推 popintaco:β=ω√με√1-(fc/f)^2，當f<<<<fc時候會變虛數 12/09 22:01
推 popintaco:e^j(-jω√με√(fc/f)^2-1) 就會decay了 12/09 22:04
→ popintaco:e^-j( )才對 打錯 12/09 22:06
推 dkcheng:請看最後一句 12/09 22:08
推 popintaco:樓上解答一下吧 12/09 22:31
(4%)Let us neglect possible absorption within rectangular metallic waveguides.
A propagating electromagnetic wave shows dacay along the waveguiding direction
if its frequency is smaller than the cut-off frequency. Please give the
physical insight why the magnitude of the wave shows decay or attenuation.
No credit will be given if you use any equation or mathematical expression
here.
這題才4分
考觀念
可是想不到
誰會呢 ?
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