ʻO ka polarization kekahi o nā hiʻohiʻona kumu o nā antennas. Pono mua mākou e hoʻomaopopo i ka polarization o nā nalu mokulele. A laila hiki iā mākou ke kūkākūkā i nā ʻano nui o ka polarization antenna.
polarization laina
E hoʻomaka mākou e hoʻomaopopo i ka polarization o kahi hawewe electromagnetic mokulele.
He mau hiʻohiʻona ka hawewe electromagnetic planar (EM). 'O ka mea mua, 'o ia ka holo 'ana o ka mana ma ka 'ao'ao ho'okahi ('a'ohe ho'ololi o ke kahua ma nā 'ao'ao orthogonal 'elua). ʻO ka lua, ʻo ke kahua uila a me ke kahua magnetic he perpendicular kekahi i kekahi a he orthogonal kekahi i kekahi. ʻO nā māla uwila a me ka mākēneki pili i ke kuhikuhi o ka hoʻolaha ʻana o ka nalu mokulele. E like me ka laʻana, e noʻonoʻo i kahi māla uila uila (E) i hāʻawi ʻia e ka hoohalike (1). Ke holo nei ke kahua electromagnetic ma ke kuhikuhi +z. Ua kuhikuhi ʻia ke kahua uila ma ka + x. Aia ka mākia ma ka ʻaoʻao +y.
Ma ka hoohalike (1), e nana i ka notation: . ʻO kēia kahi vector unit (he vector o ka lōʻihi), e ʻōlelo ana aia ke kiko kahua uila ma ka ʻaoʻao x. Hōʻike ʻia ka nalu mokulele ma ke Kiʻi 1.
kiʻi 1. Hōʻike kiʻi kiʻi o ke kahua uila e holo ana ma ka ʻaoʻao +z.
ʻO ka polarization ke ʻano a me ke ʻano hoʻolaha (contour) o kahi māla uila. E like me ka la'ana, e no'ono'o i ka ha'iha'i hawewe uila (1). E nānā kākou i ke kūlana o ke kahua uila (X,Y,Z) = (0,0,0) ma ke ʻano he hana o ka manawa. Hoʻolālā ʻia ka amplitude o kēia kahua ma ka Figure 2, i kekahi mau manawa i ka manawa. Ke oscillating nei ke kahua ma ke alapine "F".
kiʻi 2. E nānā i ke kahua uila (X, Y, Z) = (0,0,0) i nā manawa like ʻole.
ʻIke ʻia ke kahua uila ma ke kumu, oscillating i hope a i waho i ka amplitude. Aia mau ke kahua uila ma ka axis-x i hōʻike ʻia. Ma muli o ka mālama ʻia ʻana o ke kahua uila ma kahi laina hoʻokahi, hiki ke ʻōlelo ʻia kēia kahua i ka linearly polarized. Eia hou, inā pili ka X-axis me ka honua, ua wehewehe ʻia kēia kahua me he polarized horizontally. Inā kuhikuhi ʻia ke kahua ma ka axis Y, hiki ke ʻōlelo ʻia he polarized vertically.
ʻAʻole pono ke kuhikuhi ʻia ʻana o nā nalu polarized linearly ma ke koʻi ākea a i ʻole ke koʻikoʻi. No ka laʻana, ʻo ka nalu kahua uila me kahi kaohi e waiho ana ma kahi laina e like me ka hōʻike ʻana ma ke Kiʻi 3 e hoʻopololei ʻia.
kiʻi 3. ʻO ka amplitude kaha uila o ka nalu polarized linearly nona ke alahele he kihi.
Hiki ke wehewehe ʻia ke kahua uila ma ke Kiʻi 3 e ka hoohalike (2). I kēia manawa aia kahi ʻāpana x a me y o ke kahua uila. Ua like ka nui o na mea elua.
ʻO kahi mea e hoʻomaopopo ai e pili ana i ka hoohalike (2) ʻo ia ka xy-component a me nā māla uila ma ka pae ʻelua. ʻO ia ke ʻano o nā ʻāpana ʻelua i ka amplitude like i nā manawa a pau.
polarization pōʻai
E noʻonoʻo ʻoe ua hāʻawi ʻia ke kahua uila o ka nalu mokulele e ka hoohalike (3):
Ma keia hihia, he 90 degere ka huina X- a me ka Y ma waho o ka mahele. Inā ʻike hou ʻia ke kahua e like me (X, Y, Z) = (0,0,0) e like me ka wā ma mua, e ʻike ʻia ke kahua uila me ka pihi manawa e like me ka hōʻike ʻana ma lalo o ke Kiʻi 4.
Kiʻi 4. Ka ikaika o ke kahua uila (X, Y, Z) = (0,0,0) EQ domain. (3).
ʻO ke kahua uila ma ke Kiʻi 4 ka pōʻai. Hōʻike ʻia kēia ʻano kahua ma ke ʻano he nalu polarized. No ka circular polarization, pono e hoʻokō ʻia nā pae hoʻohālike:
- Kūlana no ka polarization pōʻai
- Pono e loaʻa i ʻelua ʻāpana orthogonal (perpendicular) ke kahua uila.
- Pono nā ʻāpana orthogonal o ke kahua uila e like nā amplitudes.
- Pono nā ʻāpana quadrature he 90 degere ma waho o ka pae.
Inā e hele ana ma ka ʻaoʻao Wave Figure 4, ʻōlelo ʻia ka hoʻololi ʻana o ke kahua he counterclockwise a me ka lima ʻākau circularly polarized (RHCP). Inā hoʻohuli ʻia ke kahua ma ka ʻaoʻao o ka uaki, e lilo ke kahua i ka polarization pōʻai hema (LHCP).
