Inā ʻoe i hana ma ka ʻoihana hoʻolaha lekiō no kekahi manawa, pono ʻoe i ʻike i kēia mau ʻāpana i kaha ʻia ma kekahi mau puke o kekahi mau mea hoʻolaha lekiō e like me FM antenna a i ʻole RF amplifier: dB, dBi, dBm. Ua like ko lākou nānā ʻana, akā ʻike anei ʻoe i ke ʻano o lākou a pehea e hoʻokaʻawale ai iā lākou? Ma hope o ka heluhelu ʻana i kēia ʻatikala, e ʻike ʻoe i ko lākou manaʻo a pehea e hoʻokaʻawale ai iā lākou.

maʻiʻo

• ʻO ka wehewehe ʻana o ka loaʻa
• Ka wehewehe a me nā ʻokoʻa o dB, dBi a me dBm
• NPP
• Panina

ʻO ka wehewehe ʻana o ka loaʻa

Ma mua o ka hele ʻana i ka manaʻo, e pane kāua i ʻelua nīnau: he aha ka loaʻa o ka Antenna hoʻolaha FM mean?

Hoʻokumu ʻia ma Wikipedia, i kahi antenna hoʻouna, wehewehe ka loaʻa i ka maikaʻi o ka hoʻololi ʻana o ka antenna i ka mana hoʻokomo i nā nalu lekiō e hele ana i kahi kuhikuhi. Ma kahi antenna loaʻa, wehewehe ka loaʻa i ka maikaʻi o ka hoʻololi ʻana o ka antenna i nā nalu lekiō e hiki mai ana mai kahi kuhikuhi i kuhikuhi ʻia i ka mana uila. Inā ʻaʻohe kuhikuhi i kuhikuhi ʻia, ʻike ʻia ka loaʻa e pili ana i ka waiwai kiʻekiʻe o ka loaʻa, ka loaʻa i ke kuhikuhi o ka lobe nui o ka antenna.

I ka pōkole, ʻaʻole hiki i ka antenna FM ke hoʻomaikaʻi i ka mana o ka mea hoʻouna a i ʻole ka mea e loaʻa ai iā ia iho, akā hiki i ka antenna ke hoʻopaʻa i kēia mau mana a i ʻole nā ​​nalu lekiō ma kahi kuhikuhi. Ma kēia ala, ʻoi aku ka ikaika o ka hawewe lekiō i hoʻopuka ʻia e ka antenna ma kēia ʻaoʻao ma mua o ka mea mua, ʻo ia hoʻi, ʻoi aku ka nāwaliwali o ka hawewe lekiō ma nā ʻaoʻao ʻē aʻe ma mua o ka mea mua. No laila, ʻo ka loaʻa ka lakio o ka hawewe lekiō ma ke ala me ka ikaika o ka radiation ikaika i ka ikaika o ka nalu radio kumu.

Loaʻa ʻokoʻa o ka Isotropic Antenna a me High Gain Antenna

Ka wehewehe a me nā ʻokoʻa o dB, dBi a me dBm

Ma hope o ka loaʻa ʻana o ka ʻike kumu o ka manaʻo o ka loaʻa, ʻoi aku ka maʻalahi o ka hoʻomaopopo ʻana i nā ʻāpana ʻekolu o dB, dBi, a me dBm.

ʻO ka wehewehe ʻana o dB

Ua aʻo mākou ma ke kula ʻo ka dB ke hōʻike nei i ka leo nui o ke kani. Eia nō naʻe, ʻokoʻa ia ma ke kahua RF. ʻO kāna kumu hoʻohālikelike ʻo dB=10log(x/y) (kahi e hōʻike ai ʻo x a me Y i ka ikaika o ka radiation o nā antenna ʻelua) a ke hōʻike nei i ka ʻokoʻa ma waena o nā pae mana o nā antenna ʻelua (loaʻa a nalowale paha)

