Simulation of 3D Global system mobile radiation from dipole antenna ...

IUG Journal of Natural Studies Peer-reviewed Journal of Islamic University-Gaza

Simulation of 3D Global system mobile radiation from dipole antenna by FDTD method

IUGNES Special Issue, March, 2017, pp 329-337

ISSN 2409-4587

Khitam Y. Elwasife1 , Mariam A. Abutailkh2 1,2Physics

Department, Islamic University of Gaza, P.O. Box 108, Gaza, Palestine. * Corresponding author e-mail address: [email protected]

Abstract:

In this work, The antenna is made to resonate at the 900 MHz. Matlab program is used for the simulation and design calculations of the half wave dipole antennas. In the antenna radiation simulation, a full-wave method of a three dimensional finite difference time domain (FDTD) method is employed to study. Numerical results of antenna for global system mobile (GSM) radiation characteristics with 900 MHz have been evaluated, The electric field, magnetic field and radiation patterns are also presented..

1. Introduction An antenna is a device for radiating and receiving electromagnetic fields. It is the component between free space and a wave-guide (Fransson, 2001) and (Singh, Sharma, Uniyal, & Kala, 2012), A dipole antenna has an easy structure and consists normally of just a metal wire with a specified length depending on the wavelength. For a half wave dipole the length of the dipole should be half of the wavelength. The dipole antenna consists of two poles into which radio frequency current flows. This current and the associated voltage causes and electromagnetic or radio signal to be radiated. The FDTD method which used their numerical values are applied to several planar antennas,(Wakabayashi, Southisombath, Sakurai, & Matsui, 2006) . numerical supposed in analysis of planar antennas using the FDTD method are considered by(Kokubo, Matsui, & Wakabayashi, 2006) K. Niikura et al, they found for a (PDA) planar dipole antenna, if using FDTD method, it is important to decide the number of layers of the

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Keywords: Global System Mobile-FDTD-Simulation. Dipole antenna

PML and the distance between the antenna and the wall of the analytical area. If they are decided appropriately, the computational time and memories are saved. Therefore, the relation between them is discussed also by author of paper(Niikura, Kokubo, Southisombath, Matsui, & Wakabayashi, 2007).The results obtained by using FDTD numerically are compared with other experimental results in many research. The effects of different antenna parameters on the resonant frequencies, the frequency ratio, and radiation pattern characteristics of the antenna has been studied by (Gao, Li, & Sambell, 2005). (Homsup, Jariyanorawiss, & Homsup, 2014)placing a one metal cell closed to a mobile phone, the mobile phone was modeled by a dipole antenna, the simulation uses Finite Difference Time Domain (FDTD) and its domain is divided into two parts: the physical domain and the artificial domain.

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The physical domain consists of a dipole antenna located at 1 cm from a human head model. A radiation pattern of dipole antenna is proposed by(Kang, Park, & Yoon, 2008), they controlling the switch states, the antenna can be worked a dipole antenna with reflector, which has directional radiation pattern. Detailed design considerations of the proposed antenna, simulated and experimental results are presented and discussed in their research. In this work we study the antenna radiation simulation, a full-wave method for three dimensional finite difference time domain (FDTD) method is employed to study. Numerical results of antenna for global system mobile (GSM) radiation characteristics have been evaluated, the electric field, magnetic field and radiation pattern can be describe by power radiated through the antenna, which depends on the direction, and it can be represented as graphical or mathematical function of the radiation properties. Also the radiation patterns have been presented.

2. Model and method A dipole antenna is a simple antenna that evaluated from electrical wire. The most common dipole antenna is a half wave dipole which is constructed from a piece of wire half wavelength long. The wire is split in the center to connect the feeding wires. In our work we suppose a simple antenna as shown in figure (1).

Khitam Y. Elwasife , Mariam A. Abutailkh2

Figure 2 The Yee’s cell represent Electric and magnetic field. It consists of two metal rod.a dipole antenna functions by having current run through the arm. The source is choice as sinusoidal wave with angular frequency= 2 f , also we consider a dipole antenna has the length L= λ/2 ,where λ=c/f. The feeding gap g=0.3522mm. In this work the feeding impedance of 73 ohms is being used as in research for (Singh et al., 2012) and the antenna is designed for the resonating frequency of 900 MHz FDTD method is described in details by Yee's cell as shown in the figure (2)(Balanis, 1997) In our analysis we suppose that the time step dt is given by the following Courant stability condition,

dt 

1 1 1 1 c ( )2  ( )2  ( )2 dx dy dz

velocity of light in the free space. Maxwell's equation is defined as:

D 1  . H . (1) t  0 0 where

Figure 1 Half wave dipole antenna

D ( )   r ( ).E ( ) . (2)

H 1  .  E . (3) t  0 0

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, where c is the


Equations (1) and (3) produced six scalar equation as

H y D x H 1  ( z  ) t z  0 0 y D y

(4.b )

H y H x D z 1  (  ) t y  0 0 x

(4.c )

t

1

 0 0

(

E y E z H x 1  (  ) t y  0 0 z

.(4,5)

Where L is the length of antenna, k is propagation constant=

(5.a )

2



, and η is the impedance of free space.

