**5.2 Radiation from small dipole**

The length of a small dipole is small compared to its wavelength and is called elementary dipole. The current along a small dipole is uniform. We can compute the electromagnetic fields radiated from the dipole in spherical coordinates by using the potential function given in Eq. (1). The electromagnetic field at a point P(r, θ, φ) is listed in Eq. (3). The electromagnetic fields in Eq. (3) vary as <sup>1</sup> *<sup>r</sup>* , <sup>1</sup> *<sup>r</sup>*<sup>2</sup> , <sup>1</sup> *<sup>r</sup>*3. For r < < 1, the dominant component of the field varies as <sup>1</sup> ð Þ*<sup>r</sup>* <sup>3</sup> and is written in Eq. (4). These fields are the dipole near fields. In the near field, the waves are standing waves and the energy oscillates in the antenna near zone and is not radiated to the free space. The real part of the pointing vector equals to zero. At r >> 1, the dominant component of the field varies as 1/r as written in Eq. (5). These fields are the dipole far fields. In the far fields, the electromagnetic fields vary as <sup>1</sup> *<sup>r</sup>* and sinθ. Wave impedance in free space is given in Eq. (6).
