An Ultrawideband Conformal Capsule Antenna With Stable Impedance Matching

An ultrawideband conformal capsule slot antenna, which has a simple configuration and a stable impedance matching characteristic, is described in this paper. In the past, wideband outer-wall antennas have been proposed for capsule-type applications. However, this paper shows that the outer wall is n...

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Bibliographic Details
Published in:IEEE transactions on antennas and propagation 2017-10, Vol.65 (10), p.5086-5094
Main Authors: Zengdi Bao, Yong-Xin Guo, Mittra, Raj
Format: Article
Language:English
Subjects:
Bandwidth
Conformal capsule antenna
Geometry
Impedance matching
inner wall
Muscles
Phantoms
slot antenna
Slot antennas
wideband
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Description
Summary:An ultrawideband conformal capsule slot antenna, which has a simple configuration and a stable impedance matching characteristic, is described in this paper. In the past, wideband outer-wall antennas have been proposed for capsule-type applications. However, this paper shows that the outer wall is not a good choice for placing capsule antennas, since such a choice exhibits a high specific absorption ratio, low gain, and low efficiency. Instead, the antenna proposed in this paper is conformal to the inner wall of a capsule shell, and it provides a wide impedance bandwidth ranging from 1.64 to 5.95 GHz (113.6%). Furthermore, the impedance matching remains stable even with a change in the operating environment. Since in a typical application scenario a capsule will move through the digestive system, and thus experience varying environments, a wide bandwidth and stable performance are both very desirable attributes of the antenna, whose design is discussed in this paper. Moreover, the proposed antenna continues to maintain a stable impedance match even when a battery is added inside the capsule, or when there is a change in the battery size and/or its position. Given these advantages, we argue that slot antennas are well suited for incorporation into capsule antennas for the present application.
ISSN:0018-926X
1558-2221
DOI:10.1109/TAP.2017.2741027