D ( )   r ( ).E ( ) We take the finite difference time domain formula to have equations (4.c) and (5.c)

3. Results and discussion

As

In our calculations we use the dipole formula to have the length of dipole as

E z E x  ) x z

(5.b )

E y H z E 1  ( x  ) t x  0 0 y

(5.c )



t

1

 0 0

(

1 n 1 1 (i , j , k  )  D z 2 (i , j , k  ) 2 2 t 1 1 1 1 n  (H y (i  , j , k  )  H yn (i  , j , k  ) 2 2 2 2 x .  0 0 n

  . (8)   

The FDTD is specified of the metal arm of dipole antenna. We simulate equation (6) and equation (7) by software program as matlab to have many results. The half-wavelength dipole is the most common length of antenna used in many applications. The coordinate system that is used in this work is taken from(Balanis, 2016)

H y

Dz

figure s as shown below in a plane along the axis of the antenna. The exact E-field can be calculated as: kL kL  cos( cos  )  cos j  I 0e  jkr  2 2 E   2 r  sin  

(4.a )

H x H z  ) z x




1 2

1 1 1 1 (H yn (i , j  , k  )  H yn (i , j  , k  )) 2 2 2 2

.(6)

1 1 1 1 H zn 1 (i  , j  , k )  H zn (i  , j  , k )  2 2 2 2 1 1 n  n  t 1 1 (E y 2 (i  1, j  , k )  E y 2 (i , j  , k ) .(7) 2 2 x .  0 0 n

E y

1 2

1 n 1 1 (i  , j  1, k )  E y 2 (i  , j , k ) 2 2

Furthermore, the electric field of the antenna has a circular pattern along a plane which cuts the axis of the antenna perpendicularly and is similar to a

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L /2 which resistance density =73.13, and the wavelength =.333m. To simulate an antenna in free space, no substrate should be used and the only layer below the metal layer should be Airbelow. Both the top and bottom cover should be set to electrical type, with surface impedance set to 377 ohms. (η=377 ohms is the intrinsic impedance of free-space). In figure (3) shows antenna pattern radiation, it is electric and magnetic field strength virus angular direction (θ, Ф ) at fixed distance from the antenna, its theta equal 3600 .Furthermore , The electric and magnetic field also plots for different angle as in figure(3). In the obtained curves we plot the electric field in x,y,z direction in term of D (x,y,z) where D= E*ε, and magnetic field in term of H(x,y,z) of dipole antenna for many time steps. In a phased radiation, each element is driven independently on phase and amplitude. The angular pattern depends on the phase shift between the




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elements. The concept has been applied for antenna structures in the global system mobile, using an dipole antennas as evaluated by(Kang et al., 2008) and (Dregely et al., 2011). Electric field Pattern of a Dipole Antenna is shown in figures below where figure (4) illustrate electric field Pattern of a Dipole Antenna with theta =180o, figure (5,6) by using theta = 90o and 60o respectively , we show that the figures is true inside an area at a more distance from the antenna known as the far-field of the antenna. Closer to the antenna i.e. in the near-field the E-field expression is more complex. The plots show the numerically calculated directivity for dipole antenna signal. The calculated directivity of the x-y plane is plotted in figures (7, 8, 9, 10), and for the y-z plane in figures (11, 12, 13). The antenna is fed by a dipole with a dipole moment along the xdirection. The emitted frequency of the dipole is 900MH Figure( 7,8,9,10 ) represent Simulation of Electric field of dipole antenna in z-direction at different time steps as 10,30,100 respectively, frequency=900MHz,PML=3, and t0=20. Again we plot many curves which shown the electric filed in x-direction and y- direction as shown below in figure (11,12,13) The magnetic field Simulation of dipole antenna in X- direction at time steps=30,frequency=900MHz,PML=3, and t0=20 is plotted in Figure (14), also many curve have been plotted in different time steppes as in figure (14,15, 16) .in figure (18) electric field simulation in z direction of dipole antenna at time step s= 30. By change the time steps we can run the program and plot another curve with different time steps as in figure (19, 20). And final we plot the radiation Pattern of half wavelength dipole.

8

120

60 6 4

150

30

2

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0

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300 270

Figure 4 Electric field Pattern in dipole antenna theta =180o 90

8

120

60 6 4

150

30

2

180

0

210

330

240

300 270

Figure 5 Electric field Pattern in dipole antenna theta =90o 90

8

120

60 6 4

150

30

2

180

0

210

330

240

300 270

Figure 3 Electric field Pattern in dipole antenna theta= 3600 992



90


6

120

60 4

150

30 2

180

0

210

330

240

300 270

Figure 6: Electric field Pattern in dipole antenna theta =60o

Figure 8: Simulation of electric field of dipole antenna in z-direction at time steps=30,frecuency =900MHz, PML=3, and t0=20

Electric field in z direction at time step = 80

Electric field in z direction at time step = 10

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0.8 1.2 0.7

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Figure 7: Simulation of Electric field of dipole antenna in zdirection at time steps=10,frequency=900MHz,PML=3, and t0=20

