Showing papers on "Phased array published in 2021"

The LOFAR Two-meter Sky Survey: Deep Fields Data Release 1. 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 Lockman Hole fields at ~150 MHz, totaling ~80 and ~100 h of integration, respectively, and reaching unprecedented noise levels at these low frequencies of ≲30 and ≲23 μ Jy beam−1 in the inner ~3 deg2 . This approach is also being used to reduce the LOTSS-wide data for the second data release.

Wideband Beamforming for Hybrid Massive MIMO Terahertz Communications

Abstract: The combination of large bandwidth at terahertz (THz) and the large number of antennas in massive MIMO results in the non-negligible spatial wideband effect in time domain or the corresponding beam squint issue in frequency domain, which will cause severe performance degradation if not properly treated. In particular, for a phased array based hybrid transceiver, there exists a contradiction between the requirement of mitigating the beam squint issue and the hardware implementation of the analog beamformer/combiner, which makes the accurate beamforming an enormous challenge. In this paper, we propose two wideband hybrid beamforming approaches, based on the virtual sub-array and the true-time-delay (TTD) lines, respectively, to eliminate the impact of beam squint. The former one divides the whole array into several virtual sub-arrays to generate a wider beam and provides an evenly distributed array gain across the whole operating frequency band. To further enhance the beamforming performance and thoroughly address the aforementioned contradiction, the latter one introduces the TTD lines and propose a new hardware implementation of analog beamformer/combiner. This TTD-aided hybrid implementation enables the wideband beamforming and achieves the near-optimal performance close to full-digital transceivers. Analytical and numerical results demonstrate the effectiveness of two proposed wideband beamforming approaches.

Joint Target Assignment and Resource Optimization Framework for Multitarget Tracking in Phased Array Radar Network

Abstract: In this article, a joint target assignment and resource optimization (JTARO) strategy is proposed for the application of multitarget tracking in phased array radar network system. The key mechanism of our proposed JTARO strategy is to employ the optimization technique to jointly optimize the target-to-radar assignment, revisit time control, bandwidth, and dwell time allocation subject to several resource constraints, while achieving better tracking accuracies of multiple targets and low probability of intercept (LPI) performance of phased array radar network. The analytical expression for Bayesian Cramer–Rao lower bound with the aforementioned adaptable parameters is calculated and subsequently adopted as the performance metric for multitarget tracking. After problem partition and reformulation, an efficient three-stage solution methodology is developed to resolve the underlying mixed-integer, nonlinear, and nonconvex optimization problem. To be specific, in Step 1, the revisit time for each target is determined. In Step 2, we implement the joint signal bandwidth and dwell time allocation for fixed target-to-radar assignments, which combine the cyclic minimization algorithm and interior point method. In Step 3, the optimal target-to-radar assignments are obtained, which results in the minimization of both the tracking accuracy for multiple targets and the total dwell time consumption of the network system. Simulation results are provided to demonstrate the advantages of the presented JTARO strategy, in terms of the achievable multitarget tracking accuracy and LPI performance of phased array radar network.

Packaging and Antenna Integration for Silicon-Based Millimeter-Wave Phased Arrays: 5G and Beyond

Abstract: This article reviews current research and development as well as future opportunities for packaging and antenna integration technologies for silicon-based millimeter-wave phased arrays in emerging communication applications. Implementations of state-of-the-art silicon-based phased arrays below 100 GHz are discussed, with emphasis on array architectures for scaling, antenna integration options, substrate materials and process, antenna design, and IC-package codesign. Opportunities and challenges to support phased array applications beyond 100 GHz are then presented, including emerging packaging architectures, interconnect characterization requirements, thermal management approaches, heterogeneous integration of multifunction chiplets, and novel antenna technologies.

Continuous monitoring of deep-tissue haemodynamics with stretchable ultrasonic phased arrays.

Abstract: Stretchable wearable devices for the continuous monitoring of physiological signals from deep tissues are constrained by the depth of signal penetration and by difficulties in resolving signals from specific tissues. Here, we report the development and testing of a prototype skin-conformal ultrasonic phased array for the monitoring of haemodynamic signals from tissues up to 14 cm beneath the skin. The device allows for active focusing and steering of ultrasound beams over a range of incident angles so as to target regions of interest. In healthy volunteers, we show that the phased array can be used to monitor Doppler spectra from cardiac tissues, record central blood flow waveforms and estimate cerebral blood supply in real time. Stretchable and conformal skin-worn ultrasonic phased arrays may open up opportunities for wearable diagnostics. A prototype skin-conformal ultrasonic phased array enables the monitoring of physiological signals from deep tissues, as shown for the measurements of cardiac Doppler waveforms and central and cerebral blood flows.

