Study of

Electromagnetic Radiation from Microwave oven

using Mathematical Model

Presented by

Kiran Phalak

ID : 6514081

Exactly What?

Characteristics and shape of signal generated

in microwave oven

Different components possessed by signal

Mathematical modeling of microwave oven

signal

What is mathematical model?

Mathematical Equation which represents the

signal response accurately

It contains all the parameter which affects the

behaviour or value of signal

Why to study Interference?

Acts as unintentional antenna for ISM band

technologies

Interference and noise is more due to very

high power

EM radiation are harmful for health of units

working in vicinity

Microwave oven signal

FM

SWEEP

TRANSIE

NT

PULSES

Microwave oven signal

Amplitude

Modulatio

n

Characteristics of Microwave

signal

Carrier frequency of 2.455 GHz

Turns ON during positive half cycle of power

signal

Frequency modulated signal having frequency

sweep proportional to 60 Hz power signal

FM signal has varying power which follows

envelope of 60 Hz power signal

Transient signals which are sinc pulses are at

the start and end of ON period

6 step approach for MWO

model

1. Effective MWO Signal

Periodic signal

C(t) is signal in

one single period

6 step approach for MWO

model

2. Signal during ON time

Transient

Pulse at the

START of ON

period

Transient

Pulse at the

END of ON

period

FM

Sweep

signal

6 step approach for MWO

model

3. Transient Pulse signal

Transient pulse can be represented as

summation of N sinc pulses having

bandwidth parameter b

transient pulses are located at ± Td from

centre of pulse

Pulse has energy is given by function E(fn)

6 step approach for MWO

model

4. Energy function of each pulse

Modified Rayleigh function[1]

N sinc pulses are situated from f1 to fN

These pulses are separated uniformly with

frequency fn

fpk is that sub carrier at which maximum

energy is situated

Fh = fN - fpk

6 step approach for MWO

model

5. AM-FM signal

Ax(t) is instantaneous amplitude of AM-FM

signal

cosine part gives frequency modulation effect

as deviation is proportional to power line

frequency fac

6 step approach for MWO

model

6. Amplitude modulation effect

x(t) shows that amplitude of AM-FM signal is

varying with power line frequency fac

Therefore envelope of signal follows 60 Hz

power signal

MWO model = 13 variables

In short, Microwave oven signal can be

represented by 13 independent variable model

1. fac

2. F1

3. fN

4. Fpk

5. fa

6. fb

7. Tp

8. Ts

9. Td

10. β

11.b

12.E0

13.A

Simulation Results

After scaling down to MHz range and

considering all the variable values of lab

experimental case, Software simulation gives :Effect of FM sweep

Effect of transient pulses

Conclusion

Microwave oven signal is mathematically

modeled through AM-FM model

Maximum radiation frequency from Microwave

oven signal

Simulation results are useful for designing

material for microwave oven

This result is also useful in data

communication technology at ISM to make

system less susceptible to these frequencies

References

[1] J. Proakis, M. Salehi, Communication Systems

Engineering, 2nd ed. Upper Saddle River, NJ: Prentice

Hall, 1994.

[2] T.M. Taher, M.J. Misurac, J.L. LoCicero, and D.R. Ucci,

“Microwave Oven Signal Interference Mitigation For Wi-

Fi Communication systems,” accepted for publication at

Proc. IEEE Consumer Communications and Networking

Conference, Jan. 2008.

[3] http://www.math.ufl.edu/help/matlab-tutorial/

[4] T.M. Taher, A.Z. Al-Banna, J.L. LoCicero, and D.R. Ucci,

“Characteristics of an Unintentional Wi-Fi Interference

Device – The Residential Microwave Oven,” in Proc.

IEEE Military Communications Conference, Oct. 2006.

Questions