ʻO ka pono o kahi antenna e pili ana i ka mana i hāʻawi ʻia i ka antenna a me ka mana i hoʻomālamalama ʻia e ka antenna. ʻO kahi antenna maikaʻi loa e hoʻomālamalama i ka hapa nui o ka ikehu i hāʻawi ʻia i ka antenna. Hoʻopili ka antenna maikaʻi ʻole i ka hapa nui o ka mana i nalowale i loko o ka antenna. Hiki i ka antenna maikaʻi ʻole ke loaʻa ka nui o ka ikehu ma muli o ka impedance mismatch. E ho'ēmi i ka mana radiated o kahi antenna maikaʻi ʻole i hoʻohālikelike ʻia me kahi antenna ʻoi aku ka maikaʻi.
[Nā ʻaoʻao: Ua kūkākūkā ʻia ka impedance Antenna ma kahi mokuna hope. Hōʻike ʻia ka Impedance mismatch i ka mana mai ka antenna no ka mea he hewa hewa ka impedance. No laila, kapa ʻia kēia impedance mismatch. ]
ʻO ke ʻano o ka nalowale i loko o ka antenna ʻo ia ka nalo conduction. ʻO nā poho conduction ma muli o ka conductivity palena o ka antenna. ʻO kekahi ʻano hana o ka poho ʻo ia ka poho dielectric. ʻO nā poho dielectric i ka antenna ma muli o ka lawe ʻana i ka mea dielectric. Aia paha nā mea hoʻokaʻawale i loko a i ʻole a puni ka antenna.
Hiki ke kākau ʻia ka ratio o ka pono o ka antenna i ka mana radiated e like me ka mana komo o ka antenna. ʻO kēia ka hoohalike [1]. ʻIke ʻia hoʻi ʻo ka radiation efficiency antenna efficiency.
[Equation 1]
He lakio ka pono. He nui mau kēia ratio ma waena o 0 a me 1. Hāʻawi pinepine ʻia ka pono ma kahi pākēneka. No ka laʻana, ʻoi aku ka maikaʻi o 0.5 i ka 50% like. Hōʻike pinepine ʻia ka hana antenna i nā decibels (dB). ʻO kahi kūpono o 0.1 e like me 10%. Ua like pū kēia me -10 decibels (-10 decibels). ʻO ka maikaʻi o 0.5 e like me 50%. Ua like pū kēia me -3 decibels (dB).
ʻO ka hoʻohālikelike mua i kapa ʻia i kekahi manawa ʻo ka radiation efficiency o ka antenna. Hoʻokaʻawale kēia iā ia mai kahi huaʻōlelo maʻamau i kapa ʻia ʻo ka huina kūpono o ka antenna. Hoʻonui ʻia ka hoʻonui ʻia ʻana o ka hoʻoheheʻe ʻana i ka impedance mismatch o ka antenna. Loaʻa nā poho impedance mismatch i ka wā e pili kino ai ka antenna i ka laina hoʻouna a i ʻole ka mea hoʻokipa. Hiki ke hōʻuluʻulu ʻia kēia ma ke ʻano [2].
[Equation 2]
kumukānāwai [2]
He helu mau ka Impedance mismatch loss ma waena o 0 a me 1. No laila, ʻoi aku ka liʻiliʻi o ka hana antenna holoʻokoʻa ma mua o ka pono radiation. No ka haʻi hou ʻana i kēia, inā ʻaʻohe poho, ua like ka pono o ka radiation me ka nui o ka antenna pono ma muli o ka impedance mismatch.