Planar Ultra-Wideband and Wide-Scanning Dual-Polarized Phased Array With Integrated Coupled-Marchand Balun for High Polarization Isolation and Low Cross-Polarization

Abstract: In this article, a dual-polarized planar phased array with high polarization isolation and low cross-polarization is presented operating from 4 to 18 GHz, i.e., 4.5:1. The proposed array is comprised of tightly coupled dipoles with integrated coupled-Marchand baluns. To improve the uniformity of fields distributed on the array, the center-feeding dipole is used in this design instead of the conventional edge-feeding one at first. Then, the outer conductors of the feed are composed of a group of shorted vias with the proper number and position. Based on these methods, the output balance of the balun is significantly improved, resulting in high isolation between ports with different polarization modes. Furthermore, this feed has a natural ability to suppress the D-plane common mode resonance. The capacitive metallic annular plate over adjacent radiating elements and the thick aluminum plate with an air cavity placed under the array are employed together to suppress the in-band coupled-loop modes. The infinite array simulation indicates that the array can achieve transmit (Tx)/receive (Rx) isolation more than 48 dB at broadside. Isolation better than 32 and 30 dB can be achieved when scanning to 45° in E-/H-planes and 60° in E-plane, respectively. The cross-polarization level is below −54 dB at broadside and remains below −29 dB when scanning to 60° in E-plane as well as 45° in H-plane. A $12\times12$ dual-polarized antenna array is fabricated and measured to validate the correctness of this design. This type of antenna can be applied in wideband simultaneous transmit and receive (STAR) monostatic systems.

38-GHz Phased Array Transmitter and Receiver Based on Scalable Phased Array Modules With Endfire Antenna Arrays for 5G MMW Data Links

Abstract: This article presents the 38-GHz phased array 32-element Tx and 16-element Rx with 2-GHz IF and 5-GHz LO for fifth-generation (5G) millimeter-wave (MMW) communications. The Tx and Rx beamformers and upconverters/downconverters are fabricated in 65-nm CMOS. The PAs and LNAs near antenna ends are fabricated in 0.15- $\mu \text{m}$ GaAs pHEMT. The eight-element Tx and four-element Rx phased array printed circuit board (PCB) modules integrated with multiple integrated circuits (ICs) and endfire antennas are implemented as unit cells. Four pieces of Tx modules are vertically stacked to construct an $8\times {4}$ brick array (planar array), while four Rx modules are to construct a $4\times {4}$ array. According to 38-GHz over-the-air (OTA) measurements, the 32-element Tx shows 47.5-dBm equivalent isotropic radiated power (EIRP) at OP $_{\mathrm {1 ~dB}}$ with −35.2-dB image rejection ratio (IMRR) and −37.4-dB $\times 8$ LORR. The 16-element Rx at 38 GHz shows −4-dBm OP $_{\mathrm {1~dB}}$ with −28-dB IMRR and −36.6-dB LORR. The Tx and Rx support the beam scanning around ±60° azimuth and ±30° elevation planes. The Tx-to-Rx wireless data link demonstrates 64 quadrature amplitude modulation (QAM)/400 M-BR, 256 QAM/200 M-BR, and 512 QAM/100 M-BR in 20 m. To the best of our knowledge, this work is the first 5G 37-/39-GHz phased array Tx/Rx using the scalable brick array configuration and demonstrating competitive performances compared with previous works.

Wideband 23.5–29.5-GHz Phased Arrays for Multistandard 5G Applications and Carrier Aggregation

