Iindaba - Ithiyori ye-Antenna - Iiparamitha eziSiseko

Esi sahluko sichaza iiparameter ezisisiseko zonxibelelwano olungenazingcingo, ngenjongo yokubonelela ngokuqonda okungcono indima yee-antenna kwiinkqubo zonxibelelwano. Unxibelelwano olungenazingcingo lwenziwa ngendlela yamaza e-electromagnetic, nto leyo eyenza kube yimfuneko ukuqonda iimpawu zokusasazwa kwamaza.

Kule sahluko, siza kuxoxa ngezi parameter zilandelayo:

•Ukuphindaphinda
•Ubude begagasi
• Ukulinganisa i-Impedance
•VSWR kunye namandla abonakalisiweyo
•Ububanzi bebhendi
•Ipesenti yeBandwidth
•Ubukhali beMisebe

Ngoku, makhe sizijonge ngokweenkcukacha.

Ubuninzi:

Ngokwenkcazo eqhelekileyo, i-frequency linani lokuphindaphinda kwe-wave ngexesha leyunithi nganye. Ngamazwi alula, i-frequency ichaza ukuba kwenzeka kangaphi isiganeko. I-periodic wave iphinda rhoqo kwimizuzwana ye-T (ixesha elinye), kwaye i-frequency yayo iyafana nexesha le-T.

Ngokwezibalo, kubonakala ngolu hlobo lulandelayo:

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

•F imele i-frequency ye-periodic wave, ngelixa

•Ixesha elifunekayo ukugqiba umjikelo omnye opheleleyo.

I-frequency ilinganiswa kwi-hertz, ifinyezwe njenge-Hz.

Umfanekiso ongasentla ubonisa i-sine wave, i-plotting voltage (kwi-mV) njengomsebenzi wexesha (kwi-ms). Olu tshintsho luphindaphinda rhoqo emva kwe-2t milliseconds; ngoko ke, ixesha layo T = 2t ms, kunye ne-frequency yayo f = 1/(2t) kHz.

Ubude bamaza:

Ngokwenkcazo eqhelekileyo, umgama ophakathi kweencochoyi ezimbini ezilandelelanayo okanye iithafa ezimbini ezilandelelanayo ubizwa ngokuba yi-wavelength.

Ngamafutshane, ubude bexesha bungumgama ophakathi kweencochoyi ezimbini ezikufutshane okanye iincochoyi ezimbini ezikufutshane. Umfanekiso ongezantsi ubonisa i-periodic waveform, apho ubude bexesha (λ) kunye ne-amplitude ziphawulwe. Okukhona ubude bexesha buphezulu, kokukhona ubude bexesha bufutshane, kwaye ngokuchaseneyo.

Ifomula ye-wavelength yile:

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

•λ imele ubude bomda

•Isantya sokukhanya (i-$3 \iphindaphindwe nge-10^8$ yeemitha ngomzuzwana)

•F yi-frequency

Ubude be-λ buchazwa ngeeyunithi zobude, ezinje ngeemitha, iinyawo, okanye ii-intshi. Iyunithi esetyenziswa kakhulu yimitha.

Ukulinganisa ukuvimba:

Ngokwenkcazo eqhelekileyo, ukulinganisa i-impedance kwenzeka xa i-impedance yomthumeli ilingana ne-impedance yommkeli.

Ukuhambelana kwe-impedance kuyafuneka phakathi kwe-antenna kunye nesekethe. Ii-impedance ze-antenna, umgca wokudlulisela, kunye nesekethe kufuneka zihambelane ukuze kufezekiswe ukudluliselwa kwamandla okuphezulu phakathi kwe-antenna kunye ne-receiver okanye i-transmitter.

Ukubaluleka Kokufanisa
Izixhobo ezivuselelayo ziyakwazi ukukhupha imveliso efanelekileyo ngaphakathi kweefrikhwensi ezithile ze-narrowband. Njengesixhobo esivuselelayo, i-antenna inokufezekisa ukusebenza ngcono kwemveliso xa i-impedance yayo ihambelana ngokufanelekileyo.

•Xa i-antenna impedance ihambelana ne-impedance yendawo ekhululekileyo, amandla akhutshwa yi-antenna aya kudluliselwa ngokufanelekileyo

•Kwi-antenna efumanayo, i-output impedance yayo kufuneka ihambelane ne-input impedance yesekethe ye-receiving amplifier.

•Kwi-antenna ethumelayo, i-input impedance yayo kufuneka ihambelane ne-output impedance ye-transmitter amplifier kunye ne-characteristic impedance yomgca wokuhambisa.

