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Electrically Small Low-Profile Wearable Patch Antenna for 868 MHz
Investigators: Anupam R. Chandran & William Scanlon
The main objective of this work is to develop compact low profile and highly efficient patch antennas for on-body communications below 1 GHz.
The desirable radiation pattern for this mode of communication should be similar to that of a monopole antenna oriented normal to the body surface.
Radiation efficiency and on-body coupling performance (between antennas located on different locations on the human body torso)
are investigated both numerically and experimentally. As part of this project we have developed a slotted-patch antenna with a monopole-like radiation pattern (null at boresight)
for on-body use at 868 MHz. The antenna offers a significant size reduction with a maximum dimension of
only 33.6% of a conventional microstrip patch antenna for the same band.
One of the main application areas for sub 1-GHz wearable on-body antennas is in Medical Body Area Networks (MBAN). Biomedical sensor networks mounted on the human body have drawn great attention for health applications such as telemonitoring where physicians can make informed decisions, monitor deterioration in chronic conditions, or assess the response of a patient to a specific treatment plan. In particular, wireless standards such as IEEE 802.15.4 (operating at 868 MHz within Europe) and IEEE 802.15.6 (in development) offer important advantages for wearable systems including sensor placement flexibility and increased usability and robustness.
Example Results
In terms of on-body radio communications, the main design criteria for MBAN devices are physical size, radiation efficiency in the presence of the user's body and on-body link performance.
The figures show the surface current distribution plot of the new slotted patch antenna (left)
and the simulated and measured on-body coupling results compared to a monopole antenna (right) at 868 MHz on a cubical-cylinder phantom
(representing muscle tissue).
The peak |S21| for both the monopole and the slotted patch antenna at 868 MHz were identical.
Furthermore, the measured (on phantom) efficiency of the new antenna was 47 % while that of the reference monopole
antenna was 59.8%.
Publication Output
- A.R. Chandran, G.A. Conway & W.G. Scanlon, 'Compact low-profile patch antenna for medical body area networks at 868 MHz,' IEEE Intl. Symp. Antennas & Propagation(IEEE APS 2008) San Diego, USA, July 2008.
- A.R. Chandran, G.A. Conway & W.G. Scanlon, 'Compact slot-loaded patch antenna for 868 MHz wireless body area networks,' Loughborough Antennas & Propagation Conf. (LAPC-2008), Loughborough, UK, pp. 433-436, March 2008.
Support
This work was funded by EPSRC under grant reference EP/D053749/1.