I-Antenna ye-Dipole emfushane: Isakhiwo, Isimiso Sokusebenza kanye Nephethini Yokushiswa Kwemisebe

I-antenna emfushane ye-dipole ingenye yamamodeli ayisisekelo asetshenziswa ku-theory ye-antenna. Iyi-antenna elula yocingo oluqondile enobude obuphelele obuncane kakhulu kunobude be-wavelength yesiginali yokusebenza. Nakuba isakhiwo sibonakala silula kakhulu, i-dipole emfushane iyimodeli ebalulekile yokubhekisela ekuqondeni ukusatshalaliswa kwamanje, ukuziphatha kwemisebe, ukuvimba kwe-antenna, kanye nobudlelwano phakathi kosayizi we-antenna kanye nobude be-wavelength.

Kubunjiniyela be-antenna, i-dipole ivame ukubhekwa “njengefushane” lapho ubude bayo bonke bungaphansi kwengxenye eyodwa kweziyishumi yobude be-wavelength:

L < \frac{\lambda}{10}

Lapha, i-(L) imele ubude bomqhubi we-dipole, kanti i-(\lambda) imele ubude be-wavelength emvamisa yokusebenza. Le ncazelo isekelwe kubude bukagesi kunebanga lemvamisa elihleliwe. Ngamanye amazwi, i-dipole emfushane ingavela ngokwemfundiso kuma-frequency band ahlukene uma nje ubude bayo obubonakalayo buhlala buncane kakhulu kunobude be-wavelength.

Ngenxa yokuthi i-antenna imfushane ngogesi, ukusatshalaliswa kwamanje eceleni komqhubi kuhlukile kokwe-half-wave dipole. Ku-dipole emfushane esebenzayo, ugesi uvame ukuba phezulu eduze kwendawo yokuphakela futhi wehle uye emaphethelweni omqhubi. Njengoba ubude bomqhubi bufushane kakhulu kunobude be-wavelength, i-antenna ayisebenzisi usayizi wayo ongokoqobo kahle kakhulu emisebeni. Ngenxa yalokho, ama-dipole amafushane ngokuvamile anokumelana okuphansi kwemisebe kanye nokusebenza kahle kwemisebe okuphansi, ikakhulukazi lapho kucatshangelwa ukulahlekelwa komqhubi kanye nokulahlekelwa okufanayo.

Imodeli yethiyori ehlobene yi-infinitesimal dipole. I-infinitesimal dipole iyi-antenna efanelekile enobude obuncane kakhulu kunobude be-wavelength. Ivame ukuvezwa kanje:

[\Delta l \ll \lambda]

Kwamanye amamodeli e-antenna alula, i-infinitesimal dipole ingacatshangwa ukuthi inokusabalalisa kwamanje okucishe kufane. Lokhu kuyenza ibe usizo ekuhlaziyweni kwethiyori, yize kungesona isakhiwo se-antenna esisebenzayo ngokwaso. Onjiniyela bavame ukusebenzisa i-infinitesimal dipole njengebhloko yokwakha ukuqonda izinkinga zokukhanya kwe-antenna eziyinkimbinkimbi kakhulu.

Ezinhlakeni zangempela ze-antenna, amapuleti okulayisha anamandla noma izinto zokulayisha phezulu zingasetshenziswa ukuthuthukisa ukusatshalaliswa kwamanje noma ukunciphisa usayizi obonakalayo wesistimu ye-antenna. Lezi zakhiwo zokulayisha zingasiza ekwenzeni i-antenna emfushane kagesi isebenziseke kakhudlwana, kodwa azishintshi iqiniso eliyisisekelo lokuthi i-dipole emfushane ayisebenzi kahle kune-antenna ephendulayo njenge-dipole ye-half-wave.

Iphethini yemisebe ye-dipole emfushane ifana ngesimo se-dipole ye-half-wave. Uma i-dipole ibekwe phezulu, iphethini yayo yemisebe cishe iqonde yonke indawo endizeni evundlile. Ngombono onezinhlangothi ezimbili, iphethini ivame ukuchazwa njengesimo sesibalo-esishiyagalombili, lapho imisebe ephezulu iqonde ngqo ku-axis ye-antenna kanye nemisebe encane eduze kwe-axis ye-antenna.

Ama-antenna amafushane e-dipole avame ukuxoxwa ngawo ezinhlelweni zokwamukela ama-frequency aphansi kanye nama-medium-frequency, lapho ubude be-wavelength bude kakhulu futhi i-antenna ephendulayo ngokomzimba ingaba nkulu kakhulu ukuba ingakhiwa. Kulezi zimo, i-dipole emfushane inikeza isakhiwo sokwamukela esincane, yize ukufaniswa kwe-impedance kanye nokusebenza kahle kumele kucatshangelwe ngokucophelela.

Ngokombono wobunjiniyela, i-short dipole ingaphezu nje kohlobo lwe-antenna olulula. Kuyasiza ukuchaza ukuthi kungani ubude be-antenna bubalulekile, ukuthi ukusatshalaliswa kwamanje kuthinta kanjani imisebe, nokuthi kungani ama-antenna amancane kagesi evame ukudinga amanethiwekhi afanayo noma amasu okulayisha. Konjiniyela be-RF kanye nama-microwave, ukuqonda i-short dipole kunikeza isisekelo esiwusizo sokufunda ama-antenna asebenzayo, ama-antenna amancane kagesi, ama-antenna okulinganisa, kanye nezinhlelo ze-antenna ezithuthukisiwe kakhulu.