Yuav ua li cas thiaj ua tiav qhov sib phim impedance ntawm waveguides? Los ntawm txoj kev xav ntawm kab kis hauv microstrip antenna txoj kev xav, peb paub tias cov kab sib txuas lossis cov kab sib luag tsim nyog tuaj yeem xaiv tau kom ua tiav qhov sib phim impedance ntawm cov kab kis lossis ntawm cov kab kis thiab cov khoom thauj kom ua tiav qhov siab tshaj plaws ntawm kev xa hluav taws xob thiab qhov poob qis tshaj plaws. Tib lub hauv paus ntsiab lus ntawm kev sib phim impedance hauv cov kab microstrip siv rau qhov sib phim impedance hauv waveguides. Kev cuam tshuam hauv cov kab ke waveguide tuaj yeem ua rau impedance mismatches. Thaum impedance puas tsuaj tshwm sim, qhov kev daws teeb meem zoo ib yam li rau cov kab kis, uas yog, hloov tus nqi xav tau. Lub lumped impedance raug muab tso rau ntawm cov ntsiab lus ua ntej hauv waveguide kom kov yeej qhov tsis sib xws, yog li tshem tawm cov teebmeem ntawm kev cuam tshuam. Thaum cov kab kis siv lumped impedances lossis stubs, waveguides siv cov hlau thaiv ntawm ntau yam duab.
daim duab 1: Waveguide irises thiab sib npaug circuit, (a) Capacitive; (b) inductive; (c) resonant.
Daim Duab 1 qhia txog ntau hom kev sib phim impedance, siv ib qho ntawm cov ntawv qhia thiab tuaj yeem ua capacitive, inductive lossis resonant. Kev tshuaj xyuas lej yog qhov nyuaj, tab sis kev piav qhia lub cev tsis yog. Xav txog thawj daim hlau capacitive hauv daim duab, nws tuaj yeem pom tias lub peev xwm uas muaj nyob nruab nrab ntawm phab ntsa sab saud thiab hauv qab ntawm waveguide (hauv hom tseem ceeb) tam sim no muaj nyob nruab nrab ntawm ob qhov chaw hlau hauv qhov ze dua, yog li lub capacitance yog Lub ntsiab lus nce. Hauv kev sib piv, lub thaiv hlau hauv Daim Duab 1b tso cai rau tam sim no ntws qhov twg nws tsis tau ntws ua ntej. Yuav muaj tam sim no ntws hauv lub dav hlau hluav taws xob uas tau txhim kho yav dhau los vim yog ntxiv cov hlau thaiv. Yog li ntawd, kev khaws cia lub zog tshwm sim hauv lub teb sib nqus thiab qhov inductance ntawm qhov ntawd ntawm waveguide nce. Tsis tas li ntawd, yog tias cov duab thiab qhov chaw ntawm lub nplhaib hlau hauv Daim Duab c tau tsim tsim nyog, qhov inductive reactance thiab capacitive reactance qhia yuav sib npaug, thiab qhov aperture yuav yog parallel resonance. Qhov no txhais tau tias qhov impedance sib phim thiab tuning ntawm hom tseem ceeb yog qhov zoo heev, thiab qhov cuam tshuam shunting ntawm hom no yuav tsis tseem ceeb. Txawm li cas los xij, lwm hom lossis zaus yuav raug txo qis, yog li lub nplhaib hlau resonant ua haujlwm ua ob qho tib si lim bandpass thiab lim hom.
daim duab 2:(a) cov ncej waveguide;(b) ob-ntsia hlau matcher
Lwm txoj hauv kev los kho qhov teeb meem yog qhia saum toj no, qhov twg ib lub ncej hlau cylindrical txuas ntxiv los ntawm ib sab dav mus rau hauv lub waveguide, muaj tib yam li ib daim hlau strip hauv kev muab cov reactance lumped ntawm qhov ntawd. Lub ncej hlau tuaj yeem yog capacitive lossis inductive, nyob ntawm seb nws txuas ntxiv mus rau hauv lub waveguide deb npaum li cas. Yeej, txoj kev sib phim no yog tias thaum lub ncej hlau zoo li no txuas ntxiv me ntsis mus rau hauv lub waveguide, nws muab capacitive susceptance ntawm qhov ntawd, thiab capacitive susceptance nce mus txog thaum qhov nkag mus txog li ib feem plaub ntawm lub wavelength, Ntawm qhov no, series resonance tshwm sim. Kev nkag mus ntxiv ntawm lub ncej hlau ua rau muaj inductive susceptance uas txo qis thaum kev ntxig ua tiav ntau dua. Lub zog resonance ntawm qhov nruab nrab installation yog inversely proportional rau txoj kab uas hla ntawm kem thiab tuaj yeem siv ua lim, txawm li cas los xij, hauv qhov no nws yog siv ua lim band nres los xa cov hom kev txiav txim siab dua. Piv nrog kev nce impedance ntawm cov hlau strips, qhov zoo tseem ceeb ntawm kev siv cov ncej hlau yog tias lawv yooj yim kho. Piv txwv li, ob lub ntsia hlau tuaj yeem siv ua cov khoom siv kho kom ua tiav qhov sib phim waveguide zoo.
Cov khoom siv resistive thiab attenuators:
Ib yam li lwm yam kev xa xov, cov waveguides qee zaum xav tau qhov sib phim impedance zoo meej thiab cov loads tuned kom nqus tau tag nrho cov nthwv dej tuaj yam tsis muaj kev cuam tshuam thiab kom tsis muaj zaus. Ib qho kev siv rau cov terminals no yog ua ntau yam kev ntsuas fais fab ntawm lub system yam tsis muaj kev xa hluav taws xob tiag tiag.
daim duab 3 waveguide tsis kam load (a) ib qho taper (b) ob chav taper
Qhov kev xaus resistive feem ntau yog ib ntu ntawm lossy dielectric ntsia rau ntawm qhov kawg ntawm lub waveguide thiab tapered (nrog rau lub taub hau taw rau lub nthwv dej tuaj) kom tsis txhob ua rau muaj kev cuam tshuam. Cov khoom nruab nrab lossy no yuav nyob rau tag nrho qhov dav ntawm lub waveguide, lossis nws tsuas yog nyob rau hauv nruab nrab ntawm qhov kawg ntawm lub waveguide, raws li pom hauv Daim Duab 3. Lub taper tuaj yeem yog ib lossis ob lub taper thiab feem ntau muaj qhov ntev ntawm λp / 2, nrog rau tag nrho qhov ntev ntawm kwv yees li ob lub wavelengths. Feem ntau ua los ntawm cov phaj dielectric xws li iav, coated nrog carbon zaj duab xis lossis dej iav rau sab nraud. Rau cov ntawv thov muaj zog siab, cov davhlau ya nyob twg no tuaj yeem muaj cov dab dej cua sov ntxiv rau sab nraud ntawm lub waveguide, thiab lub zog xa mus rau lub davhlau ya nyob twg tuaj yeem dissipated los ntawm lub dab dej cua sov lossis los ntawm kev yuam cua txias.
daim duab 4 Lub tshuab txo qis suab nrov uas txav tau
Cov dielectric attenuators tuaj yeem ua kom tshem tau raws li pom hauv Daim Duab 4. Muab tso rau hauv nruab nrab ntawm lub waveguide, nws tuaj yeem txav mus rau sab nraud ntawm qhov chaw ntawm lub waveguide, qhov twg nws yuav muab qhov attenuation loj tshaj plaws, mus rau ntug, qhov twg qhov attenuation raug txo qis heev txij li lub zog hluav taws xob ntawm hom tseem ceeb qis dua.
Kev txo qis hauv waveguide:
Qhov kev txo qis zog ntawm cov waveguides feem ntau suav nrog cov hauv qab no:
1. Kev xav los ntawm kev tsis sib txuas ntawm cov waveguide sab hauv lossis cov seem waveguide tsis sib xws
2. Kev poob qis los ntawm tam sim no ntws hauv phab ntsa waveguide
3. Kev poob dielectric hauv cov waveguides puv
Ob qhov kawg zoo ib yam li qhov poob sib xws hauv cov kab coaxial thiab ob qho tib si me me. Qhov poob no nyob ntawm cov khoom siv phab ntsa thiab nws qhov roughness, dielectric siv thiab zaus (vim yog qhov cuam tshuam ntawm daim tawv nqaij). Rau cov kav dej tooj dag, qhov ntau thiab tsawg yog txij li 4 dB / 100m ntawm 5 GHz txog 12 dB / 100m ntawm 10 GHz, tab sis rau cov kav dej txhuas, qhov ntau thiab tsawg dua. Rau cov waveguides coated nyiaj, qhov poob feem ntau yog 8dB / 100m ntawm 35 GHz, 30dB / 100m ntawm 70 GHz, thiab ze li ntawm 500 dB / 100m ntawm 200 GHz. Txhawm rau txo qhov poob, tshwj xeeb tshaj yog ntawm qhov zaus siab tshaj plaws, cov waveguides qee zaum plated (sab hauv) nrog kub lossis platinum.
