Xov xwm - Kev tshuaj xyuas ntawm Metamaterial Transmission Line Antennas

I. Kev Taw Qhia
Metamaterials tuaj yeem piav qhia tau zoo tshaj plaws raws li cov qauv tsim tsim los tsim cov khoom siv hluav taws xob uas tsis muaj nyob hauv ib txwm muaj. Metamaterials uas tsis zoo permittivity thiab tsis zoo permeability yog hu ua sab laug-tes metamaterials (LHMs). LHMs tau kawm ntau yam hauv cov zej zog scientific thiab engineering. Xyoo 2003, LHMs tau raug hu ua ib qho ntawm kaum qhov kev tshawb fawb saum toj kawg nkaus ntawm lub sijhawm tam sim no los ntawm Science magazine. Cov ntawv thov tshiab, cov tswv yim, thiab cov khoom siv tau tsim los ntawm kev siv cov khoom tshwj xeeb ntawm LHMs. Txoj kev sib kis (TL) txoj hauv kev yog ib txoj hauv kev tsim qauv zoo uas tuaj yeem txheeb xyuas cov ntsiab lus ntawm LHMs. Piv nrog rau cov tsoos TLs, qhov tseem ceeb tshaj plaws ntawm metamaterial TLs yog kev tswj hwm ntawm TL tsis tu ncua (kev nthuav tawm tas li) thiab cov yam ntxwv impedance. Lub controllability ntawm metamaterial TL tsis muab cov tswv yim tshiab rau kev tsim cov kav hlau txais xov nrog ntau qhov loj me, kev ua tau zoo dua, thiab cov haujlwm tshiab. Daim duab 1 (a), (b), thiab (c) qhia cov qauv tsis muaj hluav taws xob tsis zoo ntawm cov kab hluav taws xob sab xis (PRH), cov kab hluav taws xob sab laug (PLH), thiab cov kab sib txuas sab laug sab xis ( CRLH), raws. Raws li pom nyob rau hauv daim duab 1(a), PRH TL sib npaug Circuit Court qauv feem ntau yog ib tug ua ke ntawm series inductance thiab shunt capacitance. Raws li pom nyob rau hauv daim duab 1(b), PLH TL Circuit Court qauv yog ib tug ua ke ntawm shunt inductance thiab series capacitance. Hauv kev siv tswv yim, nws tsis muaj peev xwm los siv PLH Circuit Court. Qhov no yog vim qhov tsis tuaj yeem ua rau parasitic series inductance thiab shunt capacitance cuam tshuam. Yog li ntawd, cov yam ntxwv ntawm sab laug-tes sib kis kab uas tuaj yeem paub tau tam sim no yog tag nrho cov txheej txheem sab laug thiab sab xis, raws li pom hauv daim duab 1(c).

Daim duab 1 Cov qauv sib txawv ntawm cov kab hluav taws xob sib txawv

Qhov kev nthuav tawm tas li (γ) ntawm cov kab sib kis (TL) yog xam raws li: γ = α + jβ = Sqrt (ZY), qhov twg Y thiab Z sawv cev rau kev lees paub thiab impedance feem. Xav txog CRLH-TL, Z thiab Y tuaj yeem qhia tau tias:

Ib qho CRLH TL yuav muaj kev sib raug zoo hauv qab no:

Cov theem tas li β tuaj yeem yog tus lej tiag tiag lossis tus lej xav paub tseeb. Yog hais tias β yog kiag li tiag tiag nyob rau hauv ib tug ntau zaus, muaj ib tug passband nyob rau hauv lub zaus ntau yam vim hais tias ntawm tus mob γ = jβ. Ntawm qhov tod tes, yog tias β yog tus lej xav paub tseeb hauv qhov ntau zaus, muaj qhov nres hauv qhov ntau zaus vim qhov xwm txheej γ = α. Qhov chaw nres tsheb no yog tshwj xeeb rau CRLH-TL thiab tsis muaj nyob hauv PRH-TL lossis PLH-TL. Cov duab 2 (a), (b), thiab (c) qhia cov kab nkhaus dispersion (piv txwv li, ω - β kev sib raug zoo) ntawm PRH-TL, PLH-TL, thiab CRLH-TL, feem. Raws li kev sib kis nkhaus, cov pab pawg tshaj tawm (vg = ∂ω / ∂β) thiab theem tshaj tawm (vp = ω / β) ntawm cov kab sib kis tuaj yeem muab tau thiab kwv yees. Rau PRH-TL, nws kuj tuaj yeem raug xam los ntawm qhov nkhaus uas vg thiab vp yog sib npaug (ie, vpvg> 0). Rau PLH-TL, qhov nkhaus qhia tau tias vg thiab vp tsis sib npaug (ie, vpvg<0). Lub dispersion nkhaus ntawm CRLH-TL kuj qhia tau hais tias lub hav zoov ntawm LH cheeb tsam (ie, vpvg <0) thiab RH cheeb tsam (ie, vpvg> 0). Raws li pom tau los ntawm daim duab 2(c), rau CRLH-TL, yog tias γ yog tus lej tiag tiag, muaj qhov nres.