Abstract: This article presents a 23.5–29.5-GHz $8\times 8$ phased array for wideband multistandard applications. The array is based on wideband high-performance $2\times 2$ transmit/receive (TRX) quad-beamformer chips with 6 bit of phase control and 8 bit of gain control. The antenna is designed using a stacked-patch structure combined with a two-stage impedance matching network to enhance its bandwidth. The $8\times 8$ phased array achieves an effective isotropic radiated power (EIRP) of 54.8 dBm at P1dB with a 3-dB bandwidth of 23.5–30.5 GHz and can scan to ±60° in the azimuth plane and +/40° in the elevation plane with excellent patterns with a single-point calibration at 27 GHz. Measured error vector magnitude (EVM) for a 64-QAM 200 and 800-Mbaud waveforms result in a system EVM of 5% (−26 dB) in the TX mode at an average EIRP of 46–47 dBm at 24.5–29.5 GHz. Also, the wideband array is capable of 16-QAM 24-Gb/s links with an EVM <16% over all scan angles. An interband carrier aggregation (CA) system is also demonstrated with the wideband array using 200-Mbaud 64-QAM waveforms with 25- and 29-GHz carriers. The phased-array phase and amplitude settings are chosen such that the 25- and 29-GHz waveforms are radiating simultaneously at the same angle with low scan loss, resulting in an efficient system. Also, the out-of-band third-order intermodulation products generated by the power amplifier on each element are filtered out by the antenna. CA measurements with up to 50° scan angles are demonstrated with low EVM. To the best of our knowledge, this is the first demonstration of CA in millimeter-wave fifth-generation (5G) systems.

A Planar Dual-Polarized Phased Array With Broad Bandwidth and Quasi-Endfire Radiation for 5G Mobile Handsets

Abstract: A planar dual-polarized phased array is proposed for 5G cellular communications. The array has the properties of dual-polarization, wideband, and quasi-endfire radiation, which is printed on one side of a single-layer substrate. The design contains two eight-element subarrays including horizontally polarized endfire dipole antennas and vertically polarized endfire periodic slot antennas, employed on the PCB ground plane of the 5G mobile platform. Both subarrays provide wide bandwidth to cover 28 and 38 GHz (promising 5G candidate bands). The −10 dB impedance bandwidth of the proposed CPW-fed dipole and slot antennas are 26.5–39.5 GHz and 27.1–45.5 GHz, respectively. Moreover, for −6-dB impedance bandwidth, these values could be more than 20 GHz (24.4–46.4 GHz for the dipole antenna) and 70 GHz (22.3–95 GHz for the slot antenna). The fundamental characteristics of the proposed dual-polarized 5G antenna array in terms of the impedance bandwidth, realized gain, polarization, radiation pattern, and beam steering are investigated and good results are obtained. The clearance of the proposed dual-polarized 5G antenna array is less than 4.5 mm which is sufficient for cellular applications.

Conformal Phased Array Antenna for Unmanned Aerial Vehicle With ±70° Scanning Range

Abstract: Conformal antennas are practicable candidates to the aerodynamic platforms. A wide-angle scanning conformal phased array antenna for an unmanned aerial vehicle (UAV) platform is designed and presented in this article. An eight-element linear phased array loaded with frequency selective surface (FSS) operating in $S$ -band is investigated. The horizontally polarized antenna element is designed based on a tapered slot feeding dipole. The antenna aperture can be easily conformed to the front wing airframe of the UAV due to the flexibility of the employed polyimide film. To fulfill the requirement of the airborne communication system, two kinds of FSSs are loaded on the dipole antenna to enhance the gain and reduce the 3 dB beamwidth of the main lobe in the elevation plane. To improve the active impedance matching when the beam scans to the large angles, a novel parasitic structure is proposed. Finally, a $1 \times 8$ linear conformal array prototype is simulated, fabricated, and measured. The experimental results indicate that the antenna array achieves a fractional bandwidth of 22.1% with ±70° scanning along the E-plane. The measured results validate the performance of the proposed conformal array and the design.

Butler Matrix Based Beamforming Networks for Phased Array Antenna Systems: A Comprehensive Review and Future Directions for 5G Applications

Abstract: Due to the rapid development of wireless communication technologies, the number of wireless users are radically increasing. Currently, $\sim 23$ billion wireless devices are connected to the internet, and these numbers are expected to increase manifolds in the years to come. The technology growth of the fifth-generation (5G) wireless systems will be needed to meet this high demand of the network. 5G wireless systems offer data-rates of up to 10Gbps, 1-ms latency, and reduced power consumption. It is a known fact that 5G wireless systems will be exploiting beyond the presently used 3 GHz microwave and millimetre-wave (mm-wave) frequency bands. This is the primary driver in the development of the 5G wireless system. Multi-beam Phased array antenna (PAA) systems are typically used in the deployment of 5G systems for high-gain and directionality. In current 5G and future Beyond 5G (B5G) antenna array systems, beamforming networks (BFNs) such as the Butler Matrix (BM) will play a key role in achieving multi-beam characteristics. So, this paper presents an extensive review of the BM based BFNs, and discusses which type of BM will be suitable for the phased array antenna (PAA) systems in the upcoming 5G and next-generation of B5G wireless systems. Moreover, this paper also summarizes the different types of BM designs based on the number of layers. The BMs are classified into the bi-layer, tri-layer, and four-layer structures. It includes different techniques that have been used to solve the problem of crossing, narrow bandwidth, and size reduction of the BM. From the previous studies, it is found that most of the past research work was performed using the bi-layer BM system, whereas the difficult geometries like tri- and four-layer BM are avoided due to their complex fabrication process. It is also found in this paper that the metamaterial (MTM) based bi-layer BM achieves low insertion-loss and phase-error, excellent bandwidth and compact size, and good S-parameter performance, which makes them an ideal BFN candidate for the upcoming 5G and next-generation B5G systems.

