The Array Fractal Graphene Antenna Used for Mobile Digital

Television

Bin Lin

, Zetai Liu, Ying Zhang, Zhipeng Lin, Shaodong Shen, Ping Zheng and Xinyu Wei

Xiamen University Tan Kah Kee College, Fujian Zhangzhou 363105, China

email: linbin@xujc.com

Keywords: Mobile digital television, Growth tree fractal dipole antenna, Rectangular antenna array, Polyethylene

Terephthalate (PET) thin film substrate, Graphene conductive ink.

Abstract: According to the requirements of the mobile digital television system, the present paper creatively combines

growth tree fractal dipole antenna, rectangular antenna array, Polyethylene Terephthalate (PET) thin film

substrate, and graphene conductive ink, designed an array fractal graphene antenna used for mobile digital

television, fabricated the antenna sample and tested the radiation characteristics of the antenna. The result of

test indicate that the antenna's working frequency range is 10.841-14.136 GHz, the antenna's working

bandwidth is 3.295 GHz, the antenna's relative bandwidth is 26.38%, the minimum value of return loss is -

32.45 dB. This antenna completely covered the working frequency band of the mobile digital television

system, it is a mobile digital television antenna that have small size, broadband, highly integrated, and can

meet the requirements of mobile digital television system, such as stable signal, wide coverage, fast

receiving, clear picture, strong mobility.

1 INTRODUCTION

Mobile digital television is a new technology in the

era of mobile internet, it can realize watching digital

television in various fast moving vehicles, and

through the digital television channels to carry out

video on demand, TV shopping, propaganda and

promotion, remote consultation, interactive games

and other services. Mobile digital televisionhas

covered a number of major cities in China, has been

widely used in public transport and private cars, has

become recognized as a new media of great

influence (Wang, 2016; Carey J., 2016; Silva V.J.,

2015; Punt M., 2015; Chang, 2015).

Antenna design and manufacturing technology is

one of the key technologies of mobile digital

television system. The performance of antenna

greatly affects the performance and application field

of mobile digital television system. According to the

frequency division of ITU, the mobile digital

television band based on satellite transmission is

11.700~12.200 GHz. Mobile digital television

antenna must completely covered the 11.700~

12.200 GHz working frequency band, and can meet

the requirements of mobile digital television system,

such as stable signal, wide coverage, fast receiving,

clear picture, strong mobility (Yeo, 2017; Liao,

2017; Osklang P., 2016).

2 BRIEF INTRODUCTION OF

GROWTH TREE FRACTAL

DIPOLE ANTENNA

The growth tree fractal dipole antenna is a dipole

antenna based on growth tree fractal structure. The

iterative process of growth tree fractal structure is

shown in Figure 1, its original structure is dipole

antenna, and two dipole arms are used as "trunk". At

the top of "trunk", two "branches" grow out, they

perpendicular to the dipole arm and the length is half

of the dipole arm, which constitutes the 1st-order

growth tree fractal structure. At the top of each

"branches" of 1st-order growth tree fractal structure,

two "small branches" grow out, they perpendicular

to the "branches" and the length is half of the

"branches", which constitutes the 2nd-order growth

tree fractal structure. Followed this iteration, can get

high-order growth tree fractal structure.

Lin, B., Liu, Z., Zhang, Y., Lin, Z., Shen, S., Zheng, P. and Wei, X.

The Array Fractal Graphene Antenna Used for Mobile Digital Television.

In 3rd International Conference on Electromechanical Control Technology and Transportation (ICECTT 2018), pages 423-426

ISBN: 978-989-758-312-4

423

(

)

0-orde

(

)

1st-orde

(

)

-orde

(

)

-orde

Figure 1: The iteration process of growth tree fractal

structure.

3 BRIEF INTRODUCTION OF

POLYETHYLENE

TEREPHTHALATE (PET) THIN

FILM SUBSTRATE

Mobile digital television system is mainly used in all

kinds of vehicles, its working environment is

complex, may work in a variety of unpredictable

environment, which requires the mobile digital

television antenna has excellent mechanical

properties, good corrosion resistance, good high and

low temperature performance. Polyethylene

Terephthalate (PET) thin film substrate is a very

stable antenna substrate material, can be resistant to

oil, dilute acid, dilute alkali, resistant to most

solvents, can be in the temperature range of -70 to

150 degrees of normal work, and high and low

temperature has little impact on its mechanical

properties. Using PET thin film as antenna substrate

material can ensure the antenna has stable working

performance in all kinds of harsh environments.

4 BRIEF INTRODUCTION OF

GRAPHENE CONDUCTIVE

INK

Graphene conductive ink is a high performance

conductive ink composed of graphene conductive

fillers, adhesives and solvents. Graphene is a single

layer of graphite composed of carbon atoms, it has

very good thermal conductivity, conductivity, light

transmittance, and has high strength, ultra light,

large surface area and other characteristics.

Graphene has high electron mobility, which can

accommodate high intensity radio frequency current.

