Specifications

B-field Exposure From Induction Cooking Appliances 21
B = (
4
5
)
3/2
µ
0
NI
R
(5)
The generated B-fields in the Helmholtz coil are 8.6 µT and 0.86 µT when applying V
out
=
10 V
pp
and 1 V
pp
(peak-to-peak), in the frequency range corresponding to a flat response.
Frequency response The specifications of the Narda probe ELT-400 indicate a flat frequency
response for the frequency range from 30 Hz to 400 kHz. To validate this, the experimental setup
shown in Figure 15 was used. The probe is at a fixed position in the center of the Helmholtz coil,
and the waveform generator applies a sinusoidal voltage, with the frequency stepwise increased
from 1 Hz to 800 kHz (amplitude 10 V
pp
). The frequency response of the Narda probe ELT-400
is shown in Figure 14.
Figure 14: a) Narda probe ELT-400 frequency response, calculated from the frequency responses
of the Narda probe (ω
c
1
= 30 Hz and ω
c
2
= 400 kHz) and the Helmholtz coil (ω
c
3
= 20 kHz),
as well as the frequency responses of the Helmholtz coil system. b) Deviation from the flat
frequency response between 30 Hz and 400 kHz in [dB].
The combined frequency response of the Narda probe (ω
c
1
= 30 Hz and ω
c
2
= 400 kHz) and
the Helmholtz coil (ω
c
3
= 20 kHz) was measured using the Narda probe ELT-400. The frequency
response of the Helmholtz coil system was then assessed by measuring V
R2
as a function of the
frequency (see Figure 13). The frequency response of the Narda probe ELT-400 was calculated