A Compact Beamsteering Metasurface Lens Array Antenna With Low-Cost Phased Array

Abstract: A metasurface (MTS) lens array (MLA) fed by a phased array with less phase shifters (PSs) is proposed for compact low-cost beamsteering applications. By dividing a single-large-aperture lens into $N$ small-aperture lens elements with the focus-to-diameter ratio of a lens antenna unchanged, the overall thickness of the proposed antenna is reduced by $N$ times. The beamsteering is achieved in two steps. First, the main beam direction of MLA antenna is switched over a large angular step by shifting the feeding antennas beneath each lens element. Then, the switched beams are fine steered by a low-cost $N$ -element phased array. Theoretical analysis using array theory is performed to work out a general design method with discussion on the taper and spillover effect of feed-power pattern on the lens array. Based on the proposed method, a three-lens linear MLA fed by a phased array is designed to operate at 10 GHz. The proposed antenna achieves a 3 dB beamwidth coverage range of ±30° with a beam crossing level higher than −3 dB and a gain tolerance of 1.6 dB with a maximum gain of 19.1 dBi. The presented antenna can be used to achieve volumetric beamsteering performance directly. The proposed design features the merits of higher gain, lower cost, simpler feeding network, less PSs, and lower profile compared with conventional full phased arrays and single-aperture lens antennas.

Broadband silicon nitride nanophotonic phased arrays for wide-angle beam steering.

Abstract: In this Letter, the broadband operation in wavelengths from 520 nm to 980 nm is demonstrated on silicon nitride nanophotonic phased arrays. The widest beam steering angle of 65° on a silicon nitride phased array is achieved. The optical radiation efficiency of the main grating lobe in a broad wavelength range is measured and analyzed theoretically. The optical spots radiated from the phased array chip are studied at different wavelengths of lasers. The nanophotonic phased array is excited by a supercontinuum laser source for a wide range of beam steering for the first time to the best of our knowledge. It paves the way to tune the wavelength from visible to near infrared range for silicon nitride nanophotonic phased arrays.

Millimeter-Wave Integrated Phased Arrays

Abstract: Large-scale millimeter-wave (mm-Wave) integrated phased array is the key technology to enable broadband 5G and satellite communications. This paper details the design considerations, challenges and trade-offs of mm-Wave integrated phased arrays based on bulk CMOS and multi-layer hybrid PCB technologies. Both technologies attain high yield and low cost for mass production. Important beamforming building blocks are addressed and compared in detail. Demonstrators of integrated phased arrays are presented from circuit to board levels. The 1024- and 4096-element integrated phased arrays achieve the EIRP of 72.5 and 84.0 dBm respectively. Finally, relevant phased-array transceivers and antennas from the recent literature are discussed.

A CMOS Dual-Polarized Phased-Array Beamformer Utilizing Cross-Polarization Leakage Cancellation for 5G MIMO Systems

Abstract: This article introduces a power-efficient and low-cost CMOS 28-GHz phased-array beamformer supporting fifth-generation (5G) dual-polarized multiple-in-multiple-out (MIMO) (DP-MIMO) operation. To improve the cross-polarization (cross-pol.) isolation degraded by the antennas and propagation, a power-efficient analog-assisted cross-pol. leakage cancellation technique is implemented. After the high-accuracy cancellation, more than 41.3-dB cross-pol. isolation is maintained along with the transmitter array to the receiver array. The element-beamformer in this work adopts the compact neutralized bi-directional architecture featuring a minimized manufacturing cost. The proposed beamformer achieves 22% per path TX-mode efficiency and a 4.9-dB RX-mode noise figure. The required on-chip area for the beamformer is only 0.48 mm2. In over-the-air measurement, a 64-element dual-polarized phased-array module achieves 52.2-dBm saturated effective isotropic radiated power (EIRP). The 5G standard-compliant OFDMA-mode modulated signals of up to 256-QAM could be supported by the 64-element modules. With the help of the cross-pol. leakage cancellation technique, the proposed array module realizes improved DP-MIMO EVMs even under severe polarization coupling and rotation conditions. The measured DP-MIMO EVMs are 3.4% in both 64-QAM and 256-QAM. The consumed power per beamformer path is 186 mW in the TX mode and 88 mW in the RX mode.

