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Real-world performance of sub-1 GHz and 2.4 GHz textile antennas for RF-powered body area networks

Real-world performance of sub-1 GHz and 2.4 GHz textile antennas for RF-powered body area networks
Real-world performance of sub-1 GHz and 2.4 GHz textile antennas for RF-powered body area networks
In Radio Frequency (RF)-powered networks, peak antenna gains and path-loss models are often used to predict the power that can be received by a rectenna. However, this leads to significant over-estimation of the harvested power when using rectennas in a dynamic setting. This work proposes more realistic parameters for evaluating RF-powered Body Area Networks (BANs), and utilizes them to analyze and compare the performance of an RF-powered BAN based on 915 MHz and 2.4 GHz rectennas. Two fully-textile antennas: a 915 MHz monopole and a 2.4 GHz patch, are designed and fabricated for numerical radiation pattern analysis and practical forward transmission measurements. The antennas’ radiation properties are used to calculate the power delivered to a wireless-powered BAN formed of four antennas at different body positions. The mean angular gain is proposed as a more insightful metric for evaluating RFEH networks with unknown transmitter-receiver alignment. It is concluded that, when considering the mean gain, an RF-powered BAN using an omnidirectional 915 MHz antenna outperforms a 2.4 GHz BAN with higher-gain antenna, despite lack of shielding, by 15.4× higher DC power. Furthermore, a transmitter located above the user can result in 1× and 9× higher DC power at 915 MHz and 2.4 GHz, respectively, compared to a horizontal transmitter. Finally, it is suggested that the mean and angular gain should be considered instead of the peak gain. This accounts for the antennas’ angular misalignment resulting from the receiver’s mobility, which can vary the received power by an order of magnitude.
Antennas, Body Area Networks (BAN), Electronic Textiles, Energy Harvesting, ISM Bands, Internet of Things, RF Energy Harvesting, Wearable Antenna, Wireless Power Transfer
2169-3536
133746-133756
Wagih, Mahmoud
7e7b16ba-0c64-4f95-bd3c-99064055f693
Cetinkaya, Oktay
6cb457a5-77b8-415d-b524-9e8728c35f0a
Zaghari, Bahareh
a0537db6-0dce-49a2-8103-0f4599ab5f6a
Weddell, Alex S.
3d8c4d63-19b1-4072-a779-84d487fd6f03
Beeby, Steve
ba565001-2812-4300-89f1-fe5a437ecb0d
Wagih, Mahmoud
7e7b16ba-0c64-4f95-bd3c-99064055f693
Cetinkaya, Oktay
6cb457a5-77b8-415d-b524-9e8728c35f0a
Zaghari, Bahareh
a0537db6-0dce-49a2-8103-0f4599ab5f6a
Weddell, Alex S.
3d8c4d63-19b1-4072-a779-84d487fd6f03
Beeby, Steve
ba565001-2812-4300-89f1-fe5a437ecb0d

Wagih, Mahmoud, Cetinkaya, Oktay, Zaghari, Bahareh, Weddell, Alex S. and Beeby, Steve (2020) Real-world performance of sub-1 GHz and 2.4 GHz textile antennas for RF-powered body area networks. IEEE Access, 8, 133746-133756, [9149585]. (doi:10.1109/ACCESS.2020.3011603).

Record type: Article

Abstract

In Radio Frequency (RF)-powered networks, peak antenna gains and path-loss models are often used to predict the power that can be received by a rectenna. However, this leads to significant over-estimation of the harvested power when using rectennas in a dynamic setting. This work proposes more realistic parameters for evaluating RF-powered Body Area Networks (BANs), and utilizes them to analyze and compare the performance of an RF-powered BAN based on 915 MHz and 2.4 GHz rectennas. Two fully-textile antennas: a 915 MHz monopole and a 2.4 GHz patch, are designed and fabricated for numerical radiation pattern analysis and practical forward transmission measurements. The antennas’ radiation properties are used to calculate the power delivered to a wireless-powered BAN formed of four antennas at different body positions. The mean angular gain is proposed as a more insightful metric for evaluating RFEH networks with unknown transmitter-receiver alignment. It is concluded that, when considering the mean gain, an RF-powered BAN using an omnidirectional 915 MHz antenna outperforms a 2.4 GHz BAN with higher-gain antenna, despite lack of shielding, by 15.4× higher DC power. Furthermore, a transmitter located above the user can result in 1× and 9× higher DC power at 915 MHz and 2.4 GHz, respectively, compared to a horizontal transmitter. Finally, it is suggested that the mean and angular gain should be considered instead of the peak gain. This accounts for the antennas’ angular misalignment resulting from the receiver’s mobility, which can vary the received power by an order of magnitude.

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Access_RF_Powered_BAN - Accepted Manuscript
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Accepted/In Press date: 18 July 2020
e-pub ahead of print date: 27 July 2020
Published date: 2020
Keywords: Antennas, Body Area Networks (BAN), Electronic Textiles, Energy Harvesting, ISM Bands, Internet of Things, RF Energy Harvesting, Wearable Antenna, Wireless Power Transfer

Identifiers

Local EPrints ID: 442818
URI: http://eprints.soton.ac.uk/id/eprint/442818
ISSN: 2169-3536
PURE UUID: 56d9b5bf-7657-4e9a-9d58-74a9b50ccffd
ORCID for Alex S. Weddell: ORCID iD orcid.org/0000-0002-6763-5460
ORCID for Steve Beeby: ORCID iD orcid.org/0000-0002-0800-1759

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Date deposited: 28 Jul 2020 16:31
Last modified: 13 Apr 2021 01:41

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