Ko te tawhiti whakawhitiwhiti kōrero ka taea e tētahi pūnaha whakawhitiwhiti kōrero ahokore te whakatutuki, ka whakatauhia e ngā āhuatanga maha pērā i ngā taputapu rerekē e hanga ana i te pūnaha me te taiao whakawhitiwhiti kōrero. Ka taea te whakaatu i te whanaungatanga i waenganui i a rātou mā te whārite tawhiti whakawhitiwhiti kōrero e whai ake nei.
Mena ko te mana tuku o te taputapu tuku o te pūnaha whakawhitiwhiti kōrero ko PT, ko te whakanui pūihi tuku ko GT, ā, ko te roangaru whakahaere ko λ. Ko te aro o te taputapu whiwhi ko PR, ko te whakanui pūihi whiwhi ko GR, ā, ko te tawhiti i waenga i ngā pūihi whiwhi me ngā pūihi tuku ko R, i roto i te tawhiti tirohanga me te taiao me te kore he pokanoa hikohiko, ko te whanaungatanga e whai ake nei:
PT(dBm)-PR(dBm)+GT(dBi)+GR(dBi)=20log4pr(m)/l(m)+Lc(dB)+ L0(dB) I roto i te tātai, ko Lc te ngaronga whakaurunga whāngai o te pūihi tuku teihana turanga; ko L0 te ngaronga ngaru reo irirangi i te wā e horapa ana.
I te hoahoatanga o te pūnaha, me waiho he tawhē e rawaka ana mō te tūemi whakamutunga, arā, ko te ngaronga horapa o te ngaru reo irirangi L0.
Ko te tikanga, me whai tawhiti o te 10 ki te 15 dB ina haere ana i roto i ngā ngahere me ngā whare kāwanatanga; me whai tawhiti o te 30 ki te 35 dB ina haere ana i roto i ngā whare raima whakapakari.
Mō ngā roopu auau CDMA me GSM 800MH, 900ZMHz, e whakaponohia whānuitia ana ko te taumata paepae whiwhi o ngā waea pūkoro he tata ki te -104dBm, ā, ko te tohu tuturu i whiwhihia me neke atu i te 10dB teitei ake kia tutuki ai te ōwehenga tohu-ki-haruru e hiahiatia ana. Inaa, kia mau tonu ai te whakawhitiwhiti kōrero pai, ka tatauhia te mana i whiwhihia he -70 dBm. Me kī kei te teihana turanga ēnei tawhā e whai ake nei:
Ko te mana tuku ko PT = 20W = 43dBm; ko te mana whiwhi ko PR = -70dBm;
Ko te ngaronga o te whāngai he 2.4dB (tata ki te 60m te whāngai)
Te whakanui i te pūihi whiwhi waea pūkoro GR = 1.5dBi;
Ngaru mahi λ = 33.333cm (he rite ki te auau f0 = 900MHz);
Ka noho te whārite whakawhitiwhiti kōrero i runga ake nei hei:
43dBm-(-70dBm)+ GT(dBi)+1.5dBi=32dB+ 20logr(m) dB +2.4dB + ngaronga horapa L0
114.5dB+ GT(dBi) -34.4dB = 20logr(m)+ ngaronga horapa L0
80.1dB+ GT(dBi) = 20logr(m)+ ngaronga horapa L0
Ina nui ake te uara kei te taha maui o te tātai i runga ake nei i te uara kei te taha matau, arā:
GT(dBi) > 20logr(m)-80.1dB+ngaronga horapa L0. Ina mau tonu te kore taurite, ka taea te whakaaro ka taea e te pūnaha te pupuri i te whakawhitiwhiti kōrero pai.
Mena ka whakamahia e te teihana turanga he pūihi tuku whānui-aronga me te whakanui o GT=11dBi, ā, ko te tawhiti i waenga i ngā pūihi tuku me ngā pūihi whiwhi ko R=1000m, ka huri te whārite whakawhitiwhiti kōrero hei 11dB>60-80.1dB+ngaronga horapa L0, arā, ina iti iho te ngaronga horapa L0 i te 31.1dB, ka taea te pupuri i te whakawhitiwhiti kōrero pai i roto i te tawhiti o te 1 km.
I raro i ngā āhuatanga ngaronga horapa rite tonu ki runga ake nei, ki te mea ko te whakanui pūihi tuku GT = 17dBi, arā, he pikinga o te 6dBi, ka taea te whakaneke rua i te tawhiti whakawhitiwhiti kōrero, arā, r = 2 kiromita. Ka taea te whakatau i ētahi atu i te ara kotahi. Heoi, me mōhio ko te pūihi teihana turanga me te whakanui GT o te 17dBi ka taea anake te whai i te hipoki hihi āhua-pā me te whānui hihi o te 30°, 65°, 90° rānei, me ētahi atu, ā, kāore e taea te pupuri i te hipoki o te ahunga katoa.
Hei tāpiritanga, ki te kore e rerekē te pikinga o te pūihi tuku GT=11dBi i roto i te tataunga i runga ake nei, engari ka rerekē te taiao horapa, ko te ngaronga horapa L0=31.1dB-20dB=11.1dB, ko te ngaronga horapa 20dB kua whakaitihia ka whakanui ake i te tawhiti whakawhitiwhiti kōrero tekau ngā whakarea, arā, r=10 kiromita. Ko te wā ngaronga horapa e pā ana ki te taiao hikohiko e karapoti ana. I ngā tāone nui, he maha ngā whare teitei, ā, he nui te ngaronga horapa. I ngā tāone iti, he iti, he koretake hoki ngā whare pāmu, ā, he iti te ngaronga horapa. Nō reira, ahakoa he rite tonu ngā tautuhinga pūnaha whakawhitiwhiti kōrero, ka rerekē te whānuitanga kapinga whai hua nā te rerekētanga o te taiao whakamahi.
Nō reira, i te wā e whiriwhiri ana i ngā pūihi ahunga-katoa, ahunga-katoa me ngā momo pūihi whai-rahi, whai-iti rānei, me whakaaro ki te whakamahi i ngā momo pūihi teihana turanga me ngā whakaritenga rerekē kia rite ki ngā āhuatanga motuhake o te whatunga whakawhitiwhiti pūkoro me te taiao tono.
Mō ētahi atu kōrero mō ngā antenna, tirohia:
Wā tuku: Hurae-25-2025