Raws li tau hais lawm, lub waveguide ua haujlwm zoo li lub lim dej siab dhau. Txawm hais tias lub waveguide nws tus kheej tsis muaj kev poob, cov zaus hauv qab qhov zaus txiav tawm raug txo qis heev. Qhov kev txo qis no yog vim muaj kev cuam tshuam ntawm lub qhov ncauj waveguide es tsis yog kev nthuav dav.
Kev sib txuas ntawm waveguide:
Kev sib txuas ntawm cov waveguide feem ntau tshwm sim los ntawm cov flanges thaum cov khoom waveguide lossis cov khoom sib txuas ua ke. Lub luag haujlwm ntawm cov flange no yog kom ntseeg tau tias muaj kev sib txuas zoo thiab cov khoom siv hluav taws xob tsim nyog, tshwj xeeb tshaj yog qhov hluav taws xob sab nraud tsawg thiab qhov cuam tshuam sab hauv tsawg.
Flange:
Cov flanges waveguide siv dav hauv kev sib txuas lus microwave, radar systems, satellite communications, antenna systems, thiab cov khoom siv hauv chaw kuaj mob hauv kev tshawb fawb. Lawv siv los txuas cov ntu waveguide sib txawv, xyuas kom tsis txhob muaj kev xau thiab kev cuam tshuam, thiab tswj kev sib dhos ntawm waveguide kom ntseeg tau tias muaj kev sib kis zoo thiab qhov chaw tseeb ntawm cov nthwv dej electromagnetic zaus. Ib qho waveguide ib txwm muaj ib lub flange ntawm txhua qhov kawg, raws li pom hauv Daim Duab 5.
daim duab 5 (a) flange tiaj tus; (b) flange coupling.
Thaum muaj zaus tsawg dua, lub flange yuav raug brazed lossis welded rau lub waveguide, thaum thaum muaj zaus ntau dua, lub flange tiaj tiaj yuav siv. Thaum ob feem raug koom ua ke, cov flanges raug bolted ua ke, tab sis qhov kawg yuav tsum tau ua tiav du kom tsis txhob muaj kev sib txuas tsis sib xws. Nws yooj yim dua los kho cov khoom kom raug nrog qee qhov kev hloov kho, yog li cov waveguides me dua qee zaum muaj cov flanges threaded uas tuaj yeem ntsia ua ke nrog lub txiv ntoo ring. Thaum zaus nce ntxiv, qhov loj ntawm lub waveguide coupling yuav txo qis, thiab qhov sib txuas tsis sib xws yuav loj dua raws li qhov ntev ntawm lub teeb liab thiab qhov loj ntawm waveguide. Yog li ntawd, qhov tsis sib xws ntawm cov zaus siab dua yuav ua rau muaj teeb meem ntau dua.
daim duab 6 (a) Seem hla ntawm choke coupling; (b) qhov kawg ntawm choke flange
Yuav kom daws tau qhov teeb meem no, yuav tsum muaj qhov sib txawv me me ntawm cov waveguides, raws li pom hauv Daim Duab 6. Ib qho choke coupling uas muaj ib lub flange ib txwm thiab ib lub choke flange txuas ua ke. Txhawm rau them rau qhov tsis sib xws, ib lub nplhaib choke puag ncig nrog ib qho L-puab cross-section siv rau hauv choke flange kom ua tiav qhov kev sib txuas nruj dua. Tsis zoo li cov flanges ib txwm, choke flanges yog qhov rhiab heev rau zaus, tab sis kev tsim qauv zoo tshaj plaws tuaj yeem ua kom muaj bandwidth tsim nyog (tej zaum 10% ntawm qhov chaw zaus) uas SWR tsis tshaj 1.05.
Lub sijhawm tshaj tawm: Lub Ib Hlis-15-2024
