THESIS
2018
xiv, 73 pages : illustrations ; 30 cm
Abstract
Compact antennas have an important role in nearly all biomedical systems and are needed
for data telemetry, diagnosis devices and treatment devices. A challenge in designing compact antennas for biomedical applications is that they typically need to be matched to the
electromagnetic properties and characteristics of the human body in order to optimize their
performance in the desired biomedical application. The placement of the antennas is also an
important issue and they are usually located either directly on the human body's surface or
implanted inside the body. Implanted medical devices (IMDs) are affected by their exact location and the human tissues nearby and this depends on the application which can range from glucose monitoring to capsule endoscope.
The research described...[
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Compact antennas have an important role in nearly all biomedical systems and are needed
for data telemetry, diagnosis devices and treatment devices. A challenge in designing compact antennas for biomedical applications is that they typically need to be matched to the
electromagnetic properties and characteristics of the human body in order to optimize their
performance in the desired biomedical application. The placement of the antennas is also an
important issue and they are usually located either directly on the human body's surface or
implanted inside the body. Implanted medical devices (IMDs) are affected by their exact location and the human tissues nearby and this depends on the application which can range from glucose monitoring to capsule endoscope.
The research described in this thesis introduces three novel antenna designs to support
various biomedical applications. The first design focuses on a novel broadside beam-steering
technique that can be used to create thin planar antenna reconfigurable structures with high gain.
The novelty of the approach is that it utilizes a planar patch design with pixel antenna elements
that are adjacent to the planar patch that can be reconfigured with electronic switches. The result
is a thin planer structure that can provide broadside beam-steering capability without the need for phase shifters. In the design of the antenna the internal multiport method (IMPM) is extended to the calculation of antenna patterns. This allows the optimization of the reconfigurable
configurations to be performed in an efficient framework that can increase computational speeds
by up to eighty times compared to conventional approaches. To verify the design performance,
both measurement and simulated results are presented. The main application of the resulting
design is for non-contact vital sign detection devices, wearable devices, medical implants, on-body communications and also for future smart/reconfigurable wireless devices, without using any type of phase shifters.
The second antenna design described in this thesis is a reconfigurable endfire Yagi antenna that has a beam steering range of 300 degrees with high gain and minimal gain variation across its beam steering range. It also makes use of pixel antenna elements that can be reconfigured using electronic switches. A feature of the design is that it can provide 300 degree beam steering capability without phase shifters and this performance is unmatched by other designs. The design process has also made use of the extended IMPM developed for the planar broadside pixel reconfigurable antenna. The biomedical application scenarios for the reconfigurable antenna are similar to the planar broadside pixel reconfigurable antenna but are complementary to it in that it provides an endfire beam configuration.
The third antenna design introduced in this thesis is for implantable applications and specifically applications in wireless ingestible capsule endoscopy. The ability to implant electronic systems in the human body has led to many medical advances. Progress in semiconductor technology paved the way for small devices, but the miniaturization and higher performance of the antenna remains challenging. A novel 4 × 4 MIMO antenna is described that can increase the data rate of wireless endoscopy systems and therefore improve the video resolution of the wireless endoscopy system. The design makes use of four spiral antennas operating in the ISM band at 433 MHz. In order to keep mutual coupling low and size small careful placement and arrangement of the spirals is required. In addition, the effects of the human body on its performance needs to be taken into account. Measurement results show that in a human phantom the antenna can provide increases in capacity of up to three times compared to a single antenna system. In addition, the size of the MIMO antenna is no bigger than current single antenna systems while still maintaining good efficiency.
Conclusions for the three novel antenna designs are also provided and possible future related research is also described.
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