Izindaba - Isibuyekezo se-Antena: Isibuyekezo se-Fractal Metasurfaces kanye nomklamo we-Antena

I. Isingeniso
Ama-Fractal ayizinto zezibalo ezibonisa izakhiwo ezifanayo ngezikali ezahlukene. Lokhu kusho ukuthi uma usondeza/ukhipha isimo se-fractal, ingxenye ngayinye yaso ibukeka ifana kakhulu nayo yonke; okungukuthi, amaphethini noma izakhiwo ezifanayo zejiyometri ziyaphindaphinda emazingeni ahlukene okukhulisa (bheka izibonelo ze-fractal kuMfanekiso 1). Ama-fractal amaningi anezimo eziyinkimbinkimbi, ezinemininingwane, neziyinkimbinkimbi ngokungenamkhawulo.

isithombe 1

Umqondo wama-fractal wethulwa yisazi sezibalo uBenoit B. Mandelbrot ngawo-1970, yize imvelaphi ye-fractal geometry ingalandelelwa emuva emsebenzini wangaphambili wezazi eziningi zezibalo, njengoCantor (1870), von Koch (1904), Sierpinski (1915), Julia (1918), Fatou (1926), noRichardson (1953).
UBenoit B. Mandelbrot wafunda ubudlelwano phakathi kwama-fractal nemvelo ngokwethula izinhlobo ezintsha zama-fractal ukuze alingise izakhiwo eziyinkimbinkimbi kakhulu, njengezihlahla, izintaba, kanye nogu lolwandle. Waqamba igama elithi "fractal" elivela kwisichasiso sesiLatini esithi "fractus", okusho ukuthi "ephukile" noma "ephukile", okungukuthi eyakhiwe yizicucu eziphukile noma ezingajwayelekile, ukuchaza izimo zejiyometri ezingajwayelekile neziqhekekile ezingenakwahlukaniswa nge-geometry yendabuko ye-Euclidean. Ngaphezu kwalokho, wathuthukisa amamodeli ezibalo kanye nama-algorithms okukhiqiza nokufunda ama-fractal, okwaholela ekudalweni kwesethi edumile ye-Mandelbrot, okungenzeka ukuthi iyisimo se-fractal esidumile nesikhangayo kakhulu esinamaphethini ayinkimbinkimbi futhi aphindaphindwayo angenamkhawulo (bheka Umfanekiso 1d).
Umsebenzi kaMandelbrot awuzange ube nomthelela kuphela kwizibalo, kodwa futhi unezinhlelo zokusebenza emikhakheni eyahlukene njengefiziksi, ihluzo zekhompyutha, i-biology, ezomnotho, kanye nobuciko. Eqinisweni, ngenxa yekhono lawo lokwenza amamodeli nokumelela izakhiwo eziyinkimbinkimbi nezifanayo, ama-fractal anezinhlelo zokusebenza eziningi ezintsha emikhakheni eyahlukene. Isibonelo, asetshenziswe kabanzi ezindaweni ezilandelayo zohlelo lokusebenza, okuyizibonelo ezimbalwa nje zohlelo lokusebenza lwawo olubanzi:
1. Ihluzo zekhompyutha kanye nezithombe ezinyakazayo, ezidala izindawo zemvelo ezingokoqobo nezikhangayo nezibonakalayo;
2. Ubuchwepheshe bokucindezela idatha ukunciphisa usayizi wamafayela edijithali;
3. Ukucutshungulwa kwesithombe nesignali, ukukhipha izici ezithombeni, ukuthola amaphethini, kanye nokuhlinzeka ngezindlela ezisebenzayo zokucindezela nokwakha kabusha isithombe;
4. Ibhayoloji, echaza ukukhula kwezitshalo kanye nokuhleleka kwama-neurons ebuchosheni;
5. Ithiyori ye-antenna kanye ne-metaterials, ukuklama ama-antenna amancane/ama-band amaningi kanye ne-metasurfaces ezintsha.
Njengamanje, i-fractal geometry iyaqhubeka nokuthola ukusetshenziswa okusha nokusha emikhakheni eyahlukene yesayensi, yobuciko kanye nezobuchwepheshe.
Kubuchwepheshe be-electromagnetic (EM), izimo ze-fractal ziwusizo kakhulu ezinhlelweni zokusebenza ezidinga i-miniaturization, kusukela kuma-antenna kuya kuma-metaterials kanye nezindawo ezikhethiwe ze-frequency (FSS). Ukusebenzisa i-fractal geometry kuma-antenna avamile kungandisa ubude bawo kagesi, ngaleyo ndlela kuncishiswe usayizi ophelele wesakhiwo se-resonant. Ngaphezu kwalokho, ubunjalo obufanayo bezinhlobo ze-fractal buzenza zilungele ukufeza izakhiwo ze-resonant ze-multi-band noma ze-broadband. Amandla e-miniaturization angokwemvelo ama-fractals akhanga kakhulu ekwakhiweni kwama-reflectarrays, ama-antenna e-phased array, ama-metaterial absorbers kanye nama-metasurfaces ezinhlelo zokusebenza ezahlukahlukene. Eqinisweni, ukusebenzisa izinto ezincane kakhulu ze-array kungaletha izinzuzo eziningana, njengokunciphisa ukuhlangana okuhlangene noma ukukwazi ukusebenza nama-arrays anesikhala esincane kakhulu sezinto, ngaleyo ndlela kuqinisekiswe ukusebenza kahle kokuskena kanye namazinga aphezulu okuzinza kwe-angular.
Ngenxa yezizathu ezishiwo ngenhla, ama-antenna e-fractal kanye nama-metasurfaces amelela izindawo ezimbili ezithakazelisayo zocwaningo emkhakheni wama-electromagnetics ezidonse ukunaka okukhulu eminyakeni yamuva nje. Zombili lezi zindlela zinikeza izindlela ezihlukile zokulawula amaza kagesi, ngezinhlelo eziningi zokuxhumana ezingenantambo, izinhlelo ze-radar kanye nokuzwa. Izakhiwo zazo ezifanayo zivumela ukuthi zibe zincane ngobukhulu ngenkathi zigcina impendulo enhle kakhulu ye-electromagnetic. Lokhu kubumbana kunenzuzo ikakhulukazi ezinhlelweni zokusebenza ezivinjelwe isikhala, njengamadivayisi eselula, amathegi e-RFID, kanye nezinhlelo zezindiza.
Ukusetshenziswa kwama-antenna e-fractal kanye nama-metasurfaces kunamandla okuthuthukisa kakhulu ukuxhumana okungenantambo, izithombe, kanye nezinhlelo ze-radar, njengoba kuvumela amadivayisi amancane, asebenza kahle kakhulu anokusebenza okuthuthukisiwe. Ngaphezu kwalokho, i-fractal geometry isetshenziswa kakhulu ekwakhiweni kwezinzwa ze-microwave zokuxilonga izinto, ngenxa yamandla ayo okusebenza kuma-frequency band amaningi kanye nekhono layo lokuncishiswa. Ucwaningo oluqhubekayo kulezi zindawo luyaqhubeka nokuhlola imiklamo emisha, izinto zokwakha, kanye namasu okukhiqiza ukuze kufezwe amandla azo aphelele.
Leli phepha lihlose ukubuyekeza inqubekela phambili yocwaningo kanye nokusetshenziswa kwama-antenna e-fractal kanye nama-metasurfaces bese kuqhathaniswa ama-antenna nama-metasurfaces akhona asekelwe ku-fractal, kugqanyiswe izinzuzo kanye nemikhawulo yawo. Okokugcina, kwethulwa ukuhlaziywa okuphelele kwama-reflectarrays amasha kanye nama-metaterial units, futhi kuxoxwa ngezinselele kanye nentuthuko yesikhathi esizayo yalezi zakhiwo ze-electromagnetic.

