I. Chiyambi
Ma Fractal ndi zinthu zamasamu zomwe zimawonetsa makhalidwe ofanana pa sikelo zosiyanasiyana. Izi zikutanthauza kuti mukakulitsa/kutulutsa mawonekedwe a fractal, gawo lililonse limawoneka lofanana kwambiri ndi lonselo; ndiko kuti, mapangidwe ofanana a geometric kapena kapangidwe kamabwerezabwereza pamlingo wosiyanasiyana wa kukula (onani zitsanzo za fractal mu Chithunzi 1). Ma Fractal ambiri ali ndi mawonekedwe ovuta, ofotokoza, komanso ovuta kwambiri.
chithunzi 1
Lingaliro la ma fractal linayambitsidwa ndi katswiri wa masamu Benoit B. Mandelbrot m'zaka za m'ma 1970, ngakhale kuti chiyambi cha fractal geometry chimachokera ku ntchito yoyambirira ya akatswiri ambiri a masamu, monga Cantor (1870), von Koch (1904), Sierpinski (1915), Julia (1918), Fatou (1926), ndi Richardson (1953).
Benoit B. Mandelbrot anaphunzira ubale womwe ulipo pakati pa ma fractal ndi chilengedwe mwa kuyambitsa mitundu yatsopano ya ma fractal kuti ayerekezere mapangidwe ovuta kwambiri, monga mitengo, mapiri, ndi madera a m'mphepete mwa nyanja. Iye anayambitsa mawu akuti "fractal" kuchokera ku mawu achilatini akuti "fractus", kutanthauza "wosweka" kapena "wosweka", mwachitsanzo wopangidwa ndi zidutswa zosweka kapena zosakhazikika, pofotokoza mawonekedwe osakhazikika komanso osweka omwe sangagawidwe m'magulu malinga ndi geometry yachikhalidwe ya Euclidean. Kuphatikiza apo, adapanga zitsanzo zamasamu ndi ma algorithms opangira ndi kuphunzira ma fractal, zomwe zidapangitsa kuti pakhale gulu lodziwika bwino la Mandelbrot, lomwe mwina ndi mawonekedwe otchuka komanso osangalatsa a fractal okhala ndi mapangidwe ovuta komanso obwerezabwereza (onani Chithunzi 1d).
Ntchito ya Mandelbrot sinangokhudza masamu okha, komanso yakhala ndi ntchito m'magawo osiyanasiyana monga fizikisi, zithunzi zamakompyuta, zamoyo, zachuma, ndi zaluso. Ndipotu, chifukwa cha luso lawo lotha kupanga ndi kuyimira kapangidwe kovuta komanso kofanana, ma fractal ali ndi ntchito zambiri zatsopano m'magawo osiyanasiyana. Mwachitsanzo, agwiritsidwa ntchito kwambiri m'magawo otsatirawa ogwiritsira ntchito, omwe ndi zitsanzo zochepa chabe za momwe amagwiritsidwira ntchito kwambiri:
1. Zithunzi zamakompyuta ndi makanema ojambula, kupanga malo achilengedwe okongola komanso okongola;
2. Ukadaulo wochepetsera deta kuti uchepetse kukula kwa mafayilo a digito;
3. Kukonza zithunzi ndi zizindikiro, kuchotsa zinthu kuchokera ku zithunzi, kuzindikira mapangidwe, ndikupereka njira zogwirira ntchito zochepetsera ndi kukonzanso zithunzi;
4. Biology, kufotokoza kukula kwa zomera ndi kapangidwe ka ma neuron muubongo;
5. Chiphunzitso cha ma antenna ndi ma metamaterials, kupanga ma antenna ang'onoang'ono/ambiri komanso ma metasurfaces atsopano.
Pakadali pano, fractal geometry ikupitilizabe kupeza ntchito zatsopano komanso zatsopano m'magawo osiyanasiyana asayansi, zaluso komanso ukadaulo.
Mu ukadaulo wamagetsi (EM), mawonekedwe a fractal ndi othandiza kwambiri pa ntchito zomwe zimafuna miniaturization, kuyambira ma antenna mpaka ma metamaterials ndi malo osankha pafupipafupi (FSS). Kugwiritsa ntchito fractal geometry mu ma antenna achikhalidwe kumatha kuwonjezera kutalika kwawo kwamagetsi, motero kuchepetsa kukula konse kwa kapangidwe ka resonant. Kuphatikiza apo, mawonekedwe ofanana a fractal amawapangitsa kukhala abwino kwambiri pakukwaniritsa mapangidwe a multi-band kapena broadband resonant. Mphamvu ya miniaturization ya ma fractal ndi yokongola kwambiri popanga ma reflectarrays, ma phased array antennas, ma metamaterial absorbers ndi ma metasurfaces pazinthu zosiyanasiyana. Ndipotu, kugwiritsa ntchito zinthu zazing'ono kwambiri za array kumatha kubweretsa zabwino zingapo, monga kuchepetsa kulumikizana kwa mutual kapena kutha kugwira ntchito ndi ma arrays okhala ndi malo ochepa kwambiri a element, motero kuonetsetsa kuti magwiridwe antchito abwino a scanning ndi milingo yapamwamba ya angular stability.
Pazifukwa zomwe tatchula pamwambapa, ma antenna a fractal ndi ma metasurfaces akuyimira madera awiri ofufuza osangalatsa pankhani ya ma electromagnetic omwe akope chidwi chachikulu m'zaka zaposachedwa. Malingaliro onsewa amapereka njira zapadera zoyendetsera ndikuwongolera mafunde a electromagnetic, ndi ntchito zosiyanasiyana mu kulumikizana opanda zingwe, machitidwe a radar ndi kuzindikira. Kapangidwe kawo kofanana kamawalola kuti akhale ang'onoang'ono kukula pomwe akusunga mayankho abwino kwambiri a electromagnetic. Kuphatikizika kumeneku ndikopindulitsa makamaka pakugwiritsa ntchito malo ochepa, monga zida zam'manja, ma RFID tag, ndi machitidwe amlengalenga.
Kugwiritsa ntchito ma antenna a fractal ndi metasurfaces kuli ndi kuthekera kokweza kwambiri kulumikizana kwa opanda zingwe, kujambula zithunzi, ndi makina a radar, chifukwa zimathandiza zida zazing'ono komanso zogwira ntchito bwino komanso magwiridwe antchito abwino. Kuphatikiza apo, fractal geometry ikugwiritsidwa ntchito kwambiri popanga masensa a microwave kuti azindikire zinthu, chifukwa cha kuthekera kwake kugwira ntchito m'ma frequency band angapo komanso kuthekera kwake kocheperako. Kafukufuku wopitilira m'magawo awa akupitiliza kufufuza mapangidwe atsopano, zipangizo, ndi njira zopangira kuti akwaniritse kuthekera kwawo konse.
Cholinga cha pepalali ndikuwunikanso momwe ma antenna a fractal ndi ma metasurfaces amagwirira ntchito komanso kuyerekeza ma antenna ndi ma metasurfaces omwe alipo kale, kuwonetsa zabwino ndi zofooka zawo. Pomaliza, kusanthula kwathunthu kwa ma reflectarrays atsopano ndi ma metamaterial units kwaperekedwa, ndipo zovuta ndi chitukuko chamtsogolo cha ma electromagnetic structures awa zikukambidwa.
2. FractalAntenaZinthu
Lingaliro lalikulu la ma fractal lingagwiritsidwe ntchito popanga zinthu za antenna zachilendo zomwe zimapereka magwiridwe antchito abwino kuposa ma antenna wamba. Zinthu za antenna za Fractal zitha kukhala zazing'ono kukula kwake ndipo zimakhala ndi mphamvu ya multi-band ndi/kapena broadband.
Kapangidwe ka ma antenna a fractal kumaphatikizapo kubwereza mapangidwe enaake a geometric pa sikelo zosiyanasiyana mkati mwa kapangidwe ka antenna. Kapangidwe kofanana aka kamatithandiza kuwonjezera kutalika konse kwa antenna mkati mwa malo ochepa. Kuphatikiza apo, ma radiator a fractal amatha kukhala ndi magulu angapo chifukwa magawo osiyanasiyana a antenna ndi ofanana pa sikelo zosiyanasiyana. Chifukwa chake, zinthu za antenna za fractal zitha kukhala zazing'ono komanso zambiri, zomwe zimapereka kufalikira kwakukulu kuposa ma antenna wamba.
Lingaliro la ma antenna a fractal likhoza kutsatiridwa mpaka kumapeto kwa zaka za m'ma 1980. Mu 1986, Kim ndi Jaggard adawonetsa kugwiritsa ntchito kufanana kwa fractal mu kapangidwe ka ma antenna.
Mu 1988, katswiri wa sayansi ya zamoyo Nathan Cohen adapanga antenna yoyamba padziko lonse lapansi ya fractal element. Iye adapereka lingaliro lakuti poyika geometry yofanana mu kapangidwe ka antenna, magwiridwe ake ndi mphamvu zake zazing'ono zitha kukulitsidwa. Mu 1995, Cohen adakhazikitsa Fractal Antenna Systems Inc., yomwe idayamba kupereka mayankho oyamba padziko lonse lapansi a antenna opangidwa ndi fractal.
Pakati pa zaka za m'ma 1990, Puente ndi anzake adawonetsa luso la ma fractal pogwiritsa ntchito monopole ndi dipole ya Sierpinski.
Kuyambira ntchito ya Cohen ndi Puente, ubwino wa ma antenna a fractal wakopa chidwi chachikulu kuchokera kwa ofufuza ndi mainjiniya pankhani yolumikizirana, zomwe zapangitsa kuti pakhale kufufuza ndi chitukuko cha ukadaulo wa ma antenna a fractal.
Masiku ano, ma antenna a fractal amagwiritsidwa ntchito kwambiri m'njira zolumikizirana zopanda zingwe, kuphatikizapo mafoni am'manja, ma Wi-Fi routers, ndi ma satellite communications. Ndipotu, ma antenna a fractal ndi ang'onoang'ono, okhala ndi ma multiband, komanso ogwira ntchito bwino kwambiri, zomwe zimapangitsa kuti akhale oyenera kugwiritsa ntchito zipangizo zosiyanasiyana zopanda zingwe komanso ma network.
Zithunzi zotsatirazi zikuwonetsa ma antenna ena a fractal ozikidwa pa mawonekedwe odziwika bwino a fractal, omwe ndi zitsanzo zochepa chabe za mawonekedwe osiyanasiyana omwe afotokozedwa m'mabukuwa.
Mwachindunji, Chithunzi 2a chikuwonetsa monopole ya Sierpinski yomwe ikuperekedwa ku Puente, yomwe imatha kupereka ntchito yamagulu ambiri. Katatu ka Sierpinski kamapangidwa pochotsa katatu kozungulira pakati kuchokera ku katatu kakang'ono, monga momwe zasonyezedwera pa Chithunzi 1b ndi Chithunzi 2a. Njirayi imasiya ma triangle atatu ofanana pa kapangidwe kake, kalikonse kali ndi theka la kutalika kwa katatu koyambira (onani Chithunzi 1b). Njira yochotsera yomweyi ikhoza kubwerezedwa pa ma triangle otsalawo. Chifukwa chake, gawo lililonse mwa magawo ake atatu akuluakulu ndi lofanana ndi chinthu chonsecho, koma kawiri kuchuluka kwake, ndi zina zotero. Chifukwa cha kufanana kwapadera kumeneku, Sierpinski imatha kupereka ma frequency band angapo chifukwa magawo osiyanasiyana a antenna ndi ofanana wina ndi mnzake pa sikelo zosiyanasiyana. Monga momwe zasonyezedwera pa Chithunzi 2, monopole ya Sierpinski yomwe ikuperekedwa imagwira ntchito m'mabande 5. Zitha kuwoneka kuti chilichonse mwa ma sub-gasket asanu (zomangamanga zozungulira) mu Chithunzi 2a ndi mtundu wofanana wa kapangidwe kake konse, motero imapereka ma frequency band asanu osiyanasiyana, monga momwe zasonyezedwera mu input reflection coefficient mu Chithunzi 2b. Chithunzichi chikuwonetsanso magawo okhudzana ndi gulu lililonse la ma frequency, kuphatikiza phindu la ma frequency fn (1 ≤ n ≤ 5) pamtengo wotsika kwambiri wa kutayika kobweza kolowera (Lr), bandwidth yogwirizana (Bwidth), ndi chiŵerengero cha ma frequency pakati pa magulu awiri oyandikana nawo a frequency (δ = fn +1/fn). Chithunzi 2b chikuwonetsa kuti magulu a ma monopole a Sierpinski amagawidwa nthawi ndi nthawi ndi gawo la 2 (δ ≅ 2), lomwe likugwirizana ndi chinthu chomwecho choyezera chomwe chilipo m'mapangidwe ofanana mu mawonekedwe a fractal.
chithunzi 2
Chithunzi 3a chikuwonetsa antenna yaying'ono yayitali ya waya yochokera ku curve ya Koch fractal. Antena iyi ikuperekedwa kuti iwonetse momwe mungagwiritsire ntchito mawonekedwe a fractal kuti apange ma antenna ang'onoang'ono. Ndipotu, kuchepetsa kukula kwa ma antenna ndiye cholinga chachikulu cha mapulogalamu ambiri, makamaka omwe amagwiritsa ntchito ma terminal oyenda. Monopole ya Koch imapangidwa pogwiritsa ntchito njira yomanga ya fractal yomwe yawonetsedwa mu Chithunzi 3a. Kubwereza koyamba K0 ndi monopole yolunjika. Kubwereza kotsatira K1 kumapezeka pogwiritsa ntchito kusintha kofanana ndi K0, kuphatikiza kukula ndi gawo limodzi mwa magawo atatu ndikuzungulira ndi 0°, 60°, −60°, ndi 0°, motsatana. Njirayi imabwerezedwa mobwerezabwereza kuti mupeze zinthu zotsatirazi Ki (2 ≤ i ≤ 5). Chithunzi 3a chikuwonetsa mtundu wa Koch monopole wa maulendo asanu (mwachitsanzo, K5) wokhala ndi kutalika h kofanana ndi 6 cm, koma kutalika konse kumaperekedwa ndi fomula l = h ·(4/3) 5 = 25.3 cm. Ma antenna asanu ofanana ndi ma iterations asanu oyamba a Koch curve achitika (onani Chithunzi 3a). Kuyesera konse ndi deta zikuwonetsa kuti monopole ya Koch fractal ikhoza kukonza magwiridwe antchito a monopole yachikhalidwe (onani Chithunzi 3b). Izi zikusonyeza kuti zingatheke "kuchepetsa" ma antenna a fractal, kuwalola kuti agwirizane ndi ma voliyumu ang'onoang'ono pomwe akupitiliza kugwira ntchito bwino.
chithunzi 3
Chithunzi 4a chikuwonetsa antenna ya fractal yochokera pa seti ya Cantor, yomwe imagwiritsidwa ntchito popanga antenna ya wideband yogwiritsira ntchito kukolola mphamvu. Kapangidwe kapadera ka antenna za fractal zomwe zimayambitsa ma resonances angapo oyandikana nawo amagwiritsidwa ntchito kuti apereke bandwidth yayikulu kuposa antenna wamba. Monga momwe zasonyezedwera pa Chithunzi 1a, kapangidwe ka seti ya fractal ya Cantor ndi kosavuta kwambiri: mzere wowongoka woyamba umakopedwa ndikugawidwa m'magawo atatu ofanana, pomwe gawo lapakati limachotsedwa; njira yomweyo imagwiritsidwanso ntchito mobwerezabwereza ku magawo atsopano opangidwa. Masitepe obwerezabwereza a fractal amabwerezedwa mpaka bandwidth ya antenna (BW) ya 0.8–2.2 GHz itakwaniritsidwa (mwachitsanzo, 98% BW). Chithunzi 4 chikuwonetsa chithunzi cha prototype ya antenna yodziwika bwino (Chithunzi 4a) ndi coefficient yake yowunikira (Chithunzi 4b).
chithunzi 4
Chithunzi 5 chikupereka zitsanzo zambiri za ma antenna a fractal, kuphatikizapo antenna ya Hilbert curve-based monopole, antenna ya Mandelbrot-based microstrip patch, ndi fractal patch ya Koch island (kapena "snowflake").
chithunzi 5
Pomaliza, Chithunzi 6 chikuwonetsa makonzedwe osiyanasiyana a fractal a zinthu zomangira, kuphatikiza ma arrays a Sierpinski carpet planar, ma arrays a Cantor ring, ma arrays a Cantor linear, ndi mitengo ya fractal. Makonzedwe awa ndi othandiza popanga ma arrays a sparse ndi/kapena kukwaniritsa magwiridwe antchito a multi-band.
chithunzi 6
Kuti mudziwe zambiri zokhudza ma antenna, chonde pitani ku:
Nthawi yotumizira: Julayi-26-2024
