Izindaba - Isibuyekezo se-Metamaterial Transmission Line Antennas

I. Isingeniso
Izinto ezisetshenziswayo zingachazwa kangcono njengezakhiwo eziklanywe ngokwenziwa ukuze kukhiqizwe izakhiwo ezithile ze-electromagnetic ezingekho ngokwemvelo. Izinto ezisetshenziswayo ezinemvume engemihle kanye nokuvuleka okungemihle zibizwa ngokuthi izinto ezisetshenziswayo ngesandla sobunxele (LHMs). Izinto ezisetshenziswayo ziye zafundwa kabanzi emiphakathini yesayensi kanye nobunjiniyela. Ngo-2003, ama-LHM aqanjwa njengenye yezinguquko eziyishumi zesayensi zesikhathi samanje ngumagazini iSayensi. Izinhlelo zokusebenza ezintsha, imiqondo, namadivayisi kuye kwathuthukiswa ngokusebenzisa izakhiwo ezihlukile zama-LHM. Indlela yomugqa wokudlulisela (TL) iyindlela yokuklama ephumelelayo engahlaziya nezimiso zama-LHM. Uma kuqhathaniswa nama-TL endabuko, isici esibaluleke kakhulu sama-TL ezinto ezisetshenziswayo ukulawula amapharamitha e-TL (ukuqina kokusabalalisa) kanye nokuvinjelwa kwesici. Ukulawulwa kwamapharamitha e-TL ezinto ezisetshenziswayo kunikeza imibono emisha yokuklama izakhiwo ze-antenna ezinobukhulu obuncane, ukusebenza okuphezulu, kanye nemisebenzi emisha. Isibalo 1 (a), (b), kanye no-(c) sibonisa amamodeli wesekethe angenakulahlekelwa womugqa wokudlulisa wesandla sokudla (PRH), umugqa wokudlulisa wesandla sobunxele (PLH), kanye nomugqa wokudlulisa wesandla sokudla ohlanganisiwe (CRLH), ngokulandelana. Njengoba kuboniswe kuMfanekiso 1(a), imodeli yesekethe elinganayo ye-PRH TL imvamisa iyinhlanganisela ye-inductance yochungechunge kanye ne-shunt capacitance. Njengoba kuboniswe kuMfanekiso 1(b), imodeli yesekethe ye-PLH TL iyinhlanganisela ye-shunt inductance kanye ne-series capacitance. Ezisetshenzisweni ezisebenzayo, akunakwenzeka ukusebenzisa isekethe ye-PLH. Lokhu kungenxa yemiphumela ye-parasitic series inductance kanye ne-shunt capacitance engenakugwenywa. Ngakho-ke, izici zomugqa wokudlulisela wesandla sobunxele ezingabonakala njengamanje zonke ziyizakhiwo zesandla sobunxele nezesokudla ezihlanganisiwe, njengoba kuboniswe kuMfanekiso 1(c).

Umfanekiso 1 Amamodeli ahlukene wesekethe yomugqa wokudlulisa

I-propagation constant (γ) yomugqa wokudlulisa (TL) ibalwa kanje: γ=α+jβ=Sqrt(ZY), lapho u-Y no-Z bemelela ukungena kanye ne-impedance ngokulandelana. Uma kucatshangelwa i-CRLH-TL, u-Z no-Y bangachazwa kanje:

I-CRLH TL efanayo izoba nobudlelwano bokuhlakazeka okulandelayo:

I-phase constant β ingaba inombolo yangempela noma inombolo engokomfanekiso. Uma i-β ingokoqobo ngokuphelele ngaphakathi kwebanga lemvamisa, kukhona i-passband ngaphakathi kwebanga lemvamisa ngenxa yesimo γ=jβ. Ngakolunye uhlangothi, uma i-β iyinombolo engokomfanekiso kuphela ngaphakathi kwebanga lemvamisa, kukhona i-stopband ngaphakathi kwebanga lemvamisa ngenxa yesimo γ=α. Le stopband ihlukile ku-CRLH-TL futhi ayikho ku-PRH-TL noma ku-PLH-TL. Izibalo 2 (a), (b), kanye no-(c) zibonisa ama-dispersion curve (okungukuthi, ubudlelwano buka-ω - β) be-PRH-TL, PLH-TL, kanye ne-CRLH-TL, ngokulandelana. Ngokusekelwe kuma-dispersion curve, i-group velocity (vg=∂ω/∂β) kanye ne-phase velocity (vp=ω/β) yomugqa wokudlulisela kungatholakala futhi kulinganiswe. Ku-PRH-TL, kungaphinde kuthathwe kusukela ku-curve ukuthi i-vg kanye ne-vp ziyafana (okungukuthi, vpvg>0). Ku-PLH-TL, ijika libonisa ukuthi i-vg kanye ne-vp azifani (okungukuthi, i-vpvg<0). Ijika lokusabalala kwe-CRLH-TL libonisa nokuba khona kwesifunda se-LH (okungukuthi, i-vpvg <0) kanye nesifunda se-RH (okungukuthi, i-vpvg > 0). Njengoba kungabonakala kuMfanekiso 2(c), ku-CRLH-TL, uma i-γ iyinombolo yangempela emsulwa, kukhona ibhendi yokuma.

