偏心饋電諧振偶極子的阻抗是多少?


3

給定一個約0.48個波長的偶極子,這樣當饋入中心時,饋電點阻抗具有零電抗,當饋電點移離中心時,複數阻抗如何變化?

5

Both the real and the imaginary terms of the complex impedance across the feedpoint terminals will change as the feedpoint moves away from the electrical center of the antenna.

As an example, a NEC4.2 calculation for a nominally 1/2 wavelength radiator in free space when the feedpoint is located 0.05 wavelengths from one end is about 1340 -j1100 Ω.

A center-fed, nominally 1/2-wavelength dipole at first self-resonance in free space has a feedpoint impedance of about 65 ±j0 Ω.


4

Using a NEC-2 model, here's how R and X of a free-space 20-meter dipole made from #14 copper wire vary with feedpoint position (50 = center fed; 0 = end fed):

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