Showing papers on "Phased array published in 2020"

Large-scale optical phased array using a low-power multi-pass silicon photonic platform

Abstract: Optical phased arrays are a promising beam-steering technology for ultra-small solid-state lidar and free-space communication systems. Long-range, high-performance arrays require a large beam emission area densely packed with thousands of actively phase-controlled, power-hungry light emitting elements. To date, such large-scale phased arrays have been impossible to realize since current demonstrated technologies would operate at untenable electrical power levels. Here we show a multi-pass photonic platform integrated into a large-scale phased array that lowers phase shifter power consumption by nearly 9 times. The multi-pass structure decreases the power consumption of a thermo-optic phase shifter to a ${{\rm P}_\pi }$Pπ of ${1.7}\;{\rm mW/}\pi $1.7mW/π without sacrificing speed or optical bandwidth. Using this platform, we demonstrate a silicon photonic phased array containing 512 actively controlled elements, consuming only 1.9 W of power while performing 2D beam steering over a ${70}^\circ \times {6}^\circ $70∘×6∘ field of view. Our results demonstrate a path forward to building scalable phased arrays containing thousands of active elements.

MAJoRCom: A Dual-Function Radar Communication System Using Index Modulation

Abstract: Dual-function radar communication (DFRC) systems implement both sensing and communication using the same hardware. Such schemes are often more efficient in terms of size, power, and cost, over using distinct radar and communication systems. Since these functionalities share resources such as spectrum, power, and antennas, DFRC methods typically entail some degradation in both radar and communication performance. In this work we propose a DFRC scheme based on the carrier agile phased array radar (CAESAR), which combines frequency and spatial agility. The proposed DFRC system, referred to as multi-carrier agile joint radar communication (MAJoRCom), exploits the inherent spatial and spectral randomness of CAESAR to convey digital messages in the form of index modulation. The resulting communication scheme naturally coexists with the radar functionality, and thus does not come at the cost of reduced radar performance. We analyze the performance of MAJoRCom, quantifying its achievable bit rate. In addition, we develop a low complexity decoder and a codebook design approach, which simplify the recovery of the communicated bits. Our numerical results demonstrate that MAJoRCom is capable of achieving a bit rate which is comparable to utilizing independent communication modules without affecting the radar performance, and that our proposed low-complexity decoder allows the receiver to reliably recover the transmitted symbols with an affordable computational burden.

The LOFAR Two Meter Sky Survey: Deep Fields, I -- Direction-dependent calibration and imaging

Abstract: The Low Frequency Array (LOFAR) is an ideal instrument to conduct deep extragalactic surveys. It has a large field of view and is sensitive to large scale and compact emission. It is, however, very challenging to synthesize thermal noise limited maps at full resolution, mainly because of the complexity of the low-frequency sky and the direction dependent effects (phased array beams and ionosphere). In this first paper of a series we present a new calibration and imaging pipeline that aims at producing high fidelity, high dynamic range images with LOFAR High Band Antenna data, while being computationally efficient and robust against the absorption of unmodeled radio emission. We apply this calibration and imaging strategy to synthesize deep images of the Bootes and LH fields at 150 MHz, totaling $\sim80$ and $\sim100$ hours of integration respectively and reaching unprecedented noise levels at these low frequencies of $\lesssim30$ and $\lesssim23$ $\mu$Jy/beam in the inner $\sim3$ deg$^2$. This approach is also being used to reduce the LoTSS-wide data for the second data release.

A 28-GHz CMOS Phased-Array Beamformer Utilizing Neutralized Bi-Directional Technique Supporting Dual-Polarized MIMO for 5G NR

