Image Theory of an Antenna

Discussion in 'Homework Help' started by xz4chx, Feb 11, 2015.

  1. xz4chx

    Thread Starter Member

    Sep 17, 2012
    An infinitesimal electric dipole of length l = λ/50 is placed horizontally at a
    height of h = 2λ above a flat, smooth, perfect electric conducting plane which
    extends to infinity. It is desired to measure its far-field radiation characteristics
    (e.g. amplitude pattern, phase pattern, polarization pattern, etc.). The system
    is operating at 300 MHz. What should the minimum radius (in meters) of the
    circle be where the measurements should be carried out? The radius should
    be measured from the origin of the coordinate system, which is taken at the
    interface between the actual source and image.

    I know that far field in books calculates the far field area as (2D^2)/λ

    How is this effected with the image theory of a PEC?
    I assume that the D (maximum dimension of antenna) is different then λ/50 because of the image theory effect.

    But how exactly is this effected and a little more concept information would be nice.

    Thank you

    r = (2D^2)/λ
    λ = 3*10^8/3*10^8 = 1 m

    2(D^2)/1 = r