Retroreflective Transceiver Array Using a Novel Calibration Method Based on Optimum Phase Searching

Koo, Hyungmo; Bae, Ji Cheol; Choi, Woojin; Oh, Hansik; Lim, Hong Jun; Lee, Jongmin; Song, Chan Mi; Lee, Kang Yoon; Hwang, Keum Cheol; Yang, Youngoo

doi:10.1109/tie.2020.2973903

Cited by 30 publications

(15 citation statements)

References 40 publications

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“…The Tx element was designed to include a drive power amplifier, a 1:8 Wilkinson power splitter, an attenuator, a phase shifter, power amplifier, and an internal MCU to control the attenuator and the phase shifter, as shown in Fig. 3 curved rectangular structure for LHCP was implemented on the same RF-35 substrate [22]. In the broadside direction, a single Tx antenna exhibited a gain of 6 dBic.…”

Section: Lut-based Focal Beamformingmentioning

confidence: 99%

“…However, for short-or mid-range (less than a few meters in general) MPT applications, a technique that covers application at both far-and near-fields is required. The retroreflective method has been used for such short-or mid-range MPT systems [19]- [22]. To obtain the optimum phase sets for transmitting signals from the Tx elements, the Tx using the retroreflective method needs an additional Rx at each Tx element to receive pilot signals which are transmitted from the Rx.…”

Section: Introductionmentioning

confidence: 99%

“…The received power was improved by adaptively adjusting the number of rectennas in the Rx using the calculated size of the focal point in the near-field zone. By transmitting 250 mW, dc power of about 10 mW was obtained through three rectennas at a distance of 1 m. In [22], a retroreflective beamforming system using 64 Tx antenna elements and 6 Rx antenna elements was reported for the 5.2 GHz frequency band. A new calibration method was proposed to calculate the phase offsets for the unit's Tx and Rx circuits in the Tx.…”

Section: Introductionmentioning

confidence: 99%

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LUT-Based Focal Beamforming System Using 2-D Adaptive Sequential Searching Algorithm for Microwave Power Transfer

Bae

Koo

et al. 2020

IEEE Access

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This paper presents a look-up table (LUT)-based focal beamforming system that can effectively transmit RF power up to mid-range distances (≤ 3 m) including when the Rx is in the nearfield zones. The Tx elements control and radiate signals for the Rx even at the near-field zone ensuring the received signals are in-phase. Since the proposed system uses a LUT for storing the phase sets of the signals for the Tx elements, it requires only very simple hardware and a very simple adaptive control algorithm compared to conventional retroreflective method. In order to track the moving Rx, a 2-D adaptive sequential searching algorithm is proposed. The system can find the optimum phase set by sequentially searching the phase sets for a predetermined 2-D area. The LUT of the phase sets are generated using geometric analysis over the entire 2-D area where the Rx could be located. To verify the proposed method, a 5.2 GHz mid-range (≤ 3 m) MPT system composed of a 4×8 Tx array and a 2×3 Rx array was designed and implemented. Using the proposed 2-D adaptive sequential searching algorithm, the optimum phase set for focal beamforming can be quickly found for a given position of the Rx. In our experiments, the results showed an RF power level of 177.8 mW was received at the Rx with a distance of 1 m with a total radiated RF power of 16 W. Since the measured received power levels for various Rx positions agree well with the simulation results, the proposed system was proved to be an excellent candidate for the practical application. INDEX TERMS Microwave power transfer, Look-up table, Focal beamforming, 2-D adaptive sequential searching algorithm.

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Section: Lut-based Focal Beamformingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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LUT-Based Focal Beamforming System Using 2-D Adaptive Sequential Searching Algorithm for Microwave Power Transfer

Bae

Koo

et al. 2020

IEEE Access

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“…Content may change prior to final publication. Several beamforming methods for far-field and/or nearfield MPT applications have been reported [21]- [32]. For far-field applications, the retrodirective method has been popularly used by utilizing a pilot signal that is transmitted from the Rx, to estimate the channel condition between the Tx and Rx for beamforming [21]- [28].…”

Section: Introductionmentioning

confidence: 99%

“…For far-field applications, the retrodirective method has been popularly used by utilizing a pilot signal that is transmitted from the Rx, to estimate the channel condition between the Tx and Rx for beamforming [21]- [28]. In particular for near-field applications, the retroreflective method has also been adopted by utilizing a pilot signal transmitted from the Rx to directly acquire the optimum phase of the signal for each Tx element [29]- [32]. Since both retrodirective and retroreflective methods require a pilot Tx in the Rx and a pilot Rx in the Tx element, the systems utilizing these methods can be complex, and the Rx has additional power consumption arising from the pilot generation and transmitting circuits.…”

Section: Introductionmentioning

confidence: 99%

5.8 GHz 4-Channel Beamforming Tx IC for Microwave Power Transfer

Shin

Bae²,

Koo

et al. 2021

IEEE Access

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The microwave power transfer (MPT) system requires a massive Tx array for building a focused radio wave to efficiently transfer power to the Rx. Beamforming IC is one of the core elements for the massive Tx array. This paper presents a 5.8 GHz 4-channel beamforming Tx IC based on a CMOS process. The beamforming Tx IC includes a resistive 4-way power splitter, 5-bit differential phase shifters, drive amplifiers, and power amplifiers. Each channel is designed to transmit a power of no less than 100 mW. To verify the Tx IC, a 16-channel beamforming Tx module based on 16 patch antennas and four 4-channel Tx ICs was designed. The module also includes a PLL, a frequency doubler, and a 4-way Wilkinson power divider. MPT experiments to verify the beamforming IC and module were carried out using the implemented 16-channel Tx module at 5.8 GHz. Received power levels of 13 dBm and 2.1 dBm were achieved at distances of 0.4 and 1.4 m, respectively. The results are almost similar to the values acquired from the calculation using the Friis equation. INDEX TERMSMicrowave power transfer, massive Tx array, beamforming, complementary metal-oxidesemiconductor (CMOS), Tx IC.

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Low complexity on-board vector calibration network for optimal microwave wireless power transmission and enhanced RF-to-DC conversion efficiency

Dong,

Cho,

Lee

2024

Applied Energy

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Retroreflective Transceiver Array Using a Novel Calibration Method Based on Optimum Phase Searching

Cited by 30 publications

References 40 publications

LUT-Based Focal Beamforming System Using 2-D Adaptive Sequential Searching Algorithm for Microwave Power Transfer

LUT-Based Focal Beamforming System Using 2-D Adaptive Sequential Searching Algorithm for Microwave Power Transfer

5.8 GHz 4-Channel Beamforming Tx IC for Microwave Power Transfer

Low complexity on-board vector calibration network for optimal microwave wireless power transmission and enhanced RF-to-DC conversion efficiency

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