Iindaba - Uphononongo lwee-Antennas zoMgca woThumelo lweMetamaterial

I. Intshayelelo
IiMetaterials zingachazwa ngcono njengezakhiwo ezenziwe ngobuchule ukuvelisa iipropati ezithile ze-electromagnetic ezingekhoyo ngokwendalo. IiMetaterials ezine-permittivity engalunganga kunye ne-negative permeability zibizwa ngokuba zii-left-handed metaterials (LHMs). Ii-LHM zifundwe kakhulu kwiindawo zesayensi nezobunjineli. Ngo-2003, ii-LHM zabizwa ngokuba yenye yezona mpumelelo zilishumi zenzululwazi zexesha langoku yimagazini iScience. Izicelo ezintsha, iingcamango, kunye nezixhobo ziye zaphuhliswa ngokusebenzisa iipropati ezikhethekileyo ze-LHMs. Indlela yomgca wokudlulisela (TL) yindlela yoyilo esebenzayo enokuhlalutya imigaqo ye-LHMs. Xa kuthelekiswa nee-TL zemveli, uphawu olubalulekileyo lwee-TLs ze-metaterial kukulawulwa kweeparameters ze-TL (i-propagation constant) kunye ne-characteristic impedance. Ukulawulwa kweeparameters ze-TL ze-metaterial kubonelela ngeengcinga ezintsha zokuyila izakhiwo ze-antenna ezinobukhulu obuncinci ngakumbi, ukusebenza okuphezulu, kunye nemisebenzi emitsha. Umfanekiso 1 (a), (b), kunye (c) ubonisa iimodeli zesekethe ezingenalahleko zomgca wokudlulisa wesandla sasekunene ococekileyo (PRH), umgca wokudlulisa wesandla sasekhohlo ococekileyo (PLH), kunye nomgca wokudlulisa wesandla sasekhohlo ohlanganisiweyo (CRLH), ngokwahlukeneyo. Njengoko kubonisiwe kuMfanekiso 1(a), imodeli yesekethe elinganayo yePRH TL idla ngokuba yindibaniselwano ye-series inductance kunye ne-shunt capacitance. Njengoko kubonisiwe kuMfanekiso 1(b), imodeli yesekethe yePLH TL yindibaniselwano ye-shunt inductance kunye ne-series capacitance. Kwizicelo ezisebenzayo, akunakwenzeka ukuphumeza i-PLH circuit. Oku kungenxa ye-parasitic series inductance kunye ne-shunt capacitance effects. Ke ngoko, iimpawu zomgca wokudlulisa wesandla sasekhohlo onokubonwa okwangoku zonke zizakhiwo zesandla sasekhohlo kunye nesandla sasekunene ezihlanganisiweyo, njengoko kubonisiwe kuMfanekiso 1(c).

Umfanekiso 1 Iimodeli ezahlukeneyo zesekethe yomgca wothumelo

I-propagation constant (γ) yomgca wothumelo (TL) ibalwa ngolu hlobo: γ=α+jβ=Sqrt(ZY), apho u-Y kunye no-Z bamele ukungena kunye nokungangeni ngokulandelelana. Xa kujongwa i-CRLH-TL, u-Z kunye no-Y banokuchazwa ngolu hlobo:

I-CRLH TL efanayo iya kuba nolwalamano olulandelayo lokusasazeka:

I-phase constant β inokuba linani lokwenyani okanye inani elicingelwayo. Ukuba i-β iyinyani ngokupheleleyo kuluhlu lwe-frequency, kukho i-passband ngaphakathi kuluhlu lwe-frequency ngenxa yemeko ye-γ=jβ. Kwelinye icala, ukuba i-β linani elicingelwayo kuphela kuluhlu lwe-frequency, kukho i-stopband ngaphakathi kuluhlu lwe-frequency ngenxa yemeko ye-γ=α. Le stopband ikhethekile kwi-CRLH-TL kwaye ayikho kwi-PRH-TL okanye kwi-PLH-TL. Imifanekiso 2 (a), (b), kunye (c) ibonisa ii-dispersion curves (oko kukuthi, ubudlelwane be-ω - β) be-PRH-TL, i-PLH-TL, kunye ne-CRLH-TL, ngokwahlukeneyo. Ngokusekelwe kwii-dispersion curves, i-group velocity (vg=∂ω/∂β) kunye ne-phase velocity (vp=ω/β) yomgca wokudlulisela inokufumaneka kwaye iqikelelwe. Kwi-PRH-TL, kunokucingelwa kwakhona kwi-curve ukuba i-vg kunye ne-vp ziyafana (oko kukuthi, vpvg>0). Kwi-PLH-TL, i-curve ibonisa ukuba i-vg kunye ne-vp azihambelani (oko kukuthi, vpvg<0). I-dispersion curve ye-CRLH-TL ikwabonisa ubukho bengingqi ye-LH (oko kukuthi, vpvg <0) kunye nengingqi ye-RH (oko kukuthi, vpvg > 0). Njengoko kunokubonwa kuMfanekiso 2(c), kwi-CRLH-TL, ukuba i-γ linani lokwenyani elimsulwa, kukho ibhendi yokumisa.