Microwave Photonic Array Radars

Abstract: Phased array radars have remarkable advantages over radars with single-element antenna in terms of agility, flexibility, robustness, and reconfigurability. Current pure-electronic phased array radars face challenges when operating with a large frequency tunable range and/or with broad instantaneous bandwidth. Microwave photonics, which allows wide bandwidth, flat frequency response, low transmission loss, and immunity to electromagnetic interference, is a promising solution to cope with issues faced by pure electronics. In this paper, we introduce a general architecture of microwave photonic array radar systems and review the recent advancement of optical beamforming networks. The key elements for modelling the response of the true time delay (TTD) and/or phase-shifting unit are presented and discussed. Two typical array antenna structures are introduced, i.e., microwave photonic phase shifter based array and optical true time delay based array, of which the principle and typical implementations are described. High-resolution inverse synthetic aperture radar (ISAR) imaging is also realized based on a microwave photonic array radar. The possibility of on-chip integration of the microwave photonic array radar is discussed.

Single-Pixel Imaging Using Multimode Fiber and Silicon Photonic Phased Array

Abstract: Due to the unique nature of offering minimal invasiveness and high spatial resolution simultaneously, multimode fibers (MMFs) are receiving significant attention in bio-imaging applications. While a spatial light modulator is typically used for controlling the wavefront of the light emitted from the MMF, it makes the system slow, bulky, and expensive. To solve this problem, in this work, we demonstrate the use of a chip-scale integrated optical phased array (OPA) for imaging through an MMF. A silicon OPA with 128 independent phase shifters is fabricated and combined with a 3D waveguide interface to generate speckle patterns at the MMF output. Using the generated speckles and the optical power detected by a bucket detector, we experimentally obtain fine 2D images of the target. From the point spread function analysis of the system, the number of resolvable points is derived to be 1007 points, which is much larger than the number of phase shifters.

Real-Time 3-D Imaging Using an Air-Coupled Ultrasonic Phased-Array

Abstract: We present an air-coupled ultrasonic imaging system based on a 40-kHz $8\times 8$ phased-array for 3-D real-time localization of multiple objects in the far-field By attaching a waveguide to the array, the effective interelement spacing is reduced to half wavelength This enables grating lobe-free transmit and receive beamforming with a uniform rectangular array of efficient low-cost transducers The system further includes custom transceiver electronics, an field programmable gate array (FPGA) system-on-chip and a PC for GPU accelerated frequency domain signal processing, consisting of matched filtering, conventional beamforming, and envelope extraction using Nvidia Compute Unified Device Architecture (CUDA) and OpenGL for visualization The uniform rectangular layout allows utilizing multiple transmit and receive methods, known from medical imaging applications Thus, the system is dynamically adaptable to maximize the frame rate or detection range One implemented method demonstrates the real-time capability by transmitting a hemispherical pulse (HP) with a single transducer to irradiate the surroundings simultaneously, whereas all transducers are used for echo reception The imaging properties, such as axial and lateral resolution, field of view and range of view, are characterized in an anechoic chamber The object localization is validated for a horizontal and vertical field of view of ±80° and a range of view of 05–3 m with 29 frames/s Using the same system, a comparison between the HP method and the dynamic transmit beamforming method, which transmits multiple sequential beamformed pulses for long-range localization, is provided

A Dual-Band Shared-Aperture Antenna With Wide-Angle Scanning Capability for Mobile System Applications

Abstract: A dual-band shared-aperture phased array antenna with wide-angle scanning capability (WASC) is presented in this paper for mobile communications. Each shared-aperture antenna element consists of two wideband microstrip antenna units with air-cavity for the C -band and one wide beam magnetic-electro dipole antenna unit for the S -band. To achieve the wide-angle scanning, a phased array should have low inter-element mutual coupling and wide array-element beam-width. A simple metallic strip (MS), comprising four metal stubs and one rectangle shaped metal pillar, is utilized to improve the inter-element isolation of the array in and between the C - and S -bands. Furthermore, the metal strip can also broaden the beam-width of the C -band antenna units without distorting the wide-beam property of the S -band units. The shared-aperture array with a simple metallic strip is designed based on the above elements, and WASC is realized in both the C - and S - bands with low mutual coupling. To verify the proposed method, the shared-aperture array is fabricated and characterized, yielding good performance within the overall operating bandwidth. The measured results align very well with the simulated. The proposed array realizes the scanning coverage of ±60° with realized gain reduction of less than 3 dB in both the C - and S -bands, which is a good candidate for the base station in the mobile environment.

