Rikesh Shrestha [RC1511004010001], Anshuman Mishra [RC1511004010002], Aman Kumar [RA1511004010783]
DESIGN AND ANALYSIS FO COMPACT DIVERSITY ANTENNA FOR WEARABLE APPLICATIONS
ABSTRACT OBJECTIVES ANTENNA DESIGN DISSCUSION OF THE FINDINGS SAR ANALYSIS CONCLUSION
An Ultra Wideband (UWB) antenna is designed for wearable applications using jeans fabric as the substate. The proposed antenna has the impedance bandwidth from 3.1-11.1 GHz. The antenna footprint is of size 18mmx 26mmx 0.8mm. The radiator consists of a simple rectangular structure and an ellipse added on top with several notches removed from the radiator. Two such antennas are placed horizontally and vertically to obtain a 2-port diversity set. Radiation patterns and diversity parameters are simulated and also measured using fabricated prototype. SAR value is also calculated and fabricated antenna is subjected to bending analysis
To design a compact unit cell with jeans as a substrate To develop a diversity set of 2-port with an optimum mutual coupling performance To evaluate diversity parameters such as S-parameters Envelope Correlation Coefficient Diversity Gain Isolation Factor To compute SAR values To measure the extremity of bending for the flexible antenna to work
ANTENNA DESIGN (UNIT ELEMENT)
The proposed unit cell is a begun with a simple rectangular-shaped monopole with a microstrip line feed. Substrate : Jeans , dielectric constant : 1.7 ,loss tangent : 0.08 & thickness : 0.8mm. Frequency band : 3.1-11.1 GHz . Antenna size : 18 × 26 × 0.8 mm3 .
(a) (b) Fig. 1. Proposed monopole antenna: (a) front view, (b) rear view.
The MIMO configuration is formed by arranging four unit cells orthogonally . Due to the orthogonality, the mutual coupling is reduced, and polarization diversity is offered. Isolation of >15 dB is provided
Fig. 3. Proposed MIMO antenna configuration
DISCUSSION OF THE FINDINGS
A. Impedance performance Due to the identical unit cells, the reflection coefficient curves of antenna-1, antenna-2, antenna-3, and antenna-4 are almost similar . It is evident that the MIMO antenna’s inter-element isolation >15 dB .
......—Measured mulated Frequency (GHz)
B. Radiation Characteristics The maximum gain and efficiency values are found to be 5.3 dBi and >94%.
Fig. 7. Simulated radiation patterns of the proposed antenna: (a) 2.4 GHz, E-plane, (b) 2.4 GHz, H-plane, (c) 3 GHz, E-plane, (d) 3 GHz, H-plane, (e) 6 GHz, E-plane, (f) 6 GHz, H-plane, (g) 10 GHz, E-plane, (h) 10 GHz, H-plane.
thectvtv 150 — f"" (f-3.5) [1) — farfed (f=7.5)  — f"" (f=iO.5) (1) 210
C. Bending Analysis Bending analysis is performed on both the x- and y-directions to validate the bending nature of the proposed antenna. The proposed antenna is unaffected by bending conditions. The proposed MIMO antenna is fitting for wearable devices .
D. Diversity Performance Envelope correlation coefficient (ECC) : measures the correlation between unit cells. Diversity Gain (DG) : demonstrates how efficiently signal transmission occurs without significant degradation.
th_Gan from S 9.995 9.99 9.985 9.98 9.975 9.97
Observation: Maximum SAR value as FCC standards is 1.6W/kg for 1g of tissue. Average SAR value for proposed diversity antenna is 0.15 W/kg for 1g of tissue.
2-port diversity antenna with 8GHz bandwidth is designed. Omni-directional radiation pattern is achieved. Spatial, Polarization and pattern diversities are achieved. ECC<0.001, DG>9.9 and port isolation >-20dB Bending along X-orientation up to 20mm is possible. SAR value is within permissible limits.
The proposed antenna is conformable due to its simple structure and wide bandwidth, and it can be used for tracking and monitoring the patients, as well as other applications based on the needs of consumers.
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