Umfanekiso 2 Amajika okusabalala kwemigqa yokudlulisela ehlukene

Ngokuvamile, ama-resonance ochungechunge kanye nama-parallel e-CRLH-TL ahlukile, okubizwa ngokuthi isimo esingalingani. Kodwa-ke, lapho ama-frequencies ochungechunge kanye nama-parallel resonance afana, abizwa ngokuthi isimo esilinganiselayo, futhi imodeli yesekethe esilinganayo esilula ephumayo iboniswe kuMfanekiso 3(a).

Umfanekiso 3 Imodeli yesekethe kanye nejika lokusabalala komugqa wokudlulisela wesandla sobunxele ohlanganisiwe

Njengoba imvamisa ikhula, izici zokusabalala kwe-CRLH-TL ziyanda kancane kancane. Lokhu kungenxa yokuthi ijubane lesigaba (okungukuthi, vp=ω/β) liya ngokuya lincika kumvamisa. Kumaza aphansi, i-CRLH-TL ibuswa yi-LH, kanti kumaza aphezulu, i-CRLH-TL ibuswa yi-RH. Lokhu kubonisa uhlobo oluphindwe kabili lwe-CRLH-TL. Umdwebo wokusabalala kwe-CRLH-TL wokulingana uboniswe kuMfanekiso 3(b). Njengoba kuboniswe kuMfanekiso 3(b), ukuguquka kusuka ku-LH kuya ku-RH kwenzeka ku:

Lapho i-ω0 iyimvamisa yokuguquka. Ngakho-ke, esimweni esilinganisiwe, ushintsho olubushelelezi lwenzeka kusuka ku-LH kuya ku-RH ngoba i-γ iyinombolo ecatshangelwayo nje. Ngakho-ke, ayikho i-stopband yokusabalala kwe-CRLH-TL elinganisiwe. Nakuba i-β ingu-zero ku-ω0 (engenamkhawulo uma kuqhathaniswa nobude besikhathi obuqondisiwe, okungukuthi, λg=2π/|β|), igagasi lisaqhubeka ngoba i-vg ku-ω0 ayiyona i-zero. Ngokufanayo, ku-ω0, ukushintsha kwesigaba kungu-zero ku-TL yobude d (okungukuthi, φ= - βd=0). Ukuthuthuka kwesigaba (okungukuthi, φ>0) kwenzeka ebangeni lemvamisa ye-LH (okungukuthi, ω<ω0), kanye nokuhlehliswa kwesigaba (okungukuthi, φ<0) kwenzeka ebangeni lemvamisa ye-RH (okungukuthi, ω>ω0). Ku-CRLH TL, i-impedance yesici ichazwa kanje:

Lapho i-ZL ne-ZR kuyi-PLH kanye ne-PRH impedances, ngokulandelana. Ku-case engalingani, i-characteristic impedance incike ku-frequency. I-equation engenhla ikhombisa ukuthi i-balanced case ayincikile ku-frequency, ngakho-ke ingaba nomdlalo we-bandwidth obanzi. I-equation ye-TL ethathwe ngenhla ifana namapharamitha ahlanganisayo achaza izinto ze-CRLH. I-propagation constant ye-TL ingu-γ=jβ=Sqrt(ZY). Njengoba kunikezwe i-propagation constant yezinto (β=ω x Sqrt(εμ)), i-equation elandelayo ingatholakala:

Ngokufanayo, i-impedance yesici se-TL, okungukuthi, Z0=Sqrt(ZY), ifana ne-impedance yesici sezinto ezibonakalayo, okungukuthi, η=Sqrt(μ/ε), evezwa kanje:

Inkomba yokubuyisa ye-CRLH-TL elinganisiwe nengalingani (okungukuthi, n = cβ/ω) iboniswe kuMfanekiso 4. KuMfanekiso 4, inkomba yokubuyisa ye-CRLH-TL kububanzi bayo be-LH imbi kanti inkomba yokubuyisa kububanzi bayo be-RH imbi.

Isithombe 4 Izinkomba ezijwayelekile zokubuyisa ama-CRLH TL alinganisiwe nangalingani.