Daim duab 2 Dispersion nkhaus ntawm cov kab sib txawv

Feem ntau, cov koob thiab qhov sib npaug ntawm cov CRLH-TL sib txawv, uas yog hu ua lub xeev tsis sib npaug. Txawm li cas los xij, thaum cov koob thiab qhov sib npaug ntawm qhov sib npaug ntawm qhov sib npaug, nws yog hu ua lub xeev sib npaug, thiab qhov ua tau yooj yim sib npaug ntawm cov qauv Circuit Court yog qhia hauv daim duab 3(a).

Daim duab 3 Circuit Court qauv thiab dispersion nkhaus ntawm composite sab laug tes kis kab mob

Raws li qhov zaus nce, cov yam ntxwv dispersion ntawm CRLH-TL maj mam nce. Qhov no yog vim hais tias cov theem tshaj tawm (piv txwv li, vp = ω / β) ua rau nce nyob ntawm zaus. Ntawm qhov tsawg zaus, CRLH-TL yog dominated los ntawm LH, thaum nyob rau hauv high zaus, CRLH-TL yog dominated los ntawm RH. Qhov no qhia txog ob qhov xwm txheej ntawm CRLH-TL. Daim duab sib npaug CRLH-TL dispersion yog qhia hauv daim duab 3(b). Raws li pom hauv daim duab 3(b), kev hloov ntawm LH mus rau RH tshwm sim ntawm:

Qhov twg ω0 yog qhov hloov pauv zaus. Yog li ntawd, nyob rau hauv cov ntaub ntawv sib npaug, ib qho kev hloov pauv tau tshwm sim los ntawm LH mus rau RH vim tias γ yog tus lej xav paub. Yog li ntawd, tsis muaj qhov nres rau qhov sib npaug CRLH-TL dispersion. Txawm hais tias β yog xoom ntawm ω0 (infinite txheeb ze rau qhov taw qhia wavelength, piv txwv li, λg = 2π / | β|), yoj tseem propagates vim vg ntawm ω0 tsis yog xoom. Ib yam li ntawd, ntawm ω0, theem hloov pauv yog xoom rau TL ntawm qhov ntev d (ie, φ = - βd = 0). Cov theem ua ntej (piv txwv li, φ> 0) tshwm sim nyob rau hauv LH zaus ntau (ie, ω<ω0), thiab theem retardation (ie, φ<0) tshwm sim nyob rau hauv RH zaus ntau (ie, ω>ω0). Rau CRLH TL, tus yam ntxwv impedance tau piav raws li hauv qab no:

Qhov twg ZL thiab ZR yog PLH thiab PRH impedances, feem. Rau cov ntaub ntawv tsis sib npaug, tus yam ntxwv impedance nyob ntawm qhov zaus. Cov kab zauv saum toj no qhia tau hais tias cov ntaub ntawv sib npaug yog ywj siab ntawm zaus, yog li nws tuaj yeem muaj qhov sib tw dav bandwidth. Qhov sib npaug TL tau muab los saum toj no zoo ib yam li cov kev sib koom ua ke uas txhais cov khoom siv CRLH. Kev nthuav tawm tas li ntawm TL yog γ = jβ = Sqrt (ZY). Muab qhov kev nthuav tawm tas li ntawm cov khoom (β = ω x Sqrt (εμ)), cov kab zauv hauv qab no tuaj yeem tau txais:

Ib yam li ntawd, tus yam ntxwv impedance ntawm TL, piv txwv li, Z0 = Sqrt (ZY), zoo ib yam li cov yam ntxwv impedance ntawm cov khoom, piv txwv li, η = Sqrt (μ / ε), uas yog qhia raws li:

Lub refractive index ntawm balanced thiab unbalanced CRLH-TL (ie, n = cβ/ω) yog qhia nyob rau hauv daim duab 4. Nyob rau hauv daim duab 4, lub refractive index ntawm CRLH-TL nyob rau hauv nws cov LH ntau yam yog tsis zoo thiab lub refractive index nyob rau hauv nws RH. ntau yam yog qhov zoo.

