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Beam Switching Stacked Patch Antenna at 2.45 GHz
Investigators: Anupam R. Chandran & William Scanlon
The main aim of this project is to develop beam switching antennas for on-body and off-body communication modes in body-centric wireless systems.
The effect of antenna body coupling for both these modes of propagation and their on-body coupling performance are also investigated.
The off-body channel is concerned with communication between a device on the body and a remote location.
Example applications include short range communications between two fire and rescue personnel or the transmission of medical data from
a wireless sensor body area network to a remote station.
The on-body channel exists where there is a need for communication between devices located on, or within, the user's body.
For example, in telemedicine applications where biosensors are implemented in the body,
a wearable sensor is often located on the body to act as a relay between the biosensors and a non-local station several meters away from the user.
In such applications it is clear that both propagating modes (on-body and off-body) will be required. The prototype of the antenna is shown to the left.
Example Results
The antenna is constructed from two patch elements over a common groundplane with a single microstrip feedline. The upper patch is excited at the fundamental mode
when off-body propagation is required. The lower (higher mode) patch is activated for the on-body mode. A simple SPDT RF switch is used to select the operating mode.
The figure shows the simulated electrical field distribution for both on-body and off-body modes at 2.45 GHz.
The antenna is also low SAR (specific absorption rate, a measure of electromagnetic field exposure),
with a peak 10-g averaged SAR of 0.66 W/kg and 0.56 W/kg for the on-body and off-body modes, respectively (0.5 W rms source power).
Publication Output
- W.G. Scanlon & A.R. Chandran, 'Stacked-patch antenna with switchable propagating mode for UHF body-centric communications,' IEEE Intl. Workshop on Antenna Technology (iWAT), Santa Monica, USA, pp. 1-4, 2009.
- A.R. Chandran, G.A. Conway & W.G. Scanlon, 'Pattern switching compact patch antenna for on-body and off-body communications at 2.45 GHz,' 3rd European Conf. Antennas and Propagation (EUCAP), Berlin, Germany, pp. 2055– 2057, Mar. 2009.
Support
This work was funded by EPSRC under grant reference EP/D053749/1.