Yuav ua li cas kom tau txais impedance txuam ntawm waveguides? Los ntawm txoj kev xav ntawm kev xa xov kab hauv microstrip kav hlau txais xov txoj kev xav, peb paub tias cov kab sib txuas uas tsim nyog lossis cov kab sib txuas sib txuas tuaj yeem raug xaiv kom ua tiav impedance txuam ntawm cov kab sib txuas lossis nruab nrab ntawm cov kab sib txuas thiab cov khoom thauj kom ua tiav qhov siab tshaj plaws kev xa hluav taws xob thiab qhov tsawg kawg nkaus kev xav. Tib lub hauv paus ntsiab lus ntawm impedance txuam hauv microstrip kab siv rau impedance txuam hauv waveguides. Reflections nyob rau hauv waveguide systems yuav ua rau impedance mismatches. Thaum impedance deterioration tshwm sim, qhov kev daws teeb meem yog tib yam li rau cov kab sib kis, uas yog, hloov tus nqi uas yuav tsum tau Lub lumped impedance yog muab tso rau ntawm cov ntsiab lus ua ntej xam hauv lub waveguide kom kov yeej qhov tsis sib xws, yog li tshem tawm cov teebmeem ntawm kev xav. Thaum cov kab sib txuas siv lumped impedances lossis stubs, waveguides siv hlau blocks ntawm ntau yam duab.
Daim duab 1: Waveguide irises thiab sib npaug Circuit Court, (a) Capacitive; (b) inductive; (c) resonant.
Daim duab 1 qhia txog qhov sib txawv ntawm impedance txuam, noj ib qho ntawm cov ntawv qhia thiab tuaj yeem ua tau capacitive, inductive lossis resonant. Kev txheeb xyuas lej yog qhov nyuaj, tab sis kev piav qhia lub cev tsis yog. Xav txog thawj capacitive hlau sawb nyob rau hauv daim duab, nws yuav pom tau hais tias lub peev xwm uas muaj nyob nruab nrab ntawm lub sab saum toj thiab hauv qab phab ntsa ntawm lub waveguide (nyob rau hauv lub dominant hom) tam sim no muaj nyob nruab nrab ntawm ob lub hlau nto nyob ze ze, yog li lub capacitance yog taw tes nce. Hauv qhov sib piv, cov hlau thaiv hauv daim duab 1b tso cai rau tam sim no ntws qhov twg nws tsis ntws ua ntej. Yuav muaj tam sim no ntws nyob rau hauv lub yav tas los txhim kho hluav taws xob teb dav hlau vim qhov sib ntxiv ntawm cov hlau thaiv. Yog li ntawd, lub zog cia tshwm sim nyob rau hauv lub magnetic teb thiab qhov inductance ntawm qhov taw tes ntawm lub waveguide nce. Tsis tas li ntawd, yog tias cov duab thiab txoj hauj lwm ntawm lub nplhaib hlau nyob rau hauv daim duab c yog tsim tsim nyog, qhov inductive reactance thiab capacitive reactance qhia yuav sib npaug, thiab lub aperture yuav yog thaum uas tig mus resonance. Qhov no txhais tau hais tias lub impedance txuam thiab tuning ntawm lub ntsiab hom yog zoo heev, thiab cov nyhuv shunting ntawm hom no yuav negligible. Txawm li cas los xij, lwm hom lossis zaus yuav raug txo qis, yog li lub nplhaib hlau resonant ua raws li ob qho tib si bandpass lim thiab hom lim.
