[理工] [電磁]極化

[big1p (biglp)]

1.The electric field of a uniform plane wave propagating in free space is

given in phasor form by

                     _      _      _      _   j(0.6y-0.8z)
                     E = 10(ax+j0.4ay+j0.3az)e


What is the polarization of this wave ?



2.In air, the magnetic field of a wave is given by

                     _   _
                     H = aycos(x)sin(ωt-βz)


(a).Assuming the wave travels in positive z direction, determine the

propagation constant, electric field, and frequency.

(b).What is the polarized direction of the wave ?

(c).Explain why this wave is not circularly polarized.


第一題有三個方向不知道怎麼判斷

第二題多一個cos(x), 不知道怎麼下筆

煩請各位了


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推 akisora:先說我也不知道對不對QQ　第一題可以看出波的前進向量為
→ akisora:-0.6ay+0.8az　因為極化場的判別是從波前進的地方看進去
→ akisora:所以和電場取內積　會發現y及z分量=0　內積=0代表垂直
→ akisora:邊想邊打　結果卡住了= =　歹勢睡個覺起來再想想
推 deathlightx:幫樓上補充 把ax外積(0.8ay+0.6az)等於行進方向
→ deathlightx:極化為5(2ax+j(0.8ay+0.6az))
→ deathlightx:把偏振想成2ax+jay 行進方向az x-y = -pi/2
→ deathlightx:所以為左橢圓偏振
推 akisora:感謝樓上QQ　躺到一半想到爬起來補充　因為-0.6ay+0.8az
→ akisora:和ax及j0.4ay+j0.3az兩個向量都垂直　所以原本課本裡面的
→ akisora:az>-0.6ay+0.8az
→ akisora:ax>j0.4ay+j0.3az　ay>ax
推 akisora:...　我還是回去睡覺好了
推 akisora:就變成像j1/2ax+ay振幅　前進方向在az的波的型式
推 akisora:第二題多的cos(x)是振幅項　磁場還是只有單方向所以線極化
→ big1p:先研究一下..
→ akisora:我上面的想法　主要是把原本的座標軸　整個移動疊到題目的
→ akisora:波上　然後就像課本一樣分析了
→ sneak: 所以和電場取內積　會發 https://daxiv.com