1. Inethiwekhi ye-LC
Ngokususa amaseli e-LC e-bandpass aboniswe ku-Figure 5(a), i-CRLH-TL ejwayelekile enokulingana okusebenzayo kobude d ingakhiwa ngezikhathi ezithile noma ngaphandle ngezikhathi ezithile. Ngokuvamile, ukuze kuqinisekiswe ukuthi kulula ukubala nokukhiqizwa kwe-CRLH-TL, isekethe idinga ukuba ngezikhathi ezithile. Uma kuqhathaniswa nemodeli ye-Figure 1(c), iseli lesekethe le-Figure 5(a) alinasayizi futhi ubude obungokoqobo buncane kakhulu (okungukuthi, i-Δz ngamamitha). Uma ubheka ubude bayo kagesi θ=Δφ (rad), isigaba seseli le-LC singavezwa. Kodwa-ke, ukuze kuqashelwe ngempela i-inductance esetshenzisiwe kanye ne-capacitance, ubude obungokoqobo p budinga ukusungulwa. Ukukhetha ubuchwepheshe bokusebenzisa (njenge-microstrip, i-coplanar waveguide, izingxenye ze-surface mount, njll.) kuzothinta usayizi ongokoqobo weseli le-LC. Iseli le-LC le-Figure 5(a) lifana nemodeli ekhuphukayo ye-Figure 1(c), kanye nomkhawulo walo p=Δz→0. Ngokwesimo sokufana p→0 kuMfanekiso 5(b), i-TL ingakhiwa (ngokukhipha amaseli e-LC) okulingana ne-CRLH-TL efanayo efanelekile enobude obungu-d, ukuze i-TL ibonakale ifana namaza kagesi.

Isibalo 5 I-CRLH TL isekelwe kunethiwekhi ye-LC.

Kwiseli le-LC, uma kucatshangelwa izimo zemingcele yesikhathi (ama-PBC) afana ne-Bloch-Floquet theorem, ubudlelwano bokuhlakazeka kweseli le-LC bufakazelwa futhi buvezwa kanje:

I-series impedance (Z) kanye ne-shunt acceptance (Y) yeseli le-LC kunqunywa yizibalo ezilandelayo:

Njengoba ubude bukagesi besekethe yeyunithi ye-LC buncane kakhulu, ukusondela kukaTaylor kungasetshenziswa ukuthola:

2. Ukusetshenziswa Okubonakalayo
Esigabeni esidlule, kuxoxwe ngenethiwekhi ye-LC yokukhiqiza i-CRLH-TL. Amanethiwekhi anjalo e-LC angatholakala kuphela ngokusebenzisa izingxenye zomzimba ezingakhiqiza amandla adingekayo (i-CR ne-CL) kanye ne-inductance (i-LR ne-LL). Eminyakeni yamuva nje, ukusetshenziswa kwezingxenye ze-chip technology (i-SMT) noma izingxenye ezisatshalaliswayo kudonsele isithakazelo esikhulu. I-Microstrip, i-stripline, i-coplanar waveguide noma obunye ubuchwepheshe obufanayo bungasetshenziswa ukufeza izingxenye ezisatshalaliswayo. Kunezici eziningi okufanele uzicabangele lapho ukhetha ama-chip e-SMT noma izingxenye ezisatshalaliswayo. Izakhiwo ze-CRLH ezisekelwe ku-SMT zivame kakhulu futhi kulula ukuzisebenzisa maqondana nokuhlaziywa nokuklama. Lokhu kungenxa yokutholakala kwezingxenye ze-chip ze-SMT ezingaphandle kweshalofu, ezingadingi ukulungiswa kabusha nokukhiqizwa uma kuqhathaniswa nezingxenye ezisatshalaliswayo. Kodwa-ke, ukutholakala kwezingxenye ze-SMT kuhlakazekile, futhi ngokuvamile zisebenza kuphela kumaza aphansi (okungukuthi, i-3-6GHz). Ngakho-ke, izakhiwo ze-CRLH ezisekelwe ku-SMT zinebanga elilinganiselwe lemvamisa yokusebenza kanye nezici ezithile zesigaba. Isibonelo, ezinhlelweni zokusebenza ezikhipha imisebe, izingxenye ze-chip ze-SMT zingase zingenzeki. Isithombe 6 sibonisa isakhiwo esisatshalaliswe ngokusekelwe ku-CRLH-TL. Isakhiwo sibonakala nge-capacitance ye-interdigital kanye nemigqa ye-short-circuit, okwenza i-capacitance yochungechunge lwe-CL kanye ne-inductance ehambisanayo ye-LL ye-LH ngokulandelana. I-capacitance phakathi komugqa kanye ne-GND ithathwa njenge-RH capacitance CR, kanti i-inductance ekhiqizwa yi-magnetic flux eyenziwe ukugeleza kwamanje esakhiweni se-interdigital ithathwa njenge-RH inductance LR.