作者aloneliu (Jamie)
看板comm_and_RF
標題[問題] 訊號在無線環境下傳送的問題
時間Wed Sep 28 10:20:54 2011
因為我跨系修了一門Wireless Communication and Networking
然後我的基礎又很不足
所以希望大家可以幫我一下
問題一:
The antenna of a cellular telephone base station transmitter operating at
869 MHz has a gain of 10 dB. Assuming ideal antenna matching and orientation
conditions, find the required transmitted power in watts (W) in order for
the power received by a mobile phone antenna with gain 2 dB at distance 20 km
to be at least -60 dBm.
請問這個是要用
Pr/Pt=(lambda/4pi*d)^2*Gt*Gr
這個公式嗎?
我用這個算以後 數字奇怪到我覺得我應該是錯了
問題二:
Consider a direct television satellite system operating at 12.5 GHz with direct
link distance 35,800 km. The transmitting and receiving parabolic reflector
antennas have circular apertures of diameters 0.5 m and 1.2 m, respectively.
Their corresponding aperture efficiencies ( nap ) are 70% and 60%. Given the
transmitted power is 150 W, determine the received power for ideal link
conditions.
Note: For a parabolic reflector antenna, its effective aperture Aeff is related
to the physical aperture Aphy as follows: Aeff = nap*Aphy
這一題的話我就完全不知道該怎麼做了...
希望大家幫幫忙 謝謝
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1F：→ Justinok:照LOS在20km會衰落多少能量應該就可以反 120.96.59.197 09/30 12:22
2F：→ Justinok:推出來，公式為Pr(d)=(PtGtGrLambda^2)/ 120.96.59.197 09/30 12:24
3F：→ Justinok:(4lambda)^2 * d^2*L 120.96.59.197 09/30 12:25
4F：→ Justinok:第三行打錯 (4pi)^2*d^2*L才對 120.96.59.197 09/30 12:27