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Direction Finding Using a Single Cellphone Antenna

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Conference

ASEE-NE 2022

Location

Wentworth Institute of Technology, Massachusetts

Publication Date

April 22, 2022

Start Date

April 22, 2022

End Date

April 23, 2022

Page Count

3

DOI

10.18260/1-2--42165

Permanent URL

https://peer.asee.org/42165

Download Count

247

Paper Authors

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Anna White Wentworth Institute of Technology

biography

Kai Ren Wentworth Institute of Technology Orcid 16x16 orcid.org/0000-0003-4704-5743

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Dr. Kai Ren received the Ph. D. degree in electrical and computer engineering from The Ohio State University, Columbus in 2017. Currently, he is an assistant professor in Electrical and Computer Engineering at Wentworth Institute of Technology. He is a member of IEEE. He has published 17 journal and conference papers and holds two WO patents. His current research includes platform-based antennas, antenna characteristic modes, direction finding systems and algorithms, microwave imaging, radar signal processing, scattering problems, and medical electro-textile sensors.

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Abstract

In April of 2021 Apple released their newest line of products, the Apple AirTag. The AirTag was their version of the Tile, another small device used for locating objects. It can be attached to a variety of personal belongings like keys, wallets, pet collars, etc., in order to help owners locate their personal belongings when missing. AirTag is an ultra-wideband (UWB) transmitter, containing a transmitting antenna with an omni-directional radiation pattern. The transmitting antenna sends repeated pulsed signals, which can be detected by a receiving antenna array with multiple elements embedded in iPhone, iPad, and other Apple products. Missing belongings will be localized when the pulsed signals are received by the antenna array and the location can be retrieved by exploring the amplitude and phase of received signals through direction finding (DF) algorithms. If the lost items are out of the immediate vicinity, the transmitted signals are able to be relayed by nearby Apple products and the address can be sent through the Cloud. The current AirTag DF system is limited by the receiver antenna array placed in iPhone or iPad, due to the large physical size compared to a single antenna element and high cost in antenna array fabrication. DF accuracy of the antenna array with multiple receiver channels will be deteriorated after certain amount of operational time without channel calibrations, since the signals received by different channels will be incoherent. Due to the size constraint, an antenna used for a cellphone is considered. To overcome these limitations, a single cellphone antenna-based DF system is investigated with a central frequency of 8 GHz using synthetic aperture techniques. The cellphone structure will be simplified and utilized for the DF antenna design.

White, A., & Ren, K. (2022, April), Direction Finding Using a Single Cellphone Antenna Paper presented at ASEE-NE 2022, Wentworth Institute of Technology, Massachusetts. 10.18260/1-2--42165

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