Low frequency magnetic fields induced by car tire magnetization. — ResearchGate

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Toyota Carina ff

Low frequency magnetic fields by car tire magnetization.

Page 1



Stefan Andreas Kessi,* Olivier Be Karl Meier-Engel,* and


Abstract—Alternating magnetic fields been measured in a

variety of cars, the dominant contribution from

magnetized tires. field strengths have measured

as a function of frequency at the tires and at different

positions in cars. Measurements at the tires

field strengths up to 100 microtesla In the interior of

rolling cars, to the wheels at foot regions and at the

seat, field strengths of ?T were obtained in the 10–200

Phys. 90(2):148–153; 2006

Key magnetic fields; radiation, exposure,

radiation; radiation


IN THE present study, low magnetic fields were

at different positions in the interior of

vehicles at rest and when at defined speeds. The

main field contribution could be to the

steel-belted tires: fields are at measuring spots

close to the and spectral peaks of the alternating

correlate with the wheel frequency, inde-

pendent of aluminum or steel rims. findings

correlate with reported by other groups

1996; Jacobs et al. 1998‡; et al. 1999). Milham et

al. (1999) had tire magnetization by cutting

and using iron filings on a put on the sections.

In the present study, fields were measured by

a field sensor very to the surface of

Magnetic fields measured using a NARDA

Electromagnetic Field Analyzer with a

BN2245/90.10 field (Telemeter Electronic, El-

lighausen, The instrument uses three

ing coils at right angles to other to intercept fields of

direction. Spectral analysis of mean square

(rms) was performed in Fast Fourier

(FFT) mode at 1 hertz spectral resolution in the 5 to

2000 Hz

In the present study, magnetic are character-

ized using two parameters of the FFT spectrum:

the highest in the rms spectrum (“maximum-peak

value”) and the sum of all values in the rms

spectrum between 5 and 200 Hz of peaks”).

Magnetic fields in the of a car were deter-

mined at the locations (Fig. 1):

1. Driver’s region;

2. Driver’s head

3. Driver’s or co-driver’s foot

4. Back seat (pelvis of person in back seat).

were done in vehicles at and

when rolling at defined on public roads. The

following were used in the survey: BMW

Ford Focus 1.8, Mondeo Trend 2.0, Astra 1.6,

Opel 1.2, Opel Zafira Volvo V70 D5, Volvo

* Berne of Applied Sciences at Biel, 21,

CH-2500 Biel, Switzerland;†Swiss Office of Public Health,

‡Jacobs WL, Dietrich FM, Feero WE, A. Assessment of

magnetic fields produced by steel belted radial Poster at

EPRI/DOE Annual of Research on Biological Effects of

V40 T4, VW VW Polo, Toyota Yaris Peugeot

106 1.1i, and Renault Vehicles used for exper-

with defined magnetization included Toyota

Carina, Punto, and Daewoo Matiz. of these

vehicles were available by friends and never

the laboratories, thereby excluding any

of some unknown field within the labs them-

Wheel rotation frequencies at speed were

calculated the known geometries of rims and

Direct measurements at tire were performed

with the instrument close to the surface of

mounted on a balancing machine and at defined

speeds between 240 and 360 “Close distance” refers

to the gap the surface of the instrument’s

measuring and the surface of the tire. Since the

has a radius of 5.5 cm and the steel inlay of the lies

some millimeters the profile, a surface-to-

surface distance of 1 cm corresponds to the 7 cm

between the center of the measuring and the steel

inlay of the tire. The value has been used

analyzing distance dependencies. tires were

Toyota Carina ff

from the brands: Good Year, Pirelli,

Michelin, Firestone, and Nokian.

Tires were by using a self-made instru-

consisting of a coil of 1,200 with iron

core, metal wings 80 mm. 160 mm (Fig. 1).

a 50 Hz AC current, it was slowly removed by

from the tire spinning on a machine.

Tires were magnetized by bringing the

“degaussing attached to a 12 V battery near to the

of the tires. Magnetic field obtained close

to the surface of tires were 50–75

(?T) with a single of the DC coil and 75–150

with two at opposite parts of the wheel.

In to investigate the influence of tire

tization on the magnetic fields in a all tires of a given

car were demagnetized. One particular tire

was purposely magnetized and the magnetic

strength was measured at close from the tire

spinning on a machine. The magnetized tire

was mounted in the car and the field strength

when rolling at 80 km h?1, at the

location closest to the magnetized


Magnetic fields in

Measurements of magnetic fields at loca-

tions in the interior of at rest and rolling on public

are summarized in Table 1. Values at

position 1 (driver’s pelvis) in the at rest with the

engine were close to instrumental typi-

cally well 0.1. maximum peak.

obtained in idle mode, the car stopped

and the motor running, measurable but remained

low, in the range 0.1–0.3. at frequencies

above 30 Hz. Magnetic fields in rolling

cars, analyzed to FFT, yielded spectral

coinciding with the spinning of the wheels of

10–12 Hz at 80 km h?1, and of it. Fig. 2 shows

a typical FFT

Relatively high field of up to 9.5. were

obtained in the or co-driver’s foot regions and at

the seat in a large number of Table 2 gives an

overview of the values and sum-of-peaks

Table 1. peak values in ?T measured in the of 12 cars with untreated in different measuring

positions (1. 2. head, 3. co-driver’s foot, 4. seat). Rolling speed 80 km

Toyota Carina ff
Toyota Carina ff
Toyota Carina ff
Toyota Carina ff

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