SCIENTIA SINICA Informationis, Volume 48, Issue 6: 724-733(2018) https://doi.org/10.1360/N112018-00010

## Design of stretchable inverted-F antenna based on PDMS substrate

• AcceptedApr 13, 2018
• PublishedJun 13, 2018
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### Abstract

In recent years, the rapid development of the Internet of Things (IoT) has led to the rapid rise of wearable devices, and the emergence of body-area networks (BANs) has resulted in new demands for antennas. In some areas, such as biomedical applications, antennas are required to not only be stretchable, but also bendable. Traditional PCB antennas, usually fabricated on a rigid substrate, can hardly stretch or bend and are not suitable for wearable devices physically and electrically because, once stretched, the antenna's length will increase, resulting in a lower center frequency. In this paper, a stretchable flexible inverted-F antenna based on a PDMS substrate is designed that operates in the Bluetooth band. Because of the design of the meandered-line radiation arm and the division of the ground plane and flexible substrate, a stretchable inverted-F antenna is achieved. Simulation results of the antenna during stretching and bending show that the designed antenna is able to stretch up to 20% in the $X$ axis, 60% in $Y$ axis, and to bear bending with a minimum radius of curvature of 8 mm while still fully covering a Bluetooth band.

### References

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• Figure 1

(Color online) (a) Traditional inverted-F antenna and (b) flexible stretchable antenna

• Figure 2

(Color online) Structure parameters of stretchable inverted-F antenna

• Figure 3

(Color online) Simulated return loss (a)and normalized Smith chart (b)

• Figure 4

(Color online) Simulated radiation pattern (a), XY plane pattern (b), YZ plane pattern (c)

• Figure 5

(Color online) Simulated surface current distribution of stretchable antenna

• Figure 6

(Color online) Simulated return loss of stretchable antenna when stretched in $X$ axis

• Figure 7

(Color online) Simulated return loss of stretchable antenna when stretched in $Y$ axis

• Figure 8

(Color online) Schematic of the bending radius of stretchable antenna

• Figure 9

(Color online) Schematic of the bending radius of stretchable antenna

• Table 1   Stretchable antenna structure parameter table
 Parameter Value (mm) Parameter Value $L$1 15.8 $W$1 1 mm $L$2 2.6 $W$2 0.8 mm $L$3 2.6 $W$3 0.5 mm $L$4 2.4 $W$4 0.09 mm $H$1 4.2 $R$ 1.5 mm $H$2 3.3 $\theta_{0}$ $137.6^{\circ}$ $H$3 3.3 $\theta_{1}$ $137.6^{\circ}$
• Table 2   The relationship between $C_{x}$ and $C_{y}$ when stretched in $X$ axis and in $Y$ axis
 $X$ axial stretching $Y$ axial stretching Stretch range (%) $C_{x}$ $C_{y}$ Stretch range (%) $C_{y}$ $C_{x}$ 0 1.00 1.00 0 1.00 1.00 5 1.05 0.98 20 1.20 0.90 10 1.10 0.95 40 1.40 0.81 15 1.15 0.93 50 1.50 0.76 20 1.20 0.90 60 1.60 0.71 25 1.25 0.88 70 1.70 0.66
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