d 1 2 2 i s d i c t a t e d b y t W o c o n s t r a i n t s : 1 ) t h eresonant elements must be of a su?ici ent gauge s o a s not t oi n c u r e x c e s s i v e r e s i s t i v e l o s s e s ; a n d 2 ) t h e r e s o n a n t e l e m e n t smust be t h i n enough s o t h a t t h e r e i s n o t an u n a c c e p t a b l ed e g r e e o f c a p a c i t i v e c o u p l i n g t h a t W o u l d r e n d e r t h e a n t e n n ai n o p e r a b l e . T h e r e s o n a n t e l e m e n t s 1 0 8 , 1 1 0 , 1 1 2 , 1 1 4 , 1 1 6 ,1 1 8 , 1 2 0 , and 122 may have a c o n s t a n t gauge o r m a y bet a p e r e d .The l e n g t h o f t h e r e s o n a n t e l e m e n t s i s d i c t a t e d a p p r o x im a t e l y b y t h e f r e q u e n c y f ) a t W h i c h t h e a n t e n n a o p e r a t e s a n dWhether t h e antenna i s a s h o r t o r o p e n - c i r c u i t e d h e l i c a la n t e n n a . I n an o p e n - c i r c u i t e d a n t e n n a , t h e s e c o n d e n d s o f t h er e s o n a n t e l e m e n t s 1 0 8 b , 1 1 0 b , 1 1 2 b , 1 1 4 b , 1 1 6 b , 1 1 8 b , 1 2 0 b ,1 2 2 1 ) a r e o p e n - c i r c u i t e d a s i n FIG. 3. I n a s h o r t - c i r c u i t e da n t e n n a t h e s e c o n d e n d s o f h e r e s o n a n t e l e m e n t s 1 0 8 b , 1 1 0 b ,1 1 2 b , 1 1 4 b , 1 1 6 b , 1 1 8 b , 1 2 0 b , 1 2 2 1 ) a r e s h o r t - c i r c u i t e d t oe a c h o t h e r v i a c o n d u c t i v e e l e m e n t s . I n s h o r t - c i r c u i t e d h e l i c a la n t e n n a s t h e r e s o n a n t elements a r e t y p i c a l l y s h o r t e d t o eacho t h e r by c r o s s i n g t h e e l e m e n t s t o f o r m a s t a r c o n ? g u r a t i o n .F I G . 6 shoWs an i s o m e t r i c vieW of a t y p i c a l s h o r t - c i r c u i t e dq u a d r i ? l a r a n t e n n a 1 3 0 .

    HoWever, h i s s h o r t - c i r c u i t t e c h n i q u e c a n n o t be u s e d f o r ad u a l p o l a r i z e d m u l t i ? l a r a n t e n n a a s d e s c r i b e d h e r e i n b e c a u s et h e s t a r c o n ? g u r a t i o n o f t h e o u t e r he l i x 104 Would i n t e r f e r eW i t h t h e i n n e r h e l i x 1 0 2 . An l t e r n a t i v e t e c h n i q u e f o r s h o r t i n gt h e o u t e r r e s o n a n t e l e m e n t s 1 1 6 , 1 1 8 , 1 2 0 , and 122 s u c h a su s i n g a r i g i d r i n g e x t e n d i n g a r o u n d t h e i n n e r h e l i x 1 0 2 t oWhich l l o f t h e o u t e r r e s o n a n t e l e m e n t s 1 1 6 , 1 1 8 , 1 2 0 , a n d122 a r e attached can be u s e d .

