Overview

The basic method of electric field measurement, within a wide frequency range, involves the use of a charges' induction in a body illuminated by the field. As shown in Figure 4.1, the electromotive force (emf), e _E, induced by the electric component of the EMF generated by an arbitrary source in a symmetrical dipole antenna of total length 2h is:

Figure 4.1: A symmetrical dipole in a coordinate system.

If the source of the field is the elemental electric dipole placed in the coordinate system shown in Figure 2.4 and the length of dipole 1 fulfils the condition 1 << R ₀, then making use of formula (2.25) we write:

where R = the distance between the point of integration and the center of the coordinate system:

where

• ? = current length of the antenna, ?h ? ? ? h,

• cos ( E, dh) = 1 _E 1 _h

• 1 _E and 1 _h = versors of vector E and h respectively.

Formula (4.2) allows an estimation of the magnitude of emf induced in the measuring antenna while the latter is arbitrarily located in the space relative to the field source. Under further consideration, the formula will be applied for E-field measurement error estimations, specifically for the near-field measurements and for the antenna (E-field probe) directional pattern synthesis.