Antenna Theory - Effective Aperture & Directivity Of A Short Dipole Antenna.



Consider a plane wave incident on a short dipole. The wave is assumed to be linearly polarized with electric field in the y direction. The current in the dipole is assumed constant and in the same phase over its entire length, and the terminating resistance is assumed equal to the dipole radiation resistance.


The effective aperture of this dipole is given by
Ae = 0.119 λ


The directivity is found to be
D = 4ΠAe / sq (λ)






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