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Roy, W7EL wrote:
"---feedpoint impedance of 35-j370 at 3.8 MHz. Choose an inductor value and let me know what the output : input current ratio would be for that inductor at the base of the antenna. Assume that the inductor is physically small." I`ll assume the inductor has no resistance, loss or radiation. No loss or radiation means the inductance only delays current in the antenna circuit by the phase angle impedance makes with resistance in the circuit. We need 370 ohms of inductive reactance to counteract the capacitive reactance of the too short antenna. That calculates to 10.926 microhenry. The current into the resonant antenna circuit is E/R = E/35 The current into the too short antenna alone is E/Z = E/ 371.65 The output : input ratio of the inductor is very nearly one because the coil is lossless and its size is insignificant in terms of wavelength. Best regards, Richard Harrison, KB5WZI |
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