作者aloneliu (Jamie)
看板comm_and_RF
标题[问题] 讯号在无线环境下传送的问题
时间Wed Sep 28 10:20:54 2011
因为我跨系修了一门Wireless Communication and Networking
然後我的基础又很不足
所以希望大家可以帮我一下
问题一:
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.
请问这个是要用
Pr/Pt=(lambda/4pi*d)^2*Gt*Gr
这个公式吗?
我用这个算以後 数字奇怪到我觉得我应该是错了
问题二:
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
这一题的话我就完全不知道该怎麽做了...
希望大家帮帮忙 谢谢
--
※ 发信站: 批踢踢实业坊(ptt.cc)
◆ From: 98.230.48.89
1F：→ Justinok:照LOS在20km会衰落多少能量应该就可以反 120.96.59.197 09/30 12:22
2F：→ Justinok:推出来，公式为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:第三行打错 (4pi)^2*d^2*L才对 120.96.59.197 09/30 12:27