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40


Figure 9: Simulation of Magnetic field of dipole antenna in z-direction at steps=80,frequency=900MHz,PML=3, and t0=20



dy at time step = 80

0.3 0.4

Electric filed in zdirection at time step = 100

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Figure 12: Simulation of Electric field as a function of permittivity of dipole antenna in y-direction at time steps=80,frequency=900MHz,PML=3, and t0=20

Figure 10: Simulation of Electric field of dipole antenna in z-direction at time dz at time step = 80

steps=100,frequency=900MHz,PML=3, and t0=20

0.9 0.8

1.2

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1

dx at time step = 80

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Figure 11: Simulation of Electric field as a function of permittivity of dipole antenna in X-direction at time steps=80,frequency=900MHz,PML=3, and t0=20

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0


Figure 13: Simulation of Electric field as a function of permittivity of dipole antenna in z-direction at time steps=80,frequency=900MHz,PML=3, and t0=20



-3

hx at time step = 80

x 10 6

magneyic field in x direction at time step = 30 0.015

0.02

0.01

4

0.005

2

0

0

-0.005

-2

0.01

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0.005

0 0 -0.01 -0.005

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-0.02 40 30

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20

10

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10 0

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Figure 16: Simulation of magnetic field of dipole antenna in X- direction at time steps=80,frequency=900MHz,PML=3.

Figure 14: Simulation of magnetic field of dipole antenna in X- direction at time steps=30,frequency=900MHz,PML=3, and t0=20 -3

hy at time step = 80

x 10

6 1.4

x 10

-6

Electric Field of dipole antenna at theta =30

0.01 4 0.005

1.2

1

2 0

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0 0.6

-0.005 -2 -0.01 40

0.2

40 -4

30 30

20 20

10

10

0

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1

1.5

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2.5

-6

0 0

Figure 15 Simulation of magnetic field of dipole antenna in Y- direction at time steps=80,frequency=900MHz,PML=3, and t0=20

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0.4


Figure 17 Electric field of dipole antenna at theta =30o

3

3.5



Ez in the XZ plane at time step = 100


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Figure 18 Electric field in z direction of dipole antenna at time steps 30

0

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100

0

90

-10

80

Radiation pattern of half wavelength dipole -20

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z axis

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-0.5


-0.3

-0.8 x axis

Figure 21 Radiation Pattern of half wavelength dipole

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-0.2

0


.

Figure 22 Electric and magnetic field of dipole a ntenna at theta =60o

Conclusion Numerical results of antenna for global system mobile (GSM) radiation characteristics with 900 MHz have been evaluated; The electric field, magnetic field and radiation patterns are also presented using finite difference time domain method (FDTD). FDTD method can use to study correction factor for the near field case very efficiently. This technique , also, extended to determine the antenna factor of other types of antennas or to study the time domain characteristics of any trans-receive Antenna System(Ghosh & Chakrabarty, 2006)


Homsup, N., Jariyanorawiss, T., & Homsup, W. (2014). FDTD Simulation of a Mobile Phone Operating near a One Metal Cell. Paper presented at the Proceedings of the World Congress on Engineering and Computer Science. Kang, W., Park, J., & Yoon, Y. (2008). Simple reconfigurable antenna with radiation pattern. Electronics Letters, 44(3), 1. Kokubo, R., Matsui, H., & Wakabayashi, T. (2006). Consideration of analytical parameters in FDTD method for planar antenna analysis. Proc. of 2006 KJJC, EMT-4, 12, 417-420. Niikura, K., Kokubo, R., Southisombath, K., Matsui, H., & Wakabayashi, T. (2007). On analysis of planar antennas using FDTD method. PIERS Online, 3(7), 1019-1023. Singh, P., Sharma, A., Uniyal, N., & Kala, R. (2012). Half-Wave Dipole Antenna for GSM Applications. International Journal of Advanced Computer Research (ISSN (print): 2249-7277 ISSN (online): 2277-7970), 2. Wakabayashi, T., Southisombath, K., Sakurai, K., & Matsui, H. (2006). Miniaturization and broadband characteristics of E-type planar antennas for mobile communications. WSEAS Transactions on Communications, 5(9), 16041611.

References Balanis, C. A. (1997). Analysis and Design, Antenna Theory: John Wiley & Sons, New York. Balanis, C. A. (2016). Antenna theory: analysis and design: John Wiley & Sons. Dregely, D., Taubert, R., Dorfmüller, J., Vogelgesang, R., Kern, K., & Giessen, H. (2011). 3D optical Yagi-Uda nanoantenna array. Nature communications, 2, 267. Fransson, M. (2001). SAR Simulations with SEMCAD, a new FDTD software package for computational electrodynamics. co-operation with Moteco AB. Gao, S., Li, J. L.-W., & Sambell, A. (2005). FDTD analysis of a dual-frequency microstrip patch antenna. Progress In Electromagnetics Research, 54, 155-178. Ghosh, S., & Chakrabarty, A. (2006). Estimation of equivalent circuit of loaded trans-receive antenna system and its time domain studies. Journal of Electromagnetic Waves and Applications, 20(1), 89-103. 993
