Ipharamitha ewusizo ebala amandla okwamukela e-antenna yi-indawo ephumelelayonomaukuvuleka okusebenzayoAke sithi igagasi lendiza eline-polarization efanayo ne-antenna yokwamukela liyisigameko ku-antenna. Futhi ake sithi igagasi liya e-antenna liqonde ngqo emisebeni ephezulu ye-antenna (indlela lapho amandla amaningi azotholwa khona).

Bese kubaukuvuleka okusebenzayoipharamitha ichaza ukuthi angakanani amandla abanjwa kusuka kugagasi lendiza elinikeziwe.pkube ubuningi bamandla wegagasi lendiza (ku-W/m^2). UmaP_timele amandla (ngama-Watts) kuma-terminal e-antenna atholakala kumamukeli we-antenna, bese kuthi:

Ngakho-ke, indawo ephumelelayo imelela nje ukuthi angakanani amandla abanjwayo kusuka kugagasi lendiza futhi alethwe yi-antenna. Le ndawo ibangela ukulahlekelwa okungaphakathi kwe-antenna (ukulahlekelwa kwe-ohmic, ukulahlekelwa kwe-dielectric, njll.).

Ubudlelwano obujwayelekile bokuvulwa okusebenzayo ngokwenzuzo ye-antenna ephezulu (G) yanoma iyiphi i-antenna bunikezwa yi:

Ukuvulwa okusebenzayo noma indawo ephumelelayo ingalinganiswa kuma-antenna angempela ngokuqhathanisa ne-antenna eyaziwayo enokuvulwa okusebenzayo okunikeziwe, noma ngokubala kusetshenziswa inzuzo elinganisiwe kanye nesibalo esingenhla.

Ukuvulwa okusebenzayo kuzoba umqondo owusizo wokubala amandla atholiwe avela kugagasi lendiza. Ukuze ubone lokhu kusebenza, iya esigabeni esilandelayo sefomula yokudlulisa ye-Friis.

I-Friis Transmission Equation

Kuleli khasi, sethula esinye sezibalo eziyisisekelo kakhulu ku-antenna theory,Isibalo Sokudluliselwa Kwe-FriisI-Friis Transmission Equation isetshenziselwa ukubala amandla atholwe ku-antenna eyodwa (ngokuthola amandla).G1), uma idluliselwa kusuka kwenye i-antenna (ngokukhuluphalaG2), ihlukaniswe yibangaR, futhi isebenza ngezikhathi ezithilefnoma i-wavelength lambda. Leli khasi lifanele ukufundwa izikhathi ezimbalwa futhi kufanele liqondwe ngokugcwele.

Ukutholwa kwe-Friis Transmission Formula

Ukuze uqale ukuthola i-Friis Equation, cabanga ngama-antenna amabili asendaweni ekhululekile (akukho zithiyo eziseduze) ahlukaniswe yibanga.R:

Ake sithi () Ama-Watts wamandla aphelele alethwa ku-antenna yokudlulisa. Okwamanje, ake sithi i-antenna yokudlulisa iqondisa yonke indawo, ayinawo ukulahleka, nokuthi i-antenna yokwamukela isensimini ekude ye-antenna yokudlulisa. Khona-ke ubuningi bamandlap(ngama-Watts ngemitha yesikwele) yesigameko segagasi lendiza ku-antenna yokwamukela ibangaRI-antenna yokudlulisa inikezwa yi:

Umfanekiso 1. Ama-Antenna okudlulisa (Tx) kanye nokwamukela (Rx) ahlukaniswe yiR.

Uma i-antenna yokudlulisa inenzuzo ye-antenna ohlangothini lwe-antenna yokwamukela enikezwe yi-（）, khona-ke i-equation yobuningi bamandla engenhla iba:

I-gain term ibangela ukuqondiswa kanye nokulahlekelwa kwe-antenna yangempela. Ake sithi manje i-antenna yokwamukela inomgodi osebenzayo onikezwe yi(). Bese amandla atholwa yile antenna ( ) anikezwa yi:

Njengoba i-aperture esebenzayo yanoma iyiphi i-antenna ingachazwa kanje:

Amandla atholiwe avelayo angabhalwa kanje:

Isibalo1

Lokhu kwaziwa ngokuthi i-Friis Transmission Formula. Kuhlobanisa ukulahleka kwendlela yesikhala esikhululekile, izinzuzo ze-antenna kanye nobude be-wavelength namandla atholiwe nadluliswayo. Lokhu kungenye yezibalo eziyisisekelo ku-antenna theory, futhi kufanele kukhunjulwe (kanye nomphumela ongenhla).