Conductive ink made from graphene as conductive

filler has lighter quality, lower cost, higher

conductivity and better heat resistance than

traditional metal conductive filler ink. The printed

antenna made of graphene conductive ink has no

metal in the radiation patch, and is not easy to be

corroded in the open working environment, and has

high working stability.

5 STRUCTURE DESIGN OF

ARRAY FRACTAL GRAPHENE

ANTENNA

The antenna substrate used in the design is PET film

substrate, the shape is rectangle, the size is 8.8 mm x

8.8 mm, the thickness is 0.2 mm. PET thin film

substrate consists of 8 rows and 8 columns were 64

regions, the relative dielectric constant of each film

substrate region gradual change along the length and

width direction ; the region that has minimum

relative dielectric constant is located in the upper left

corner of the film substrate, the relative dielectric

constant is 3.5; the region that has maximum relative

dielectric constant is located in the lower right

corner of the film substrate, the relative dielectric

constant is 4.9; the relative dielectric constant of

each film substrate region increases gradually from

left to right, from top to bottom, the difference of

relative dielectric constant between the two adjacent

regions is 0.1. The structure of the PET film

substrate is shown in Figure 2, the number in the

figure represents the relative dielectric constant of a

region. After using this new thin film substrate, the

relative dielectric constant of each element antenna

of the array antenna is different, so the frequency of

each element antenna is different. When the working

frequencies of different element antennas are close,

their radiation and operating frequency bands

overlap each other, forming a working band with

large radiation intensity and working bandwidth,

which can improve the radiation performance and

bandwidth performance of the array antenna.

The growth tree fractal dipole antenna is used as

the element antenna in the design, and its structure is

shown in Figure 3. The size of the growth tree

fractal dipole antenna is 1.1 mm x 1.1 mm, which

ICECTT 2018 - 3rd International Conference on Electromechanical Control Technology and Transportation

424

consists of a pair of symmetric dipole arms, and

each dipole arm uses a 3rd-order growth tree fractal

structure. The opening gap is arranged on the

symmetrical central line of two dipole arms, and the

antenna feed point is arranged on both sides of the

opening gap.

The structure of array fractal graphene antenna is

shown in Figure 4, it use the rectangular array

structure as the basic array arrangement structure, 64

growth tree fractal dipole element antennas are

arranged in accordance with the rectangular array

structure, form the antenna array. Although the

working bandwidth of the single growth tree fractal

dipole antenna is large, but its radiation intensity is

weak. Multiple element antennas are arranged in

rectangular array structure to form an antenna array,

can let their radiation overlap, and further enhance

the radiation intensity of the antenna. The radiation

structure of the array fractal graphene antenna is all

printed by graphene conductive ink.

Figure 2: The structure schematic diagram of PET film

substrate.

Figure 3: The structure schematic diagram of growth tree

fractal dipole element antenna.

Figure 4: The structure schematic diagram of array fractal

graphene antenna.

6 FABRICATION AND TEST OF

ANTENNA SAMPLE

According to the design scheme mentioned above,

we use the conductive ink printing process to

produce the antenna sample. The radiation

performance and directional performance of the

antenna sample are tested, and the results are shown

in Figure 5 and Figure 6.

The tested results show that this antenna's

working center frequency is 12.000 GHz, the

antenna's working frequency range is 10.841-14.136

GHz, the antenna's working bandwidth is 3.295 GHz,

the antenna's relative bandwidth is 26.38%, the

minimum value of return loss is -32.45 dB. This

antenna completely covered the working frequency

band of the mobile digital television system. The E

and H plane patterns of the antenna have good

omnidirectional coverage characteristics.

Figure 5: The tested radiation characteristics of antenna.

The Array Fractal Graphene Antenna Used for Mobile Digital Television

425

Figure 6: The measured directional pattern of antenna.

7 CONCLUSIONS

In this paper, according to the performance

requirements of the mobile digital television system

based on satellite transmission, we use the gradient

dielectric constant PET film substrate as the antenna

substrate material, and use the graphene conductive

ink to make the antenna radiation structure,

combines growth tree fractal dipole antenna and

rectangular antenna array, designed a array fractal

graphene antenna used for mobile digital television,

fabricated the antenna sample and tested the

radiation characteristics of the antenna. In the case

of having 64 element antennas, the size of the

antenna is only 8.8 mm×8.8 mm×0.2 mm, it is a

miniature ultra thin antenna, which can be put into

all kinds of mobile digital television equipment. This

antenna has excellent physical and mechanical

properties, and can work normally in the

temperature range from -70 to 150. It has the

advantages of oil resistance, acid resistance, alkali

resistance and corrosion resistance. It has stable and

reliable working performance in outdoor

environment. This antenna completely covered the

working frequency band of the mobile digital

television system, and it has large performance

redundancy, it can guarantee the transmission

quality of mobile digital television signal in a variety

of unpredictable harsh environment. This antenna is

expected to be widely used in mobile digital

television equipment.

ACKNOWLEDGEMENTS

The project was supported by the Natural Science

Foundation of Fujian Province of China (No.

2016J01318).

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