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<blockquote data-quote="Aki_Megumi" data-source="post: 739876">In a coaxial cable, we are familiar with the capacitance per unit length between the two metal conductors, which is given by C=(2pi epsilon)/log(r/R). However, in my circuit design, the static mutual capacitance between the metal in the coaxial cable and the surrounding environment increases the power transmission losses. Therefore, I want to understand the magnitude of this stray capacitance.According to electrostatics theory, an ideal infinitely long coaxial cable (infinite cylinder) should not produce any electric field outside the conductor. Does this mean that after adding other electrically neutral metals in space, the electric field in the space still remains zero everywhere? (Uniqueness theorem? I&#039;m not sure.) Can we deduce from this that there is no mutual capacitance between the metal in the coaxial cable and any electrically neutral metal in the surrounding space? And can this be extended to practical non-ideal coaxial cables, where the mutual capacitance with environmental metals is expected to be very small in magnitude?I apologize for the many questions here. I greatly appreciate any replies, guidance, and discussions. Thank you.</blockquote>

[QUOTE="Aki_Megumi, post: 739876"] In a coaxial cable, we are familiar with the capacitance per unit length between the two metal conductors, which is given by C=(2pi epsilon)/log(r/R). However, in my circuit design, the static mutual capacitance between the metal in the coaxial cable and the surrounding environment increases the power transmission losses. Therefore, I want to understand the magnitude of this stray capacitance. According to electrostatics theory, an ideal infinitely long coaxial cable (infinite cylinder) should not produce any electric field outside the conductor. Does this mean that after adding other electrically neutral metals in space, the electric field in the space still remains zero everywhere? (Uniqueness theorem? I'm not sure.) Can we deduce from this that there is no mutual capacitance between the metal in the coaxial cable and any electrically neutral metal in the surrounding space? And can this be extended to practical non-ideal coaxial cables, where the mutual capacitance with environmental metals is expected to be very small in magnitude? I apologize for the many questions here. I greatly appreciate any replies, guidance, and discussions. Thank you. [/QUOTE]

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