daim duab 2: (a) waveguide posts; (b) ob-ntsia hlau matcher
Lwm txoj hauv kev rau kev qhib yog qhia saum toj no, qhov twg lub cylindrical hlau ncej txuas mus los ntawm ib qho ntawm sab dav rau hauv lub waveguide, muaj cov nyhuv tib yam li cov hlau sawb nyob rau hauv cov nqe lus ntawm kev muab lumped reactance ntawm qhov point. Cov ncej hlau tuaj yeem yog capacitive lossis inductive, nyob ntawm seb nws txuas mus rau lub waveguide. Qhov tseem ceeb, txoj kev sib txuam no yog tias thaum tus ncej hlau txuas me ntsis mus rau hauv lub waveguide, nws muab lub capacitive susceptance ntawm lub sijhawm ntawd, thiab lub capacitive susceptance nce mus txog rau thaum qhov nkag mus txog li ib feem peb ntawm ib lub wavelength, ntawm no, series resonance tshwm sim. . Kev nkag mus ntxiv ntawm cov ncej hlau ua rau muaj kev cuam tshuam inductive tau muab uas txo qis thaum qhov ntxig ua tiav ntau dua. Lub zog resonance ntawm qhov nruab nrab ntawm qhov nruab nrab yog qhov sib npaug ntawm txoj kab uas hla ntawm kem thiab tuaj yeem siv los ua cov lim dej, txawm li cas los xij, qhov no nws yog siv los ua band nres lim kom xa cov kev txiav txim siab dua. Piv nrog rau kev nce impedance ntawm cov hlau strips, ib qho txiaj ntsig loj ntawm kev siv cov ncej hlau yog tias lawv yooj yim kho. Piv txwv li, ob lub hau ntswj tuaj yeem siv los ua cov khoom siv kho kom ua tiav kev sib tw waveguide zoo.
Resistive loads thiab attenuators:
Ib yam li lwm yam kev sib kis, waveguides qee zaum yuav tsum muaj qhov zoo tshaj plaws impedance txuam thiab tuned loads kom nqus tau cov nthwv dej uas tsis muaj kev xav thiab ua kom tsis muaj zog. Ib daim ntawv thov rau cov terminals no yog ua kom muaj ntau yam kev ntsuas hluav taws xob ntawm lub system yam tsis muaj hluav taws xob tiag tiag.
daim duab 3 waveguide kuj load(a) ib taper(b) ob npaug taper
Qhov feem ntau resistive termination yog ib feem ntawm lossy dielectric ntsia nyob rau hauv lub kawg ntawm lub waveguide thiab tapered (nrog rau lub ntsis taw tes rau lub yoj los) thiaj li tsis mus ua reflections. Qhov nruab nrab lossy no tuaj yeem tuav tag nrho qhov dav ntawm lub waveguide, lossis nws tsuas yog nyob nruab nrab ntawm qhov kawg ntawm lub waveguide, raws li pom hauv daim duab 3. Lub taper tuaj yeem yog ib leeg lossis ob npaug taper thiab feem ntau muaj qhov ntev ntawm λp / 2, nrog tag nrho ntev ntawm kwv yees li ob lub wavelengths. Feem ntau yog ua los ntawm dielectric daim hlau xws li iav, coated nrog carbon zaj duab xis los yog dej iav rau sab nraud. Rau cov ntawv thov hluav taws xob siab, cov khoom siv hluav taws xob zoo li no tuaj yeem muaj cov dab dej kub ntxiv rau sab nraud ntawm lub waveguide, thiab lub zog xa mus rau lub davhlau ya nyob twg tuaj yeem tawg los ntawm lub dab dej kub lossis los ntawm kev quab yuam cua txias.
Daim duab 4 Movable vane attenuator
Dielectric attenuators tuaj yeem ua kom tshem tau raws li qhia hauv daim duab 4. Muab tso rau hauv nruab nrab ntawm lub waveguide, nws tuaj yeem txav mus tom qab ntawm qhov nruab nrab ntawm lub waveguide, qhov uas nws yuav muab qhov zoo tshaj plaws attenuation, mus rau cov npoo, qhov twg lub attenuation yog heev txo. txij li lub zog hluav taws xob ntawm lub hom tseem ceeb yog qis dua.
Attenuation nyob rau hauv waveguide:
Lub zog attenuation ntawm waveguides feem ntau suav nrog cov hauv qab no:
1. Kev cuam tshuam los ntawm cov kev cuam tshuam hauv waveguide discontinuities los yog misaligned waveguide seem
2. Kev puas tsuaj los ntawm cov dej ntws tam sim no hauv cov phab ntsa waveguide
3. Dielectric poob nyob rau hauv cov waveguide puv
Qhov kawg ob yog zoo ib yam li cov kev poob hauv coaxial kab thiab ob qho tib si kuj me me. Qhov kev poob no nyob ntawm cov khoom siv phab ntsa thiab nws qhov roughness, dielectric siv thiab zaus (vim cov nyhuv ntawm daim tawv nqaij). Rau tooj dag conduit, qhov ntau yog los ntawm 4 dB / 100m ntawm 5 GHz txog 12 dB / 100m ntawm 10 GHz, tab sis rau aluminium conduit, qhov ntau yog qis dua. Rau cov nyiaj-coated waveguides, poob feem ntau yog 8dB / 100m ntawm 35 GHz, 30dB / 100m ntawm 70 GHz, thiab ze rau 500 dB / 100m ntawm 200 GHz. Txhawm rau kom tsis txhob poob, tshwj xeeb tshaj yog nyob rau hauv ntau zaus, waveguides qee zaum plated (sab hauv) nrog kub lossis platinum.