Umfanekiso 2 Iigophe zokusasazeka kwemigca eyahlukeneyo yothumelo

Ngokwesiqhelo, ii-series kunye nee-parallel resonances ze-CRLH-TL zahlukile, ezibizwa ngokuba yi-unbalanced state. Nangona kunjalo, xa ii-series kunye nee-parallel resonance frequencies zifana, zibizwa ngokuba yi-balanced state, kwaye imodeli yesekethe esilinganayo esisindisiweyo eboniswa kuMfanekiso 3(a).

Umfanekiso 3 Imodeli yesekethe kunye nejika lokusasazwa komgca wothumelo oludibeneyo olusebenzisa isandla sasekhohlo

Njengoko i-frequency isanda, iimpawu ze-dispersion ze-CRLH-TL ziyanda kancinci kancinci. Oku kungenxa yokuba i-phase velocity (oko kukuthi, vp=ω/β) ixhomekeka ngakumbi kwi-frequency. Kwii-frequency eziphantsi, i-CRLH-TL ilawulwa yi-LH, ngelixa kwii-frequency eziphezulu, i-CRLH-TL ilawulwa yi-RH. Oku kubonisa uhlobo oluphindwe kabini lwe-CRLH-TL. Umzobo we-equilibrium CRLH-TL dispersion uboniswe kuMfanekiso 3(b). Njengoko kubonisiwe kuMfanekiso 3(b), utshintsho oluvela kwi-LH ukuya kwi-RH lwenzeka kwi:

Apho i-ω0 ilutshintsho oluphindaphindeneyo. Ke ngoko, kwimeko elinganisiweyo, utshintsho oluthambileyo lwenzeka ukusuka kwi-LH ukuya kwi-RH kuba i-γ linani elicingelwayo kuphela. Ke ngoko, akukho stopband ye-balanced CRLH-TL dispersion. Nangona i-β ingu-zero kwi-ω0 (engenasiphelo xa ithelekiswa nobude obuqondisiweyo, oko kukuthi, λg=2π/|β|), i-wave isasasazeka kuba i-vg kwi-ω0 ayingu-zero. Ngokufanayo, kwi-ω0, i-phase shift ingu-zero kwi-TL yobude d (oko kukuthi, φ= - βd=0). I-phase advance (oko kukuthi, φ>0) yenzeka kuluhlu lwe-LH frequency (oko kukuthi, ω<ω0), kwaye i-phase retardation (oko kukuthi, φ<0) yenzeka kuluhlu lwe-RH frequency (oko kukuthi, ω>ω0). Kwi-CRLH TL, i-characteristic impedance ichazwa ngolu hlobo lulandelayo:

Apho i-ZL kunye ne-ZR ziyi-PLH kunye ne-PRH impedances, ngokulandelelana. Kwityala elingalinganiyo, i-characteristic impedance ixhomekeke kwi-frequency. I-equation engentla ibonisa ukuba ityala elilinganisiweyo alixhomekekanga kwi-frequency, ngoko ke linokuba nomdlalo we-bandwidth obanzi. I-equation ye-TL efunyenwe ngasentla ifana neeparameters ezichaza izinto ze-CRLH. I-propagation constant ye-TL yi-γ=jβ=Sqrt(ZY). Ngenxa ye-propagation constant yezinto (β=ω x Sqrt(εμ)), le equation ilandelayo ingafumaneka:

Ngokufanayo, i-impedance yeempawu ze-TL, oko kukuthi, Z0=Sqrt(ZY), iyafana ne-impedance yeempawu zezinto, oko kukuthi, η=Sqrt(μ/ε), echazwa ngolu hlobo:

Isalathisi sokuchasana kwe-CRLH-TL elinganisiweyo nengalinganiyo (oko kukuthi, n = cβ/ω) iboniswe kuMfanekiso 4. KuMfanekiso 4, isalathisi sokuchasana kwe-CRLH-TL kuluhlu lwayo lwe-LH sibi kwaye isalathisi sokuchasana kwe-RH sibi kakhulu.

Umzobo 4 Iimpawu eziqhelekileyo zokurhawuzelela ze-CRLH TLs ezilinganisiweyo nezingalinganiyo.