Abstract: This article presents a low-cost and area-efficient 28-GHz CMOS phased-array beamformer chip for 5G millimeter-wave dual-polarized multiple-in-multiple-out (MIMO) (DP-MIMO) systems. A neutralized bi-directional technique is introduced in this work to reduce the chip area significantly. With the proposed technique, completely the same circuit chain is shared between the transmitter and receiver. To further minimize the area, an active bi-directional vector-summing phase shifter is also introduced. Area-efficient and high-resolution active phase shifting could be realized in both TX and RX modes. In measurement, the achieved saturated output power for the TX-mode beamformer is 15.1 dBm. The RX-mode noise figure is 4.2 dB at 28 GHz. To evaluate the over-the-air performance, 16 H+16 V sub-array modules are implemented in this work. Each of the sub-array modules consists of four 4 H+4 V chips. Two sub-array modules in this work are capable of scanning the beam from −50° to +50°. A saturated EIRP of 45.6 dBm is realized by 32 TX-mode beamformers. Within 1-m distance, a maximum SC-mode data rate of 15 Gb/s and the 5G new radio downlink packets transmission in 256-QAM could be supported by the module. A $2\times 2$ DP-MIMO communication is also demonstrated with two 5G new radio 64-QAM uplink streams. Thanks to the proposed area-efficient bi-directional technique, the required core area for a single element-beamformer is only 0.58 mm2. Compact and low-cost 5G millimeter-wave MIMO systems could be realized.

Finite Element Analysis Model on Ultrasonic Phased Array Technique for Material Defect Time of Flight Diffraction Detection

Abstract: In this study, the finite element method (FEM) for phased array technology in ultrasonic time of flight diffraction (TOFD) for the defect detection of two-dimensional (2-D) geometric materials was researched. The phased array technology generated the FEM model for the TOFD signal. We have established the finite element model by the FEM software ANSYS based on the ultrasonic mechanism about the defects and the phased array transducer. A plane strain elements have simulated the reflected signal of the defect. We can compare the error ratio between simulation and experiment by using the theoretical calculation value as the benchmark, and find the feasibility of the FEM detection.

Microwave Liquid Crystal Enabling Technology for Electronically Steerable Antennas in SATCOM and 5G Millimeter-Wave Systems

Abstract: Future satellite platforms and 5G millimeter wave systems require Electronically Steerable Antennas (ESAs), which can be enabled by Microwave Liquid Crystal (MLC) technology. This paper reviews some fundamentals and the progress of microwave LCs concerning its performance metric, and it also reviews the MLC technology to deploy phase shifters in different topologies, starting from well-known toward innovative concepts with the newest results. Two of these phase shifter topologies are dedicated for implementation in array antennas: (1) wideband, high-performance metallic waveguide phase shifters to plug into a waveguide horn array for a relay satellite in geostationary orbit to track low Earth orbit satellites with maximum phase change rates of 5.1°/s to 45.4°/s, depending on the applied voltages, and (2) low-profile planar delay-line phase shifter stacks with very thin integrated MLC varactors for fast tuning, which are assembled into a multi-stack, flat-panel, beam-steering phased array, being able to scan the beam from −60° to +60° in about 10 ms. The loaded-line phase shifters have an insertion loss of about 3 dB at 30 GHz for a 400° differential phase shift and a figure-of-merit (FoM) > 120°/dB over a bandwidth of about 2.5 GHz. The critical switch-off response time to change the orientation of the microwave LCs from parallel to perpendicular with respect to the RF field (worst case), which corresponds to the time for 90 to 10% decay in the differential phase shift, is in the range of 30 ms for a LC layer height of about 4 µm. These MLC phase shifter stacks are fabricated in a standard Liquid Crystal Display (LCD) process for manufacturing low-cost large-scale ESAs, featuring single- and multiple-beam steering with very low power consumption, high linearity, and high power-handling capability. With a modular concept and hybrid analog/digital architecture, these smart antennas are flexible in size to meet the specific requirements for operating in satellite ground and user terminals, but also in 5G mm-wave systems.

