Re: [理工] [電磁]多層膜
※ 引述《u61i6m4 (嗯..)》之銘言：
: A 500MHz uniform plane wave is normally incident on a freshwater
: (εr=88) lake covered with a layer os ice (εr=3.2) ,as shown
: in Fig.P4.
: (1)Find the minimum thickness of the ice such that the reflected wave
: has a maximum strengh. Assume the lake water to be very deep.
: (注意:他的要求是"最大"強度的反射係數哦 不是"零"反射係數)
兩邊介質不同 中間厚度 d 為λ'/4 時無反射
此題求"最強反射" 則可以知道當厚度為λ'/2 時 最強反射(by Smith Chart)
f=500*10^6 Hz 則λo =0.6 m(空氣中波長)
λ' = λo /(根號3.2)
d = λ'/2 = 16.77 cm
: (2) What is the ratio of the amplitude of the reflected and incident
: electric fields ? (就是在問反射係數的絕對值 )
: 附連結如下
: http://www.lib.nsysu.edu.tw/exam/master/eng/comm/comm_96.pdf
: 電磁學的第4題
: 卡很久 請神手解惑~ m(_ _)m
反射係數= 後-前 / 後+前 = η3 - η1 / η3 + η1
= - 0.8073
取絕對值 = 0.8073 #
來源: 自己+李長綱題庫本
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