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 by spinning steel belted tires. Poster at

EPRI/DOE Annual Review of on Biological Effects of

V40 T4, VW Golf, VW Toyota Yaris 1.4i,

106 1.1i, and Renault Express. used for exper-

iments defined magnetization also Toyota

Carina, Fiat and Daewoo Matiz. Some of

vehicles were made by friends and never

entered the thereby excluding any influence

of unknown field source the labs them-


rotation frequencies at given were

calculated from the geometries of rims and tires.

measurements at tire surface performed

with the NARDA close to the surface of tires

on a balancing machine and spinning at

speeds between 240 and 360 rpm. distance” refers

to the gap between the of the instrument’s

measuring bulb and the of the tire. Since the bulb

has a of 5.5 cm and the steel inlay of the tires

some millimeters beneath the a surface-to-

surface distance of 1 cm to the 7 cm distance

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 then purposely magnetized and the field

strength was measured at distance from the tire

on a balancing machine. The magnetized

was then mounted in the car and the field

measured when rolling at 80 km at the measuring

location closest to the tire.


Magnetic in cars

Measurements of magnetic at different loca-

tions in the of cars at rest and rolling on

roads are summarized in Table 1. obtained at

position 1 (driver’s in the vehicle at rest with the

stopped were close to noise, typi-

cally below 0.1. maximum

Values obtained in idle with the car stopped

and the motor were measurable but remained

typically in the range 0.1–0.3. at

slightly above 30 Hz. Magnetic measured in rolling

cars, according to FFT, yielded peaks

coinciding with the frequency of the wheels of

10–12 Hz at 80 km and harmonics of it. Fig. 2 shows

a typical FFT reading.

Relatively field values of up to 9.5.

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

the back seat in a number of cases. Table 2 an

overview of the maximum-peak values and

Table 1. Maximum peak in ?T measured in the interior of 12 cars untreated tires in different

positions (1. pelvis, 2. head, 3. foot, 4. back seat). speed 80 km h?1.

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


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