Dual-Polarized Phased Array With End-Fire Radiation for 5G Handset Applications

Abstract: This communication proposes a dual-polarized end-fire phased array for 5G handset devices at 28 GHz. The proposed four-element array has low profile of 1.1 mm, small clearance of 2.7 mm, and symmetric patterns in the vertical plane. The array element is fed by substrate-integrated waveguide (SIW), which works as a waveguide (WG) antenna with vertically polarized radiation pattern. Two transition plates are introduced to improve the impedance matching of the WG antenna. The horizontal polarization is generated by exciting one of the transition plates as an antenna. The other transition plate is modified as a group of triangle strips to minimize its reflection to the horizontal radiation patterns. A −10 dB frequency bandwidth of 5.3% and a −6 dB bandwidth of 25% are achieved, overlapping between the vertical and horizontal polarization. The array scanning angle is from −54° to 44° at 29 GHz for both polarization. Within the scanning range, the end-fire gain varies from 7.48 to 8.14 dBi for the horizontal polarization, whereas from 4.49 to 8.05 dBi for the vertical polarization. Good agreements between simulations and measurements are well achieved and shown in this communication.

Energy-Efficient 5G Phased Arrays Incorporating Vertically Polarized Endfire Planar Folded Slot Antenna for mmWave Mobile Terminals

Abstract: An energy-efficient 5G phased array incorporating a novel vertically polarized (V-pol) endfire planar folded slot antenna (PFSA) for user devices (UE) is presented. First, we analytically amend existing millimeter-wave (mmWave) hybrid beamforming architectures that have precluded the uniqueness of 5G antennas and UEs. The total power consumption of the derived switchable 5G UE antenna system is estimated to be reduced by approximately 70% in comparison with a recently reported fully digital mmWave 5G UE antenna system under identical conditions. This is attributed to the ability to deactivate certain RF chains based on the directive nature of antenna elements. The PFSA featuring a height profile of less than 1/ $9~\lambda _{ {0}}$ is derived from a planar folded slot structure. The designed and fabricated $1\times 4$ PFSA array features an impedance bandwidth of approximately 4 GHz with a center frequency of 37–39 GHz and the gain of 7.7 dBi with antenna efficiency of 94.12% at 39 GHz. An mmWave 5G beamforming module is demonstrated using the presented energy-efficient 5G beamforming architecture and V-pol endfire PFSA array. The fabricated module achieves a measured EIRP of 18.2 dBm and a scanning range of ±50° in azimuth at 28 GHz.

Silicon integrated microwave photonic beamformer

Abstract: Optical beam-forming networks (OBFNs) based on optical true-time delay lines (OTTDLs) are well known as the promising candidate for solving the bandwidth limitation of traditional electronic phased array antennas (PAAs) due to beam squinting. Here we report, to the best of our knowledge, the first monolithic 1×8 microwave photonic beamformer, based on switchable OTTDLs on the silicon-on-insulator platform. The chip consists of a modulator, an eight-channel OBFN, and eight photodetectors, thus including hundreds of active and passive components in total. It has a wide operating bandwidth from 8 to 18 GHz, which is almost two orders larger than that of electronic PAAs. The beam can be steered to 31 distinguishable angles in the range from −75.51∘ to 75.64°, based on the beam pattern calculation with the measured radiofrequency response. The response time for beam steering is 56 µs. These results represent a significant step toward the realization of integrated microwave photonic beamformers that can satisfy compact-size and low-power consumption requirements for the future radar and wireless communication systems.

Enabling Panoramic Full-Angle Reflection Via Aerial Intelligent Reflecting Surface

Abstract: This paper proposes a new three dimensional (3D) networking architecture enabled by aerial intelligent reflecting surface (AIRS) to achieve panoramic signal reflection from the sky. Compared to the conventional terrestrial IRS, AIRS not only enjoys higher deployment flexibility, but also is able to achieve 360° panoramic full-angle reflection and requires fewer reflections in general due to its higher likelihood of having line-of-sight (LoS) links with the ground nodes. We focus on the problem to maximize the worst-case signal-to-noise ratio (SNR) in a given coverage area by jointly optimizing the transmit beamforming of the source node, the placement and phase shifts of the AIRS. The formulated problem is non-convex and the optimization variables are coupled with each other in an intricate manner. To tackle this problem, we first consider the special case of single-location SNR maximization to gain useful insights, for which the optimal solution is obtained in closed-form. Then for the general case of area coverage, an efficient suboptimal solution is proposed by exploiting the similarity between phase shifts optimization for IRS and analog beamforming for the conventional phase array. Numerical results show that the proposed design can achieve significant performance gain than heuristic AIRS deployment schemes.

A 37–42-GHz 8 × 8 Phased-Array With 48–51-dBm EIRP, 64–QAM 30-Gb/s Data Rates, and EVM Analysis Versus Channel RMS Errors

Abstract: This article presents a 5G 37–42-GHz $8\times 8$ phased array. The array is based on $2\times 2$ SiGe transmit/receive (TRX) beamformer chips in the SiGe technology with 6 bits of phase control and 8 bits of gain control. A detailed study is presented, showing the effects of array-level amplitude and phase errors on the radiated error vector magnitude (EVM) of 64-element arrays. The array scans to ±60° in the azimuth plane and ±50° in the elevation plane with low sidelobes. The measured peak effective isotropic radiated power (EIRP) is 51 dBm at Psat with a 3-dB bandwidth of 36–41.5 GHz. A 39-GHz communication system is also demonstrated along with a high-pass filter and an integrated upconverter/downconverter and achieves a local oscillator (LO) and image rejection level of 50 dBc, meeting FCC requirements of <−13 dBm/MHz of total leakage power. The array achieves < 5% EVM (−26 dB) using a 64-QAM 200-MHz waveform at an average EIRP of 44 dBm over all scan angles, including the LO and upconverter/downconverter contributions. A 30-Gb/s communication link with 64-QAM modulation is also shown. To our knowledge, this is the first demonstration of a 39-GHz phased-array communication system for 5G applications.

mm-Wave Beam-Steerable Endfire Array Embedded in a Slotted Metal-Frame LTE Antenna

Abstract: In this article, a new principle to overcome the blockage of metallic frames in mobile terminals to endfire millimeter-wave (mm-wave) arrays is proposed. The obstruction is solved by etching several slots in the top part of the frame. It is shown that the slots in the handset frame can further enhance the beam-steering gain of a mm-wave bow-tie array. A very small array-frame distance can also be realized without degrading much the array performance. Several considerations in the slot design are assessed first. A prototype of the PCB and frame has been built and the results show that the array is matched in the desired frequency bands of 24.25–27.5 and 27.5–28.35 GHz. The mm-wave array can scan 80° in the endfire direction, and the realized gain obtained is higher than 7 dBi in the operating frequency bands. At the same time, the frame performs as a sub-3 GHz dual-loop antenna. The covered bands are 760–980 and 1240–2870 MHz.

A Scalable Ka-Band 1024-Element Transmit Dual-Circularly-Polarized Planar Phased Array for SATCOM Application

Abstract: This paper presents a scalable 1024-element transmit dual-circularly-polarized phased array for Ka-band satellite communication (SATCOM) terminal applications. The transmit array based on the CMOS beamformer and a multilayer printed circuit board (PCB) can steer up to large scan angles (±60°) with a scan loss less than 4.5 dB. With the 8-channel transmit beamformer, the array can realize dual circular polarization and the axial ratio (AR) of the array is less than 3 dB in the scanning range of ±30° in both left-hand circular polarization (LHCP) and right-hand circular polarization (RHCP) mode. The effective isotropic radiated power (EIRP) of the array achieves 74 dBm from 29.5 GHz to 30 GHz. The design and measurement of the 1024-element transmit array have presented a feasible way for mass production of a low cost active phased array.

M-Cube: a millimeter-wave massive MIMO software radio

Abstract: Millimeter-wave (mmWave) technologies represent a cornerstone for emerging wireless network infrastructure, and for RF sensing systems in security, health, and automotive domains. Through a MIMO array of phased arrays with hundreds of antenna elements, mmWave can boost wireless bit-rates to 100+ Gbps, and potentially achieve near-vision sensing resolution. However, the lack of an experimental platform has been impeding research in this field. This paper fills the gap with M3 (M-Cube), the first mmWave massive MIMO software radio. M3 features a fully reconfigurable array of phased arrays, with up to 8 RF chains and 288 antenna elements. Despite the orders of magnitude larger antenna arrays, its cost is orders of magnitude lower, even when compared with state-of-the-art single RF chain mmWave software radios. The key design principle behind M3 is to hijack a low-cost commodity 802.11ad radio, separate the control path and data path inside, regenerate the phased array control signals, and recreate the data signals using a programmable baseband. Extensive experiments have demonstrated the effectiveness of the M3 design, and its usefulness for research in mmWave massive MIMO communication and sensing.

Chip-scale blue light phased array

Abstract: Compact beam steering in the visible spectral range is required for a wide range of emerging applications, such as augmented and virtual reality displays, optical traps for quantum information processing, biological sensing, and stimulation. Optical phased arrays (OPAs) can shape and steer light to enable these applications with no moving parts on a compact chip. However, OPA demonstrations have been mainly limited to the near-infrared spectral range due to the fabrication and material challenges imposed by the shorter wavelengths. Here, we demonstrate the first chip-scale phased array operating at blue wavelengths (488 nm) using a high-confinement silicon nitride platform. We use a sparse aperiodic emitter layout to mitigate fabrication constraints at this short wavelength and achieve wide-angle beam steering over a 50° field of view with a full width at half-maximum beam size of 0.17°. Large-scale integration of this platform paves the way for fully reconfigurable chip-scale three-dimensional volumetric light projection across the entire visible range.

Enhanced Single-Sideband Time-Modulated Phased Array With Lower Sideband Level and Loss

Abstract: This article presents an enhanced single-sideband time-modulated phased array (ESTMPA) using modulating pulses with stepped waveforms. Based on the in-phase/quadrature (I/Q) complex modulation technique, this phase-only weighting array generates a scanning beam at the 1st sideband. The proposed modulating pulses realized through a reconfigurable power divider in I/Q time modulator can avoid the power loss from the switches during switch-OFF state and eliminate the maximum undesired sideband—the 5th harmonic in STMPA. As a result, it brings a power spectrum with less undesired sidebands, lower sideband level (−16.9 dB), higher harmonic efficiency (94.96%), and wider allowable signal bandwidth (eight times as wide as that of the conventional time modulated array). To experimentally verify the feasibility of the proposed design, a wideband enhanced I/Q time modulator and its corresponding eight-element ESTMPA are designed and manufactured. A detailed study on the effect of the magnitude and phase deviations in the circuit and the transition period of modulating pulse are presented. The measured results of power spectrum and radiation pattern have a good agreement with the simulated ones.

2 $\times$ 64-Element Dual-Polarized Dual-Beam Single-Aperture 28-GHz Phased Array With 2 $\times$ 30 Gb/s Links for 5G Polarization MIMO

Abstract: This article presents a 5G 28-32 GHz 2 × 64-element dual-polarized (DP) dual-beam transmit/receive (TRX) phased array. The array is based on a SiGe 2 × 4 TRX dual-beamformer chip with 6 bits of phase and 25 dB of gain control. The chip delivers 11-12 dBm/channel in the transmit-mode and has a noise figure (NF) of 4.8 dB in the receive-mode. Sixteen chips are employed for the construction of a low-cost printed circuit board (PCB) based 2 × 64-element dual-beam array using flip-chip technology. The phased-array has two 1:16 dual Wilkinson networks and microstrip antennas with rotated feeds for cross-polarization cancellation. The array demonstrates a measured effective isotropic radiated power (EIRP) at Psat of 52 dBm for each beam and is capable of scanning ±50° in azimuth and ±25° in elevation with >28-dB cross-polarization rejection. Simultaneous dual-beam operation is demonstrated with near-ideal patterns for each beam. The array demonstrates independent simultaneously transmitted 2 × 16-quadrature amplitude modulation (QAM) and 2 × 64QAM data streams delivering an aggregate maximum data rate of 2 × 20 and 2 × 30 Gb/s, respectively. Also, measurements done over all scan angles at an EIRP of 41 dBm per polarization and 64-QAM waveforms show a data rate of 2 × 4.8 Gb/s with an EVM ≤ -25 dB. To our knowledge, this is the first demonstration of a dual-polarized dual-beam phased array for 5G polarization-based multiple-input-multiple-output (MIMO) systems with 60-Gb/s maximum data rates.

A Metamaterial-Based $S/X$ -Band Shared-Aperture Phased-Array Antenna With Wide Beam Scanning Coverage

Abstract: This article proposes an ultralow profile $S/X$ -band shared-aperture phased-array antenna (SAPAA), which can achieve wide beam scanning coverage in both the $S$ - and $X$ -bands. The SAPAA consists of an $S$ -band array with a triangular placement that has 11 elements and a grid array with $8\times 16\,\,X$ -band elements. To avoid grating lobes in wide beam scanning coverage, a metamaterial-based stacked mushroom structure is proposed to reduce the array spacing of the two bands, where an $X$ -band patch antenna is stacked on a traditional mushroom structure. A $4\times4$ subarray of the stacked mushroom structure operates as a single antenna element in $S$ -band. Consequently, each $S$ -band element corresponds to a $4\times4$ subarray of the $X$ -band element. Because a triangular arrangement in the $S$ -band array and a square arrangement in the $X$ -band array are employed, the array spacing of the two bands is $0.54\lambda _{\mathrm {L0}}$ and $0.51\lambda _{\mathrm {H0}}$ , respectively, which is suitable for wide beam scanning coverage. Moreover, the shorting pin of the mushroom structure is also the feeding pin of the $X$ -band patch. This structure reuse technology reduces the whole profile to less than $0.04\lambda _{0}$ . To verify this design, a prototype is fabricated through the multilayer printed circuit board process. It realizes ±50° beam coverage in both the $S$ - and $X$ -bands.

Phased Array With Low-Angle Scanning and 46:1 Bandwidth

Abstract: An extremely wideband (EWB) antenna array is presented that covers the UHF to $C$ -bands (0.13–6 GHz). The array has dual-linear polarization and is capable of wide-angle scanning. Notably, this array achieves a 46:1 contiguous impedance bandwidth at broadside with VSWR $12\times12$ array prototype was fabricated and tested to verify the bandwidth and gain performance of a finite array. The simulated radiation efficiency was demonstrated to be 72% on average across the band.

Scanning Range Expansion of Planar Phased Arrays Using Metasurfaces

Abstract: We propose a novel method to extend the scanning range of planar phased arrays based on a phase gradient metasurface. The phase gradient metasurface is developed by the generalized Snell’s law, which can irregularly tailor the direction of propagation of the traversing electromagnetic waves. The proposed transmission gradient phase metasurface (TGPMS) uses bidirectional expansion of the scanning range in a phased array application. The TGPMS consists of periodic and multilayer subwavelength elements that contribute to a wide range of transmission phase shift and multiple incident angular stability. The design is verified experimentally with a compact microstrip phased array that is integrated with the proposed TGPMS. Results demonstrate that the TGPMS extends the scanning range of the integrated array symmetrically, from [−36°, 38°] to [−56°, 60°]. The proposed TGPMS has additional desirable characteristics, such as high transmission, polarization insensitivity, tunable transmission phases in a wide range, and transmission phase stability for waves incident at different angles.

Fully-Planar Ultrawideband Tightly-Coupled Array (FPU-TCA) With Integrated Feed for Wide-Scanning Millimeter-Wave Applications

Abstract: We present a linearly polarized ultrawideband design for millimeter-wave phased array antennas over 17–42 GHz. The design comprises tightly coupled dipoles, integrated with a specific feeding mechanism. The proposed antenna provides a relative bandwidth of 2.7:1 and 2.47:1 with VSWR $8\times 4$ arrays are fabricated using standard PCB technology. The measurement results of the array prototypes show a good agreement with the simulations in terms of VSWR, radiation pattern, and realized gain.

Array-Level Inverse Design of Beam Steering Active Metasurfaces.

Abstract: We report an array-level inverse design approach to optimize the beam steering performance of active metasurfaces, thus overcoming the limitations posed by nonideal metasurface phase and amplitude tuning. In contrast to device-level topology optimization of passive metasurfaces, the outlined system-level optimization framework relies on the electrical tunability of geometrically identical nanoantennas, enabling the design of active antenna arrays with variable spatial phase and amplitude profiles. Based on this method, we demonstrate high-directivity, continuous beam steering up to 70° for phased arrays with realistic tunable antenna designs, despite nonidealities such as strong covariation of scattered light amplitude with phase. Nonintuitive array phase and amplitude profiles further facilitate beam steering with a phase modulation range as low as 180°. Furthermore, we use the device geometries presented in this work for experimental validation of the system-level inverse design approach of active beam steering metasurfaces. The proposed method offers a framework to optimize nanophotonic structures at the array level that is potentially applicable to a wide variety of objective functions and actively tunable metasurface antenna array platforms.

A Novel Compact, Broadband, High Gain Millimeter-Wave Antenna for 5G Beam Steering Applications

Abstract: The millimeter-wave (mmWave) antennas for smartphones are one of the key components to complete the transition to 5G mobile networks. Although research and development of mmWave 5G antennas for cellular handsets are currently at the center of a significant research effort in both academia and telecommunication industry, a systematic antenna design approved by wireless community has not been proposed yet. With this communication, we propose a novel, high gain, wide band and compact mmWave 5G antenna, namely clover antenna for cellular handsets. The presented antenna has clover like conductor profile whose parameters can be adjusted to obtain high gain or wide band. The designed antennas are simulated with a widely used full-wave analysis tool. Numerical results of the mmWave antenna are confirmed successfully by the experimental results in ${{\text{24}}}$ – ${\text{28}}$ GHz band. The antenna achieves measured peak gain of ${\text{ 7.8}}$ – ${\text{9}}$ dBi in the band. Besides, with a ${\text{16}}$ -element clover antenna array, the beam steering capability of the antenna is demonstrated. Beam steering between ${{ \pm \text{45}^\circ }}$ is achieved with low side lobe levels. Practical design considerations for the integration of the arrays in handset to obtain full-coverage in horizontal plane are investigated. The calculated spatial peak power density values of the proposed array on the outer surface of a head phantom are demonstrated for different scan angles.

Development of Flat Panel Active Phased Array Antennas Using 5G Silicon RFICs at Ku - and Ka -Bands

Abstract: This article presents the design and development of two all flat panel phased array antennas (PAA) by using emerging 5G Silicon radio frequency integrated circuits (RFICs) at Ku- and Ka-bands. First, an X-/Ku-band wideband dual circular polarized Transmit (Tx)/Receive (Rx) phased array antenna with the capability of scanning (±45°) is presented. The frequency of operation is centered around 12.5 GHz within the X/Ku-Bands (3dB Axial Ratio (AR) bandwidth at broadside = 32%). The array has 16-elements with a $4\times 4$ lattice arrangement. This array utilizes a nested sequential rotation architecture, which enhances the axial ratio (AR) bandwidth. Secondly, a dual slant linear polarized (±45°) transmit and receive (T/R) phased array antenna, that operates in the Ka-Band and covers the millimeter-wave 5G band (27.5 – 28.35 GHz) is discussed. Beam scanning range is up to ±60° in both polarizations. In both cases, the array apertures have been integrated with an active beamforming networks (BFN) utilizing 5G silicon Tx/Rx beamformer RFIC chips. Measured and simulated performance results agree reasonably well in both cases. These arrays are scalable to larger size arrays to provide higher gain for applications like satellite communications (SATCOM) and 5G communications.

Wide-Angle Scanning Lens Fed by Small-Scale Antenna Array for 5G in Millimeter-Wave Band

Abstract: This article aims at high-gain and wide-angle scanning lens antenna design in millimeter-wave (MMW) band. The proposed antenna consists of a novel gradient-index (GRIN) lens and a phased array antenna (PAA) feed with aperture-coupled microstrip antenna (ACMA) elements. A new design methodology of the GRIN lens antenna is proposed, which comprises a preliminary design for rough shapes of GRIN lenses and two successive optimization steps. In the first optimization step, parameters of the GRIN lens are determined to achieve high directivity and wide scanning angle based on particle swarm optimization (PSO) algorithm and a quasi-2-D model. In the second step, the excitation coefficients of all elements for beam-steering purpose are obtained by the PSO algorithm with the goal of maximum directivity. To validate the approach, an MMW lens antenna, operating at 28 GHz, is numerically demonstrated with high directivity and a wide scanning range up to ±58°. Finally, the proposed antenna is fabricated by 3-D printing techniques. The measured results are in acceptable agreement with simulations.

