Exposure at Ground Level
Several methods can be employed to determine the EME exposure at ground level. Such an
assessment is not necessary if the mounting height of the antenna is larger than the compliance
distance in front of the antenna, computed using the EN50383:2010 methodology outlined in
Exposure in Front of the Antenna on page 155. If this is not feasible, then the following approach can
be employed.
At ground level exposure occurs in the antenna far-field. The antenna phase center is assumed to be
the mounting height. The resulting predictive equation for the power density is:
where is the elevation gain pattern, which is approximated by the following expression:
where is the free-space wavenumber and L is the effective antenna length yielding
the appropriate vertical beamwidth, while H is the antenna height above ground and d is the point of
interest (POI) distance from the vertical antenna projection to ground (see Figure 101: Schematic of
the ground-level exposure model adopted for the assessment on page 157 ). The multiplicative factor
2.56 is introduced to enforce near-perfect, in-phase ground reflection as recommended in [2]. In this
case, spatial averaging is not carried out to make the EME exposure assessment more conservative.
Figure 101: Schematic of the ground-level exposure model adopted for the assessment
Appendix F : MOTOTRBO Repeater – EME ASSESSMENT
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