Lub Physics ntawm Foil Enclosure
Lub tawb Faraday ua haujlwm los ntawm ob lub tswv yim: kev xav ntawm qhov xwm txheej nthwv dej ntawm qhov chaw ua haujlwm, thiab nqus ntawm lub zog uas nkag mus. Kev tiv thaiv kev ua tau zoo yog qhia raws li SE hauv decibels, cov txiaj ntsig ntawm kev xav poob, kev nqus nqus thiab ntau qhov kev hloov kho. Reflection poob dominates rau ib tug nyias conductor nyob rau hauv ib tug tsawg impedance los yog dav hlau yoj teb, thaum nqus absorbs loj hlob nrog tuab thiab zaus. Rau txhuas nrog ib tug conductivity ntawm 3.77 x 107S / m thiab tus txheeb ze permeability ntawm 1, ob qho tib si mechanisms muaj los ntawm cov khoom siv ob peb micrometers tuab.
Daim tawv nqaij qhov tob: Vim li cas Foil Thickness Matters Tsuas yog tsawg zaus
Qhov tob ntawm daim tawv nqaij yog qhov tob ntawm qhov tam sim no qhov ceev tau poob mus rau 1 / e ntawm nws tus nqi nto, thiab nws tau muab los ntawm lub hauv paus square ntawm 2 faib los ntawm cov khoom ntawm angular zaus, permeability thiab conductivity. Rau aluminium qhov txiaj ntsig tshwm sim yog:
| Ntau zaus | Daim tawv nqaij tob hauv aluminium | Absorption poob rau 12 micrometer ntawv ci |
|---|---|---|
| 10 kHz | cav 0.8mm | tsawg dua 1 dB |
| 1 MHz | txog 82 micrometers | cav 1dB |
| 100 MHz | txog 8 micrometers | cav 13dB |
| 1 GHz | txog 2.6 micrometers | cav 40dB |
Absorption poob yog kwv yees li 8.7 npaug ntawm cov thickness muab faib los ntawm daim tawv nqaij qhov tob, hauv decibels. Lub rooj qhia tau hais tias tus ciam teb siv tau: cov qauv ntawv hauv tsev nyob ib ncig ntawm 10 mus rau 15 micrometers tuab coj raws li cov khoom siv hluav taws xob tuab los ntawm kwv yees li 10 MHz upwards, tab sis ntawm lub ntsiab lus thiab lub suab zaus nws nyob deb dua li ntawm daim tawv nqaij qhov tob thiab feem ntau ntawm qhov attenuation los ntawm kev xav thiab los ntawm cov av ntawm lub qhov rooj. Qhov no yog vim li cas ib daim ntawv qhwv tuaj yeem thaiv lub xov tooj ntawm tes hauv tsev thiab tseem ua tsis tau zoo raws li cov ntaub thaiv npog tsis tshua muaj hlau nplaum.
Qhov twg tiag Faraday Cages Leak
Qhov tseem ceeb poob ntawm kev tiv thaiv nyob rau hauv ib lub hnab ntawv ci tsis yog cov ntawv ci tab sis qhov tsis sib xws. Ib qho aperture loj dua li ntawm ib nrab ntawm ib lub wavelength ua raws li lub kav hlau txais xov thiab xau tau zoo. Ntawm 1 GHz, ib lub wavelength yog hais txog 300 hli, yog li qhov sib txawv 15 hli twb yog radiator loj. Lwm txoj hauv kev xau yog cov seam sib tshooj, uas yuav tsum yog tsawg kawg 10 hli thiab khi los yog folded es tsis yog pob tw; cable nkag, uas yuav tsum tau lim los yog txiav mus rau phab ntsa thaiv; thiab oxide zaj duab xis ntawm txhuas, uas loj hlob mus rau 2 mus rau 4 nm tam sim ntawd nyob rau hauv huab cua thiab tsim ib tug rectifying, siab tiv thaiv kev sib cuag tshwj tsis yog lub sib koom ua ke yog mechanically bonded los yog pab nrog ib tug conductive compound.
Cov ntaub ntawv, cov ntaub ntawv thiab kev tsim kho
Aluminium ntawv ci, metallised zaj duab xis thiab conductive ntaub tag nrho tshwm sim nyob rau hauv shielding khoom. Cov ntawv ci muab qhov zoo tshaj plaws conductivity thiab ruaj khov rau lub sij hawm ntev tshaj plaws, tab sis nws creases thiab punctures yooj yim thiab creasing tuaj yeem tawg ib txheej nyias heev. Metallised zaj duab xis yog hloov tau ntau dua thiab tiv taus flexing qaug zog zoo dua, ntawm tus nqi qis dua. Rau kev ntim khoom uas yuav tsum tau tswj cov paug tawm zoo li qub, kev tsim kho ib txwm yog txheej txheej txheej txheej ntawm cov khoom siv hluav taws xob zoo li qub los ntawm cov txheej hlau, thiab cov hnab no tsim nyog rau ANSI / ESD S541 rau kev tiv thaiv electrostatic tawm rhiab heev. Seams nyob rau hauv ib lub tsev enclosure yog tsim los ntawm folding, los ntawm conductive nplaum daim kab xev los yog welding, thiab lub continuation ntawm kev sib koom tes yuav tsum tau xyuas los ntawm kev ntsuas kev tiv thaiv nyob rau hauv lub seam.