A 1024-Element Ku-Band SATCOM Dual-Polarized Receiver With >10-dB/K G/T and Embedded Transmit Rejection Filter

Abstract: This article presents a 1024-element dual-polarized Ku-band (10.7–12.7 GHz) satellite communication (SATCOM) receive (RX) phased array. The array consists of four 16 $\times16$ subarray tiles, each of which comprises 64 eight-channel beamformer chips, 256 dual-channel low-noise amplifiers (LNAs), and 256 dual-polarized antennas built on an affordable printed circuit board (PCB). The antennas spaced at $\lambda $ /2 spacing at 12.2 GHz in an equilateral triangular grid allow scanning up to x±70° in all planes while maintaining a cross-polarization level $ dB. The use of LNAs just after the antennas enables a low-noise operation with an antenna gain-to-noise temperature (G/T) of 10.5 dB/K ( $T_{\mathrm {ant}} =20$ K) at broadside while maintaining a directivity of 34 dB at 11.7 GHz. Also, a two-pole/two-zero filter is placed between the LNA and the beamformer chip to greatly attenuate any transmit leakage signal at 14–14.5 GHz. The lightweight, low-cost PCB with all silicon chips and a thickness of 3.4 mm presents a viable candidate for Ku-band SATCOM ground and Satcom-On-The-Move (SOTM) terminals.

A 256-Element Dual-Beam Polarization-Agile SATCOM Ku -Band Phased-Array With 5-dB/K G/T

Abstract: This article presents a $16\times 16$ dual-polarized $Ku$ -band (10.7–12.7 GHz) satellite communications (SATCOM) phased-array receiver with simultaneous dual-beam reception capability. The array incorporates 64 16-channel beamformer chips and 256 dual-polarized antennas. A dual-channel low noise amplifier (LNA) is employed on every antenna to lower the system noise figure (NF) and increase the antenna gain-to-noise temperature (G/T). The phased-array is built on a low-cost printed circuit board (PCB), with an antenna spacing of $\lambda $ /2 at 12.2 GHz in an equilateral triangular grid to result in ±70° scan volume, and is capable of receiving two concurrent data-streams with a distinct direction of arrival (DOA) since it employs two 64:1 Wilkinson combiner networks. A transmit band (14–14.5 GHz) filter is also implemented between the LNA and the beamformer chip. The 256-element array has a directivity of 28 dB at mid-band with a G/T of 5 dB/K ( $T_{\mathrm{ ant}}=20$ K), which results in a G/T of 11 dB/K for a 1024-element array. This array is a feasible solution for make-before-break connections and for multi-satellite reception systems, such as simultaneous television (TV) reception and connectivity.

Transmit Beampattern Synthesis for Frequency Diverse Array With Particle Swarm Frequency Offset Optimization

Abstract: Different from the conventional phased array radar, a frequency diverse array (FDA) applies additional frequency shift across the array elements, yielding a range–angle-dependent transmit beampattern that provides a huge potential opportunity for target estimation and range-dependent clutter and interference suppression. Generally, the conventional FDA employs a linear small frequency increment, forming a time-varying “S”-shape range–angle beampattern, which is range–angle coupled. In this article, a range–angle transmit beampattern synthesis method for FDA based on frequency offset optimization is proposed. Particle swarm optimization (PSO) is adopted in the FDA element frequency increment design to achieve a dot-shaped transmit beampattern. Meanwhile, matched weights are designed for time-modulation compensation. Numerical simulation results demonstrate that the proposed approach achieves better time-invariant performance over other FDA frameworks.