Wide Field-of-View Locating and Multimodal Vital Sign Monitoring Based on ${X}$ -Band CMOS-Integrated Phased-Array Radar Sensor

Abstract: In this article, an X -band complementary metal-oxide-semiconductor (CMOS)-integrated phased-array radar sensor is proposed to enable the subject localization and multimodal vital sign monitoring. With the accurate beam-steering (ABS) technique realized by both true-time delay and phase shifting at the transmitter, the phased-array radar sensor achieves 60° steering coverage for the locating and monitoring on the targeted subjects with fine beam-steering precision. With the interferometric time-phase analysis (ITPA) algorithm adopted to the dechirped signal at the receiver, the vital signs and falling are detected by the radar sensor. Fabricated in 65-nm CMOS technology, the radar sensor occupies 5.8 mm 2 of silicon area and consumes 740.7-mW power. A series of experiments was carried out to demonstrate the capabilities of the prototype radar sensor on localizing the targeted subjects, discerning vital signs, and detecting falling in a wide field of view (FoV).

Limited Scan-Angle Phased Arrays Using Randomly Grouped Subarrays and Reduced Number of Phase Shifters

Abstract: This article presents randomly grouped subarray techniques to reduce the number of phase shifters in a 2-D phased array while maintaining a certain scan range in the azimuth and elevation planes and keeping sidelobes below a specified level. It is shown that controlling random groups of elements in such a manner suppresses these grating lobes and allows the use of fewer phase shifters. Guidelines for finding the best partition of a phased array into random subgroups are presented. It is shown that 75% reduction in phase shifters can be achieved while maintaining a 40° scan range in the azimuth plane, 15° scan range in the elevation plane, and keeping −10 to −12 dB sidelobes without tapering and with 6 dB taper. Other partitions are also presented with up to 88% reduction in phase shifters while maintaining a 5° scan range in elevation. Measurements on a $16\times16\,\,2$ -D phased array at 14 GHz are used to confirm the performance of randomly partitioned phased arrays. Application areas are in arrays with limited scan angle in the elevation plane, such as automotive radars, aircraft landing systems, and point-to-point communication systems.

Modular Design of Hexagonal Phased Arrays Through Diamond Tiles

Abstract: The modular design of planar phased array antennas with hexagonal apertures is addressed by means of innovative diamond-shaped tiling techniques. Both tiling configuration and subarray coefficients are optimized to fit user-defined power-mask constraints on the radiation pattern. Toward this end, suitable surface-tiling mathematical theorems are customized to the problem at hand to guarantee optimal performance in case of low/medium-size arrays, while the computationally hard tiling of large arrays is yielded thanks to an effective integer-coded GA -based exploration of the arising high-cardinality solution spaces. By considering ideal as well as real array models, a set of representative benchmark problems is dealt with to assess the effectiveness of the proposed architectures and tiling strategies. Moreover, comparisons with alternative tiling architectures are also performed to show to the interested readers the advantages and the potentialities of the diamond subarraying of hexagonal apertures.

A 5.8-GHz Phased Array System Using Power-Variable Phase-Controlled Magnetrons for Wireless Power Transfer

Abstract: We build a phased array system with four power-variable phase-controlled magnetrons (PCMs) by applying the injection-locking method and phase-locked-loop method. To reduce the cost and ensure the durability of the phased array, a waveguide slot array antenna was designed and used for the output antenna of power-variable PCMs. The slot antenna has an expected angle deflection of 22.5°, a gain of 24.9 dBi, and the half bandwidth of the main lobe was 10°. We demonstrated the properties of microwave beamforming and wireless power transfer based on the magnetron phased array system. In horizontal directions, a beam scanning range of ±3° was obtained by adjusting the output phase of the magnetrons. Furthermore, the received dc power reaches 142 W at a distance of 5 m when the output microwave power of the magnetron phased array is 1304 W.