Fig. 4 Qhov ntsuas qhov ntsuas qhov ntsuas ntawm qhov sib npaug thiab tsis sib npaug CRLH TLs.

1. LC network
Los ntawm cascading lub bandpass LC hlwb pom nyob rau hauv daim duab 5(a), ib tug raug CRLH-TL nrog zoo uniformity ntawm ntev d yuav tsim tau raws sij hawm los yog tsis-periodically. Feem ntau, txhawm rau ua kom yooj yim ntawm kev suav thiab kev tsim khoom ntawm CRLH-TL, lub voj voog yuav tsum muaj sijhawm. Piv nrog rau cov qauv ntawm daim duab 1(c), lub xov tooj ntawm tes ntawm daim duab 5(a) tsis muaj qhov loj me thiab lub cev ntev yog infinitely me me (piv txwv li, Δz hauv meters). Xav txog nws cov hluav taws xob ntev θ = Δφ (rad), theem ntawm LC ntawm tes tuaj yeem qhia tau. Txawm li cas los xij, txhawm rau kom paub tseeb qhov siv inductance thiab capacitance, lub cev ntev p yuav tsum tau tsim. Kev xaiv ntawm kev siv tshuab (xws li microstrip, coplanar waveguide, nto mount Cheebtsam, thiab lwm yam) yuav cuam tshuam rau lub cev loj ntawm LC cell. Lub LC cell ntawm daim duab 5(a) zoo ib yam li cov qauv incremental ntawm daim duab 1(c), thiab nws txwv p=Δz→0. Raws li cov xwm txheej zoo sib xws p → 0 hauv daim duab 5(b), TL tuaj yeem tsim tau (los ntawm cascading LC hlwb) uas yog sib npaug rau ib qho zoo tagnrho CRLH-TL nrog ntev d, kom lub TL zoo nkaus li zoo li electromagnetic nthwv dej.

Daim duab 5 CRLH TL raws li LC network.

Rau LC ntawm tes, xav txog cov xwm txheej nyob ib puag ncig (PBCs) zoo ib yam li Bloch-Floquet theorem, kev sib cuam tshuam ntawm LC cell yog pov thawj thiab qhia raws li hauv qab no:

Lub series impedance (Z) thiab shunt admittance (Y) ntawm LC cell yog txiav txim los ntawm cov nram qab no sib npaug:

Txij li thaum hluav taws xob ntev ntawm chav tsev LC Circuit Court yog me me, Taylor approximation yuav siv tau kom tau:

2. Kev siv lub cev
Hauv seem dhau los, LC network los tsim CRLH-TL tau tham. Xws li LC tes hauj lwm tsuas tuaj yeem paub tau los ntawm kev siv lub cev cov khoom uas tuaj yeem tsim cov peev txheej uas xav tau (CR thiab CL) thiab inductance (LR thiab LL). Nyob rau hauv xyoo tas los no, daim ntawv thov ntawm nto mount technology (SMT) nti Cheebtsam los yog faib cov khoom tau nyiam heev txaus siab. Microstrip, stripline, coplanar waveguide lossis lwm yam thev naus laus zis zoo sib xws tuaj yeem siv los paub txog cov khoom faib. Muaj ntau yam yuav tsum tau xav txog thaum xaiv SMT chips lossis faib cov khoom. SMT-based CRLH cov qauv muaj ntau dua thiab yooj yim rau kev siv raws li kev txheeb xyuas thiab tsim qauv. Qhov no yog vim muaj cov khoom tawm ntawm lub txee SMT nti, uas tsis tas yuav hloov kho thiab tsim khoom piv rau cov khoom faib. Txawm li cas los xij, qhov muaj ntawm SMT cov khoom tawg yog tawg, thiab lawv feem ntau tsuas yog ua haujlwm ntawm qhov tsawg zaus (piv txwv li, 3-6GHz). Yog li, SMT-raws li CRLH cov qauv muaj kev ua haujlwm tsawg zaus thiab cov yam ntxwv tshwj xeeb theem. Piv txwv li, hauv kev siv hluav taws xob, SMT chip Cheebtsam yuav tsis ua tau. Daim duab 6 qhia txog cov qauv faib raws li CRLH-TL. Cov qauv yog pom tau los ntawm interdigital capacitance thiab luv-circuit kab, tsim cov series capacitance CL thiab parallel inductance LL ntawm LH feem. Lub capacitance ntawm kab thiab GND yog suav tias yog RH capacitance CR, thiab cov inductance tsim los ntawm cov hlau nplaum tsim los ntawm cov dej ntws tam sim no hauv cov qauv interdigital yog suav tias yog RH inductance LR.