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    US 7 , 8 1 7 , 1 0 1 B25

    F o r a n o p e n - c i r c u i t e d m u l t i ? l a r a n t e n n a t h e l e n g t h s o f t h ei n d i v i d u a l r e s o n a n t e l e m e n t s 1 0 8 , 1 1 0 , 1 1 2 , 1 1 4 , 1 1 6 , 1 1 8 ,1 2 0 , and 1 2 2 a r e a p p r o x i m a t e l y e q u a l t o a m u l t i p l e o f h a l fW a v e l e n g t h s (M ) W h e r e t h e w a v e l e n g t h 7 ) i s i n v e r s e l y p r op o r t i o n a l t o t h e o p e r a t i n g f r e q u e n c y f ) . A c c o r d i n g l y , t h es m a l l e s t o p e n - c i r c ui t e d m u l t i ? l a r a n t e n n a o p e r a t i n g a t 300M H Z a W a v e l e n g t h 7 ) o f m e t e r ) r e q u i r e s r e s o n a n t e l e m e n tl e n g t h s o f a p p r o x i m a t e l y 0 . 5 m e t e r s . F o r a s h o r t - c i r c u i t e dm u l t i ? l a r a n t e n n a t h e l e n g t h o f t h e r e s o n a n t e l e m e n t s i sa p p r o x i m a t e l y e q u a l t o a m u l t i p l e o f q u a r t e r W a v e l e n g t h s( N 4 ) . A N4 s h o r t - c i r c u i t e d a n t e n n a Would c l e a r l y b e as m a l l e r a n t e n n a t h a n a N2 p e n - c i r c u i t e d a n t e n n a , b u t t h es h o r t - c i r c u i t e d a n t e n n a Would r e q u i r e a d d i t i o n a l p a r t s a n dj o i n t s t o c o n n e c t t h e r e s o n a n t e l e m e n t s and Would h a v e l e s sg a i n . The e s o n a n t e l e m e n t l e n g t h s a r e n o t e x a c t m u l t i p l e s o fa h a l f - W a v e l e n g t h (M2) o r a q u a r t e r - W a v e l e n g t h (M4) due ot h e f a c t t h a t t h e Wave i l l p r o p a g a t e a l o n g a r e s o n a n t e l e m e n ta t l e s s t h a n t h e s p e e d o f i g h t d u e t o t h e p r e s e n c e o f t h e o t h e rr e s o n a n t e l e m e n t a n d t h e c o u p l i n g o f e n e r g y t o t h e f r e e - s p a c eWave.

    I n t h e e x e m p l a r y embodiment shoWn i n F I G S . 3 and 4 t h el e n g t h o f t h e r e s o n a n t e l e m e n t s 1 0 8 , 1 1 0 , 1 1 2 , 1 1 4 , 1 1 6 , 1 1 8 ,1 2 0 , a n d 1 2 2 i s a p p r o x i m a t e l y e q u a l t o a h a l f - W a v e l e n g t h( N 2 ) . I n t h e c a s e Where both t h e i n n e r and o u t e r r e s o n a n te l e m e n t s a r e o f e q u a l n o m i n a l l e n g t h , t h e i r p e r f o r m a n c e i . e .r a d i a t i o n p a t t e r n a n d g a i n p r o ? l e ) W i l l b e s i m i l a r i f n o t v e r yc l o s e l y r e l a t e d . H o W e v e r , i t i s n o t n e c e s s a r y t h a t t h e l e n g t h o ft h e i n n e r r e s o n a n t e l e m e n t s 1 0 8 , 1 1 0 , 1 1 2 , 1 1 4 , b e e q u a l t o t h el e n g t h o f t h e o u t e r r e s o n a n t e l e m e n t s 1 1 6 , 1 1 8 , 1 2 0 , a n d 1 2 2 .The l e n g t h o f t h e i n n e r r e s o n a n t e l e m e n t s 1 0 8 , 1 1 0 , 1 1 2 , a n d114 may e a h i g h e r m u l t i p l e of h a l f - W a v e l e n g t h o r a quart e r - W a v e l e n g t h t h a n t h e l e n g t h o f t h e o u t e r r e s o n a n t e l e m e n t s1 1 6 , 1 1 8 , 1 2 0 , a n d 1 2 2 .