Raws li twb tau taw qhia, lub waveguide ua raws li cov lim dej siab. Txawm hais tias lub waveguide nws tus kheej yog qhov tsis zoo, ntau zaus hauv qab qhov kev txiav tawm zaus yog qhov hnyav heev. Qhov attenuation no yog vim xav txog ntawm lub qhov ncauj waveguide es tsis yog propagation.
Waveguide coupling:
Waveguide coupling feem ntau tshwm sim los ntawm flanges thaum waveguide pieces los yog cov khoom sib txuas ua ke. Lub luag haujlwm ntawm lub flange no yog los xyuas kom meej qhov kev sib txuas ntawm cov neeg kho tshuab zoo thiab cov khoom siv hluav taws xob tsim nyog, tshwj xeeb tshaj yog cov hluav taws xob sab nraud thiab tsis tshua muaj kev cuam tshuam sab hauv.
Flange:
Waveguide flanges yog dav siv hauv kev sib txuas lus microwave, radar systems, satellite kev sib txuas lus, kav hlau txais xov systems, thiab cov cuab yeej kuaj hauv kev tshawb fawb. Lawv tau siv los txuas cov ntu sib txawv ntawm cov waveguide, xyuas kom cov dej xau thiab cuam tshuam raug tiv thaiv, thiab tswj cov kev sib raug zoo ntawm cov waveguide kom ntseeg tau tias muaj kev sib kis tau zoo thiab qhov tseeb ntawm qhov zaus electromagnetic waves. Ib tus qauv waveguide muaj flange ntawm txhua qhov kawg, raws li pom hauv daim duab 5.
daim duab 5 (a) tiaj flange; (b) flange coupling.
Nyob rau hauv qis zaus lub flange yuav brazed los yog welded rau lub waveguide, thaum nyob rau ntawm ntau zaus ib tug flatter taub qab flange yog siv. Thaum ob qhov sib koom ua ke, cov flanges yog bolted ua ke, tab sis qhov kawg yuav tsum tau ua kom tiav kom tsis txhob muaj kev cuam tshuam hauv kev sib txuas. Nws yooj yim dua los kho cov khoom kom raug nrog qee qhov kev hloov kho, yog li me me waveguides qee zaum txawm peem rau nrog threaded flanges uas yuav tsum tau screwed ua ke nrog ib lub nplhaib txiv ntseej. Raws li qhov zaus nce, qhov loj ntawm waveguide coupling ib txwm txo qis, thiab qhov sib txuas tsis sib txuas ua rau loj dua nyob rau hauv kev faib ua feem rau lub teeb liab wavelength thiab waveguide loj. Yog li ntawd, discontinuities ntawm ntau zaus ua teeb meem ntau dua.
daim duab 6 (a) Hla ntu ntawm choke coupling; (b) kawg saib ntawm choke flange
Txhawm rau daws qhov teeb meem no, qhov sib txawv me me tuaj yeem sab laug ntawm cov waveguides, raws li qhia hauv daim duab 6. Lub choke coupling uas muaj cov flange zoo tib yam thiab choke flange txuas ua ke. Txhawm rau them nyiaj rau qhov tsis sib xws, lub nplhaib ncig lub nplhaib nrog L-shaped cross-section yog siv rau hauv choke flange kom ua tiav qhov kev sib txuas nruj dua. Tsis zoo li cov flanges zoo tib yam, choke flanges yog qhov rhiab heev, tab sis qhov kev tsim kho kom zoo tuaj yeem ua kom muaj qhov tsim nyog bandwidth (tej zaum 10% ntawm qhov nruab nrab zaus) tshaj qhov SWR tsis tshaj 1.05.
Post lub sij hawm: Jan-15-2024
