A retrodirective null-scanning array

Iwami, Reece T.; Zamora, Alexis; Chun, Tyler F.; Watanabe, Monte; Shiroma, Wayne A.

doi:10.1109/mwsym.2010.5518000

Cited by 3 publications

(8 citation statements)

References 7 publications

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“…The null-scanning RDA of [17] was developed to address the R 4 path loss issue by utilizing a power-detection approach, thereby decoupling the received and transmitted signals, and achieving an R 2 path loss. It was shown that by utilizing a null for minimum power detection, a twoelement microstrip patch array was much more capable in resolving an interrogator signal' s direction-of-arrival (DOA) when compared to an identically equipped beam-steering RDA.…”

Section: Modu Le Vomentioning

confidence: 99%

“…In contrast to the architecture in [17] , which uses one array for DOA detection and another array for transmit communications, the architecture in Fig. 11 combines both functions into one array.…”

Section: Detection and Communication Arraymentioning

confidence: 99%

“…This is achieved by siphoning off one-tenth of the received interrogator signal power from the two central antenna elements using 1 0-dB couplers. Combining the detection and communication arrays not only reduces the physical size of the array, but also improves the steering accuracy as both arrays are collocated at their centers, rather than being laterally offset from each other [17].…”

Section: Detection and Communication Arraymentioning

confidence: 99%

“…The array utilizes the null-scanning approach for power detection, first presented in [17]. This information is then used by the control module to retrodirect a signal back to the interrogator.…”

Section: Doa Detection Modulementioning

confidence: 99%

“…Compared to the analog phase shifters used in previous designs [5] , [17], [18] the discrete nature of digital phase shifters resulted in tolerance to small variations in control voltage, which are inherent in any control circuit. The analog phase shifters used previously were extremely sensitive at 221.4 degN [ 17], where commonly occurring variations in control voltages on the order of tenths and hundredths of volts would cause steering angle errors and instability.…”

Section: Doa Detection Modulementioning

confidence: 99%

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Miniaturized Retrodirective Arrays for a Nanosatellite Platform

Shiroma¹,

Iwami²,

Tonaki³

2012

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Section: Modu Le Vomentioning

confidence: 99%

Section: Detection and Communication Arraymentioning

confidence: 99%

Section: Detection and Communication Arraymentioning

confidence: 99%

Section: Doa Detection Modulementioning

confidence: 99%

Section: Doa Detection Modulementioning

confidence: 99%

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Miniaturized Retrodirective Arrays for a Nanosatellite Platform

Shiroma¹,

Iwami²,

Tonaki³

2012

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Smart Solutions in Smart Spaces: Getting the Most from Far-Field Wireless Power Transfer

Costanzo

Masotti

2016

IEEE Microwave

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MotivationNowadays there is an almost unlimited number of monitoring applications, such as structural health, logistic, security, healthcare and agriculture, which are planning to be based on a large deployment of co-operative wireless microsystems, with sensing capabilities, moving closer to the effective realization of the paradigm of the Internet of Things. The main open challenge is the reliability of maintenance-free devices, with life-time duration, especially from the energy sustainability point of view. Such systems are required to power themselves, by harvesting energy from the ambient, thus eliminating battery needs. To minimize energy requirements, wake-up radios able to be activated by signals as low as -50 dBm are already available [1]. RF/microwave energy sources are foreseen as one of the best candidates to comply with energy autonomy, either because they are widely distributed in humanized environments or because they can be efficiently provided on demand. These two different ways of providing RF energy can be referred to as RF energy harvesting (EH) and wireless power transmission (WPT), respectively. In both cases a delicate design of the RF power transfer link, consisting of the nonlinear sub-systems and the radiating elements, is required, providing that their characteristics are carefully optimized depending on the particular contest and scenario. Intensive industrial and academic activities has been devoted to this field: several and concurrent techniques and circuit solutions have been proposed and tested to ensure nonintermittent, sufficient wireless power transfer, with the lowest possible density. In this way, it is possible to comply with maximum transfer efficiency and minimum EM interference and pollution, at the same time. Typical frequencies adopted for these purposes are in the UHF and SHF bands around 400-800 MHz, for terrestrial TV signals, and around 900, 1800, 2400 and 5800 MHz, for different wireless standards: since the geometrical area to be covered are usually of the order of few meters, the devices to be powered are in the far-field region of their known or unknown RF/microwave sources. This article reviews some of the recent and promising circuit and antenna solutions and discusses reliable sub-systems adopted for receiving and transmitting subsystems, their associated radiating elements, with a focus on minimizing the power budget for enabling device operations.

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Time-Modulation of Linear Arrays for Real-Time Reconfigurable Wireless Power Transmission

Masotti

Costanzo

Prete

et al. 2016

IEEE Trans. Microwave Theory Techn.

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This paper proposes a smart wireless power transmission method, based on a two-step procedure, exploiting real-time beaming of time-modulated arrays. The sideband radiation phenomenon, which is usually a drawback of these radiating systems, is favorably used for intentional wireless power transfer (WPT): in a first step, to precise localize the tag to be powered, in the second one, to perform directive WPT. The approach is first theoretically discussed, then the numerical procedure, which integrates full-wave analysis of the antenna array with nonlinear simulation of the modulated nonlinear feeding network, is used to validate the principle of operation and to include nonlinearities and electromagnetic couplings affecting the whole system performance. The procedure allows a flexible design of the TMA-based WPT system, taking into account the impact of different array elements layout and spacing on localization and power transmission performance. Experiment of the first step is carried out in a real indoor environment at 2.45 GHz: a TI MSP430 drives a Schottky-diode-based network to provide proper modulated RF excitations of the array elements. Measurements show that the system is able to select tags to be energized randomly distributed in a 100°-scanning range.

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A retrodirective null-scanning array

Cited by 3 publications

References 7 publications

Miniaturized Retrodirective Arrays for a Nanosatellite Platform

Miniaturized Retrodirective Arrays for a Nanosatellite Platform

Smart Solutions in Smart Spaces: Getting the Most from Far-Field Wireless Power Transfer

Time-Modulation of Linear Arrays for Real-Time Reconfigurable Wireless Power Transmission

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