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Richard Clark wrote:
"What is the Q of her mud?" First, the Q of mud is likely less useful than antenna Q. That is, not worth much. Second, Q depends on mud consistency, temperature, location, and frequency of interest. The earth behaves like a lossy capacitor. Above 10 MHz, the capacitnce in ordinary soil bypasses the resistance of the soil. Below 10 MHz, conductance of the soil shunts the capacitance making soil capacitance (permittivity) less important. Soil as a lossy dielectric has a dielectric constant which is defined as the capacitance with dielectric material filling the void versus the capacitance without the dielectric material. Thickness of a mud layer is relevant. At medium wave and lower frequencies, where the earth is mainly resistive, r-f renetration of the earth, not sea water, is so deep that rain wetting has little effect on propagation or refleection. But, at h-f, penetration of the earth is shallow. Water and salt content are significant to penetration and loss. An ideal capacitor is lossless. There`s no dielectric leakage nor conductor loss resistance. Earth is not ideal. Capacitor quality is judged by how much its current`s phase angle deviates from 90-degrees lead of the applied voltage. This deviation angle is called the capacitor`s "phase angle". The tangent of this angle is called the "dissipation factor". The reciprocal of this dissipation factor is the Q of the capacitor. As mud is wet soil, it has Q, but not just one Q value. Best regards, Richard Harrison, KB5WZI |