1. Inethiwekhi ye-LC
Ngokususa iiseli ze-LC ze-bandpass eziboniswe kuMfanekiso 5(a), i-CRLH-TL eqhelekileyo enobunye obusebenzayo bobude d inokwakhiwa ngamaxesha athile okanye ngaphandle kwamaxesha athile. Ngokubanzi, ukuqinisekisa ukuba kulula ukubala kunye nokuveliswa kwe-CRLH-TL, isekethe kufuneka ibe ngamaxesha athile. Xa kuthelekiswa nomzekelo woMfanekiso 1(c), iseli yesekethe yoMfanekiso 5(a) ayinabukhulu kwaye ubude bomzimba buncinci kakhulu (oko kukuthi, Δz kwiimitha). Xa kujongwa ubude bayo bombane θ=Δφ (rad), isigaba seseli ye-LC sinokubonakaliswa. Nangona kunjalo, ukuze kufezekiswe i-inductance esetyenzisiweyo kunye ne-capacitance, kufuneka kusekwe ubude bomzimba p. Ukukhetha ubuchwepheshe besicelo (njenge-microstrip, i-coplanar waveguide, izinto zokufaka umphezulu, njl.njl.) kuya kuchaphazela ubungakanani bomzimba beseli ye-LC. Iseli ye-LC yoMfanekiso 5(a) ifana nemodeli ekhulayo yoMfanekiso 1(c), kwaye umda wayo p=Δz→0. Ngokwemeko yokufana p→0 kuMfanekiso 5(b), i-TL inokwakhiwa (ngokudibanisa ii-LC cells) elingana ne-CRLH-TL efanelekileyo enobude obungu-d, ukuze i-TL ibonakale ifana namaza e-electromagnetic.

Umfanekiso 5 I-CRLH TL isekelwe kwinethiwekhi ye-LC.

Kwiseli ye-LC, xa kujongwa iimeko zemida ye-periodic (ii-PBC) ezifana ne-Bloch-Floquet theorem, ubudlelwane bokusasazwa kweseli ye-LC bubonakaliswa kwaye buchazwa ngolu hlobo lulandelayo:

I-series impedance (Z) kunye ne-shunt admittance (Y) yeseli ye-LC zimiselwa ngala ma-equation alandelayo:

Ekubeni ubude bombane besekethe yeyunithi ye-LC buncinci kakhulu, uqikelelo lweTaylor lungasetyenziselwa ukufumana:

2. Ukuphunyezwa Ngokwendalo
Kwicandelo elingaphambili, inethiwekhi ye-LC yokuvelisa i-CRLH-TL ixutyushiwe. Ezi nethiwekhi ze-LC zinokufezekiswa kuphela ngokwamkela izinto ezibonakalayo ezinokuvelisa amandla afunekayo (i-CR kunye ne-CL) kunye ne-inductance (i-LR kunye ne-LL). Kwiminyaka yakutshanje, ukusetyenziswa kwezinto ze-chip technology (i-SMT) okanye izinto ezisasazwayo kutsale umdla omkhulu. I-Microstrip, i-stripline, i-coplanar waveguide okanye ezinye iitekhnoloji ezifanayo zinokusetyenziselwa ukufezekisa izinto ezisasazwayo. Kukho izinto ezininzi ekufuneka ziqwalaselwe xa ukhetha ii-chips ze-SMT okanye izinto ezisasazwayo. Izakhiwo ze-CRLH ezisekwe kwi-SMT ziqheleke ngakumbi kwaye kulula ukuzisebenzisa ngokwemigaqo yohlalutyo kunye noyilo. Oku kungenxa yokufumaneka kwezinto ze-chip ze-SMT ezikwishelufu, ezingadingi ukuhlaziywa kunye nokuveliswa xa kuthelekiswa nezinto ezisasazwayo. Nangona kunjalo, ukufumaneka kwezinto ze-SMT kusasazeka, kwaye zihlala zisebenza kuphela kwiifrikhwensi eziphantsi (oko kukuthi, i-3-6GHz). Ke ngoko, izakhiwo ze-CRLH ezisekwe kwi-SMT zinemida yefrikhwensi yokusebenza elinganiselweyo kunye neempawu ezithile zesigaba. Umzekelo, kwizicelo ze-radiating, izinto ze-chip ze-SMT zisenokungenzeki. Umfanekiso 6 ubonisa isakhiwo esisasazwe ngokusekelwe kwi-CRLH-TL. Isakhiwo siqatshelwa yi-interdigital capacitance kunye nemigca ye-short-circuit, eyenza i-series capacitance CL kunye ne-parallel inductance LL ye-LH ngokwahlukeneyo. I-capacitance phakathi komgca kunye ne-GND ithathwa njenge-RH capacitance CR, kwaye i-inductance eveliswa yi-magnetic flux eyenziwe yi-current flow kwisakhiwo se-interdigital ithathwa njenge-RH inductance LR.