Ma o ka helu ʻana, hiki iā mākou ke ʻike inā ʻoi aku ka nāwaliwali o x ma mua o y, ʻo ka dB ka ʻino; Inā like ka x a me ka y, ua like ka dB me 0; Ke like ka x = 2y, ua like ka dB me 3. Pela no, ua like ka 6dB i ka x me 4 manawa y a ua like ka 12dB i ka x me 16 manawa y. Pono e hoʻomaopopo ʻia inā makemake ʻoe e ana i ka loaʻa maoli a i ʻole ka ʻokoʻa o ka mana maoli o ka antenna uea, e ʻoluʻolu e noʻonoʻo i ka nalowale o ke kaula RF ponoʻī.

ʻO ka wehewehe ʻana o dBi

Inā makemake ʻoe e hoʻohālikelike i ka ikaika radiation o ka gain directional antenna a me omnidirectional antenna, pono ʻoe e lawe i ka dBi ma ke ʻano he ʻāpana, kahi i hōʻike ai ʻo "i" i ka isotopic, a ua like ke ʻano helu helu o dBi me ka dBi.

No ka mea, e hoʻomālamalama ka antenna omnidirectional i ka hōʻailona lekiō me kahi "sphere" kūpono loa, ʻo ia hoʻi, loaʻa iā ia ka nui o ka lekiō ma kēlā me kēia ʻaoʻao. I ka loaʻa ʻana o ka antenna i kahi kuhikuhi i kuhikuhi ʻia, e haiki kona lobe, ʻo ia hoʻi, lawe ka antenna lekiō FM i kahi kihi e like me ke kuhikuhi radiation nui, a ʻoi aku ka ikaika o ka radiation ma mua o ka ikaika radiation kumu. ʻO ka ratio o ka ikaika o ka radiation o kēia kihi radiation nui i ka ikaika radiation kumu ka loaʻa o kēia antenna kuhikuhi. No laila, ke ʻoi aku ka nui o ka dBi ma mua o 0, e hōʻike ana he kuhikuhi pololei ka antenna.

ʻO ke ʻano Radiation o kahi Antenna Isotropic

ʻO ka wehewehe ʻana o dBm

ʻOiai ua like ka dBm me ka dBi, ʻaʻole ia e hōʻike i ka ikaika o ka radiation. ʻO ka "m" ma ka dBm e hōʻike ana i nā milliwatts (MW), kahi like me dBi, he waiwai pili nō hoʻi ia, akā hōʻike ia i ka waiwai pili o ka mana hoʻoili me 1MW ma ke ʻano he kumu kuhikuhi. ʻO ke kumu: dBm = 10 log (P1/1MW)

ʻOiai he waiwai pili ka dBm, hiki ke hoʻololi ʻia i ka mana maoli o nā mea hana ma hope o ka hoʻololi ʻana o ka ʻāpana. No ka laʻana, 0dbm = 1MW, 1dbm = 1.3MW, 10dBm = 1W, 60dbm = 1000W... Hiki ke ʻike ʻia hiki ke hoʻohana i nā waiwai maʻalahi e hōʻike i ka mana liʻiliʻi a i ʻole ka mana nui loa. No laila, e hōʻike ʻia ka mana maoli o nā mea like ʻole ma dBm.

ʻO nā ʻokoʻa ma waena o dB, dBi a me dBm

Ma ka hōʻuluʻulu manaʻo, ʻo dB, dBm, a me dBm nā waiwai pili, akā aia nā ʻokoʻa 2 e like me:

1. Hoʻohana ʻia ka dB a me ka dBi e hōʻike i ka ikaika pili (loaʻa a nalowale paha) o ka lekiō lekiō o ka antenna, ʻoiai hoʻohana ʻia ka dBm e hōʻike i ka mana maoli o nā mea hana.
2. ʻO ka dB ka waiwai pili o ka ʻokoʻa ikaika o ka radiation ma waena o nā antenna ʻelua, a ʻo dBi ka hoʻohālikelike ikaika o ka lekiō o kahi antenna ma mua a ma hope o ka loaʻa (a i ʻole orientation).

