[題目] 共振腔Q101 Qmax a=d怎推來的@_@

[iyenn (曉風)]

[領域]電磁學

[來源]Dk cheng

[題目]P10.41
A rectangular cavity resonator of length d is constructed
from an axb rectangular waveguide.It is to be operated at
the TE101 mode

a)For a fixed b, determine the relative magnitudes of a
  and d s.t. the Q max


[瓶頸]解答說it will be max when a=d
            which give a max. volume-to-surface ratio. <--這不懂
            a=d時為啥體積/表面積 會最大= =?
      雖然我從Q=wU/P_L 可以理解U  跟體積有關
                               P_L跟表面積有關
            但為什麼a=d時volume-to-surface ratio 會max ,卡這邊>"<

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