ʻO ka hoʻomaikaʻi ʻana i ka pono kekahi o nā ʻāpana antenna koʻikoʻi. Hiki iā ia ke kokoke loa i ka 100% me kahi kīʻaha ukali, antenna horn, a i ʻole ka hapalua hawewe lōʻihi me ka ʻole o nā mea poho a puni. ʻO nā antenna kelepona kelepona a i ʻole nā antenna uila mea kūʻai aku maʻamau ka hana o 20% -70%. Ua like kēia me -7 dB -1.5 dB (-7, -1.5 dB). ʻO ka pinepine ma muli o ka nalowale o nā mea uila a me nā mea e hoʻopuni ana i ka antenna. Hoʻopili kēia mau mea i kekahi mana radiated. Hoʻololi ʻia ka ikehu i ikehu wela a ʻaʻohe pāhawewe. Hoʻemi kēia i ka pono o ka antenna. Hiki i nā antenna lekiō kaʻa ke hana ma nā alapine lekiō AM me ka pono o ka antenna o 0.01. [He 1% a i ʻole -20 dB kēia. ] ʻO kēia kūpono ʻole no ka mea ʻoi aku ka liʻiliʻi o ka antenna ma mua o ka hapalua o ka nalu nalu ma ke alapine hana. Hoʻemi nui kēia i ka pono o ka antenna. Mālama ʻia nā loulou pili ʻole no ka mea hoʻohana nā hale kiaʻi hoʻolaha AM i ka mana hoʻouna kiʻekiʻe loa.
Kūkākūkā ʻia nā poho impedance mismatch ma ka Smith Chart a me nā ʻāpana Impedance Matching. Hiki i ka hoʻohālikelike impedance ke hoʻomaikaʻi nui i ka pono o ka antenna.
Loaʻa ka Antenna
ʻO ka loaʻa ʻana o ka antenna lōʻihi e wehewehe i ka nui o ka mana i hoʻouna ʻia i ka kuhikuhi radiation peak, pili i kahi kumu isotropic. ʻOi aku ka maʻamau o ka loaʻa ʻana o ka Antenna i ka pepa kikoʻī o kahi antenna. He mea nui ka loaʻa ʻana o ka Antenna no ka mea e noʻonoʻo ana i nā poho maoli e kū mai ana.
ʻO kahi antenna me 3 dB loaʻa ʻo ia ka mana i loaʻa mai ka antenna he 3 dB ʻoi aku ka kiʻekiʻe ma mua o ka loaʻa ʻana mai kahi antenna isotropic nalowale me ka mana hoʻokomo like. Ua like ka 3 dB me ka palua o ka lako mana.
Kūkākūkā ʻia ka loaʻa ʻana o Antenna ma ke ʻano he hana o ke kuhikuhi a i ʻole ke kihi. Eia naʻe, ke kuhikuhi ʻia kahi helu hoʻokahi i ka loaʻa, a laila ʻo ia helu ka loaʻa kiʻekiʻe no nā kuhikuhi āpau. Hiki ke hoʻohālikelike ʻia ka "G" o ka loaʻa antenna me ke kuhikuhi ʻana o "D" o ke ʻano futuristic.
[Equation 3]
ʻO ka loaʻa ʻana o kahi antena maoli, hiki ke kiʻekiʻe e like me kahi kīʻaha satellite nui loa, ʻo 50 dB. Hiki ke kuhikuhi i ka haʻahaʻa e like me ka 1.76 dB e like me ka antenna maoli (e like me ka antenna dipole pōkole). ʻAʻole hiki ke emi ma lalo o 0 dB ka kuhikuhi. Eia nō naʻe, hiki ke liʻiliʻi ka loaʻa ʻana o ka antenna peak. ʻO kēia ma muli o nā poho a i ʻole nā hana ʻole. ʻO nā antenna liʻiliʻi liʻiliʻi he mau antenna liʻiliʻi e hana ana ma ka lōʻihi o ka nalu o ke alapine e hana ai ka antenna. Hiki i nā antenna liʻiliʻi ke kūpono ʻole. Loaʻa pinepine ka loaʻa ʻana o Antenna ma lalo o -10 dB, ʻoiai ʻaʻole i noʻonoʻo ʻia ka impedance mismatch.
Ka manawa hoʻouna: Nov-16-2023