2. I-FractalI-AntennaIzinto
Umqondo ojwayelekile wama-fractal ungasetshenziswa ukuklama izakhi ze-antenna ezingavamile ezinikeza ukusebenza okungcono kune-antenna evamile. Izakhi ze-antenna ze-fractal zingaba zincane ngobukhulu futhi zibe namakhono e-multi-band kanye/noma e-broadband.
Ukwakheka kwama-antenna e-fractal kuhilela ukuphinda amaphethini athile ejiyometri ezikalini ezahlukene ngaphakathi kwesakhiwo se-antenna. Le patheni efanayo isenza sikwazi ukwandisa ubude be-antenna ngaphakathi kwesikhala esilinganiselwe somzimba. Ngaphezu kwalokho, ama-radiator e-fractal angafinyelela amabhendi amaningi ngoba izingxenye ezahlukene ze-antenna ziyafana ezikalini ezahlukene. Ngakho-ke, izakhi ze-antenna ze-fractal zingaba zincane futhi zibe namabhendi amaningi, zinikeze ukumbozwa okubanzi kwemvamisa kune-antenna evamile.
Umqondo wama-antenna e-fractal ungalandelelwa emuva ngasekupheleni kwawo-1980. Ngo-1986, uKim noJaggard babonisa ukusetshenziswa kokufana kwe-fractal ekuhlanganisweni kwe-antenna array.
Ngo-1988, isazi sefiziksi uNathan Cohen wakha i-antenna yokuqala ye-fractal element emhlabeni. Waphakamisa ukuthi ngokufaka i-geometry efanayo esakhiweni se-antenna, ukusebenza kwayo kanye namakhono amancane kungathuthukiswa. Ngo-1995, uCohen wasungula i-Fractal Antenna Systems Inc., eyaqala ukuhlinzeka ngezixazululo ze-antenna zokuqala zezentengiselwano ezisekelwe ku-fractal emhlabeni.
Maphakathi nawo-1990, uPuente nabanye babonise amakhono amaningi ama-fractal besebenzisa i-monopole ne-dipole kaSierpinski.
Kusukela emsebenzini kaCohen noPuente, izinzuzo ezingokwemvelo zama-antenna e-fractal zidonsele isithakazelo esikhulu kubacwaningi nonjiniyela emkhakheni wezokuxhumana, okuholele ekuhlolweni okuqhubekayo kanye nentuthuko yobuchwepheshe be-antenna ye-fractal.
Namuhla, ama-antenna e-fractal asetshenziswa kabanzi ezinhlelweni zokuxhumana ezingenantambo, okuhlanganisa omakhalekhukhwini, ama-router e-Wi-Fi, kanye nokuxhumana ngesathelayithi. Eqinisweni, ama-antenna e-fractal mancane, anama-band amaningi, futhi asebenza kahle kakhulu, okwenza afaneleke kumadivayisi ahlukahlukene angenantambo kanye namanethiwekhi.
Izibalo ezilandelayo zibonisa ama-antenna athile e-fractal asekelwe ezimeni ze-fractal ezaziwayo, okuyizibonelo ezimbalwa nje zezilungiselelo ezahlukahlukene okuxoxwe ngazo ezincwadini.
Ngokuqondile, uMfanekiso 2a ukhombisa i-monopole kaSierpinski ehlongozwayo ePuente, ekwazi ukunikeza ukusebenza kwama-band amaningi. Unxantathu kaSierpinski wakhiwa ngokususa unxantathu ophakathi oguquliwe kunxantathu oyinhloko, njengoba kuboniswe kuMfanekiso 1b nakuMfanekiso 2a. Le nqubo ishiya onxantathu abathathu abalinganayo esakhiweni, ngamunye enobude obuyisigamu sonxantathu wokuqala (bheka uMfanekiso 1b). Inqubo efanayo yokususa ingaphindaphindwa konxantathu abasele. Ngakho-ke, ngayinye yezingxenye zayo ezintathu eziyinhloko ilingana ncamashi nento yonke, kodwa kabili ngesilinganiso, njalo njalo. Ngenxa yalokhu kufana okukhethekile, iSierpinski inganikeza ama-frequency band amaningi ngoba izingxenye ezahlukene ze-antenna ziyafana ngezikali ezahlukene. Njengoba kuboniswe kuMfanekiso 2, i-monopole kaSierpinski ehlongozwayo isebenza ngama-band angu-5. Kungabonakala ukuthi ngayinye yama-sub-gasket amahlanu (izakhiwo zendilinga) kuMfanekiso 2a iyinguqulo elinganisiwe yesakhiwo sonke, ngaleyo ndlela ihlinzeka ngama-frequency band amahlanu ahlukene okusebenza, njengoba kuboniswe ku-input reflection coefficient kuMfanekiso 2b. Lesi sibalo sibonisa namapharamitha ahlobene nebhendi ngayinye yemvamisa, kufaka phakathi inani lemvamisa fn (1 ≤ n ≤ 5) ngenani elincane lokulahlekelwa kokubuyiselwa kokufaka okulinganisiwe (Lr), i-bandwidth ehlobene (Bwidth), kanye nesilinganiso semvamisa phakathi kwamabhendi amabili emvamisa aseduze (δ = fn +1/fn). Isibalo 2b sibonisa ukuthi amabhendi ama-monopole aseSierpinski ahlukaniswa ngezikhathi ezithile nge-logarithmic ngesici esingu-2 (δ ≅ 2), okuhambisana nesici esifanayo sokukala esikhona ezakhiweni ezifanayo ngesimo se-fractal.

isithombe 2

Isithombe 3a sibonisa i-antenna encane ende ende esekelwe ku-Koch fractal curve. Le antenna ihlongozwa ukukhombisa indlela yokusebenzisa izakhiwo zokugcwalisa isikhala zezimo ze-fractal ukuklama ama-antenna amancane. Eqinisweni, ukunciphisa usayizi wama-antenna kuwumgomo wokugcina wenani elikhulu lezinhlelo zokusebenza, ikakhulukazi lezo ezihilela ama-terminals eselula. I-monopole ye-Koch idalwe kusetshenziswa indlela yokwakha i-fractal eboniswe ku-Figure 3a. Ukuphindaphinda kokuqala i-K0 kuyi-monopole eqondile. Ukuphindaphinda okulandelayo i-K1 kutholakala ngokusebenzisa ukuguqulwa kokufana ku-K0, kufaka phakathi ukukala ngengxenye eyodwa kwezintathu nokujikeleza ngo-0°, 60°, −60°, kanye no-0°, ngokulandelana. Le nqubo iphindaphindwa ngokuphindaphindiwe ukuthola izakhi ezilandelayo i-Ki (2 ≤ i ≤ 5). Isithombe 3a sibonisa inguqulo ye-Koch monopole eneziphindaphindo ezinhlanu (okungukuthi, i-K5) enokuphakama okungu-h okulingana no-6 cm, kodwa ubude obuphelele bunikezwa yifomula l = h ·(4/3) 5 = 25.3 cm. Ama-antenna amahlanu ahambisana nokuphindaphinda okuhlanu kokuqala kwejika le-Koch aqaliwe (bheka uMfanekiso 3a). Kokubili ukuhlolwa kanye nedatha kubonisa ukuthi i-monopole ye-fractal ye-Koch ingathuthukisa ukusebenza kwe-monopole yendabuko (bheka uMfanekiso 3b). Lokhu kusikisela ukuthi kungenzeka "ukuncishisa" ama-antenna e-fractal, okuwavumela ukuthi angene kumavolumu amancane ngenkathi egcina ukusebenza kahle.

isithombe 3

Isithombe 4a sibonisa i-antenna ye-fractal esekelwe kusethi ye-Cantor, esetshenziselwa ukuklama i-antenna ye-wideband yezinhlelo zokusebenza zokuvuna amandla. Impahla eyingqayizivele yama-antenna e-fractal aletha ama-resonance amaningi aseduze isetshenziswa ukuze inikeze i-bandwidth ebanzi kune-antenna evamile. Njengoba kuboniswe ku-Figure 1a, ukwakheka kwesethi ye-fractal ye-Cantor kulula kakhulu: umugqa wokuqala oqondile uyakopishwa futhi uhlukaniswe izingxenye ezintathu ezilinganayo, lapho ingxenye ephakathi isuswa khona; inqubo efanayo bese isetshenziswa ngokuphindaphindiwe ezigabeni ezisanda kukhiqizwa. Izinyathelo zokuphindaphinda kwe-fractal ziyaphindwa kuze kube yilapho kufezwa i-bandwidth ye-antenna (BW) engu-0.8–2.2 GHz (okungukuthi, i-98% BW). Isithombe 4 sibonisa isithombe se-prototype ye-antenna eqashelwayo (Isithombe 4a) kanye ne-coefficient yayo yokubonisa okufakwayo (Isithombe 4b).

isithombe 4

Umfanekiso 5 unikeza izibonelo ezengeziwe zama-antenna e-fractal, okuhlanganisa i-antenna ye-monopole esekelwe ku-Hilbert curve, i-antenna ye-microstrip patch esekwe ku-Mandelbrot, kanye ne-fractal patch yesiqhingi saseKoch (noma "i-snowflake").

isithombe 5

Okokugcina, uMfanekiso 6 ukhombisa ukuhlelwa okuhlukene kwe-fractal kwezinto ze-array, kufaka phakathi ama-array e-planar e-Sierpinski carpet, ama-array e-Cantor ring, ama-array aqondile e-Cantor, kanye nezihlahla ze-fractal. Lawa malungiselelo awusizo ekudaleni ama-array a-sparse kanye/noma ekufezeni ukusebenza kwama-multi-band.