Analysis of Coupling Effectiveness on Concealed Signal Cable Slot with Different Shapes

Transcription

1 Sensos & ansdces, Vol. 6, sse, Janay 4, pp. 9-7 Sensos & ansdces 4 by SA Pblshng, S.. Analyss of oplng Effectveness on oncealed Sgnal able Slot wth Dffeent Shapes hn-jang Sha Shaanx nvesty of echnology, School of Physcs and Electonc nfomaton Engneeng, Shaanx, Han Zhong, hna, 7 E-mal: hwesc@6.com Receved: Octobe /Accepted: Decembe 4 /Pblshed: Janay 4 Abstact: t s mpotant to stdy the sheldng effectveness to edce the electomagnetc ntefeence and to potect electonc components. akng the concealed sgnal cable whch s set n sheldng shell as the eseach obect. he nflence of dffeent slot shapes on sheldng effectveness was analyzed by applyng the mxed methods (adc E-EM). he eslts show that the coplng capactance of a tapezodal slot s the bggest, the one of ectangla slot s medm, and the one of a tape slot s the smallest fo sheldng pa cable, bt the change tend ae almost the same. n addton, wth the vaos slot shapes wdth nceasng, sheldng pa cable coplng capactance s lttle changed. he stdy s nstctve fo moe effectve to defense EM and wll mpove the agcltal concealed sheldng cable electomagnetc compatblty. opyght 4 SA Pblshng, S.. Keywods: oncealed sgnal cable, Slot wth dffeent shapes, oplng capactance, the mxed methods (adc E-EM).. ntodcton Wth the apd development of electonc techne, the concealed sgnal cable has wdely sed n many mpotant epment connectons, sch as fe fghtng epment, commncatons epment, etc. []. Howeve, the poblem of electomagnetc ntefeence becomes moe and moe seos [-4]. he sheldng laye s an effectve method to edce the electomagnetc ntefeence, bt thee ae nevtable slt o slot of dffeent hole pattens n the sheldng laye, to connect the powe lnes, ventlate, o fo othe ppose. hese slots can edce sheldng effectveness of the sheldng laye, whch can make the electomagnetc wave copled nto the sgnal cable, affectng the egla wok of the electonc epments. heefoe t s necessay to stdy the coplng chaactestcs of vaos slot shapes to edce the ntefeence of electomagnetc wave. oncealed cables [5] ae one of the mpotant pats of the whole system that sed fo wng domestc and commecal bldngs, and ndetake the ados task of sgnal tansmsson. nde exteme ccmstances, the coplng capactances of coe wes n electonc devces cold be detemned only when paametes sch as ndctances [6-7] and capactances wee gven [8-]. hs, the coplng chaactestcs of the concealed sgnal cables contanng ccmfeental weld shelds mst be stded to mnmze the dstbances of electomagnetc waves. At pesent, thee wee many stdes on the concealed cables, and the methods wee vaed, sch as Mlt-pole theoy [], DD [4], MOM [5] and tansmsson lne method [5, 6]. Howeve, the stdy on the nflence of coplng capactance effect of concealed cable wth dffeent slot shapes s fa fom enogh. n most cases, the slots on the sheldng Atcle nmbe P_85 9

2 Sensos & ansdces, Vol. 6, sse, Janay 4, pp. 9-7 laye ae not sngle slots. n ths pape, wth the concealed shelded coaxal cable and the two-coe cable as the eseach obects, the nflence of dffeent slot shapes (sch as tape slot, tapezodal slot, ectangla slot) n shelded effectveness wee analyzed by applyng the mxed methods (adc E-EM) [7-9] wth Matlab [-5]. o demonstate the accacy and flexblty of the mxed methods, the nflence of the defomaton degee of shelded defomed coaxal cable compaed wth the mlt-pole theoy and othes on the eslts wee dscssed. he engneeng example eslts showed that fo the concealed sgnal two-coe cable, the change of coplng capactance was elated wth the slot shapes n deep laye at the locaton of paallel coe dstance; and the change tendency of coplng capacto wth the slot shapes at the vetcal coe dstance was almost the same as the slots at the paallel coe dstance. t, when the slots depth was te deep, vey lkely one coe was exposed, and then the coplng capacto deceased apdly. heefoe the stdy was nstctve fo moe effectve to defense EM and wold mpove the concealed sgnal cable electomagnetc compatblty.. Mxed Method (adc E-EM).. adc EM A tangle element abot adc EM have sx nodes (ncldes thee vetces and a mddle node of each sdes). As shown n g., sppose that a node feld n tangle element s adc ntepolatng of the felds abot sx nodes [9]: c 6 c c f g.. adc element (EM). x c, f x y c x he E o k 4 c y 5 l y, k l c x y Z H Z (longtdnal components of felds) shold meet Helmholtz eaton, when waves tacng n the metal wavegde [9]. 6 () k k p () x y Evalent fnctonal s J s x y k k p dxdy Dscete (), maxmzed fnctonal, s: K K p kk p p p,,, n K p pn n p p n n (), (4) Matx fom s conssted of evey coeffcent s: e K t ctg n (5), K e e t, t,,.. adc EM m m ctg m ctg (5) ae the symmetcal matx,, ae the constants. A -dmenson bonday ntegal eaton s deved by Geen's theoem [4]: G p ( ) G g d n' n' G (6) G d n' adc segment of EM, as shown n g., a element s dscete segments ( nodes), and of thee nodes means,,, and,, next, nteelated nodal vale and,, adc fncton can be sed to epesent any pont of and, namely [4]: whee,, ae the adatc fncton. ( ) ( ) ( )( ) Evalent fnctonal s, (7)

3 Sensos & ansdces, Vol. 6, sse, Janay 4, pp. 9-7 J dx d dy d d d (8) Abbevated fomla was: A X, () and x x x x, (9) y y y y whee ( x, y ) s the coodnates of the nodes n the coodnate system of all system elements. Add (7), (8), (9) to (6), abbevated fomla s N ( N ) H N G + *(element) (node) () whee A s the N N ank phalanx, X and ae the N ank aay. Eaton () s the eaton of lnea bonday element method... Mxed Method (adc E- EM) Solvng of the two-dmensonal aplace eaton s taken as an example. Assme that thee s an aea wth nfom medm as shown n g., n whch, the fnte element method analyss (EM) s sed n aea, whle the bonday element method (EM) n aea. And. As shown n g., sng the fnte element method analyss n aea, matx eaton cold always be obtaned as follows: P P K, (4) * * ( N ) whee s the bt vecto of the node of and Г ; P s the extenal exctaton vecto actng at the node of Г. And both and P ae vectos on the ntenal bonday Г. g.. ne segment. n eaton (), vales of N on l k and N on l k wee gven by bonday condton, shown them wth ( N) and ( N ) ; vales of N / n on l k and N as ncetan vaate, shown them wth ( N ) and ( N ). hen eaton (7) cold be expessed as the followng block matx ( N ) ( ) ( ) N H H G G ( ) () N N f the ncetan tems wee pt on the left of the eaton, and the cetan tems wee pt on the ght of the eaton, then eaton () cold be changed nto the followng: H G ( N) ( N) ( N) G H ( N) () g.. Regon of mxed method. sng bonday element method on the bonday Г + Г of aea, the esltant algebac eaton s geneally shown n the followng fom: H G, (5) whee and ae the electcal potental of the node on Г В, and the vecto conssted by ts devatve

4 Sensos & ansdces, Vol. 6, sse, Janay 4, pp. 9-7 n the nomal decton, espectvely. And and ae vectos on the ntenal bonday Г. Aeas and shae a common bonday Г. onsdeng that P s elated to, the electcal potentals on both sdes of Г and the vectos of the devatves on the nomal decton shall satsfy the compatblty condton and elbm condton, espectvely:, (6) he smltaneos eatons of (4) and (5) ae solved, and nknown anttes cold be theoetcally detemned. f the and of and meda ae dffeent, the elbm condton shold be changed nto. Assme that thee s an aea wth a bonday of Г=Г +Г. he s gven on Г, wheeas the s known on Г. o the fll bonday Г, the basc elatonshp of bonday element method s defned as: ( ) Wd ( ) Wd W ( ) n d ntegaton by pats s pefomed twce on the eaton above, and ths obtanng: ( W ) d Wd W d n Wd W d n f W s the basc solton of the eston, the followng eaton to the bonday pont shold be as follow: d n d Afte dscetzaton, a systemc matx eaton set to bonday shold be as follow: H G (7) he bonday condton s not consdeed n the eaton above, and t s a classc algebac eaton set based on bonday element method. Whee both and ae vectos of node on the bonday. When the aea s exactly n g., eaton (7) cold be expessed as eaton (5) by block vectos. On the othe hand, the fnte element analyss s sed fo the same aea. stly, stat fom the followng eaton: ( ) d ( ) d (8) Assme that fncton satsfes the basc bonday condton of. ntegaton by pats on eaton (8) once, ths obtanng: x k d x k d (9) he matx algebac eaton set based on fnte element analyss, coespondng to eaton (9), s: K P () K P () Eaton () s the classc algebac eaton set based on fnte element analyss. n eaton (), s the electcal potental of all the nodes n aea and on the bonday ; K s the matx that only elated to the geometcal shape and sze of vaos elements; P s the vecto obtaned thogh calclatng the bonday ntegals on the ght of eaton (9). f the aea s exactly, eaton () cold be n the fom of block vectos,.e., eaton (4). P and ae the vectos n the eaton obtaned by the two methods sed fo the same aea, and they ae deved by the same lne ntegal. hs, they ae cetanly elated. P epesents the exctaton povded by the extenal soce on bonday to the system. Dng the fnte element patton of, the bonday s also pattoned nto segments, and they belong to each fnte element, espectvely. f egadng these bonday segments as elements, the followng eaton cold be obtaned: P ( d), () whee ( ) s the element nmbe on bonday. nctons and cold be appoxmately expessed by ntepolaton fncton and nodal vale on bonday element ( ) as: ( ), ( ),

5 Sensos & ansdces, Vol. 6, sse, Janay 4, pp. 9-7 whee ( ) and ( ) epesent the nodal electcal potental on bonday element ( ) and the vecto of ts devatve on the nomal decton, espectvely. Sbsttte the two eatons above nto eaton (), ths obtanng: P ) ( ) d ( n ode to bng the vecto ( ) on bonday element ( ) nto of the fll system (ncldng nteo aea), and bng ( ) nto the vecto of the node of fll bonday (excldng the nteo aea), the oole matx s sed. ( ) ( ), ( ) ( ) f element ( ) has N nodes and the ente aea (ndcng the bonday) has a total of N nodes, ( ) s a N N -ode matx. hey all consst of o. Nonzeo elements ae memoed only n calclaton, as n the smla case of ( ). Wheeas t cold only establsh connecton between bonday element ( ) and the fll bonday. wo eatons above ae sed and then the followng eaton cold be obtaned: P heefoe M ( ) [ ( ) d ] P M () hs eaton () cold be as follow: K M (4) o a combned solton to eate a fnte element analyss-based aea nto a bonday element method-based aea, t ees to deve the bonday element method-based eaton set fom aea (ncldng and ). As fo, and P epesent those n eaton (4), espectvely:, P P P As shown n eaton (4): K M n hee, fnte element analyss-based aea s sed to consttte the bonday element method-based eaton set, whch cold be wtten n a block fom as followng: K M M K (5) On the othe hand, n bonday element aea (ncldng and ), eaton set s eaton (5), whch cold be wtten as followng afte conveson: H G G H (6) ased on eaton (5) and (6), and takng nto consdeaton of the compatblty condton and elbm condton,, (7) he bonday element method-based system eaton of the ente aea cold be obtaned: H G H K M G M K (8) Sbsttte the bonday condton nto the eaton above, the nknown anttes cold ths be detemned.. oncealed able apactance alclaton Pncple.. able apactance oplng Mechansm apactve coplng s the electomagnetc ntefeence phenomenon whch cased by dstbted capactance between the electonc devces, electonc components, P lne, and so on. he capactance wold be exsted between the two condctos when they close to each othe. And the condctve pathway wold be fomed thogh ths eactance. hs phenomenon s called capactance coplng that the potental of othe condctos wee effect by the sgnals voltage (o nose voltage) of condcto thogh dstbted capactance, namely, electostatc coplng o electostatc ndcton. he chaactestc mpedance Z of EM tansmsson lne as follows:

6 Sensos & ansdces, Vol. 6, sse, Janay 4, pp. 9-7 Z, ( ) whee /, the capactance s compted at fst. he sgnal wold be eflex n the node of mpedance dscontnty f the mpedance of the tansmsson path had changed dng the sgnal tansmsson. hs, the changes of coplng capactance ae closely wth electomagnetc ntefeence, whch wold be affectng the alty of the sgnal tansmsson... oncealed able apactance alclaton Pncples One of the man woks of the electomagnetc compatblty analyss n the system s to calclate the capactance coplng of gde lne to coe we, ths, the coplng capactance and fee capactance ae compted at fst. As shown n g. 4, assme the shelded stcte (condcto ) s zeo potental condctos, and the potentals of the othe N condctos ae espectvely V, V,, V N, then the bonday vale poblems of electostatc feld as follows l ( ),, (9), l V, l V,, l N V N whee s the feld, l k s k condcto bonday cve of k condcto, V k s k condcto potental. / V capactance. V V, V(,,, N; ).. Matlab ntodcton ae coplng Matlab was both a powefl comptatonal envonment and a pogammng langage that easly handles matx and complex athmetc. t was a lage softwae package that has many advanced feates blt-n, and t had become a standad tool fo many wokng n scence o engneeng dscplnes. Among othe thngs, t wold allow easy plottng n both two and thee dmensons. Matlab had two dffeent methods fo exectng commands: nteactve mode and batch mode. n nteactve mode, commands ae typed (o ct-andpasted) nto the 'command wndow'. n batch mode, a sees of commands wee saved n a text fle (ethe sng Mat lab s blt-n edto, o anothe text edto sch as Emacs) wth a '.m' extenson. he batch commands n a fle wee then exected by typng the name of the fle at the Matlab command pompt. he advantage to sng a '.m' fle was that yo cold make small changes to yo code (even n dffeent Matlab sessons) wthot havng to emembe and etype the ente set of commands. Also, when sng Matlab's blt-n edto, thee wee smple debggng tools that can come n handy when yo pogams stat gettng lage and complcated. Moe on wtng.m fles late. 4. Analyzed Reslts V l V K l K 4.. ompason of heoy and the Mlt-pole heoy V N l N l As shown n g. 5, a coss-secton of long staght cable, whee means ads of ccla condctos, and a=. m means sde length of ectangla, appled voltage between the nne and ote condctos s = V. g. 4. Vaos sheldng cable. y he capactance matx of shelded mltcondcto cable s N N N N V N V, NN V N () a x whee / V capactances, ae fee V V, V a g. 5. ansmsson lne consstng of ectangla and ccla condctos. 4

7 Sensos & ansdces, Vol. 6, sse, Janay 4, pp. 9-7 he bonday of nne condcto wold be evenly sbdvded fo the 46 nets by the EM, the bonday of ote condcto wold be sbdvded fo the 48 lnea segments, then the eslts of chaactestc mpedance of ccla-ectangla tansmsson lne by the mxed method (adc E- EM) compason lteate [4, 8, 6] and as llstated n able. able. haactestc mpedance of ccla-ectangla tansmsson lne (nt: V/m). /a Pape EM teate teate [4] [8] [6] See able, the calclaton eslts ae well n ageement wth that of the pevos pblshed data. heefoe, the mxed method pecson was te hgh. he shelded defomed coaxal cable [6] as shown n g. 6, the cables easly lead to defomed n pactce, when placed on the gond fo long tmes de to gavty and the fcton between the sface. he paametes: R =.455 mm, R =.49 mm, =.,. y the geneal pogam of the mxed method, the followng calclaton eslts of shelded defomed coaxal cable abot capacto wee obtaned, as llstated n able. R R o x able. ompason of the calclaton eslts of the shelded defomed coaxal cable wth the othe methods (p). h/mm Pape EM [] M Slots ommncaton able oplng apactance alclaton As shown n g. 7, the commncaton shelded two-coe cable was conssted of cylndcal condctos and shelded condcto nmbe*secton (mm )=*. mm ; ote damete R=.86 mm, space between coes a=*.64 mm; d s the slot depth of sheld laye, s s slot wdth; the etaned laye s between the shelded laye and condctos (consstng of lamnated steel plastc stp), wth the delectc constant =.. y sng the adc E-EM nvesal pocede calclaton, the nflences of dffeent slot shapes (tapezodal slot, ectangla slot, tape slot) on sheldng effectveness wee analyzed. R s d o x h a g. 6. Shelded defomed coaxal cable. As shown n able, the calclaton eslts of shelded defomed coaxal cable abot capacto wee well n ageement wth the lnea bonday method and mlt-pole theoy vale [], and the capacto nceased wth the defomaton degee of the shelded defomed coaxal cable. g. 7. Shelded defomed pa cable. As shown n g. 8, fo the shelded commncaton cable, the capacto of dffeent slots n shelded two-coe cable vaed wth the slot depth d of shelded shell by applyng the mxed method wth Matlab wee gven. 5