    The i n n e r r e s o n a n t e l e m e n t s 1 0 8 , 1 1 0 , 112 a nd 114 a r eWound o form a h e l i x W i t h a n i n i t i a l d i a m e t e r d 1 , h e i g h t h la n d p i t c h a n g l e X I . The o u t e r r e s o n a n t e l e m e n t s 1 1 6 , 1 1 8 ,1 2 0 , 122 a r e Wound o form h e l i x With an n i t i a l d i a m e t e r d 2 ,h e i g h t h 2 a n d p i t c h a n g l e x 2 . T h e r a d i a t i o n p a t t e r n p r o v i d e dby e a c h o f t h e h e l i c e s 1 0 2 and 104 s p r i m a r i l y a f u n c t i o n o ft h e l e n g t h o f t h e r e s o n a n t e l e m e n t s 1 0 8 , 1 1 0 , 1 1 2 , 1 1 4 , 1 1 6 ,1 1 8 , 1 2 0 and 122 t h a t make up t h e h e l i c e s . The n i t i a l diame t e r , p i t c h a n g l e a n d h e i g h t o f t h e h e l i x d o n o t i n ? u e n c e t h ea n t e n n a s a b i l i t y t o t r a n s m i t o r r e c e i v e . As a r e s u l t , a multi?l a r antenna With a t l e a s t f o u r ? l a r s of h e same fundamentall e n g t h h a s b r o a d l y s i m i l a r p e r f o r m a n c e o v e r a r a n g e o f p i t c ha n g l e s a n d d i a m e t e r s .

    F I G . 7 shoWs t h e r a d i a t i o n p a t t e r n ( r e f e r e n c e d t o c i r c u l a rp o l a r i z a t i o n ) o f b o t h h e l i c e s 1 0 2 and 1 0 4 o f a d u a l p o l a r i Z e dm u l t i ? l a r a n t e n n a 1 0 0 W i t h t h e f o l l o W i n g e x e m p l a r y dimens i o n s : t h e i n n e r h e l i x 102 h a s an n i t i a l diameter of . 2 5 m, ap i t c h a n g l e o f 2 0 . 0 0 and 1 . 5 0 t u r n s ; t h e o u t e r h e l i x 1 0 4 h a s ad i a m e t e r o f 0 . 5 2 5 m, a p i t c h a n g l e o f 1 5 . 7 0 and 0 . 7 5 t u r n s .Curve 1 5 0 r e p r e s e n t s t h e r a d i a t io n p a t t e r n o f t h e o u t e r h e l i x1 0 4 and u r v e 152 e p r e s e n t s t h e r a d i a t i on p a t t e r n o f h e i n n e rh e l i x 1 0 2 . As c a n b e s e e n , p e a k g a i n s o f a r o u n d 5 d B i c ( t h ea n t e n n a g a i n i n d e c i b e l s r e f e r e n c e d t o a c i r c u l a r l y p o l a r i Z e d ,t h e o r e t i c a l i s o t r o p i c r a d i a t o r ) a r e a c h i e v e d f o r b o t h h e l i c e s102 a nd 1 0 4 .

    The i n i t i a l d i a m e t e r d 1 o f t h e h e l i x f o r m e d by t h e i n n e rr e s o n a n t e l e m e n t s 1 0 8 , 1 1 0 , 1 1 2 , a n d 1 1 4 i s l e s s t h a n t h ei n i t i a l d i a m e t e r d 2 o f t h e h e l i x for med by t h e o u t e r r e s o n a n te l e m e n t s 1 1 6 , 1 1 8 , 120 and 122 s u c h t h a t t h e i n n e r r e s o n a n te l e m e n t s 1 0 8 , 1 1 0 , 112 a nd 114 a r e c o n c e n t r i c W i t h t h e o u t e rr e s on a n t e l e m e n t s 1 1 6 , 1 1 8 , 1 2 0 and 1 2 2 . The i n i t i a l h e l i xd i a m e t e r s d l and 2 a r e s e l e c t e d s u c h t h a t t h e tWo h e l i c e s 102a n d 1 0 4 h a v e s i m i l a r e l e c t r i c a l p e r f o r m a n c e W i t h l i m i t e di n t e r f e r e n c e a n d c o u p l i n g b e t W e e n t h e m .

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    6S e l e c t i n g h e l i x d i a m e t e r s d l a n d d 2 t h a t a r e t o o s i m i l a r

    c r e a t e s t h e p o s s i b i l i t y t h a t e n e r g y from one h e l i x m a y bec o u p l e d i n t o t h e o t h e r h e l i x . T h i s c o u p l i n g i s u n d e s i r a b l eb e c a u s e i t r e d u c e s t h e poWer h a t i s t r a n s f e r r e d t o / f r o m f r e es p a c e b y t h e h e l i x . F u r t h e r m o r e , t h e c o u p l i n g c a n a d v e r s e l yi m p a c t t h e r a d i a t i o n p a t t e r n s o f t h e h e l i c e s 1 0 2 a n d 1 0 4 . Ar e a s o n a b l e g o a l i s t o h a v e 1 5 dB c o u p l i n g b e t W e e n t h eh e l i c e s . The i n i t i a l d i a m e t e r s d l a n d d 2 o f t h e h e l i c e s a l s oc a n n o t be s o l a r g e t h a t t h e r e s o n a n t e l e m e n t s form o n l y as m a l l p o r t i o n o f t h e c i r c u m f e r e n c e o f a d e ? n i n g c y l i n d e r . Thei n i t i a l d i a m e t e r s a l s o should n o t be t o o s m a l l a s i n c r e a s e de l e c t r i c a l l o s s can a r i s e . I n an exemplary embodiment, t h ei n i t i a l d i a m e t e r o f t h e o u t e r h e l i x d 2 i s t W i c e t h a t o f t h e i n i t i a ld i a m e t e r o f t h e i n n e r h e l i x d 1 .

    I n t h e e x e m p l a r y embodiment shoWn i n F I G S . 3 and 4 t h eh e l i c e s 102 a nd 104 have c o n s t a n t d i a m e t e r s and a r e t h u sc y l i n d r i c a l i n s h a p e . A l t e r n a t i v e l y o n e o r b o t h o f t h e h e l i c e s1 0 2 and 1 0 4 m a y a v e v a r i a b l e d i a m e t e r s t h a t v a r i e s a l o n g t h ea x i s o f t h e a n t e n n a . H o W e v e r , a t a l l p o i n t s t h e i n n e r h e l i x 1 0 2must have a s m a l l e r diameter t h a n t h e o u t e r h e l i x 1 0 4 .

    FIG. 8 shoWs a s i d e vieW of an l t e r n a t i v e embodiment ofa d u a l p o l a r i z e d m u l t i ? l a r a n t e n n a 200 i n Which t h e o u t e rh e l i x r e s o n a n t e l e m e n t s a r e Wound With an i n c r e a s i n g diame t e r . I n t h e a l t e r n a t i v e embodiment t h e i n n e r h e l i x 202 i sc o m p r i s e d o f f o u r r e s o n a n t e l e m e n t s 2 0 8 , 2 1 0 , 2 1 2 , 2 1 4 a n dt h e o u t e r h e l i x 204 i s c o m p r i s e d o f f o u r r e s o n a n t e l e m e n t s2 1 6 , 2 1 8 , 2 2 0 , 2 2 2 . The i n n e r r e s o n a n t e l e m e n t s 2 0 8 , 2 1 0 ,2 1 2 , 214 a r e c y l i n d r i c a l l y Wound t o f o r m a h e l i x With ac o n s t a n t d i a m e t e r . HoWever, t h e o u t e r r e s o n a n t e l e m e n t s 2 1 6 ,2 1 8 , 2 2 0 , 2 2 2 , a r e Wound W i t h a n i n c r e a s i n g d i a m e t e r s u c ht h a t t h e o u t e r h e l i x 204 i s cone o r f u n n e l s h a p e d . The c y l i nd r i c a l h e l i x embodiment m a y e u s e d i n a p p l i c a t i o n s , s u c h a sm o b i l e d e v i c e i . e . c e l l p h o n e ) a p p l i c a t i o n s , W h e r e t h e r e i sl i m i t e d s p a c e f o r t h e a n t e n n a . The v a r i a b l e d i a m e t e r h e l i xembodiment m a y e u s e d i n s a t e l l i t e a p p l i c a t i o n s Where h e r em a y b e v i r t u a l l y u n l i m i t e d s p a c e f o r t h e d e p l o y e d a n t e n n a ,b u t t h e volume o f t h e stoWed a n t e n n a i s s m a l l .

