I. Isingeniso
Ama-Fractals yizinto zezibalo ezibonisa izici ezifanayo ezikalini ezahlukene. Lokhu kusho ukuthi uma usondeza/usondeza umumo we-fractal, ingxenye yawo ngayinye ibukeka ifana kakhulu nayo yonke; okungukuthi, amaphethini ejiyomethri afanayo noma izakhiwo ziphinda emazingeni ahlukene okukhulisa (bona izibonelo ze-fractal kuMfanekiso 1). Ama-fractals amaningi anomumo oyinkimbinkimbi, onemininingwane, futhi oyinkimbinkimbi ngokungapheli.
umfanekiso 1
Umqondo wama-fractals wethulwa isazi sezibalo u-Benoit B. Mandelbrot ngeminyaka yawo-1970, nakuba umsuka we-fractal geometry ungalandelelwa emuva emsebenzini wangaphambili wochwepheshe bezibalo abaningi, njengoCantor (1870), von Koch (1904), Sierpinski (1915) ), uJulia (1918), uFatou (1926), noRichardson (1953).
U-Benoit B. Mandelbrot ufunde ubudlelwano phakathi kwama-fractals nemvelo ngokwethula izinhlobo ezintsha zama-fractals ukuze zilingise izakhiwo eziyinkimbinkimbi, njengezihlahla, izintaba, nogu. Waqamba igama elithi “fractal” lisuselwa kusichasiso sesiLatini esithi “fractus”, elisho “ukuphuka” noma “ukuqhekeka”, okungukuthi okwakhiwe izingcezu eziphukile noma ezingajwayelekile, ukuchaza izimo zejiyomethri ezingajwayelekile nezihlukene ezingakwazi ukuhlukaniswa ngejometri yendabuko ye-Euclidean. Ngaphezu kwalokho, wakha amamodeli ezibalo kanye nama-algorithms okukhiqiza nokufunda ama-fractals, okwaholela ekudalweni kwesethi edumile ye-Mandelbrot, okungenzeka ukuthi iyisimo se-fractal esidume kakhulu nesibukeka kahle esinamaphethini ayinkimbinkimbi futhi aphindaphindiwe (bheka Umfanekiso 1d).
Umsebenzi kaMandelbrot awubanga nomthelela kuzibalo kuphela, kodwa futhi unezinhlelo zokusebenza emikhakheni eyahlukene efana nefiziksi, ihluzo zekhompyutha, i-biology, ezomnotho, nezobuciko. Eqinisweni, ngenxa yekhono lawo lokumodela nokumelela izakhiwo eziyinkimbinkimbi nezifanayo, ama-fractals anezinhlelo eziningi zokusungula emikhakheni ehlukahlukene. Isibonelo, zisetshenziswe kabanzi ezindaweni ezilandelayo zohlelo, okuyizibonelo ezimbalwa zokusetshenziswa kwazo okubanzi:
1. Imifanekiso yekhompyutha nokugqwayiza, ekhiqiza izindawo ezingokoqobo nezibukekayo zemvelo ezikhangayo, izihlahla, amafu, nendlela yokwenza;
2. Ubuchwepheshe bokucindezela idatha ukunciphisa usayizi wamafayela edijithali;
3. Ukucutshungulwa kwesithombe nesignali, ukukhipha izici ezithombeni, ukuthola amaphethini, nokuhlinzeka ngokucindezelwa kwesithombe nezindlela zokwakha kabusha;
4. I-Biology, echaza ukukhula kwezitshalo kanye nokuhlelwa kwama-neurons ebuchosheni;
5. Ithiyori ye-antenna kanye ne-metamatadium, ukuklama izimpondo ezihlangene/ama-multi-band nama-metasurface asungulayo.
Njengamanje, i-fractal geometry iyaqhubeka nokuthola ukusetshenziswa okusha nokusha emikhakheni eyahlukene yesayensi, ezobuciko kanye nezobuchwepheshe.
Kubuchwepheshe be-electromagnetic (EM), umumo we-fractal uwusizo kakhulu ezinhlelweni ezidinga i-miniaturization, ukusuka kuma-antenna kuya ku-metamatadium kanye nezindawo ezikhethiwe ze-frequency (FSS). Ukusebenzisa i-geometry ye-fractal kuma-antenna avamile kungakhuphula ubude bawo kagesi, ngaleyo ndlela kunciphise usayizi wesakhiwo esizwakalayo. Ukwengeza, imvelo efanayo yomumo we-fractal ibenza bafaneleke ukubona izakhiwo zama-multi-band noma i-broadband resonant. Amakhono emvelo okwenza ama-fractals amancane athandeka kakhulu ekuklameni i-reflections, ama-antenna ahlelwe ngezigaba, ama-metamaterial absorbers kanye nama-metasurface ezinhlelo zokusebenza ezihlukahlukene. Eqinisweni, ukusebenzisa izakhi ezincane kakhulu zamalungu afanayo kungaletha izinzuzo ezimbalwa, njengokunciphisa ukuhlangana okuhlangene noma ukukwazi ukusebenza ngamaqoqo anezikhala ezincane kakhulu, ngaleyo ndlela kuqinisekiswe ukusebenza okuhle kokuskena kanye namazinga aphezulu okuzinza kwe-angular.
Ngenxa yezizathu ezishiwo ngenhla, ama-antenna ama-fractal nama-metasurface amele izindawo ezimbili zocwaningo ezihehayo emkhakheni wezibuthe kagesi ezidonse ukunaka okukhulu eminyakeni yamuva nje. Yomibili le mibono inikezela ngezindlela ezihlukile zokuphatha nokulawula amaza kagesi, ngezinhlelo eziningi ezahlukahlukene kwezokuxhumana okungenantambo, izinhlelo ze-radar nezinzwa. Izakhiwo zazo ezizifanayo ziwavumela ukuthi abe mancane ngosayizi ngenkathi egcina impendulo enhle kakhulu ye-electromagnetic. Lokhu kubumbana kunenzuzo ikakhulukazi ezinhlelweni ezibambezeleke emkhathini, njengamadivayisi eselula, amathegi e-RFID, namasistimu omkhathi.
Ukusetshenziswa kwama-antenna ama-fractal nama-metasurfaces kunamandla okuthuthukisa kakhulu ukuxhumana okungenantambo, ukuthwebula izithombe, namasistimu e-radar, njengoba kunika amandla amadivayisi ahlangene, asebenza kahle kakhulu ngokusebenza okuthuthukisiwe. Ngaphezu kwalokho, i-fractal geometry iya ngokuya isetshenziswa ekwakhiweni kwezinzwa ze-microwave zokuhlola izinto ezibonakalayo, ngenxa yekhono layo lokusebenza kumabhendi amafrikhwensi amaningi kanye nekhono layo lokwenza i-miniaturized. Ucwaningo oluqhubekayo kulezi zindawo luyaqhubeka nokuhlola imiklamo emisha, izinto zokwakha, namasu okwenziwa ukuze kufezeke amandla azo aphelele.
Leli phepha lihlose ukubuyekeza ucwaningo nenqubekelaphambili yokusetshenziswa kwezimpondo ze-fractal kanye ne-metasurfaces futhi kuqhathanise izimpondo ezikhona ezisuselwe ku-fractal nama-metasurface, kugqamisa izinzuzo nemikhawulo yazo. Okokugcina, kwethulwa ukuhlaziya okuphelele kwama-reflectory amasha namayunithi e-metamaterial, futhi kuxoxiswana ngezinselele nentuthuko yesikhathi esizayo yalezi zakhiwo zikazibuthe.
2. I-FractalI-AntennaIzinto
Umqondo ojwayelekile wama-fractals ungasetshenziswa ukuklama izici ze-antenna ezinikeza ukusebenza okungcono kunezimpondo ezivamile. Ama-elementi e-antenna e-Fractal angase ahlanganiswe ngosayizi futhi abe nekhono le-multi-band kanye/noma le-broadband.
Idizayini yezimpondo ze-fractal ihlanganisa ukuphinda amaphethini athile ejometri ezikalini ezihlukene ngaphakathi kwesakhiwo sezimpondo. Le phethini ezifuze yona isivumela ukuthi sikhulise ubude bonke be-antenna ngaphakathi kwesikhala esilinganiselwe somzimba. Ngaphezu kwalokho, ama-radiator angama-fractal angafinyelela amabhande amaningi ngoba izingxenye ezihlukene ze-antenna ziyefana komunye nomunye ezikalini ezihlukene. Ngakho-ke, izakhi ze-antenna ze-fractal zingaba zihlangene futhi zibe ne-multi-band, zinikeze ukumbozwa kwefrikhwensi ebanzi kunezimpondo ezivamile.
Umqondo wama-antenna ama-fractal ungalandelelwa emuva ngasekupheleni kwawo-1980. Ngo-1986, uKim noJaggard bakhombise ukusetshenziswa kokufana kwe-fractal ku-antenna array synthesis.
Ngo-1988, isazi sefiziksi uNathan Cohen wakha i-antenna yokuqala yomhlaba eyi-fractal element. Uhlongoze ukuthi ngokuhlanganisa i-geometry efana nayo esakhiweni se-antenna, ukusebenza kwayo kanye nekhono le-miniaturization kungathuthukiswa. Ngo-1995, u-Cohen wasungula ngokuhlanganyela i-Fractal Antenna Systems Inc., eyaqala ukuhlinzeka ngezisombululo zokuqala zomhlaba ezisekelwe ku-fractal-based antenna.
Maphakathi nawo-1990, uPuente et al. ibonise amandla amabhendi amaningi ama-fractals kusetshenziswa i-monopole ne-dipole ye-Sierpinski.
Kusukela emsebenzini ka-Cohen no-Puente, izinzuzo ezingokwemvelo zama-antenna e-fractal zihehe isasasa elikhulu kubacwaningi nonjiniyela emkhakheni wezokuxhumana, okuholela ekuhloleni okuqhubekayo nasekuthuthukisweni kobuchwepheshe be-antenna ye-fractal.
Namuhla, ama-antenna ama-fractal asetshenziswa kakhulu ezinhlelweni zokuxhumana ezingenantambo, okuhlanganisa omakhalekhukhwini, amarutha e-Wi-Fi, nokuxhumana ngesathelayithi. Eqinisweni, ama-antenna ama-fractal mancane, anamabhande amaningi, futhi asebenza kahle kakhulu, okuwenza afanelekele izinhlobonhlobo zamadivayisi angenawaya namanethiwekhi.
Izibalo ezilandelayo zibonisa ama-antenna angama-fractal asekelwe kumomo owaziwayo we-fractal, okuyizibonelo ezimbalwa zokucushwa okuhlukahlukene okuxoxwe ngakho ezincwadini.
Ngokucacile, Umfanekiso 2a ubonisa i-Sierpinski monopole ehlongozwayo e-Puente, ekwazi ukuhlinzeka ngokusebenza kwamaqembu amaningi. Unxantathu we-Sierpinski wakhiwa ngokukhipha unxantathu ohlanekezelwe omaphakathi kunxantathu omkhulu, njengoba kukhonjisiwe kuMfanekiso 1b kanye noMfanekiso 2a. Le nqubo ishiya onxantathu abalinganayo esakhiweni, ngamunye unobude obuyingxenye obuyingxenye kanxantathu wokuqala (bheka uMdwebo 1b). Inqubo efanayo yokukhipha ingaphinda konxantathu abasele. Ngakho-ke, ingxenye ngayinye yazo ezintathu eziyinhloko ilingana ncamashi nento yonke, kodwa ngesilinganiso esiphindwe kabili, njalonjalo. Ngenxa yalokhu kufana okukhethekile, i-Sierpinski ingahlinzeka ngamabhendi efrikhwensi amaningi ngoba izingxenye ezihlukene ze-antenna ziyafana ezikalini ezihlukene. Njengoba kuboniswe kuMfanekiso 2, i-Sierpinski monopole ehlongozwayo isebenza ngamabhendi angu-5. Kungabonakala ukuthi i-sub-gaskets ngayinye emihlanu (izakhiwo zomjikelezo) ku-Figure 2a inguqulo enezilinganiso zesakhiwo sonke, ngaleyo ndlela ihlinzeka ngamabhande amahlanu ahlukene wokusebenza, njengoba kuboniswe ku-coefficient yokubonisa okokufaka ku-Figure 2b. Isibalo siphinde sibonisa amapharamitha ahlobene nebhendi yefrikhwensi ngayinye, okuhlanganisa inani lemvamisa elingu-fn (1 ≤ n ≤ 5) enanini elincane lokulahlekelwa kokubuyisela okokufaka okulinganisiwe (Lr), umkhawulokudonsa ohlobene (Bwidth), kanye nesilinganiso semvamisa phakathi amabhendi amabili aseduze (δ = fn +1/fn). Umfanekiso 2b ubonisa ukuthi amabhendi we-Sierpinski monopoles ahlukaniswa nge-logarithm ngezikhathi nge-factory engu-2 (δ ≅ 2), ehambisana nesici sokukala esifanayo esikhona ezakhiweni ezifanayo ezinomumo we-fractal.
umfanekiso 2
Umfanekiso 3a ubonisa uthi oluncane lwentambo ende olusekelwe ejikeni le-Koch fractal. Le antenna ihlongozwa ukukhombisa ukuthi ungasebenzisa kanjani izakhiwo zokugcwalisa isikhala zomumo we-fractal ukuklama izimpondo ezincane. Eqinisweni, ukunciphisa usayizi wezimpondo kuwumgomo omkhulu wenani elikhulu lezinhlelo zokusebenza, ikakhulukazi lezo ezibandakanya amatheminali eselula. I-Koch monopole idalwe kusetshenziswa indlela yokwakha i-fractal eboniswe kuMfanekiso 3a. I-iteration yokuqala K0 iyi-monopole eqondile. Ukuphindaphinda okulandelayo kwe-K1 kutholwa ngokusebenzisa ukuguqulwa kokufana ku-K0, okuhlanganisa ukukala ngengxenye eyodwa kwezintathu nokuzungezisa ngo-0°, 60°, −60°, no-0°, ngokulandelana. Le nqubo iphindaphindiwe ngokuphindaphindiwe ukuze kutholwe izakhi ezilandelayo Ki (2 ≤ i ≤ 5). Umfanekiso 3a ubonisa inguqulo ephindwe kahlanu ye-Koch monopole (okungukuthi, i-K5) enobude obulingana no-6 cm, kodwa ubude obuphelele bunikezwa ifomula l = h · (4/3) 5 = 25.3 cm. Izimpondo ezinhlanu ezihambisana neziphindaphindo ezinhlanu zokuqala zejika le-Koch ziye zabonwa (bona Umfanekiso 3a). Kokubili ukuhlolwa nedatha kubonisa ukuthi i-Koch fractal monopole ingathuthukisa ukusebenza kwe-monopole yendabuko (bheka Umfanekiso 3b). Lokhu kuphakamisa ukuthi kungase kwenzeke "ukwenza kube ncane" izimpondo ze-fractal, zivumeleke ukuthi zilingane kumavolumu amancane kuyilapho kugcinwa ukusebenza kahle.
umfanekiso 3
Umfanekiso 4a ubonisa i-antenna ephukile esekelwe kusethi ye-Cantor, esetshenziselwa ukuklama i-wideband antenna yezinhlelo zokusebenza zokuvuna amandla. Impahla eyingqayizivele yezimpondo ze-fractal ezethula ama-resonance amaningi asondelene iyaxhashazwa ukuze kuhlinzekwe umkhawulokudonsa obanzi kunezimpondo ezivamile. Njengoba kuboniswe ku-Figure 1a, ukuklanywa kwesethi ye-Cantor fractal kulula kakhulu: umugqa oqondile wokuqala ukopishwa futhi uhlukaniswe izingxenye ezintathu ezilinganayo, lapho ingxenye ephakathi isuswa khona; inqubo efanayo bese isetshenziswa ngokuphindaphindiwe kumasegimenti asanda kukhiqizwa. Izinyathelo ze-fractal iteration ziyaphindwa kuze kufinyelelwe umkhawulokudonsa we-antenna (BW) we-0.8–2.2 GHz (okungukuthi, 98% BW). Umfanekiso wesi-4 ubonisa isithombe se-antenna prototype (Umfanekiso 4a) kanye ne-coefficient yaso yokubonisa okokufaka (Umfanekiso 4b).
umfanekiso 4
Umfanekiso wesi-5 unikeza izibonelo eziningi zezimpondo ze-fractal, okuhlanganisa i-monopole antenna esekelwe ku-Hilbert curve, i-microstrip patch antenna esekelwe e-Mandelbrot, kanye nesiqephu se-Koch island (noma "i-snowflake").
umfanekiso 5
Okokugcina, Umfanekiso wesi-6 ubonisa ukuhlelwa okuhlukile kwe-fractal kwezakhi ze-array, okuhlanganisa i-Sierpinski carpet planar arrays, i-Cantor ring array, i-Cantor linear array, nezihlahla eziqhekekile. Lawa malungiselelo awusizo ekukhiqizeni amalungu afanayo amancane kanye/noma ukuzuza ukusebenza kwamabhendi amaningi.
umfanekiso 6
Ukuze ufunde kabanzi ngama-antenna, sicela uvakashele:
Isikhathi sokuthumela: Jul-26-2024