Polarization Elliptical
Inā loaʻa i ʻelua ʻāpana kū pololei ke kahua uila, 90 degere ma waho o ke kaʻina akā like ka nui, e polarized elliptically ke kahua. E noʻonoʻo ana i ke kahua uila o ka nalu mokulele e holo ana ma ka ʻaoʻao +z, i wehewehe ʻia e ka Haʻawina (4):
Hāʻawi ʻia ka wahi o ka lae e manaʻo ai ka piko o ke kahua uila ma ke Kiʻi 5
Kiʻi 5. Elliptical polarization hawewe uila kahua uila. (4).
ʻO ke kahua ma ke Kiʻi 5, e hele ana ma ka ʻaoʻao kūʻē i ka ʻāʻī, he elliptic lima ʻākau ke hele i waho o ka pale. Inā hoʻololi ke kahua uila ma ka ʻaoʻao ʻē aʻe, e hoʻopololei ʻia ka lima hema.
Eia kekahi, pili ka polarization elliptical i kona eccentricity. ʻO ka lakio o ka eccentricity i ka amplitude o nā koʻi nui a me nā koʻi liʻiliʻi. No ka laʻana, ʻo ka eccentricity hawewe mai ka hoohalike (4) he 1/0.3= 3.33. Hōʻike hou ʻia nā hawewe polarized Elliptically e ke kuhikuhi o ke axis nui. ʻO ka haʻihaʻi hawewe (4) he axis i loaʻa mua i ka axis-x. E hoʻomaopopo he hiki ke axis nui ma kēlā me kēia kihi mokulele. ʻAʻole koi ʻia ka kihi e kūpono i ke koʻi X, Y a i ʻole Z. ʻO ka hope, he mea nui e hoʻomaopopo i ka polarization circular a me linear he mau hihia kūikawā o ka polarization elliptical. ʻO 1.0 eccentric elliptically polarized hawewe he pōʻai polarized. Nā hawewe polarized Elliptically me ka eccentricity palena ʻole. Nā nalu polarized linearly.
Antenna polarization
I kēia manawa ua ʻike mākou i nā māla electromagnetic polarized plane wave, ua wehewehe maʻalahi ka polarization o kahi antena.
Antenna Polarization He antenna loa-field loiloi, ka polarization o ka hopena radiated kahua. No laila, helu pinepine ʻia nā antenna ma ke ʻano he "linearly polarized" a i ʻole "lima ʻākau circularly polarized antennas".
He mea nui kēia manaʻo maʻalahi no ke kamaʻilio antenna. ʻO ka mea mua, ʻaʻole e kamaʻilio ka antenna polarized horizontally me kahi antenna polarized vertically. Ma muli o ka theorem reciprocity, hoʻouna a loaʻa ka antenna i ke ala like. No laila, hoʻouna a loaʻa i nā antenna polarized vertically polarized. No laila, inā ʻoe e hoʻāʻo e haʻi i kahi antenna polarized horizontally polarized, ʻaʻole e loaʻa.
Ma ka hihia maʻamau, no nā antenna polarized ʻelua i hoʻololi ʻia e pili ana i kekahi i kekahi e kahi kihi (), e wehewehe ʻia ka nalowale o ka mana ma muli o kēia polarization mismatch e ka polarization loss factor (PLF):
No laila, inā loaʻa ka polarization like ʻelua antennas, ʻo ka ʻoki ma waena o kā lākou radiating electron field he zero a ʻaʻohe nalowale o ka mana ma muli o ka polarization mismatch. Inā hoʻopololei pololei ʻia kekahi antenna a ʻo kekahi polarized horizontally, ʻo ke kihi he 90 degere, ʻaʻohe mana e hoʻololi ʻia.
NĀ MEA: ʻO ka neʻe ʻana i ke kelepona ma luna o kou poʻo i nā kihi ʻokoʻa e wehewehe i ke kumu e hoʻonui ʻia ai ka hoʻokipa ʻana i kekahi manawa. Hoʻopili pinepine ʻia nā antenna kelepona, no laila hiki ke hoʻohālikelike i ke kelepona i ka polarization o ke kelepona, no laila e hoʻomaikaʻi ai i ka hoʻokipa.
ʻO ka polarization circular kahi ʻano makemake o nā antenna he nui. Hoʻopili ʻia nā antenna ʻelua a ʻaʻole e ʻeha i ka nalo hōʻailona ma muli o ka polarization mismatch. ʻO nā Antenna i hoʻohana ʻia i nā ʻōnaehana GPS he polarized circularly polarized.
E noʻonoʻo ʻoe e loaʻa i kahi antenna polarized linearly nā nalu polarized. E like hoʻi, manaʻo ʻia e hoʻāʻo ana kahi antenna circularly polarized e loaʻa nā nalu polarized linearly. He aha ka hopena polarization poho kumu?
E hoʻomanaʻo ʻo ka polarization pōʻaiʻe he ʻelua mau nalu polarized orthogonal, 90 degere ma waho o ka pae. No laila, e loaʻa wale i ka antenna linearly polarized (LP) i ka ʻāpana hawewe circularly polarized (CP). No laila, e loaʻa i ka antenna LP kahi polarization mismatch nalowale o 0.5 (-3dB). He ʻoiaʻiʻo kēia inā ʻaʻohe kihi o ka antenna LP i hoʻohuli ʻia. nolaila:
ʻO ka polarization loss factor i kekahi manawa i kapa ʻia ʻo ka polarization efficiency, antenna mismatch factor, a i ʻole ka mea hoʻokipa antenna. Pili kēia mau inoa a pau i ka manaʻo like.
Ka manawa hoʻouna: Dec-22-2023