Impedance ilinganiswa kwi-ohms, echazwe luphawu lwe-Z.

I-VSWR kunye namandla abonakalisiweyo:

Ngokwenkcazo eqhelekileyo, umlinganiselo wevolthi ephezulu kwivolthi encinci kwi-standing wave ubizwa ngokuba yi-voltage standing wave ratio (VSWR).

Xa izithintelo ze-antenna, umgca wothumelo, kunye nesekethe zingahambelani, amandla awanakutsalwa ngokufanelekileyo; endaweni yoko, inxalenye yamandla ibonakaliswa ngasemva.

Iimpawu eziphambili zezi —

•Ipharamitha ebonisa inqanaba lokungalingani kwe-impedance ibizwa ngokuba yi-Voltage Standing Wave Ratio (VSWR)

•I-VSWR imele iVoltage Standing Wave Ratio kwaye ikwabizwa ngokuba yi-SWR

• Okukhona ukungalingani kwe-impedance kukhulu, kokukhona ixabiso le-VSWR liphezulu

•Ukuze kufezekiswe imitha esebenzayo, ixabiso elifanelekileyo le-VSWR yi-1:1

•Amandla abonakalisiweyo abhekisa kwinxalenye yamandla angaphambili achithekayo. Amandla abonakalisiweyo kunye ne-VSWR ngokusisiseko zichaza into efanayo ebonakalayo kwiimbono ezahlukeneyo.

Ibhendi yobubanzi:

Ngokwenkcazo eqhelekileyo, ibhendi yefrikhwensi ngaphakathi koluhlu oluthile lwamaza olubekelwe unxibelelwano oluthile ibizwa ngokuba yi-bandwidth.

Xa isignali ithunyelwa okanye ifunyanwa, isebenza ngaphakathi koluhlu oluthile lwefrikhwensi. Olu luhlu oluthile lwefrikhwensi lunikezelwa kwisignali ethile ukuthintela ukuphazamiseka kwezinye izignali ngexesha lodluliselo.

•Ububanzi bebhendi bubhekisa kuluhlu lweefrikhwensi phakathi kwemida yeefrikhwensi eziphezulu kunye neefrikhwensi eziphantsi zothumelo lwesignali

•Nje ukuba i-bandwidth inikezelwe, ayinakusetyenziswa ngabanye abantu

• Lonke uluhlu lwahlulwe lwamacandelo e-bandwidth, ngalinye linikezelwe kwiitransmitter ezahlukeneyo

I-bandwidth esisandula ukuyithetha ingabizwa ngokuba yi-bandwidth epheleleyo.

Ipesenti ye-bandwidth:

Ngokwenkcazo eqhelekileyo, umlinganiselo we-bandwidth epheleleyo kwi-center frequency yayo ubizwa ngokuba yi-percentage bandwidth.

I-frequency ngaphakathi kwebhendi apho amandla esignali afikelela khona kubuninzi bawo ibizwa ngokuba yi-resonant frequency, eyaziwa ngokuba yi-center frequency yebhendi, echazwa njenge-fC.

•Iifrequensi eziphezulu nezisezantsi zebhendi zibonakaliswa njenge-fH kunye ne-fL, ngokulandelelanayo

•I-bandwidth epheleleyo inikwa yi-fH − fL

•Ukuvavanya ububanzi bebhendi yefrikhwensi, kuyimfuneko ukubala i-bandwidth yayo yeqhezu okanye i-bandwidth yepesenti.

I-bandwidth yepesenti ibalwa ukuze kuqondwe uluhlu lweenguqu zefrikhwensi ezinokuthi ziphathwe yinxalenye okanye inkqubo.

•fH ibonisa i-frequency ephezulu

•fL ibonisa i-frequency ephantsi

•fc ibonisa i-frequency esembindini

Okukhona i-bandwidth yepesenti inkulu, kokukhona i-bandwidth yetshaneli ibanzi.

Ubunzulu bemitha:

Ubungakanani bemitha buchazwa njengamandla akhutshwayo nge-engile eqinileyo nganye.

I-antenna ikhupha imitha ngamandla ngakumbi kwicala elithile, nto leyo ehambelana nobukhulu bayo obukhulu bemitha. Uluhlu oluphezulu lwemitha lubonakaliswa bubukhulu bemitha.

Inkcazo yeMathematika
Ubunzulu bemitha bufumaneka ngokuphindaphinda uxinano lwamandla akhutshwe nge-square yomgama we-radial: