Izindaba - Ithiyori ye-Antenna - Amapharamitha Ayisisekelo

Lesi sahluko sethula imingcele eyisisekelo yokuxhumana okungenantambo, okuhloswe ngayo ukunikeza ukuqonda okungcono ngendima yama-antenna ezinhlelweni zokuxhumana. Ukuxhumana okungenantambo kwenziwa ngendlela yamagagasi kagesi, okwenza kube kubalulekile ukuqonda izici zokusabalala kwamagagasi.

Kulesi sahluko, sizoxoxa ngalezi zindlela ezilandelayo:

•Imvamisa
•Ubude begagasi
•Ukufaniswa kwe-Impedance
•I-VSWR kanye Namandla Abonisiwe
•Ububanzi bebhendi
•Iphesenti Lomkhawulokudonsa
•Ukuqina Kwemisebe

Manje, ake sibheke kabanzi ngazo.

Imvamisa:

Ngokusho kwencazelo ejwayelekile, imvamisa yinani lokuphindaphinda kwegagasi ngesikhathi seyunithi ngayinye. Ngamagama alula, imvamisa ichaza ukuthi kwenzeka kangaki isenzakalo. Igagasi eliphindaphindayo liphinda njalo ngemizuzwana engu-T (inkathi eyodwa), futhi imvamisa yalo iwukuphindaphinda kwesikhathi u-T.

Ngokwezibalo, kuvela kanje:

$$f = \frac{1}{T}$$

•F imelela imvamisa yegagasi eliphindaphindayo, kuyilapho

•Isikhathi esidingekayo ukuqeda umjikelezo owodwa ogcwele.

Imvamisa ilinganiswa nge-hertz, efushanisiwe njenge-Hz.

Isithombe esingenhla sibonisa igagasi le-sine, elihlela i-voltage (ku-mV) njengomsebenzi wesikhathi (ku-ms). Leli gagasi liphinda njalo ngemizuzwana emi-2; ngakho-ke, isikhathi salo T = 2t ms, kanye nemvamisa yalo f = 1/(2t) kHz.

Ubude begagasi:

Ngokusho kwencazelo ejwayelekile, ibanga eliphakathi kweziqongo ezimbili ezilandelanayo noma imifudlana emibili elandelanayo libizwa ngokuthi ubude be-wavelength.

Kalula nje, ubude be-wavelength buyibanga eliphakathi kweziqongo ezimbili ezinhle eziseduze noma iziqongo ezimbili ezimbi eziseduze. Isithombe esingezansi sibonisa i-waveform ye-periodic, lapho ubude be-wavelength (λ) kanye ne-amplitude kuphawulwe. Uma imvamisa iphakeme, ubude be-wavelength bufushane, futhi ngokuphambene nalokho.

Ifomula ye-wavelength yile:

$$\lambda = \frac{c}{f}$$

•λ imelela ubude be-wavelength

•I-C yijubane lokukhanya ($3 \iphindwe ka-10^8$ amamitha ngomzuzwana)

•F imvamisa

Ubude be-λ buvezwa ngamayunithi obude, njengamamitha, izinyawo, noma amasentimitha. Iyunithi evame ukusetshenziswa yimitha.

Ukufaniswa kwe-Impedance:

Ngokusho kwencazelo ejwayelekile, ukufaniswa kwe-impedance kwenzeka lapho i-impedance yomthumeli icishe ilingane ne-impedance yomamukeli.

Kudingeka ukufanisa i-impedance phakathi kwe-antenna kanye nesekethe. I-impedance ye-antenna, umugqa wokudlulisa, kanye nesekethe kufanele ifaniswe ukuze kufezwe ukudluliswa kwamandla okuphezulu phakathi kwe-antenna kanye ne-receiver noma i-transmitter.

Isidingo Sokufanisa
Amadivayisi e-Resonant ayakwazi ukuletha umphumela omuhle kakhulu ngaphakathi kwemvamisa ethile ye-narrowband. Njengedivayisi ye-resonant, i-antenna ingafinyelela ukusebenza okungcono komphumela uma i-impedance yayo ifaniswe kahle.

•Uma i-antenna impedance ifana ne-impedance yesikhala samahhala, amandla akhishwa yi-antenna azodluliselwa ngempumelelo

•Ku-antenna eyamukelayo, i-output impedance yayo kufanele ifane ne-input impedance yesekethe ye-receiving amplifier

•Ku-antenna edlulisa ugesi, ukuvimba kwayo kokufaka kufanele kufane nokuvimba kokukhipha kwe-amplifier edlulisa ugesi kanye nokuvimba okubonakalayo komugqa wokudlulisa ugesi.

Impedance ilinganiswa ngama-ohms, ekhonjiswa uphawu Z.

I-VSWR & Amandla Abonisiwe:

Ngokusho kwencazelo ejwayelekile, isilinganiso se-voltage esiphezulu ne-voltage encane ku-standing wave sibizwa ngokuthi i-voltage standing wave ratio (VSWR).

Uma izithiyo ze-antenna, umugqa wokudlulisa, kanye nesekethe zingahambisani, amandla awakwazi ukukhanyiswa ngempumelelo; kunalokho, ingxenye yamandla ibukiswa emuva.

Izici eziyinhloko yilezi —

•Ipharamitha ekhombisa izinga lokungafani kwe-impedance ibizwa ngokuthi i-Voltage Standing Wave Ratio (VSWR)

•I-VSWR imele i-Voltage Standing Wave Ratio futhi ivame ukubizwa ngokuthi i-SWR

• Uma ukungalingani kwe-impedance kukhulu, kulapho inani le-VSWR liphakama khona

•Ukuze kutholakale imisebe ephumelelayo, inani elifanele le-VSWR lingu-1:1

•Amandla abonisiwe abhekisela engxenyeni yamandla angaphambili echithwayo. Amandla abonisiwe kanye ne-VSWR ngokuyisisekelo zichaza into efanayo ebonakalayo evela emibonweni ehlukene.

Ububanzi bomkhawulo:

Ngokusho kwencazelo ejwayelekile, ibhendi yemvamisa ngaphakathi kwebanga elithile lamaza e-wavelength elabelwe ukuxhumana okuthile libizwa ngokuthi i-bandwidth.

Uma isignali idluliselwa noma yamukelwa, isebenza ngaphakathi kwebanga elithile lemvamisa. Leli banga elithile lemvamisa linikezwa isignali ethile ukuvimbela ukuphazamiseka kwezinye izimpawu ngesikhathi sokudluliselwa.

•Ububanzi bebhendi bubhekisela kububanzi bemvamisa phakathi kwemikhawulo yemvamisa ephezulu kanye nemvamisa ephansi yokudluliselwa kwesignali

•Uma i-bandwidth isibekiwe, ayikwazi ukusetshenziswa abanye

• Lonke uhlobo lwe-spectrum luhlukaniswe ngezigaba ze-bandwidth, ngayinye inikezwe ama-transmitter ahlukene

I-bandwidth esisanda kuxoxa ngayo ingabizwa nangokuthi i-bandwidth ephelele.

Iphesenti Lomkhawulokudonsa:

Ngokusho kwencazelo ejwayelekile, isilinganiso se-bandwidth ephelele nemvamisa yayo ephakathi sibizwa ngokuthi i-bandwidth yephesenti.

Imvamisa ngaphakathi kwebhendi lapho amandla esignali efinyelela khona esiphezulu ibizwa ngokuthi imvamisa ye-resonant, eyaziwa nangokuthi imvamisa ephakathi yebhendi, ekhonjiswe njenge-fC.

• Amaza aphezulu naphansi ebhendi achazwa njenge-fH kanye ne-fL, ngokulandelana

•Umkhawulokudonsa ophelele unikezwa yi-fH − fL

•Ukuhlola ububanzi bebhendi yemvamisa, kubalulekile ukubala i-bandwidth yayo eyingxenye noma i-bandwidth yephesenti

I-bandwidth yephesenti ibalwa ukuze kuqondwe ububanzi bokuhlukahluka kwemvamisa okungaphathwa yisakhi noma uhlelo.

•fH isho imvamisa ephezulu

•fL isho imvamisa ephansi

•fc imelela imvamisa ephakathi

Uma i-bandwidth yephesenti inkulu, i-bandwidth yesiteshi iba nkulu.

Ukuqina kwemisebe:

Ukuqina kwemisebe kuchazwa njengamandla akhishwa nge-engeli eqinile yeyunithi ngayinye.

I-antenna ikhipha imisebe ngamandla amakhulu ngezindlela ezithile, okuhambisana namandla ayo aphezulu emisebeni. Ububanzi obukhulu obungenzeka bomsebe bubonakala ngamandla emisebe.

Ukuvezwa Kwezibalo
Ukuqina kwemisebe kutholakala ngokuphindaphinda ubuningi bamandla akhishwe nge-skwele sebanga le-radial: