Nhau - Ongororo yeAntena: Ongororo yeFractal Metasurfaces uye Dhizaini yeAntena

I. Nhanganyaya
Mafractal zvinhu zvemasvomhu zvinoratidza hunhu hwakafanana pazviyero zvakasiyana. Izvi zvinoreva kuti kana uchizorora/kubuda pachimiro chefractal, chikamu chimwe nechimwe chayo chinotaridzika chakafanana chose; ndiko kuti, mapatani akafanana ejometri kana maumbirwo anodzokororwa pamazinga akasiyana ekukura (ona mienzaniso yefractal muMufananidzo 1). Mafractal mazhinji ane maumbirwo akaomarara, akadzama, uye akaomarara asingaperi.

mufananidzo 1

Pfungwa yemafractals yakaunzwa nenyanzvi yemasvomhu Benoit B. Mandelbrot muma1970, kunyange hazvo mavambo efractal geometry achigona kuteverwa kumashure nebasa rekutanga renyanzvi dzakawanda dzemasvomhu, dzakadai saCantor (1870), von Koch (1904), Sierpinski (1915), Julia (1918), Fatou (1926), naRichardson (1953).
Benoit B. Mandelbrot akadzidza hukama huripo pakati pemafractal nezvisikwa nekuunza mhando itsva dzemafractal kuti dzifananidze maumbirwo akaomarara, akadai semiti, makomo, uye mahombekombe. Akagadzira izwi rekuti "fractal" kubva muchiLatin chinoreva "fractus", zvichireva kuti "yakatyoka" kana "yakatyoka", kureva kuti yakaumbwa nezvidimbu zvakatyoka kana zvisina kurongeka, kutsanangura maumbirwo ejometri asina kurongeka uye akapatsanurwa asingagone kupatsanurwa neEuclidean geometry yechinyakare. Pamusoro pezvo, akagadzira mamodheru nemaalgorithms ekugadzira nekudzidza mafractal, izvo zvakatungamira pakuumbwa kweseti yakakurumbira yeMandelbrot, iyo ingangodaro iri chimiro chefractal chakakurumbira uye chinonakidza chinoonekwa chine mapatani akaomarara uye anodzokororwa asingaperi (ona Mufananidzo 1d).
Basa raMandelbrot harina kungobatsira chete pamasvomhu, asiwo rine mashandisirwo muzvikamu zvakasiyana-siyana zvakaita sefizikisi, mifananidzo yemakombiyuta, biology, economics, uye hunyanzvi. Kutaura zvazviri, nekuda kwekugona kwavo kutevedzera uye kumiririra maumbirwo akaomarara uye akafanana, mafractal ane mashandisirwo akawanda matsva muzvikamu zvakasiyana-siyana. Semuenzaniso, akashandiswa zvakanyanya munzvimbo dzinotevera dzekushandisa, idzo dziri mienzaniso mishoma yekushandiswa kwawo kwakakura:
1. Mifananidzo yemakombiyuta uye mifananidzo yemifananidzo, zvichigadzira nzvimbo dzechisikigo dzinoyevedza uye dzinoyevedza;
2. Tekinoroji yekudzvanya data yekuderedza saizi yemafaira edhijitari;
3. Kugadzirisa mifananidzo nezviratidzo, kubvisa zvinhu kubva mumifananidzo, kuona mapatani, uye kupa nzira dzinoshanda dzekudzvanya mifananidzo uye kugadzirisa patsva;
4. Biology, inotsanangura kukura kwezvirimwa uye kurongeka kwema neuron muuropi;
5. Dzidziso yeAntena uye metamaterials, kugadzira ma antennas madiki/ma multi-band uye metasurfaces itsva.
Parizvino, fractal geometry iri kuramba ichiwana mashandisirwo matsva uye matsva muzvidzidzo zvakasiyana-siyana zvesainzi, zvehunyanzvi uye zvetekinoroji.
Mu tekinoroji yemagetsi (EM), maumbirwo efractal anobatsira zvikuru kumashandisirwo anoda miniaturization, kubva kumaantenna kusvika kumametaterials uye frequency selective surfaces (FSS). Kushandisa fractal geometry mumaantennas enguva dzose kunogona kuwedzera kureba kwawo kwemagetsi, nokudaro kuderedza saizi yese ye resonant structure. Pamusoro pezvo, hunhu hwakafanana hwema fractal shapes hunoita kuti zvive zvakanaka pakugadzira multi-band kana broadband resonant structures. Kugona kwemukati kwefractals miniaturization kunonyanya kukwezva pakugadzira reflectarrays, phased array antennas, metamaterial absorbers uye metasurfaces yemashandisirwo akasiyana-siyana. Kutaura zvazviri, kushandisa zvinhu zvidiki kwazvo zvearray kunogona kuunza mabhenefiti akati wandei, akadai sekuderedza kubatana kwekuwirirana kana kukwanisa kushanda nema arrays ane nzvimbo diki kwazvo ye element, nokudaro zvichiita kuti scanning performance yakanaka uye mazinga akakwira e angular stability.
Nezvikonzero zvataurwa pamusoro apa, ma fractal antennas uye metasurfaces zvinomiririra nzvimbo mbiri dzinonakidza dzekutsvagisa mumunda we electromagnetics dzakakwezva kutariswa kukuru mumakore achangopfuura. Pfungwa dzese dziri mbiri dzinopa nzira dzakasiyana dzekushandisa nekudzora mafungu e electromagnetic, nekushandiswa kwakasiyana-siyana mukutaurirana kwe wireless, radar systems uye sensing. Hunhu hwavo hwakafanana hunovabvumira kuva vadiki muhukuru uku vachichengetedza mhinduro yakanaka ye electromagnetic. Kubatana uku kunonyanya kubatsira mukushandiswa kwakamanikana munzvimbo, senge nharembozha, RFID tag, uye aerospace systems.
Kushandiswa kwema fractal antennas uye metasurfaces kune mukana wekuvandudza zvakanyanya kutaurirana kusina waya, mifananidzo, uye radar systems, sezvo zvichigonesa michina midiki, inoshanda zvakanyanya ine mashandiro akawedzerwa. Pamusoro pezvo, fractal geometry iri kushandiswa zvakanyanya mukugadzira ma microwave sensors ekuongorora zvinhu, nekuda kwekugona kwayo kushanda muma frequency bands akawanda uye kugona kwayo kudiki. Tsvagiridzo iri kuenderera mberi munzvimbo idzi iri kuramba ichiongorora magadzirirwo matsva, zvinhu, uye matekiniki ekugadzira kuti zvizadzise kugona kwazvo.
Chinyorwa ichi chine chinangwa chekuongorora kufambira mberi kwekutsvaga nekushandisa ma fractal antennas uye metasurfaces uye kuenzanisa ma fractal-based antennas uye metasurfaces aripo, zvichiratidza zvakanakira uye zvisingakwanisike. Pakupedzisira, kuongororwa kwakazara kwe reflectarrays itsva uye metamaterial units kunoratidzwa, uye matambudziko nekuvandudzwa kweramangwana kweaya ma electromagnetic structures zvinokurukurwa.

2. FractalKanyangaZvinhu zviri mukati
Pfungwa huru yemafractals inogona kushandiswa kugadzira zvinhu zve antenna zvinopa mashandiro ari nani pane ma antenna echinyakare. Zvinhu zve antenna zvefractal zvinogona kunge zvidiki muhukuru uye zvine hunyanzvi hwe multi-band uye/kana broadband.
Kugadzirwa kwema fractal antennas kunosanganisira kudzokorora mapatani chaiwo ejometri pamakero akasiyana mukati mechimiro che antenna. Iyi pateni yakafanana inotibvumira kuwedzera hurefu hwese hwe antenna mukati menzvimbo diki yemuviri. Pamusoro pezvo, ma fractal radiators anogona kuwana mabhendi akawanda nekuti zvikamu zvakasiyana zve antenna zvakafanana pamakero akasiyana. Nokudaro, zvinhu zve fractal antenna zvinogona kuva zvidiki uye zvakawanda, zvichipa kufukidzwa kwakakura kupfuura ma antenna akajairwa.
Pfungwa yema fractal antennas inogona kuteverwa kudzokera kumashure kusvika kuma1980. Muna 1986, Kim naJaggard vakaratidza kushandiswa kwe fractal self-similarity mukugadzirwa kwe antenna array.
Muna 1988, nyanzvi yefizikisi Nathan Cohen akagadzira antenna yekutanga pasi rose yefractal element. Akakurudzira kuti nekuisa geometry yakafanana muchimiro cheantenna, mashandiro ayo uye kugona kwayo kuita kuti zvinhu zviite zvishoma kunogona kuvandudzwa. Muna 1995, Cohen akatanga Fractal Antenna Systems Inc., iyo yakatanga kupa mhinduro dzekutanga pasi rose dzefractal-based antenna.
Pakati pemakore ekuma1990, Puente nevamwe vake vakaratidza kugona kwema "fractals" akawanda vachishandisa "monopole" na "dipole" zvaSierpinski.
Kubva pakatanga basa raCohen naPuente, mabhenefiti efractal antennas akakwezva kufarira kukuru kubva kuvaongorori nemainjiniya munyaya dzekutaurirana, zvichikonzera kutsvaga nekuvandudza tekinoroji yefractal antenna.
Nhasi uno, ma fractal antenna anoshandiswa zvakanyanya mumasisitimu ekutaurirana asina waya, anosanganisira nharembozha, maWi-Fi routers, uye kutaurirana nesatellite. Kutaura zvazviri, ma fractal antenna madiki, ane mabhendi akawanda, uye anoshanda zvakanyanya, zvichiita kuti akwanise kushandiswa mumidziyo yakasiyana-siyana isina waya uye network.
Mifananidzo inotevera inoratidza mamwe ma fractal antennas akavakirwa pama fractal shapes anozivikanwa, ayo ari mimwe mienzaniso yezvakasiyana-siyana zvakakurukurwa mumabhuku.
Zvikuru, Mufananidzo 2a unoratidza Sierpinski monopole yakataurwa muPuente, iyo inokwanisa kupa mashandiro emabhendi akawanda. Sierpinski triangle inoumbwa nekubvisa triangle yepakati yakapindurwa kubva kutriangle huru, sezvakaratidzwa muMufananidzo 1b neMufananidzo 2a. Maitiro aya anosiya matriangle matatu akaenzana pachimiro, chimwe nechimwe chine kureba kwehafu yetriangle yekutanga (ona Mufananidzo 1b). Maitiro akafanana ekubvisa anogona kudzokororwa kune matriangle asara. Nokudaro, chimwe nechimwe chezvikamu zvaro zvikuru zvitatu chakaenzana nechinhu chose, asi kaviri chiyero, zvichingodaro. Nekuda kwekufanana uku kwakakosha, Sierpinski inogona kupa mabhendi akawanda ema frequency nekuti zvikamu zvakasiyana zve antenna zvakafanana pazviyero zvakasiyana. Sezvakaratidzwa muMufananidzo 2, Sierpinski monopole yakataurwa inoshanda mumabhendi mashanu. Zvinogona kuonekwa kuti chimwe nechimwe chema sub-gasket mashanu (zvimiro zvedenderedzwa) muMufananidzo 2a ishanduro yakayerwa yechimiro chose, nokudaro ichipa mabhendi mashanu akasiyana ekushanda kwema frequency, sezvakaratidzwa mu input reflection coefficient muMufananidzo 2b. Mufananidzo uyu unoratidzawo maparamita ane chekuita nebhendi yega yega yefrequency, kusanganisira frequency value fn (1 ≤ n ≤ 5) pamutengo wepasi wekurasikirwa kwekupinda kwakayerwa (Lr), bandwidth (Bwidth), uye frequency ratio pakati pemabhendi maviri efrequency ari pedyo (δ = fn +1/fn). Mufananidzo 2b unoratidza kuti mabhendi eSierpinski monopoles anopatsanurwa nguva nenguva nechikamu che2 (δ ≅ 2), icho chinoenderana nechiyero chimwe chete chiripo muzvivakwa zvakafanana muchimiro chefractal.

mufananidzo 2

Mufananidzo 3a unoratidza antenna diki refu yakavakirwa paKoch fractal curve. Iyi antenna inokurudzirwa kuratidza mashandisirwo ezvimiro zvekuzadza nzvimbo zvema fractal kugadzira ma antenna madiki. Kutaura zvazviri, kuderedza saizi yema antenna ndicho chinangwa chikuru chezvishandiso zvakawanda, kunyanya izvo zvinosanganisira ma mobile terminals. Koch monopole inogadzirwa uchishandisa nzira yekuvaka fractal inoratidzwa muMufananidzo 3a. Kutanga K0 i monopole yakatwasuka. Kutevera K1 kunowanikwa nekushandisa shanduko yakafanana kuK0, kusanganisira kuyera nechetatu uye kutenderera ne0°, 60°, −60°, uye 0°, zvichiteerana. Maitiro aya anodzokororwa kakawanda kuti uwane zvinotevera Ki (2 ≤ i ≤ 5). Mufananidzo 3a unoratidza shanduro yeKoch monopole ine zvikamu zvishanu (kureva, K5) ine urefu h hwakaenzana ne6 cm, asi hurefu hwese hunopiwa nefomula l = h ·(4/3) 5 = 25.3 cm. Maantenna mashanu anoenderana nematanho mashanu ekutanga eKoch curve akaonekwa (ona Mufananidzo 3a). Zvese zviri zviviri kuyedza nedata zvinoratidza kuti Koch fractal monopole inogona kuvandudza mashandiro emonopole yechinyakare (ona Mufananidzo 3b). Izvi zvinoratidza kuti zvinogona "kuderedzwa" maantenna efractal, zvichivabvumira kuti vakwane mumavhoriyamu madiki uku vachiramba vachiita basa nemazvo.

mufananidzo 3

Mufananidzo 4a unoratidza antenna yefractal yakavakirwa paseti yeCantor, iyo inoshandiswa kugadzira antenna yebroadband yekushandisa pakuunganidza simba. Hunhu hwakasiyana hwe fractal antennas dzinounza ma resonances akawanda ari pedyo hunoshandiswa kupa bandwidth yakafara kupfuura ma antenna echinyakare. Sezvakaratidzwa muMufananidzo 1a, dhizaini yeseti yefractal yeCantor iri nyore kwazvo: mutsetse wekutanga wakatwasuka unokopwa uye unokamurwa kuita zvikamu zvitatu zvakaenzana, umo chikamu chepakati chinobviswa; maitiro akafanana anobva ashandiswa zvakare kune zvikamu zvitsva zvakagadzirwa. Matanho e fractal iteration anodzokororwa kusvika antenna bandwidth (BW) ye 0.8–2.2 GHz yawanikwa (kureva, 98% BW). Mufananidzo 4 unoratidza mufananidzo we antenna prototype yakagadziriswa (Mufananidzo 4a) uye input reflection coefficient yayo (Mufananidzo 4b).

mufananidzo 4

Mufananidzo 5 unopa mimwe mienzaniso yemaantenna efractal, kusanganisira antenna yeHilbert curve-based monopole, antenna yeMandelbrot-based microstrip patch, uye fractal patch yeKoch island (kana kuti "snowflake").

mufananidzo 5

Pakupedzisira, Mufananidzo 6 unoratidza marongero akasiyana efractal ezvinhu zvearray, kusanganisira Sierpinski carpet planar arrays, Cantor ring arrays, Cantor linear arrays, uye fractal trees. Marongero aya anobatsira pakugadzira sparse arrays uye/kana kuwana multi-band performance.