1. Antenna yog dab tsi?
Raws li peb paub, muaj txhua yam ntawm wireless kev sib txuas lus lihauv peb lub neej, xws li drone video downlink,wireless txuas rau neeg hlau, digital mesh systemthiab cov xov tooj cua kis tau tus mob no siv xov tooj cua yoj mus rau wireless kis cov ntaub ntawv xws li video, suab thiab cov ntaub ntawv.Lub kav hlau txais xov yog ib qho cuab yeej siv rau radiating thiab txais xov tooj cua nthwv dej.
2. Kav hlau txais xov bandwidth
Thaum lub sijhawm ua haujlwm ntawm lub kav hlau txais xov hloov pauv, qhov kev hloov pauv ntawm cov hluav taws xob cuam tshuam ntawm tus kav hlau txais xov yog nyob rau hauv qhov kev tso cai.Qhov ntau zaus tso cai rau lub sijhawm no yog tus kav hlau txais xov zaus band dav, feem ntau hu ua bandwidth.Txhua tus kav hlau txais xov muaj qee qhov kev khiav hauj lwm bandwidth, thiab nws tsis muaj qhov cuam tshuam sab nraud ntawm qhov zaus band.
Absolute bandwidth: ABW = fmax - fmin
kwv tij bandwidth: FBW = (fmax - fmin) / f0 × 100%
f0 = 1/2 (fmax + fmin) yog qhov nruab nrab zaus
Thaum lub kav hlau txais xov ua haujlwm ntawm qhov nruab nrab zaus, qhov sawv yoj piv yog qhov tsawg tshaj plaws thiab qhov ua tau zoo tshaj plaws.
Yog li ntawd, cov qauv ntawm cov txheeb ze bandwidth feem ntau yog qhia raws li: FBW = 2 (fmax- fmin) / (fmax + fmin)
Vim hais tias tus kav hlau txais xov bandwidth yog qhov kev khiav hauj lwm ntau zaus qhov twg ib lossis qee qhov hluav taws xob tsis zoo ntawm lub kav hlau txais xov ua tau raws li qhov yuav tsum tau ua, cov khoom siv hluav taws xob sib txawv tuaj yeem siv los ntsuas qhov ntau zaus band dav.Piv txwv li, qhov dav dav ntawm qhov sib thooj rau 3dB lobe dav (lub lobe dav yog hais txog lub kaum sab xis ntawm ob lub ntsiab lus uas cov hluav taws xob siv hluav taws xob txo qis los ntawm 3dB, uas yog, lub zog ntom ntom ntawm ib nrab, ntawm ob sab ntawm qhov siab tshaj plaws hluav taws xob kev taw qhia. ntawm lub ntsiab lobe), thiab lub zaus band dav qhov twg qhov sawv yoj piv raws li tej yam yuav tsum tau.Ntawm lawv, feem ntau siv yog bandwidth ntsuas los ntawm qhov sawv yoj piv.
3.Qhov kev sib raug zoo ntawm kev khiav hauj lwm zaus thiab kav hlau txais xov loj
Hauv tib qhov nruab nrab, qhov kev nthuav tawm ceev ntawm electromagnetic tsis yog qhov tseeb (sib npaug rau qhov ceev ntawm lub teeb hauv lub tshuab nqus tsev, kaw cia li c≈3 × 108m / s).Raws li c = λf, nws tuaj yeem pom tias lub wavelength yog inversely proportional rau qhov zaus, thiab ob yog tib qho kev sib raug zoo.
Qhov ntev ntawm lub kav hlau txais xov yog ncaj qha proportional rau lub wavelength thiab inversely proportional rau qhov zaus.Ntawd yog, qhov siab dua qhov zaus, qhov luv dua lub wavelength, thiab lub kav hlau txais xov luv yuav ua tau.Tau kawg, qhov ntev ntawm tus kav hlau txais xov feem ntau tsis sib npaug rau ib lub wavelength, tab sis feem ntau yog 1/4 wavelength los yog 1/2 wavelength (feem ntau lub wavelength sib haum mus rau lub hauv paus ua haujlwm zaus siv).Vim hais tias thaum qhov ntev ntawm tus neeg xyuas pib yog qhov sib npaug ntawm 1/4 wavelength, tus neeg xyuas pib nthuav tawm cov yam ntxwv ntawm qhov zaus ntawm qhov wavelength.Thaum tus neeg xyuas pib ntev yog 1/4 wavelength, nws muaj cov yam ntxwv ntawm resonance, thiab thaum tus neeg xyuas pib ntev yog 1/2 wavelength, nws muaj cov yam ntxwv sib luag.Nyob rau hauv lub xeev resonance no, tus kav hlau txais xov radiates muaj zog thiab kis tau tus mob thiab txais kev hloov dua siab tshiab efficiency siab.Txawm hais tias cov hluav taws xob ntawm lub oscillator tshaj 1/2 ntawm lub wavelength, cov hluav taws xob yuav txuas ntxiv mus ntxiv, tab sis cov hluav taws xob tiv thaiv ntawm cov feem ntau yuav ua rau muaj kev tshem tawm, yog li tag nrho cov hluav taws xob hluav taws xob cuam tshuam.Yog li, cov kav hlau txais xov zoo siv lub oscillator ntev chav tsev ntawm 1/4 wavelength lossis 1/2 wavelength.Ntawm lawv, 1/4-wavelength kav hlau txais xov tsuas yog siv lub ntiaj teb ua daim iav es tsis txhob siv ib nrab-yoj kav hlau txais xov.
1/4 wavelength kav hlau txais xov tuaj yeem ua tiav qhov zoo tshaj plaws sawv yoj piv thiab siv cov nyhuv los ntawm kev kho cov array, thiab tib lub sijhawm, nws tuaj yeem txuag qhov chaw teeb tsa.Txawm li cas los xij, cov kav hlau txais xov ntawm qhov ntev no feem ntau muaj qhov nce qis thiab tsis tuaj yeem ua tau raws li qhov xav tau ntawm qee qhov kev sib kis tau zoo.Hauv qhov no, 1/2-wavelength antennas feem ntau yog siv.
Tsis tas li ntawd, nws tau raug pov thawj nyob rau hauv txoj kev xav thiab xyaum hais tias 5/8 wavelength array (qhov ntev no yog ze rau 1/2 wavelength tab sis muaj zog hluav taws xob ntau dua li 1/2 wavelength) lossis 5/8 wavelength loading shortening array (muaj. lub loading coil ntawm ib nrab ntawm lub wavelength deb ntawm sab saum toj ntawm lub kav hlau txais xov) kuj tuaj yeem tsim los yog xaiv kom tau txais tus nqi qis thiab nce siab dua kav hlau txais xov.
Nws tuaj yeem pom tau tias thaum peb paub qhov kev khiav hauj lwm zaus ntawm tus kav hlau txais xov, peb tuaj yeem xam qhov sib thooj wavelength, thiab tom qab ntawd ua ke nrog txoj kab xaim hluav taws xob, kev teeb tsa chaw teeb tsa thiab kev sib kis tau zoo, peb tuaj yeem paub qhov tsim nyog ntev ntawm lub kav hlau txais xov. .
Post lub sij hawm: Oct-13-2023