    The h e i g h t h l o f t h e i n n e r h e l i x 1 0 2 i s g r e a t e r t h a n t h eh e i g h t h 2 o f t h e o u t e r h e l i x 1 0 4 . T h i s h e i g h t d i f f e r e n c e i sn e c e s s a r y t o e n s u r e t h a t both e l i c e s 102 and 104 a r e o p e r a b l ea t t h e same f r e q u e n c y f ) s i m u l t a n e o u s l y . I f t h e i n n e r h e l i x102 Were s h o r t e r t h a n t h e o u t e r h e l i x 104 h e n t h e i n n e r s i g n a lWould n e c e s s a r i l y p r o p a g a t e t h r o u g h t h e o u t e r h e l i x 1 0 4 , t ot h e d e t r i m e n t o f t s e l e c t r o m a g n e t i c p e r f o r m a n c e .

    The p i t c h a n g l e x 1 i s t h e p i t c h o f one t u r n o f a r e s o n a n te l e m e n t . FIG. 9 i s a s i d e vieW of one-Wire h e l i x 250 and su s e d t o shoW h e p i t c h a n g l e o f a h e l i x . The a r a m e t e r S i s t h et u r n s p a c i n g o r t h e l i n e a r l e n g t h of o ne t u r n o f t h e h e l i x . Thep a r a m e t e r D s t h e d i a m e t e r . I f a s i n g l e t u r n i s s t r e t c h e d ? a t ,t h e r i g h t t r i a n g l e shoWn on h e r i g h t s i d e o f F I G . 9 i s o b t a i n e d .The p a r a m e t e r C n d i c a t e s t h e c i r c u m f e r e n c e o f t h e t u r n ,W h i l e L i n d i c a t e s t h e l e n g t h o f W i r e t o o b t a i n a s i n g l e t u r n .The n g l e 0 t i s t h e p i t c h o f h e h e l i x a n d s e q u a l t o t a n 1 ( S / C ) .

    The e l i c a l W i n d i n g o f l l r e s o n a n t e l e m e n t s 1 0 8 , 1 1 0 , 1 1 2 ,1 1 4 , 1 1 6 , 1 1 8 , 1 2 0 a n d 1 2 2 b e g i n s a t t h e g r o u n d p l a n e 1 0 6 .The r e s o n a n t e l e m e n t s of each h e l i x 102 and 104 a r e p h y s ic a l l y s p a c e d 3 6 0 / N a p a r t . I n t h e e x e m p l a r y e m b o d i m e n tshoWn n FIG. , N:4 nd h e r e f o r e t h e r e s o n a n t e l e m e n t s a r es p a c e d 9 0 a p a r t . H o W e v e r , N a n a l s o b e o t h e r v a l u e s , Whichi s d i s c u s s e d b e l o W .

    Winding o f t h e ? r s t h e l i c a l r e s o n a n t e l e m e n t 1 0 8 o f t h ei n n e r h e l i x 1 0 2 b e g i n s a t t h e ? r s t r e f e r e n c e p o i n t 1 2 4 . TheW i n d i n g o f t h e s e c o n d i n n e r r e s o n a n t e l e m e n t 1 1 8 b e g i n s a tt h e s e c o n d r e f e r e n c e p o i n t 1 2 6 , Which s 9 0 f r o m t h e ? r s tr e f e r e n c e p o i n t 1 2 4 . Winding o f t h e t h i r d i n n e r r e s o n a n t e l ement 1 1 0 b e g i n s a t t h e t h i r d r e f e r e n c e p o i n t 1 2 8 , Which s 9 0 f r o m t h e s e c o n d r e f e r e n c e p o i n t 1 2 6 , a n d 1 8 0 0 f r o m t h e ? r s t

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