Kev Ntsuas Kev Tiv Thaiv Kev Ua Tau Zoo
Cov ntaub ntawv qib shielding yog ntsuas los ntawm flange coaxial kis kab txoj kev ntawm ASTM D4935, uas muab kev tiv thaiv zoo tiv thaiv lub dav hlau nthwv dej tshaj qhov ntau zaus, feem ntau 30 MHz txog 1.5 GHz. Enclosure theem kev ua tau zoo yog ntsuas los ntawm cov txheej txheem ntawm IEEE 299, uas siv calibrated kav hlau txais xov sab hauv thiab sab nraum lub enclosure thiab ceeb toom attenuation ntawm lub frequencies. Ob txoj kev tshaj tawm decibels, thiab ib daim duab hais tsis muaj nuj nqis yam tsis muaj qhov ntau zaus, txoj kev sim thiab hom teb, vim hais tias ib lub tawb ntawv ci uas ntsuas 60 dB ntawm 900 MHz yuav ntsuas tsuas yog ob peb decibels ntawm 50 Hz.
Kev txwv thiab kev nkag siab tsis meej
Peb lub ntsiab lus yog ib txwm to taub yuam kev. Ua ntej, lub tawb Faraday thaiv hluav taws xob thiab xov tooj cua tsis muaj zog, tab sis nws tsis thaiv qhov chaw sib nqus zoo li qub. Qhov thib ob, aluminium ntawv ci tsis thaiv los ntawm earthing ib leeg; lub kaw lus yuav tsum yog hluav taws xob tas mus li, thiab ib lub pob ntab ntab yuav ntws tawm tsuas yog tias nws raug khi rau qhov muaj peev xwm. Thib peb, qhwv lub cuab yeej uas xa tawm nws tus kheej lub teeb liab yuav tsis ntsiag to hauv txhua qhov xwm txheej, vim tias cov ntawv ci nyob ze rau ntawm lub kav hlau txais xov detunes tus kav hlau txais xov thiab tuaj yeem hloov cov emission spectrum es tsis txhob nqus nws. Txhua daim ntawv thov kev tiv thaiv uas cuam tshuam rau cov khoom pov thawj yuav tsum tau kuaj xyuas los ntawm kev ntsuas, tsis yog los ntawm kev xav.
Cov lus nug nquag
Q:Yuav tuab npaum li cas cov ntawv txhuas yuav tsum thaiv lub xov tooj ntawm tes?
A: Ib txheej ntawm cov ntawv ci hauv tsev ib txwm nyob ib ncig ntawm 10 mus rau 15 micrometers tuab yog feem ntau txaus siab tshaj li ob peb puas megahertz, tab sis qhov tshwm sim nyob ntawm seb cov khoom ntim tag nrho. Kev npog thiab seam sib tshooj tseem ceeb tshaj qhov ntxiv txheej thib ob.
Q:Puas yog aluminium foil thaiv cov hlau nplaum?
A: Tsuas yog alternating magnetic teb, thiab tsuas yog kom deb li deb raws li nws thickness mus txog ib qhov tob ntawm daim tawv nqaij. Ib qho chaw zoo li qub tsis yog attenuated, thiab ntawm 50 lossis 60 Hz ntawm daim tawv nqaij qhov tob hauv txhuas yog ntawm qhov kev txiav txim ntawm 10 hli, tuab dua li cov ntawv ci.
Q:Vim li cas ib daim ntawv qhwv qee zaum tsis thaiv txawm tias nws zoo li kaw?
A: Npog, creases thiab seams dominates. Lub aperture loj dua li ntawm ib tug nees nkaum ntawm ib lub wavelength radiates muaj zog, thiab lub ntuj oxide zaj duab xis ntawm txhuas tsim ib tug siab tiv thaiv kev sib cuag ntawm seams tshwj tsis yog tias qhov sib koom ua ke yog sib koom.
Q:Cov qauv twg yog siv los ntsuas kev tiv thaiv kev ua tau zoo?
A: ASTM D4935 ntsuas qhov kev tiv thaiv kev ua tau zoo ntawm cov khoom siv tiaj tus nrog lub flange coaxial tuav hla qhov ntau zaus tau hais tseg, thiab IEEE 299 txhais cov txheej txheem los ntsuas kev tiv thaiv kev ua tau zoo ntawm lub kaw lus.
Q:Dab tsi yog qhov txawv ntawm lub hnab ntawv ci thiab lub hnab metallised film?
A: Ib txheej ntawv ci muab cov conductivity ntau dua thiab ruaj khov dua tab sis creases thiab tuaj yeem tawg. Ib zaj duab xis metallised yog hloov tau yooj yim dua thiab muaj sia nyob rov folding zoo dua, nrog qis conductivity. Cov hnab ntim khoom zoo li qub tau tsim nyog rau ANSI/ESD S541.
Q:Cov ntawv txhuas puas tuaj yeem siv los tiv thaiv tag nrho chav?
A: Nws tuaj yeem muab kev txo qis, tab sis tsuas yog yog tias tag nrho rau qhov chaw txuas ntxiv thiab txhua qhov kev nkag cable raug lim ntawm ciam teb. Cov tswv yim tiv thaiv chav siv cov ntawv ci tawv ntsej muag, cov hlua khi thiab cov dej lim dej tsis yog cov ntawv xoob xoob.