Olunye uhlobo oluwusizo lwe-Friis Transmission Equation lunikezwe ku-Equation [2]. Njengoba ubude be-wavelength kanye ne-frequency f kuhlobene nesivinini sokukhanya c (bheka isingeniso ekhasini le-frequency), sine-Friis Transmission Formula ngokwe-frequency:

Isibalo 2

I-Equation [2] ikhombisa ukuthi amandla amaningi alahleka kuma-frequency aphezulu. Lokhu kuwumphumela oyisisekelo we-Friis Transmission Equation. Lokhu kusho ukuthi kuma-antenna anezinzuzo ezithile, ukudluliselwa kwamandla kuzoba phezulu kakhulu kuma-frequency aphansi. Umehluko phakathi kwamandla atholiwe namandla adlulisiwe waziwa ngokuthi ukulahleka kwendlela. Kuthiwa ngendlela ehlukile, i-Friis Transmission Equation ithi ukulahleka kwendlela kuphakeme kuma-frequency aphezulu. Ukubaluleka kwalomphumela ovela ku-Friis Transmission Formula akunakugcizelelwa ngokweqile. Yingakho amafoni aphathekayo ngokuvamile esebenza ngaphansi kwama-2 GHz. Kungase kube ne-frequency spectrum eyengeziwe etholakalayo kuma-frequency aphezulu, kodwa ukulahleka kwendlela okuhlobene ngeke kuvumele ukwamukelwa kwekhwalithi. Njengomphumela owengeziwe we-Friss Transmission Equation, ake sithi ubuzwa ngama-antenna angu-60 GHz. Uma uqaphela ukuthi le frequency iphezulu kakhulu, ungase uthi ukulahleka kwendlela kuzoba phezulu kakhulu ekuxhumaneni okude - futhi uqinisile ngokuphelele. Kuma-frequency aphezulu kakhulu (ama-60 GHz ngezinye izikhathi abizwa ngokuthi isifunda sama-mm (millimeter wave)), ukulahleka kwendlela kuphezulu kakhulu, ngakho-ke ukuxhumana okuqondile kuya endaweni kuphela okungenzeka. Lokhu kwenzeka lapho umamukeli nomthumeli besegumbini elifanayo, futhi bebhekene. Njengomphumela we-Friis Transmission Formula, ucabanga ukuthi opharetha befoni ephathekayo bayajabula ngebhendi entsha ye-LTE (4G), esebenza ku-700MHz? Impendulo inguyebo: lokhu kuyimvamisa ephansi kune-antenna ezivame ukusebenza kuyo, kodwa kusukela ku-Equation [2], siphawula ukuthi ukulahleka kwendlela nakho kuzoba phansi. Ngakho-ke, bangakwazi "ukumboza umhlabathi omningi" ngale mvamisa, futhi umphathi we-Verizon Wireless muva nje ubize lokhu ngokuthi "i-spectrum yekhwalithi ephezulu", ngenxa yalesi sizathu. Qaphela Ohlangothini: Ngakolunye uhlangothi, abenzi befoni yeselula kuzodingeka bafake i-antenna enobude be-wavelength obukhulu kudivayisi ehlanganisiwe (imvamisa ephansi = ubude be-wavelength obukhulu), ngakho-ke umsebenzi womklami we-antenna waba nzima kakhulu!

Okokugcina, uma ama-antenna engalingani nge-polarization, amandla atholiwe angenhla angaphindaphindwa yi-Polarization Loss Factor (PLF) ukuze kubhekwe kahle lokhu kungafani. I-Equation [2] engenhla ingashintshwa ukuze kukhiqizwe i-generalized Friis Transmission Formula, ehlanganisa ukungafani nge-polarization: