I. Intshayelelo
Iifractal zizinto zezibalo ezibonisa iimpawu ezifanayo kwizikali ezahlukeneyo. Oku kuthetha ukuba xa usondeza/ukhupha kwimilo yefractal, inxalenye nganye yayo ifana kakhulu nayo yonke; oko kukuthi, iipateni zejometri ezifanayo okanye izakhiwo ziphinda-phinda kumanqanaba ahlukeneyo okukhulisa (jonga imizekelo yefractal kuMfanekiso 1). Uninzi lweefractal lunemilo entsonkothileyo, eneenkcukacha, neyinkimbinkimbi ngokungenasiphelo.
umfanekiso 1
Ingcamango yama-fractals yaziswa yingcali yezibalo uBenoit B. Mandelbrot ngeminyaka yoo-1970, nangona imvelaphi ye-fractal geometry inokulandelwa emva kumsebenzi wangaphambili weengcali ezininzi zezibalo, ezifana noCantor (1870), von Koch (1904), Sierpinski (1915), Julia (1918), Fatou (1926), kunye noRichardson (1953).
UBenoit B. Mandelbrot wafunda ubudlelwane phakathi kwama-fractal kunye nendalo ngokwazisa iintlobo ezintsha zama-fractal ukuze afane nezakhiwo ezintsonkothileyo, ezifana nemithi, iintaba, kunye nonxweme. Waqamba igama elithi "fractal" elivela kwisichazi sesiLatini esithi "fractus", esithetha "ukuqhekeka" okanye "ukuqhekeka", oko kukuthi, esenziwe ngamaqhekeza aphukileyo okanye angalinganiyo, ukuchaza iimilo zejiyometri ezingaqhelekanga neziqhekekileyo ezingenakuhlelwa ngokwe-geometry yendabuko ye-Euclidean. Ukongeza, waphuhlisa iimodeli zezibalo kunye ne-algorithms zokuvelisa nokufunda ama-fractal, nto leyo eyakhokelela ekudalweni kweseti edumileyo ye-Mandelbrot, mhlawumbi yeyona milo ye-fractal idumileyo nenomtsalane eneepateni ezintsonkothileyo neziphindaphindayo ngokungapheliyo (jonga uMfanekiso 1d).
Umsebenzi kaMandelbrot awuzange ube nefuthe kuphela kwizibalo, kodwa ukwanokusetyenziswa kwiindawo ezahlukeneyo ezifana nefiziksi, imizobo yekhompyutha, ibhayoloji, ezoqoqosho, kunye nobugcisa. Enyanisweni, ngenxa yokukwazi kwawo ukwenza imodeli nokumela izakhiwo ezintsonkothileyo nezifanayo, iifractals zinezicelo ezininzi ezintsha kwiindawo ezahlukeneyo. Umzekelo, zisetyenziswe kakhulu kwiindawo ezilandelayo zokusetyenziswa, eziyimizekelo embalwa yokusetyenziswa kwazo ngokubanzi:
1. Imizobo yekhompyutha kunye noopopayi, okuvelisa iindawo zemvelo ezinomtsalane nezibonakalayo, imithi, amafu, kunye nobume;
2. Itekhnoloji yokucinezela idatha ukunciphisa ubungakanani beefayile zedijithali;
3. Ukucubungula imifanekiso kunye nemiqondiso, ukukhupha iimpawu kwimifanekiso, ukubona iipatheni, kunye nokubonelela ngeendlela ezisebenzayo zokucinezela kunye nokwakha ngokutsha imifanekiso;
4. Ibhayoloji, echaza ukukhula kwezityalo kunye nokulungelelaniswa kwee-neurons engqondweni;
5. Ithiyori ye-antenna kunye neemetaterials, ukuyila ii-antenna ezincinci/ezineebhendi ezininzi kunye neemetasurfaces ezintsha.
Okwangoku, i-fractal geometry iyaqhubeka nokufumana iindlela ezintsha nezintsha zokusetyenziswa kwiinkalo ezahlukeneyo zesayensi, zobugcisa kunye netekhnoloji.
Kwiteknoloji ye-electromagnetic (EM), iimilo ze-fractal ziluncedo kakhulu kwizicelo ezifuna i-miniaturization, ukusuka kwi-antenna ukuya kwi-metamaterials kunye ne-frequency selective surfaces (FSS). Ukusebenzisa i-fractal geometry kwi-antennas eziqhelekileyo kunokunyusa ubude bazo bombane, ngaloo ndlela kunciphisa ubungakanani besakhiwo se-resonant. Ukongeza, ubume obufanayo beemilo ze-fractal buzenza zilungele ukufezekisa izakhiwo ze-resonant ze-multi-band okanye ze-broadband. Amandla e-miniaturization angaphakathi e-fractals anomtsalane ngokukodwa ekuyileni ii-reflectarrays, ii-antennas ze-array eziphased, ii-metamaterial absorbers kunye ne-metasurfaces kwizicelo ezahlukeneyo. Enyanisweni, ukusebenzisa izinto ezincinci kakhulu ze-array kunokuzisa iingenelo ezininzi, ezinje ngokunciphisa i-mutual coupling okanye ukukwazi ukusebenza nee-arrays ezinesithuba esincinci kakhulu sezinto, ngaloo ndlela kuqinisekisa ukusebenza kakuhle kwe-scanning kunye namanqanaba aphezulu ozinzo lwe-angular.
Ngenxa yezizathu ezikhankanyiweyo apha ngasentla, ii-antenna ze-fractal kunye ne-metasurfaces zimele iindawo ezimbini ezinomdla zophando kwicandelo le-electromagnetics eziye zatsala ingqalelo enkulu kwiminyaka yakutshanje. Zombini ezi ngcamango zibonelela ngeendlela ezizodwa zokulawula amaza e-electromagnetic, kunye noluhlu olubanzi lwezicelo kunxibelelwano olungenazingcingo, iinkqubo ze-radar kunye nokuva. Iimpawu zazo ezifanayo zivumela ukuba zibe ncinci ngobukhulu ngelixa zigcina impendulo egqwesileyo ye-electromagnetic. Olu xinana luluncedo ngakumbi kwizicelo ezixinzelelweyo, njengezixhobo eziphathwayo, iithegi ze-RFID, kunye neenkqubo ze-aerospace.
Ukusetyenziswa kwee-antenna ze-fractal kunye nee-metasurfaces kunamandla okuphucula kakhulu unxibelelwano olungenazingcingo, imifanekiso, kunye neenkqubo ze-radar, njengoko zivumela izixhobo ezincinci nezisebenza kakuhle ezinemisebenzi ephuculweyo. Ukongeza, i-fractal geometry isetyenziswa ngakumbi kuyilo lwee-microwave sensors zokuxilongwa kwezinto, ngenxa yamandla ayo okusebenza kwiibhendi ezininzi ze-frequency kunye nokukwazi kwayo ukwenziwa ibe yi-miniaturized. Uphando oluqhubekayo kwezi ndawo luyaqhubeka nokuphonononga uyilo olutsha, izixhobo, kunye neendlela zokwenza ukuze kufezekiswe amandla azo apheleleyo.
Eli phepha lijolise ekuphononongeni inkqubela phambili yophando kunye nokusetyenziswa kwee-antenna ze-fractal kunye nee-metasurfaces kunye nokuthelekisa ii-antenna kunye nee-metasurfaces ezikhoyo ezisekelwe kwi-fractal, ziqaqambisa iingenelo kunye nemida yazo. Okokugqibela, kuchazwe uhlalutyo olupheleleyo lwee-reflectarrays ezintsha kunye neeyunithi ze-metamaterial, kwaye kuxoxwa ngemingeni kunye nophuhliso lwexesha elizayo lwezi zakhiwo ze-electromagnetic.
2. I-FractalI-antennaIzinto
Ingcamango ngokubanzi yeefractals ingasetyenziselwa ukuyila izinto ze-antenna ezingaqhelekanga ezibonelela ngokusebenza okungcono kunee-antenna eziqhelekileyo. Izinto ze-antenna zefractal zinokuba zincinci ngobukhulu kwaye zibe nezakhono ze-multi-band kunye/okanye ze-broadband.
Uyilo lwee-antenna ze-fractal lubandakanya ukuphinda iipateni ezithile zejiyometri kwizikali ezahlukeneyo ngaphakathi kwesakhiwo se-antenna. Le pateni ifanayo isenza sikwazi ukwandisa ubude be-antenna ngaphakathi kwendawo encinci ebonakalayo. Ukongeza, ii-radiator ze-fractal zinokufikelela kwiibhendi ezininzi kuba iindawo ezahlukeneyo ze-antenna ziyafana kwizikali ezahlukeneyo. Ke ngoko, izinto ze-antenna ze-fractal zinokuba zincinci kwaye zibe neebhendi ezininzi, zibonelela ngokugubungela i-frequency ebanzi kunee-antenna eziqhelekileyo.
Ingcamango yee-antenna ze-fractal ingalandelwa emva ekupheleni kweminyaka yoo-1980. Ngo-1986, uKim noJaggard babonisa ukusetyenziswa kokufana kwe-fractal kwi-antenna array synthesis.
Ngo-1988, isazinzulu sefiziksi uNathan Cohen wakha i-antenna yokuqala yehlabathi ye-fractal element. Wacebisa ukuba ngokufaka i-geometry efanayo kwisakhiwo se-antenna, ukusebenza kwayo kunye nokukwazi kwayo ukwenza izinto zibe lula kunokuphuculwa. Ngo-1995, uCohen waseka i-Fractal Antenna Systems Inc., eyaqala ukubonelela ngezisombululo ze-antenna zokuqala zehlabathi ezisekelwe kwi-fractal zorhwebo.
Phakathi kwiminyaka yoo-1990, uPuente nabanye babonise amandla ee-fractals ezininzi besebenzisa i-monopole kunye ne-dipole kaSierpinski.
Ukususela kumsebenzi kaCohen noPuente, iingenelo ze-fractal antennas zitsale umdla omkhulu kubaphandi kunye neenjineli kwicandelo lezonxibelelwano, nto leyo ekhokelela ekuphononongweni ngakumbi nasekuphuhlisweni kwetekhnoloji ye-fractal antenna.
Namhlanje, ii-antenna ze-fractal zisetyenziswa kakhulu kwiinkqubo zonxibelelwano ezingenazingcingo, kuquka iifowuni eziphathwayo, ii-Wi-Fi routers, kunye nonxibelelwano lwesathelayithi. Enyanisweni, ii-antenna ze-fractal zincinci, zinebhendi ezininzi, kwaye zisebenza kakuhle kakhulu, nto leyo eyenza ukuba zifaneleke kwiindidi ezahlukeneyo zezixhobo ezingenazingcingo kunye neenethiwekhi.
Le mifanekiso ilandelayo ibonisa ezinye ii-antenna ze-fractal ezisekelwe kwiimilo ze-fractal ezaziwayo, eziyimizekelo embalwa yeendlela ezahlukeneyo ezixutyushwa ngazo kwiincwadi.
Ngokukodwa, uMfanekiso 2a ubonisa i-monopole kaSierpinski ecetywayo ePuente, ekwaziyo ukubonelela ngokusebenza kweebhendi ezininzi. Unxantathu kaSierpinski wenziwa ngokususa unxantathu ongaphakathi oguqulweyo kunxantathu oyintloko, njengoko kubonisiwe kuMfanekiso 1b nakuMfanekiso 2a. Le nkqubo ishiya oonxantathu abathathu abalinganayo kwisakhiwo, ngamnye enobude obusecaleni obuyisiqingatha sonxantathu oqalayo (jonga uMfanekiso 1b). Inkqubo efanayo yokukhupha inokuphindwa kwiinxantathu ezisele. Ke ngoko, inxalenye nganye kwezithathu eziphambili ilingana ncakasana nento yonke, kodwa ngokuphindwe kabini ngomlinganiselo, njalo njalo. Ngenxa yezi zinto zifanayo, iSierpinski inokubonelela ngeebhendi ezininzi zefrikhwensi kuba iindawo ezahlukeneyo ze-antenna ziyafana kwiikali ezahlukeneyo. Njengoko kubonisiwe kuMfanekiso 2, i-monopole kaSierpinski ecetywayo isebenza kwiibhendi ezi-5. Kuyabonakala ukuba nganye kwii-sub-gaskets ezintlanu (izakhiwo zesangqa) kuMfanekiso 2a yinguqulelo elinganisiweyo yesakhiwo sonke, ngaloo ndlela ibonelela ngeebhendi ezintlanu ezahlukeneyo zefrikhwensi yokusebenza, njengoko kubonisiwe kwi-coefficient yokubonakalisa okungenayo kuMfanekiso 2b. Lo mfanekiso ukwabonisa iiparameter ezinxulumene nebhendi nganye yefrikhwensi, kubandakanya ixabiso lefrikhwensi fn (1 ≤ n ≤ 5) kwixabiso elincinci lelahleko yokubuyisela okulinganisiweyo (Lr), i-bandwidth ehambelanayo (Bwidth), kunye nomlinganiselo wefrikhwensi phakathi kweebhendi ezimbini zefrikhwensi ezikufutshane (δ = fn +1/fn). Umfanekiso 2b ubonisa ukuba iibhendi ze-monopoles zeSierpinski zibekwe ngokwe-logarithmically ngamaxesha athile yi-factor ye-2 (δ ≅ 2), ehambelana ne-scaling factor efanayo ekhoyo kwizakhiwo ezifanayo kwimo ye-fractal.
umfanekiso 2
Umfanekiso 3a ubonisa i-antenna encinci ende esekwe kwi-Koch fractal curve. Le antenna icetywayo ukubonisa indlela yokusebenzisa iipropati zokuzalisa isithuba seemilo ze-fractal ukuyila ii-antenna ezincinci. Enyanisweni, ukunciphisa ubungakanani bee-antenna yeyona njongo iphambili yenani elikhulu lezicelo, ingakumbi ezo zibandakanya ii-terminals ezihambayo. I-Koch monopole yenziwe kusetyenziswa indlela yokwakha i-fractal eboniswe kuMfanekiso 3a. Ukuphindaphinda kokuqala i-K0 yi-monopole ethe tye. Ukuphindaphinda okulandelayo i-K1 kufunyanwa ngokusebenzisa utshintsho lokufana kwi-K0, kubandakanya ukulinganisa ngesinye kwisithathu kunye nokujikeleza nge-0°, 60°, −60°, kunye ne-0°, ngokulandelelana. Le nkqubo iphindaphindwa ngokuphindaphindiweyo ukuze kufunyanwe izinto ezilandelayo i-Ki (2 ≤ i ≤ 5). Umfanekiso 3a ubonisa inguqulelo ye-Koch monopole ephindaphindwayo kahlanu (oko kukuthi, i-K5) enokuphakama kwe-h okulingana ne-6 cm, kodwa ubude bubonke bunikwe yifomula l = h ·(4/3) 5 = 25.3 cm. Ii-antenna ezintlanu ezihambelana nokuphindaphinda okuhlanu kokuqala kwe-Koch curve ziye zaphunyezwa (jonga uMfanekiso 3a). Zombini iimvavanyo kunye nedatha zibonisa ukuba i-monopole ye-fractal ye-Koch inokuphucula ukusebenza kwe-monopole yendabuko (jonga uMfanekiso 3b). Oku kuthetha ukuba kunokwenzeka "ukuzinciphisa" ii-antenna ze-fractal, ezivumela ukuba zingene kwiivolumu ezincinci ngelixa zigcina ukusebenza okusebenzayo.
umfanekiso 3
Umfanekiso 4a ubonisa i-antenna ye-fractal esekelwe kwiseti yeCantor, esetyenziselwa ukuyila i-antenna ye-wideband yokusetyenziswa kokuvuna amandla. Ipropati ekhethekileyo yee-antenna ze-fractal ezizisa ii-resonances ezininzi ezikufutshane isetyenziswa ukubonelela nge-bandwidth ebanzi kunee-antenna eziqhelekileyo. Njengoko kubonisiwe kuMfanekiso 1a, uyilo lweseti ye-fractal yeCantor lulula kakhulu: umgca wokuqala othe tye uyakopishwa kwaye wahlulwe ube ngamacandelo amathathu alinganayo, apho icandelo eliphakathi lisuswa khona; inkqubo efanayo emva koko isetyenziswa ngokuphindaphindiweyo kumacandelo asandul’ ukuveliswa. Amanyathelo okuphindaphinda kwe-fractal aphindaphindwa de kufikelelwe kwi-bandwidth ye-antenna (BW) ye-0.8–2.2 GHz (oko kukuthi, i-98% BW). Umfanekiso 4 ubonisa ifoto ye-prototype ye-antenna eqatshelweyo (Umfanekiso 4a) kunye ne-input reflection coefficient yayo (Umfanekiso 4b).
umfanekiso 4
Umfanekiso 5 unika eminye imizekelo yee-antenna ze-fractal, kuquka i-antenna ye-monopole ye-Hilbert curve-based, i-antenna ye-microstrip patch ye-Mandelbrot, kunye ne-fractal patch yesiqithi saseKoch (okanye "i-snowflake").
umfanekiso 5
Okokugqibela, uMfanekiso 6 ubonisa ulungelelwaniso olwahlukeneyo lwe-fractal lwezinto ze-array, kuquka i-Sierpinski carpet planar arrays, i-Cantor ring arrays, i-Cantor linear arrays, kunye ne-fractal trees. Olu lungelelwaniso luluncedo ekuveliseni i-sparse arrays kunye/okanye ekufezekiseni ukusebenza kwe-multi-band.
umfanekiso 6
Ukuze ufunde okungakumbi ngee-antenna, nceda undwendwele:
Ixesha leposi: Julayi-26-2024
