Showing papers on "Phased array published in 2013"
TL;DR: This work demonstrates that a robust design, together with state-of-the-art complementary metal-oxide–semiconductor technology, allows large-scale NPAs to be implemented on compact and inexpensive nanophotonic chips and therefore extends the functionalities of phased arrays beyond conventional beam focusing and steering, opening up possibilities for large- scale deployment.
Abstract: A large-scale silicon nanophotonic phased array with more than 4,000 antennas is demonstrated using a state-of-the-art complementary metal-oxide–semiconductor (CMOS) process, enabling arbitrary holograms with tunability, which brings phased arrays to many new technological territories. Nanophotonic approaches allow the construction of chip-scale arrays of optical nanoantennas capable of producing radiation patterns in the far field. This could be useful for a range of applications in communications, LADAR (laser detection and ranging) and three-dimensional holography. Until now this technology has been restricted to one-dimensional or small two-dimensional arrays. This paper reports the construction of a large-scale silicon nanophotonic phased array containing 4,096 optical nanoantennas balanced in power and aligned in phase. The array was used to generate a complex radiation pattern—the MIT logo—in the far field. The authors show that this type of nanophotonic phased array can be actively tuned, and in some cases the beam is steerable. Electromagnetic phased arrays at radio frequencies are well known and have enabled applications ranging from communications to radar, broadcasting and astronomy1. The ability to generate arbitrary radiation patterns with large-scale phased arrays has long been pursued. Although it is extremely expensive and cumbersome to deploy large-scale radiofrequency phased arrays2, optical phased arrays have a unique advantage in that the much shorter optical wavelength holds promise for large-scale integration3. However, the short optical wavelength also imposes stringent requirements on fabrication. As a consequence, although optical phased arrays have been studied with various platforms4,5,6,7,8 and recently with chip-scale nanophotonics9,10,11,12, all of the demonstrations so far are restricted to one-dimensional or small-scale two-dimensional arrays. Here we report the demonstration of a large-scale two-dimensional nanophotonic phased array (NPA), in which 64 × 64 (4,096) optical nanoantennas are densely integrated on a silicon chip within a footprint of 576 μm × 576 μm with all of the nanoantennas precisely balanced in power and aligned in phase to generate a designed, sophisticated radiation pattern in the far field. We also show that active phase tunability can be realized in the proposed NPA by demonstrating dynamic beam steering and shaping with an 8 × 8 array. This work demonstrates that a robust design, together with state-of-the-art complementary metal-oxide–semiconductor technology, allows large-scale NPAs to be implemented on compact and inexpensive nanophotonic chips. In turn, this enables arbitrary radiation pattern generation using NPAs and therefore extends the functionalities of phased arrays beyond conventional beam focusing and steering, opening up possibilities for large-scale deployment in applications such as communication, laser detection and ranging, three-dimensional holography and biomedical sciences, to name just a few.
1,065 citations
TL;DR: The starting point of this analysis is the frequency diverse array (FDA), which has been demonstrated to generate a range-angle pattern, and a new pattern, "orthogonal" to that of the standard phased array, can be achieved through a reconsideration of the organization of the array, which is termed the wavelength array (WA).
Abstract: It has been shown over several decades of radar research that the exploitation of diversity in a number of domains (space, frequency, time, polarization, and, recently, waveform) can provide increased agility, flexibility, robustness, and capabilities to the radar system. However this is often achieved either through efforts in system design, increased hardware complexity, or by employing additional resources. A conventional antenna array is considered with the intention of introducing, not major, but minor mismatches, in particular in the carrier frequencies and, eventually in the codes at the element level. The starting point of this analysis is the frequency diverse array (FDA), which has been demonstrated to generate a range-angle pattern. Through a reconsideration of the organization of the array, which we have termed the wavelength array (WA), a new pattern, "orthogonal" to that of the standard phased array, can be achieved. The bistatic combination of a WA and a receiver leads to the frequency diverse bistatic system (FDBS), which can be a significant application of this concept. In a second stage the analysis focuses on the effects of introducing waveform diversity in such a system. In particular, if the elements of an electronically steered array (ESA) simultaneously transmit a number of pseudonoise (PN) codes at slightly different carrier frequencies, the coherent summation of the codes gives rise to a waveform whose shape is a function of both angle and range. In fact this is the consequence of applying the multiple-input multiple-output (MIMO) technique to the FDA, which has the result of associating a waveform to each point range/angle of the space, with the possibility of recovering this information in receive after appropriate processing.
