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Cecil, W5DXP wrote:
"---isn`t everything moot after Kraus tells us that the antenna coil can cause a 180 degree phase reversal?" Yes. The Kraus example is a resonant circuit of a coil which with its inherent self capacitance which can produce a leading or lagging total impedance, depending on frequency. B. Whitfield Griffith, Jr. demonstrates this with a series LRC circuit on page 108 of "Radio-Electronic Transmission Fundamentals". Total impedance, Zt = R+jomegaL-J/omegaC. Griffith tabulates ZL, ZC, and Zt for 2.4, 2.5, 2.6, 2.7, and 2.8 MHz. R=30 ohms at all frequencies. 2.4 MHz, j226ZL, -265ZC, 30-j39Zt 2.5 MHz, j236ZL, -j255ZC, 30-j19Zt 2.6 MHz, j245ZL, -j245ZC, 30-j0Zt 2.7 MHz, j254ZL, -j236ZC, 30+j18Zt 2.8 MHz, j264ZL, -j227ZC, 30+j37Zt Griffith also gives Zt in polar coordinates but I don`t need to copy that to show that reactance can be either positive or negative in a circuit with both inductance and capacitance. Best regards, Richard Harrison, KB5WZI |
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