Ultralow-Power Radio Frequency Beamformer Using Transmission-Line Transformers and Tunable Passives

Anderson, Matthew G.; Thielens, Arno; Wielandt, Stijn; Niknejad, Ali M.; Rabaey, Jan M.

doi:10.1109/lmwc.2018.2886628

Cited by 5 publications

(7 citation statements)

References 4 publications

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“…Each antenna in the phased array can be driven independently via its own SMA connector to steer the array’s beam. These arrays were leveraged from the work done in [44]. Dipole antennas are chosen because they are an efficient solution for planar, uniform, linear arrays.…”

Section: Methodsmentioning

confidence: 99%

A Comparative Study of On-Body Radio-Frequency Links in the 420 MHz–2.4 GHz Range

Thielens

Benarrouch

Wielandt

et al. 2018

Sensors

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While there exists a wide variety of radio frequency (RF) technologies amenable for usage in Wireless Body Area Networks (WBANs), which have been studied separately before, it is currently still unclear how their performance compares in true on-body scenarios. In this paper, a single reference on-body scenario—that is, propagation along the arm—is used to experimentally compare six distinct RF technologies (between 420 MHz and 2.4 GHz) in terms of path loss. To further quantify on-body path loss, measurements for five different on-body scenarios are presented as well. To compensate for the effect of often large path losses, two mitigation strategies to (dynamically) improve on-body links are introduced and experimentally verified: beam steering using a phased array, and usage of on-body RF repeaters. The results of this study can serve as a tool for WBAN designers to aid in the selection of the right RF frequency and technology for their application.

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Section: Methodsmentioning

confidence: 99%

A Comparative Study of On-Body Radio-Frequency Links in the 420 MHz–2.4 GHz Range

Thielens

Benarrouch

Wielandt

et al. 2018

Sensors

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“…The VNA registered two-port S-parameters of two antennas mounted at a fixed distance of 61 cm. S-parameter were averaged over 50 sweeps from 500 to 1500 MHz with 1001 frequency steps of 1 MHz and were then used in the three-antenna method 70 to determine antenna gain. During these measurements, all antennas were placed parallel with their printed sides facing each other in a mirrored configuration.…”

Section: Methodsmentioning

confidence: 99%

Printed, flexible, compact UHF-RFID sensor tags enabled by hybrid electronics

Baumbauer

Anderson

Ting

et al. 2020

Sci Rep

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Sensor data can be wirelessly transmitted from simple, battery-less tags using Radio Frequency Identification (RFID). RFID sensor tags consist of an antenna, a radio frequency integrated circuit chip (RFIC), and at least one sensor. An ideal tag can communicate over a long distance and be seamlessly integrated onto everyday objects. However, miniaturized antenna designs often have lower performance. Here we demonstrate compact, flexible sensor tags with read range comparable to that of conventional rigid tags. We compare fabrication techniques for flexible antennas and demonstrate that screen and stencil printing are both suitable for fabricating antennas; these different techniques are most useful at different points in the design cycle. We characterize two versions of flexible, screen printed folded dipoles and a meandered monopole operating in the 915 MHz band. Finally, we use these antennas to create passive sensor tags and demonstrate over the air communication of sensor data. These tags could be used to form a network of printed, flexible, passive, interactive sensor tags.

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“…Comparing the resulting system using this new architecture (b) with more conventional RF beamformers (c), we see that potential sources of ohmic loss in the RF combiner are reduced along with the number of power hungry transceivers. and [5] reduces power consumption when compared to typical RF beamforming techniques by defying this convention and moving the beamforming functions to the antenna node, thereby reducing the number of power-hungry RF signal chains that are needed. As shown in Fig.…”

Section: Introductionmentioning

confidence: 99%

“…There are three primary contributions in this paper. First, we show how the theory introduced in [5] can be expanded to arrays with three or more antenna elements, introducing a crossover switch to handle the larger phase shifts necessary with bigger arrays. Second, we present analysis for the limits such techniques impose on array size.…”

Section: Introductionmentioning

confidence: 99%

Analysis of Ultralow Power Radio Frequency Beamforming Using Transmission-Line Transformers and Tunable Passives

Anderson

Thielens

Wielandt

et al. 2022

IEEE Trans. Microwave Theory Techn.

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Traditional methods for RF beamforming require significant amounts of power, making them difficult to deploy in some low-power applications. A detailed analysis of radio frequency (RF) beamforming utilizing transmission-line transformers (TLT) and balanced impedance phaseshifters (BIPS) is presented. This technique enables ultra-low power RF beamformers by (1) leveraging the RF feed-lines to implement a low-loss TLT for signal combining and (2) using the balanced impedance tuning of shunt passives to implement simple, lowloss phase shifters. We highlight some of the key advantages of this beamforming approach for low-power systems and show how this idea can be expanded to arrays of more than two antenna elements by introducing a crossover switch into the phaseshifters to extend the beamsteering range. Additionally, a thorough comparison between theoretical and measured performance of a simplified prototype system is provided for key system metrics, including loss and bandwidth. The prototype system is a fully passive 2 GHz two-element RF beamformer, utilizing TLTs and BIPS, realized with off-the-shelf components and a standard FR4 PCB.

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Ultralow-Power Radio Frequency Beamformer Using Transmission-Line Transformers and Tunable Passives

Cited by 5 publications

References 4 publications

A Comparative Study of On-Body Radio-Frequency Links in the 420 MHz–2.4 GHz Range

A Comparative Study of On-Body Radio-Frequency Links in the 420 MHz–2.4 GHz Range

Printed, flexible, compact UHF-RFID sensor tags enabled by hybrid electronics

Analysis of Ultralow Power Radio Frequency Beamforming Using Transmission-Line Transformers and Tunable Passives

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