Download Cost 286 Split, Electromagnetic Coupling

EMC Europe Workshop 2005
Electromagnetic Coupling between Mobile
Wireless Devices and Wiring Systems
in Vehicles
Yaping Zhang, John Paul, Christos Christopoulos
( George Green Institute for Electromagnetic Research
University of Nottingham, Nottingham NG7 2RD, UK )
Outline
• Evolution of the Mobile Phone Technologies
• Concerns over the Mobile Phones’ Adversary
Effects and positive Solution
• Simulation Configurations and Simulation Models
• Simulation Results
• Conclusions
Evolution of the Mobile Phone Technologies
• Over the last two decades, mobile phones have evolved from
simple single-channel two-way radios and text messaging
devices to advanced multifunctional multimedia and
entertainment marvels.
• In recent years, wireless communication has experienced an
explosive growth globally, considerable worldwide interest in
the development of nomadic wireless devices brought about a
new generation of 3G mobile phones and related networks.
• The new generation mobile phones not only support the basic
voice service in multiple frequency bands, but also support
high-speed data, multimedia applications, global positioning
system (GPS) location technology and Bluetooth (BT) wireless
connectivity.
Concerns Over the Mobile Phones’
Adversary Effects and Positive Solution
• CONCERNS:
• Adverse direct coupling to, and possibly malfunctioning of,
the control, sensor and communication devices interconnected
through cables and wires.
• Adverse impact on the electromagnetic (EM) noise floor of
environments densely populated with such devices.
• POSITIVE SOLUTION
• It is highly desirable to assess the level of coupling between
such systems and therefore offer the capability to designers of
estimating the risk of malfunction and the effectiveness of
proposed remedies using computer aided design (CAD) tools.
Introduction to the Simulations
• Simulations of mobile phone electromagnetic
coupling to a typical long thin wire inside a vehicle
were carried out for the cases with and without a
passenger.
• Results presented in this paper are obtained at mobile
phone frequency of 900 MHz by sinusoidal excitation,
and compared with Fast Fourier Transform (FFT)
analyses of the electromagnetic coupling of a dipole
antenna to a thin wire excited by a Gaussian source,
with a halfwidth of 0.556 ns. .
Introduction to the Simulations (I)
• The vehicle is 6m long, 3m wide and 2m high, with 8
windows. One is in the front, one is in the back, and three are
on each side in the longitudinal direction (schematically shown
in Fig. 1).
• The front and back windows are 2.33m wide and 1.667m
high. The windows on both sides in the longitudinal direction
are 1.5m wide and 1.33m high (Fig. 1)
• The dielectric material properties of the human are selected
as  r' 56,  e 1 S m . These properties are representative of
biological tissues at 900 MHz.
Configuration of a Simulated Vehicle
Fig. 1 Schematic configuration of a simulated vehicle
Introduction to the Simulations (II)
• A thin wire, 5 m long, of 2 mm diameter, is parallel to, and 5 cm
from the top plane of the vehicle. It is open at one end and
terminated by a load of 150 Ohms at the other to the top plane. The
wire junction is 1 m from the back plane on the origin side ( Fig. 2).
• A passenger with a mobile is sitting underneath the thin wire, with
the mobile antenna perpendicular to the thin wire. The center of the
dipole is 18 cm directly below the thin wire junction end. The
passenger is located centrally above the bottom plane of the vehicle
in the z-direction, facing the front in the x-direction (Fig. 2).
• The mobile phone is held against the ear. The cross section of the
simulation model in the y-direction is schematically shown in Fig. 2.
The cross section of the simulation model in the x-direction is
schematically shown in Fig. 3.
Cross section of the simulation model in the
y-direction
Fig. 2 Cross section of the simulation model in the y-direction
Cross section of the simulation model in the
x-direction
Fig. 3 Cross section of the simulation model in the x-direction
Introduction to the Simulations (III)
• Simulations are carried out on a Compaq ES45
Workstation with 1.2GHz CPU, Running TRU64 UNIX.
• For the TLM simulation results presented in this paper,
the mesh size is chosen as 1.67cm. The numbers of nodes
are: Nx=360, Ny=120, Nz=180.
• The numbers of time steps for a sinusoidal and a Gaussian
excitations are NT=16000, and NT=16384, respectively.
• The typical calculation times for a Sinusoidal and a
Gaussian excitations are 388126 seconds and 417564
seconds, respectively.
Simulation Results by Using of 900 MHz
Sinusoidal Excitation Source (I)
The voltages across the load with and without a passenger inside
a vehicle are shown in Fig. 4 (a) and (b), respectively.
(a)
(b)
Fig. 4 Voltages across the load inside a vehicle: (a) with a passenger;
(b) without a passenger.
Simulation Results by Using of 900 MHz
Sinusoidal Excitation Source (II)
The magnetic field distributions in the x-y plane inside a vehicle
with and without a passenger are shown in Fig. 5 (a) and (b),
respectively, with the range of 40 dB from peak to minimum in
the plots.
(a)
(b)
Fig. 5 The magnetic field distributions in the x-y plane inside a
vehicle: (a) with a passenger; (b) without a passenger.
Simulation Results by Using of 900 MHz
Sinusoidal Excitation Source (III)
The maximum currents along the thin wire for the cases with and
without a passenger inside a vehicle are compared and shown in
Fig. 6.
Fig. 6 Comparison of the maximum currents along the thin wire .
Simulation Results by Using of 900 MHz
Sinusoidal Excitation Source (IV)
The maximum currents along the thin wire for the cases with and
without a passenger, and with 4 passengers in front of each other
in Fig. 2 with 50 cm space between them inside a vehicle are
compared and shown in Fig. 7.
Fig. 7
Simulation Results by Using Gaussian
Excitation Source (I)
The voltages across the load with and without a passenger inside
a vehicle are shown in Fig. 8 (a) and (b), respectively.
(a)
(b)
Fig. 8 Voltages across the load inside a vehicle: (a) with a passenger;
(b) without a passenger.
Simulation Results by Using Gaussian
Excitation Source (II)
The ratio of the FFT voltage across the load, to the FFT voltage at
the gap of a dipole as a function of frequency, for the cases with
and without a passenger inside a vehicle, are compared and shown
in Fig. 9.
Fig. 9
Simulation Results by Using Gaussian
Excitation Source (III)
The ratio of the FFT voltage across the load, to the FFT voltage at
the gap of a dipole as a function of frequency, for the cases with
and without a passenger, and with 4 passengers inside a vehicle,
are compared and shown in Fig. 10.
Fig. 10
Conclusions
• Electromagnetic couplings of a mobile phone to a typical long thin
wire inside a vehicle are simulated for the cases with and without a
passenger inside a vehicle.
• Simulation results are further compared with those of 4 passengers
inside a vehicle.
• Materials with electrical properties resembling those of humans
inside vehicles are described.
• Very long run time has been used in the simulations for both
Sinusoidal and Gaussian excitations in order to achieve convergence.
• Simulation results show that the passenger inside a vehicle has
some impact on the level of the electromagnetic coupling of a mobile
phone to a typical long thin wire.