8 Sensos & ansdces, Vol. 6, sse, Janay 4, pp. 9-7 d tape ectangla tapezodal he analyss on the shelded effectveness of commncaton two-coe cable wth dffeent slot shapes showed that the ntenal electomagnetc coplng ntefeence ablty was close elated wth the slot shapes n deep laye, not shallow laye. he coplng capactance deceased geatly wth the slot depth d ncease, and the coplng capactance of tapezodal slot shelded commncaton cable changed the bggest, followed by the ectangla slot, and the tape slot was the smallest. When the coplng capactance changed geatly, the chaactestc mpedance of tansmsson lne wold change, and so was the dspeson, whch wold have geat nflence on the tansmsson alty of cable commncaton. g. 8. oplng capacto of shelded pa cable of dffeent slot shapes vaed wth d. See g. 8, when the slot depth d was small, the change of coplng capactance was scacely, whle when the slot depth d was geate than.5 mm, the coplng capactance deceased geatly, and the coplng capactance of tapezodal slot shelded commncaton cable changed the bggest, followed by the ectangla slot, and the tape slot was the smallest. he eslts show that the change of coplng capactance was elated wth the slot shapes n deep laye of shelded two-coe cable, bt showed the change tend wee almost the same. As shown n g. 9, fo the shelded commncaton cable, the capacto of dffeent slots n shelded two-coe cable vaed wth the slot wdth s of shelded shell by applyng the mxed method wth Matlab wee gven. See g. 9, when the slot was n the shallow laye wth the depth of. mm, the coplng capactance of shelded two-coe cable of dffeent slot shapes had lttle change. t showed no sgnfcant elatonshp wth the slot wdth. tape ectangla tapezodal g. 9. oplng capacto of shelded pa cable of dffeent slot shapes vaed wth s. 5. onclsons he bonday element eaton of lnea segment was dscete fom lnea ntepolatng appoxmaton, whch was appled to deal wth the poblem of -dmensonal electostatc feld, sch as two dmenson mlt-bonday condtons and shelded defomed coaxal tansmsson lnes, and t shows ths method s effectve and feasble thogh nmecal examples. hs method not only solves the dscontnos poblem, bt also the pecson of the method was hgh. o the ovehead sheld coaxal cable of ng seam and the ovehead sheld two-coe cable of ng seam that not had been pblshed, ths pape povdes coplng capacto of these cable by ths method fo the fst tme. t had been shown that ths method s povded wth a geat deal of mets sch as smple opeaton and convenent calclaton, so t wold be have fne geneal avalablty. ) hs pape poposed to se the mxed method (adc E-EM) to deal wth the capacto of dffeent slots whch was set n shelded shell by Matlab, sch as concealed sheld coaxal cable, concealed sheld two-coe cable. ) he slot shape had become one of the man cases fo edcton the cable shelded effectveness. he analyss on the shelded effectveness of commncaton cables showed that the coplng capactance of shelded two-coe cable of dffeent slots vaed scacely f the slot was n shallow laye, the coplng capactance changed geatly when the slot depth was geate than.5 mm; and the change of coplng capactance was elated wth the slot n deep laye of shelded two-coe cable at the locaton of paallel coe dstance. he change tendency of coplng capactance wth the dffeent slot shapes at the vetcal coe dstance was almost the same. And, the coplng capactance of tapezodal slot shelded commncaton cable changed the bggest, followed by the ectangla slot, and the tape slot was the smallest. ) heefoe, the electcal wokes shold se the tape shape slot n shelded cable slot desgns. 6

9 Sensos & ansdces, Vol. 6, sse, Janay 4, pp ) he coplng effect of any one mlt-coe cable and dffeent sectons cable wold be analyzed by the mxed method. Acknowledgements Poect: the Scence and echnology Pogam of the Edcaton Depatment of Shaanx Povnce Govenment (No. JK). Refeences []. Z. Y., lta-hgh voltage gd, hnese Economc Pess, eng, 5, pp. -. []. Zheng J.., EM desgn and test cases analyss, Electoncs ndsty Pess, eng, 6, pp. -. []. Sha. J., Analyss on the oplng Effect of Vaos Shpboad Sheldng Mlt-condcto able, Mane echnology,,, pp [4]. Sha. J., Han. J., nea bonday element of angle ac method analyss on specal tansmsson lnes wth offset nne condcto, Jonal of Shaanx nvesty of echnology (Natal Scence Edton), 6,,, pp. 8-. [5]. Wang Y.., Zhao X. H., Wen., Sheldng effectveness analyss of vehcle electonc epment wth cable holes, Jonal of Jln nvesty (nfomaton Scence Edton),, 5,, pp [6].. Y., Wang H., Zhang Z. J., Reseach on hst haactestcs n Pemanent Magnet nea Synchonos Moto ased on Analyss of Nonlnea ndctance, n Poceedngs of the SEE,,,, pp [7]. N Y. Y., Hang Y., n Y., -D magnetc feld analyss and self-ndctance comptaton fo cable, Jonal of HEE nvesty of echnology (Natal Scence Edton), 5,,, pp. -4, 4. [8]. Sha. J., nea bonday element method analyss on the capactance of vaos defomed symmety shelded mltcondcto cable, Jonal of Henan Nomal nvesty (Natal Scence Edton), 4,,, pp [9]. X Y., alclaton of the apactance of eaky oaxal ablen, XDAN nvesty, X an,. []. Ma X. P., Analyss of oplng apactances and eang ents of Asynchonos Motos ed by PWM nvetes, eng Jao ong nvesty, eng,. []. J. Adab,. Zae, A. Ghost, R. D. oenz, alclatons of capactve coplngs n ndcton geneatos to analyze shaft voltage, E Powe Electoncs,,, pp []. Sha. J., Analyss on Ovehead Shelded oplng Effectveness of Rng Seam by Matlab, Jonal of omptes, 8, 8,, pp []. Zheng. H., Xe. Y., a W. D., Mltpole theoy analyss on the capactance of shelded mltcondcto cable, Hgh Powe ase & Patcle eams, 5,,, pp [4]. Gao. P., Zhang., Stablty and spe-convegence analyss of the DD scheme fo the D Maxwell eatons n a lossy medm, Scence hna (Mathematcs), 54,,, pp [5].. S., Wang Y. Z., W. N., MOM/DD Appoach fo Evalatng sse Specfed SAR of Hman Exposed to Electomagnetc eld of Omndectonal ase Staton, Jonal of Mcowaves, 6,, pp. -7. [6]. Y. M., Zheng. X., Hao Z. Z., etc., Analyss of a mltmode tansmsson lne model of the sheldng effectveness of encloses wth apetes, Jonal of hongng nvesty, 4,,, pp. 7-. [7]. Sha. J., he Mxed Method Analyss of Hghe Ode Mode n Wavegde of Pecewse Homogeneos Delectc, Appled Mechancs and Mateals, 4,, pp [8]. Z. Y., Electomagnetc feld bonday element method, Pess of eng nsttte of echnology, eng, 987. [9]. Sheng J. N., Nmecal analyss of electomagnetc felds poect, Pess of X'an Jaotong nvesty, San, 99. []. Sha. J., Analyss on the D Electostatc eld of Polygon Goove by MAA, Jonal of Shaanx nvesty of echnology (Natal Scence Edton),,, pp []. R. M., Zhang J. S., he pofessonal techncans pefomance appasal of coal mne, oal echnology, 7,, pp []. R. M., Analyss on management obect classfcaton wth clste analyss method by Matlab, hna Hgh echnology Entepses, 7,, pp []. Matlab ntodcton, Reteved Octobe, 7, fom the Wold Wde Web: ed/~elec4/matlab html. [4]. Sha. J., Zheng. H., et al., he nea onday Element Method of alclatng the Poblems of D Electostatc eld, Jonal of Ynnan Nomal nvesty (Natal Scence Edton), 6, 5, 6, pp [5]. N G. Z., Yang S. Y., et al., Nmecal calclaton of electomagnetc felds poect, Machne Pess, eng, 4. [6]. n W., A ctcal stdy of the coaxal tansmsson lne tlzng condctos both ccla and sae coss secton, EEE ans., M-, 98,, pp opyght, ntenatonal eency Senso Assocaton (SA) Pblshng, S.. All ghts eseved. ( 7