The Physics and Mathematics of Electromagnetic Wave Propagation in Cellular Wireless Communication by Mohammad Najib Abdallah & Magdalena Salazar Palma & Tapan K. Sarkar

Author:Mohammad Najib Abdallah & Magdalena Salazar Palma & Tapan K. Sarkar [Mohammad Najib Abdallah]
Language: eng
Format: epub
Publisher: Wiley-IEEE Press
Published: 2018-07-17T16:00:00+00:00

The conclusion is that when D >> λ, the reactive near field region is from 0 to , and the radiating near field region is from to 2D2/λ, and then the far field starts after 2D2/λ. This is true for D >> λ only.

Observing the results given in (2A.10) and (2A.12), we see that the far E and H fields decrease as the inverse of the distance for an antenna radiating in free space. Furthermore, the electric and the magnetic far fields are in space quadrature but they are coherent in time. The fields form a locally plane wave, and the ratio ; where η is the intrinsic impedance of the medium. This concludes the discussion for the derivation of the various subtleties in the near and far fields of an antenna.

It is interesting to observe again the patterns of the array given by Figures in 2A.1. For a distance the antenna pattern is close to an omni directional antenna as seen in Figure 2A.1a, when r is between and 2D2/λ the antenna pattern is beginning to take shape as seen in Figure 2A.1b, and finally when r > , one is in the far field and the antenna radiation pattern is given by Figure 2A.1c.

Next we observe the angular variation for the criteria to be in the far field.

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