A 1024-Element Ku-Band SATCOM Phased-Array Transmitter With 45-dBW Single-Polarization EIRP

Abstract: This article presents a 1024-element Ku-band phased-array transmitter for mobile satellite communications. The array is based on eight-channel transmit (TX) SiGe beamformer chips. Dual-polarized stacked-patch antennas enable the array to synthesize linear, rotated-linear, and left- and right-hand circular polarization. The array consists of four quadrants of 256-element subarrays, each of which has 64 beamformer chips and a driver chip assembled on a printed circuit board (PCB). The array achieves an effective isotropic radiated power (EIRP) of 75 dBm per polarization (78-dBm circular polarization) and scans to ±75° in all planes. This is achieved using an antenna spacing of $\lambda $ /2 at 14.4 GHz in an equilateral triangular grid. The array also results in 30-dB cross-polarization rejection up to 60° scan angles. Measured error vector magnitude (EVM) for 50-, 100-, 200-, and 500-MBd QPSK and 8 phase-shift keying (8PSK) waveforms results in at most 1.5%rms and 2.5%rms at $P_{1\textrm {dB}}$ and $P_{\mathrm{ sat}}$ , respectively, at 14 GHz over all scan angles. Also, the adjacent channel power ratio (ACPR) was measured as −32 dB for 200- and 500-MBd QPSK and 8 phase-shift keying (8PSK) waveforms at $P_{1\textrm {dB}}$ at 14 GHz. To the authors’ knowledge, this work presents a state-of-the-art planar phased-array system with high EIRP for Ku-band satellite communication (SATCOM) mobile transmitter terminals.

High-Resolution and Wide-Swath SAR Imaging Mode Using Frequency Diverse Planar Array

Abstract: The challenging problem to realize high-resolution and wide-swath (HRWS) synthetic aperture radar (SAR) imaging is the ambiguity suppression in the azimuth and range directions. According to the spatial angle difference of each ambiguity component, the current technical approach is to design the spatial filter for achieving the ambiguity suppression based on the 2-D multichannel system. Along with the increasing of HRWS imaging requirements, the number of system channels also gradually increase and further result in the complex structure design of the phased array antenna system. Meanwhile, the traditional phased array antenna cannot effectively control the direction of the transmit beampattern in range. Unlike the traditional phased array, frequency diverse array (FDA) employs a small-frequency increment across the whole array elements and forms the range-angle-dependent S-shaped transmit beampattern, which can be utilized to separate the different range ambiguous region. Considering the above-mentioned characteristics and the range periodicity problem of transmit beampattern, this letter devises a scheme for spaceborne SAR HRWS imaging mode in the view of transmit beampattern utilizing 2-D planar array, i.e., the FDA in azimuth for removing the range nonperiodicity ambiguity and the conventional phased array in elevation for removing the range periodicity ambiguity. Simulation results have been presented to validate the effectiveness of the proposed scheme.

Thermally Actuated SOI RF MEMS-Based Fully Integrated Passive Reflective-Type Analog Phase Shifter for mmWave Applications

Abstract: This article presents a monolithically integrated reflective-type phase shifter (RTPS) utilizing silicon-on-insulator (SOI) radio frequency (RF) microelectromechanical systems (MEMS). The analog phase shifter employs a hybrid coupler and two identical reflective loads optimized to achieve a large phase shift range. The hybrid coupler is designed using two CPW-based couplers connected in a folded tandem configuration to achieve a compact size design. Various reflective load topologies are studied for optimum phase shift range and phase linearity over the bandwidth of interest. Measurement results demonstrate a continuous 120° tunable range from 26 to 30 GHz. The mmWave phase shifter exhibits a low insertion loss of 5.35 dB ± 0.6 dB at 28 GHz. The fabricated phase shifter has an overall device footprint of 4.0 $\text {mm}\times 2.6$ mm. All the components of the phase shifter module are co-fabricated in the 20 $\mu \text{m}$ device layer of a SOI wafer, which provides the flexibility of monolithic integration with other RF modules in phased array antenna systems. Contactless thermally actuated MEMS varactors are used in the reflective loads which do not suffer from the conventional contact-based reliability issues.

22.2 A 300GHz-Band Phased-Array Transceiver Using Bi-Directional Outphasing and Hartley Architecture in 65nm CMOS

Abstract: This paper presents a CMOS bi-directional phased-array transceiver that covers the frequency range from 242 to 280GHz. The array consists of 4 elements with beamforming ability in the H-plane of the on-PCB Vivaldi antennas. The LO phase-generation scheme enables two different architectures for TX and RX modes. The TX mode utilizes an outphasing architecture while the Hartley architecture is adopted in the RX mode. The maximum achieved baud rates in the TX mode and the RX mode are 26Gbaud and 18Gbaud, respectively.

Antenna-in-Package Integration for a Wideband Scalable 5G Millimeter-Wave Phased-Array Module

Abstract: This work introduces a multilayered organic package with embedded antennas that enables the integration of a scalable wideband phased array module supporting the n257, n258, and n261 5G frequency bands (24.25–29.5 GHz). The package comprises: 1) an $8\times 8$ array of dual-polarized antenna elements with 5.1-mm spacing; 2) RF, intermediate frequency (IF), dc, and digital interconnects to support radio-frequency integrated circuits (RFICs), filters, and combiners; and 3) a ball-grid array (BGA); it is implemented in a compact 42.5 mm $\times 42.5$ mm $\times 1.65$ mm form factor. The design achieves wideband operation with a minimal cost or a complexity overhead (e.g., air cavities or additional substrates) by integrating a novel magnetoelectric dipole antenna in the package. Direct probing and radiation pattern measurements of three antenna variants in two prototype antenna array packages demonstrate >6-GHz bandwidth with 0–5-dBi gain. Measurement results for associated liquid crystal polymer-based bandpass filters and power combiners are also presented.

A 256-Element Ku-Band Polarization Agile SATCOM Receive Phased Array With Wide-Angle Scanning and High Polarization Purity

Abstract: This article presents a Ku-band phased-array receive tile with 256 elements. The design is based on 64 dual-polarized beamformer chips assembled on a printed circuit board (PCB) with dual-polarized antennas and an integrated Wilkinson combiner network and can operate at any polarization (linear, rotated-linear, and circular). The 256 elements are spaced $0.52\lambda $ apart at 12.7 GHz in the $x$ - and $y$ -directions. The measured patterns show near ideal patterns with a wide beam scanning range of ±70° (V- and H-pol) and a high cross-polarization rejection of 27 dB. The array has a 3-dB instantaneous scanning bandwidth of 10.6–12.5 GHz. In circular polarization mode, the measured axial ratio (AR) is 0.5 dB at 11.75 GHz for both left- and right-hand circular polarizations. The tile design is scalable to allow large-scale phased-array construction with 1024 elements or higher. Extensive measurements are presented, showing the versatility of this approach. Also, the dual-polarization feeds can be optimized to result in very low cross-polarization for circular and slanted-linear polarizations at all scan angles. The array performance, compact size, ultralightweight of 258 g, and low profile with 3.5-mm thickness make it suitable for affordable mobile Ku-band SATCOM on the move (SOTM) terminals.

Wideband Multimode Leaky-Wave Feed for Scanning Lens-Phased Array at Submillimeter Wavelengths

Abstract: In this article, we propose a hybrid electromechanical scanning lens antenna array architecture suitable for the steering of highly directive beams at submillimeter wavelengths with field-of-views (FoV) of ±25°. The concept relies on combining electronic phase shifting of a sparse array with a mechanical translation of a lens array. The use of a sparse-phased array significantly simplifies the RF front-end (number of active components, routing, thermal problems), while the translation of a lens array steers the element patterns to angles off-broadside, reducing the impact of grating lobes over a wide FoV. The mechanical translation required for the lens array is also significantly reduced compared to a single large lens, leading to faster and low-power mechanical implementation. In order to achieve wide bandwidth and large steering angles, a novel leaky wave lens feed concept is also implemented. A 550-GHz prototype was fabricated and measured demonstrating the scanning capabilities of the embedded element pattern and the radiation performance of the leaky wave fed antenna.

A Low Cost, Low in-Band RCS Microstrip Phased-Array Antenna With Integrated 2-bit Phase Shifter

Abstract: In this article, we present a low-cost microstrip phased-array antenna, which is composed of electronically reconfigurable elements. The p-i-n diodes’ integrated elements have various functions, such as tunable polarization characteristics and adjustable radiation phases. The high sidelobe level (SLL) due to the 2-bit phase shifter can be reduced by a randomly rotated (RR) array element. It is shown that the array can realize electronic beam-steering capabilities and keep −10 to −14 dB sidelobes without tapering. To verify the above theory, an eight-element linear array prototype working at 3 GHz was designed, fabricated, and tested. Numerical simulations and experimental results show that, by controlling the “ON” and “OFF” states of p-i-n diodes, the radiation beam can be controlled to steer in a circular polarization (CP) mode, wherein the scanning angle is up to ±45°. Furthermore, the principle of suppressing the vector scattering field by the opposite phasing cancellation method can achieve in-band radar cross section (RCS) reduction. Simulation results show that approximately 15 dB in-band RCS reduction can be realized for both bistatic and monostatic RCS reduction with an $8\times 8$ array.