Pinepine ninau ninaninau 'ana i

1. Nīnau: He aha ka dB Gain no kahi FM Broadcast Antenna?

A: ʻO ia ka hiki ke hoʻomālamalama a ʻoi aʻe paha i kahi kuhikuhi no FM Broadcast Antennas.

Ana ʻia ka dB e ka ratio o ka mana, ka manawa a i ʻole ka volta o nā hōʻailona ʻelua. ʻO ia ka mea hoʻohana maʻamau no ka loaʻa.

2. N: No ke aha e ana ʻia ai ka ikaika hōʻailona e ka dB?

A: No ka mea, ʻokoʻa ka ikaika o ka hōʻailona me ka logarithmically akā ʻaʻole laina.

Hoʻohana mākou i ka dB e ana i ka ikaika hōʻailona no ka mea ʻokoʻa ka ikaika o ka hōʻailona ma ka logarithmically, ʻaʻole ma ka laina. ʻO ka unahi logarithmic e hiki ai i nā helu maʻalahi ke hōʻike i nā loli nui i nā pae hōʻailona. 

3. Nīnau: He aha ka -3 dB Gain Mean no ka Antenna?

A: -3dB loaʻa, ʻo ia hoʻi, ua hoʻemi ʻia ka loaʻa o ka hoʻopuka i 70.71% o kona pae kiʻekiʻe.

ʻO ka -3dB loaʻa wahi e wehewehe i ka pae kiʻekiʻe o ka loaʻa i hoʻemi ʻia i 70.71% o kona pae kiʻekiʻe. A i ʻole hiki iā mākou ke ʻōlelo ʻo ka helu -3dB ʻo ia hoʻi ke alapine o ka loaʻa ʻana o ka ʻōnaehana i hōʻemi i ka 0.707 o kona waiwai nui.

4. Nīnau: ʻOi aku ka maikaʻi o ka dBi kiʻekiʻe ma mua o ka mea haʻahaʻa?

A:  ʻOiaʻiʻo ʻaʻole, ʻelua ʻaoʻao nā keneta āpau. ʻO ka dBi kiʻekiʻe, ʻo ia ka hoʻomālamalama ʻana aʻe akā ʻoi aku ka haiki.

ʻO ke kiʻekiʻe o ka helu dBi o ka antenna, ʻoi aku ka kiʻekiʻe o ka loaʻa iā ia, akā ʻoi aku ka liʻiliʻi o ke ʻano ākea ākea. 'O ia ho'i, e hele 'oi aku ka ikaika o ka hō'ailona akā ma ke ala haiki. Inā makemake ʻoe e hoʻomālamalama i kahi ala ākea, pono ʻoe e hoʻohui i nā antenna hou aʻe.

Panina

Aʻo mākou i nā wehewehe a me nā ʻokoʻa o dB, dBi, a me dBm ma o ka ʻike ma luna. He mea kōkua nui iā ʻoe e ʻike maikaʻi i ka manaʻo antenna ma mua o ke komo ʻana i ke kahua RF. Inā makemake ʻoe e ʻike hou aku e pili ana i ka hoʻolaha ʻana, a i ʻole makemake ʻoe i nā lako hoʻolele lekiō e kūʻai aku, e ʻoluʻolu e ʻoluʻolu e e kelepona i kā mākou hui loea RF, e pane koke ʻia ʻoe. A mai poina e kaʻana like i kēia blog inā kōkua ia iā ʻoe!

E heluhelu pū hoʻi

• ʻO kahi hōʻike pōkole e pili ana i ka Sigal to Noise Ratio ma ka Wireless Broadcasting
• 4 Nā noi nui o nā mea hoʻouna hoʻolaha FM
• Pre-emphasis and De-emphasis in FM Broadcasting | Hoʻolauna
• Introduction to FM Radio Dipole Antenna | PALAPALA FMUSER