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1. Modeling and Optimization of the Steering Range of a Phased Array Antenna for Neuromodulation Applications in the Near-Field Region

   https://doi.org/10.1109/USNC-URSI52151.2023.10238083  

   Saha, Nabanita; Mahbub, Ifana (July 2023, 2023 IEEE International Symposium on Antennas and Propagation and USNC-URSI Radio Science Meeting (USNC-URSI))

   This paper presents modeling and optimization of the steering range of a microstrip planar phased array antenna to steer the unidirectional near-field focused beam towards a certain direction. This antenna can be implemented in headstage-based neural stimulation system and wireless recording system for optogenetic neuromodulation applications. The proposed phased-array antenna consists of sixteen elements that are designed to provide a uniform power transmission over the 27 cm×23 cm×16 cm rat behavioral cage area. The proposed transmitter (TX) antenna implements a near-field-based wireless power transmission system operating at 2.4 GHz frequency. The phased array antenna steers the beam from -30° to 60° in the elevation plane by feeding the individual elements with different phases using four 4-bit phase shifters. A design analysis of the beam-steering approach of the phased array antenna is presented and the corresponding simulation and measurement results are included in this paper. 

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2. Computational Analysis of a 200 GHz Phased Array Using Lens-Coupled Annular-Slot Antennas

   https://doi.org/10.3390/app12031407  

   Li, Peizhao; Shi, Yu; Deng, Yijing; Liu, Lei (February 2022, Applied Sciences)

   We report the design, simulation, and analysis of a THz phased array, using lens-coupled annular-slot antennas (ASAs) for potential beyond 5G or 6G wireless communications. For a prototype demonstration, the ASA employed was designed on a high resistivity Si substrate with a radius of 106 μm, and a gap width of 6 um for operation at 200 GHz. In order to achieve higher antenna gain and efficiency, an extended hemispherical silicon lens was also used. To investigate the effect of the silicon lens on the ASA phased array, a 1 × 3 array and 1 × 5 array (the element distance is 0.55λ) were implemented with a silicon lens using different extension lengths. The simulation shows that for a 1 × 3 array, a ±17° scanning angle with an about −10 dB sidelobe level and 11.82 dB gain improvement (compared to the array without lens) can be achieved using a lens radius of 5000 μm and an extension length of 1000 μm. A larger scanning angle of ±31° can also be realized by a 1 × 5 array (using a shorter extension length of 250 μm). The approach of designing a 200 GHz lens-coupled phased array reported here is informative and valuable for the future development of wireless communication technologies. 

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3. L Band Phased Array Feed Noise Figure and Radiation Efficiency Measurement with the Antenna Y Factor Method

   https://doi.org/10.1142/S2251171723500022  

   Burnett, Mitchell C.; Buck, David; Ashcraft, Nathaniel; Ammermon, Spencer; Jeffs, Brian D.; Warnick, Karl F. (March 2023, Journal of Astronomical Instrumentation)

   The noise performance of a high sensitivity, wide-field astronomical phased array feed receiver can be characterized by measurements using the antenna Y factor method. These measurements are used to determine figures of merit for an active array receiver. Antenna elements for the Advanced L Band Phased Array Camera for Astronomy (ALPACA) were measured using the antenna Y factor method to determine the active array and receiver noise figure, the antenna loss, receiver equivalent noise temperature, and radiation efficiency of the system over its 500[Formula: see text]MHz operating bandwidth. The completed ALPACA instrument will feature a fully cryogenic design with both the low-noise amplifiers and array elements cryogenically cooled. The uncooled performance measurements from the antenna Y factor method are used to extrapolate the elements cryogenic radiation efficiency and antenna loss showing that it is expected that the elements will contribute less than 1 K to the overall system noise temperature. These results validate the antenna Y factor method to measure key antenna parameters such as the antenna radiation efficiency and show that the instruments front-end array and electronics meets expected performance targets. 

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4. A Magnetic Sensor based Auto-tracking system for 2.4 GHz Near-field Phased-Array based Wireless Power Transfer System in Neuromodulation Applications

   Nabanita Saha, Erik Pineda (January 2023, 2023 USNC-URSI National Radio Science Meeting)

   This paper presents a magnetic sensor based autotracking method for a phased array based wireless power transfer system to be implemented in neuromodulation applications. This method is proposed to track the position of the receiver(placed on a freely moving animal) and transmit the microwave signal with a focused beam to the target receiver. The coordinate locations of the target are obtained from the magnetic sensor and converted into phase information for the phased array. The system is constructed by a 2.4 GHz near-field 4×4 phased array transmitter antenna with 4-bit phase shifters. The phased array TX antenna steers the beam from -5° to -155° in the θ plane. The magnetic sensor can detect the location of the receiver and the in this steering range. The process of tracking the the target and focusing the beam has been evaluated by simulation. 

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5. 10.1109/MCAS.2019.2909447

   https://doi.org/10.1109/MCAS.2019.2909447  

   Yan, Han; Ramesh, Sridhar; Gallagher, Timothy; Ling, Curtis; Cabric, Danijela (April 2019, IEEE circuits and systems magazine)

   Millimeter wave (mmW) communications is viewed as the key enabler of 5G cellular networks due to vast spectrum availability that could boost peak rate and capacity. Due to increased propagation loss in mmW band, transceivers with massive antenna array are required to meet a link budget, but their power consumption and cost become limiting factors for commercial systems. Radio designs based on hybrid digital and analog array architectures and the usage of radio frequency (RF) signal processing via phase shifters have emerged as potential solutions to improve radio energy efficiency and deliver performances close to the conventional digital antenna arrays. In this paper, we provide an overview of the state-of-the-art mmW massive antenna array designs and comparison among three array architectures, namely digital array, partially-connected hybrid array (sub-array), and fully-connected hybrid array. The comparison of performance, power, and area for these three architectures is performed for three representative 5G downlink use cases, which cover a range of pre-beamforming signal-to-noise-ratios (SNR) and multiplexing regimes. This is the first study to comprehensively model and quantitatively analyze all design aspects and criteria including: 1) optimal linear precoder, 2) impact of quantization error in digital-to-analog converter (DAC) and phase shifters, 3) RF signal distribution network, 4) power and area estimation based on state-of-the-art mmW circuits including baseband digital precoding, digital signal distribution network, high-speed DACs, oscillators, mixers, phase shifters, RF signal distribution network, and power amplifiers. Our simulation results show that the fully-digital array architecture is the most power and area efficient compared against optimized designs for sub-array and hybrid array architectures. Our analysis shows that digital array architecture benefits greatly from multi-user multiplexing. The analysis also reveals that sub-array architecture performance is limited by reduced beamforming gain due to array partitioning, while the system bottleneck of the fully-connected hybrid architecture is the excessively complicated and power hungry RF signal distribution network. 

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