327 citations
TL;DR: This paper proposes a range-angle dependent beampattern synthesis scheme for linear frequency diverse array (FDA) using the discrete spheroidal sequence, with an aim to focus the transmit energy in a desired two-dimensional spatial section.
Abstract: Phased-array is widely used in communication and radar systems, but the beam steering is fixed in an angle for all the ranges. In this paper, we propose a range-angle dependent beampattern synthesis scheme for linear frequency diverse array (FDA) using the discrete spheroidal sequence, with an aim to focus the transmit energy in a desired two-dimensional spatial section. Different from conventional phased-arrays, FDA employs a small frequency increment, compared to the carrier frequency across the array elements. The range-angle dependent beampattern synthesis method allows the FDA to transmit energy over a desired range or angle sector. This provides a potential to suppress range-dependent clutter and interference, which is not accessible for conventional phased-arrays. The system performance of the proposed FDA is evaluated by the output signal-to-interference-plus-noise ratio (SINR). The effectiveness is verified by comprehensive numerical simulation results.
176 citations
TL;DR: The theoretical and experimental basis for the trend towards higher channel counts relying on insights gained from modeling and experimental studies as well as the theoretical analysis of the so-called "ultimate" SNR and g-factor is reviewed.
146 citations
TL;DR: In this article, a non-symmetric tightly coupled dipole element for wideband phased arrays is proposed to control capacitance and cancel the ground plane inductance, where each arm on the dipole is different than the other, forming a ball-and-cup.
Abstract: It is traditionally known that wideband apertures lose bandwidth when placed over a ground plane. To overcome this issue, this paper introduces a new non-symmetric tightly coupled dipole element for wideband phased arrays. The proposed array antenna incorporates additional degrees of freedom to control capacitance and cancel the ground plane inductance. Specifically, each arm on the dipole is different than the other (or non-symmetric). The arms are identical near the center feed section but dissimilar towards the ends, forming a ball-and-cup. It is demonstrated that the non-symmetric qualities achieve wideband performance. Concurrently, a design example for planar installation with balun and matching network is presented to cover X-band. The balun avoids extraneous radiation, maintains the array's low-profile height and is printed on top of the ground plane connecting to the array aperture with 180° out of phase vertical twin-wire transmission lines. To demonstrate the concept, a 64-element array with integrated feed and matching network is designed, fabricated and verified experimentally. The array aperture is placed λ/7 (at 8 GHz) above the ground plane and shown to maintain a active VSWR less than 2 from 8-12.5 GHz while scanning up to 70° and 60° in E- and H-plane, respectively. The array's simulated diagonal plane cross-polarization is approximately 10 dB below the co-polarized component during 60° diagonal scan and follows the theoretical limit for an infinite current sheet.
132 citations
09 Apr 2013
TL;DR: An overview of past and present Japanese MPT experiments using phased-array technologies is provided.
Abstract: Beam control and/or beamforming technologies involving phased arrays can be used to enable highly efficient microwave power transmission (MPT) systems. In Japan, several field MPT experiments using a phased array have been conducted over the years. In 1992, a joint collaborative group successfully conducted a fuel-free flight experiment using phased-array technology, which was referred to as the MIcrowave Lifted Airplane eXperiment. In 2008, Kobe University (Kyoto, Japan) and a U.S. research group successfully conducted an MPT experiment using a phased array that resulted in power transmission over a distance of 150 km. Furthermore, Kyoto University proposed and demonstrated a magnetron-based phased array and conducted MPT from an airship to the ground in spring 2009. In FY2010, Kyoto University developed new highly efficient phased arrays for MPT and solar power satellites. This study provides an overview of past and present Japanese MPT experiments using phased-array technologies.
130 citations
TL;DR: Reflectarrays composed of resonant microstrip gold patches on a dielectric substrate are demonstrated for operation at terahertz frequencies, showing that up to nearly 80% of the incident amplitude is deflected into the desired direction at an operation frequency close to 1 THz.
Abstract: Reflectarrays composed of resonant microstrip gold patches on a dielectric substrate are demonstrated for operation at terahertz frequencies. Based on the relation between the patch size and the reflection phase, a progressive phase distribution is implemented on the patch array to create a reflector able to deflect an incident beam towards a predefined angle off the specular direction. In order to confirm the validity of the design, a set of reflectarrays each with periodically distributed 360 × 360 patch elements are fabricated and measured. The experimental results obtained through terahertz time-domain spectroscopy (THz-TDS) show that up to nearly 80% of the incident amplitude is deflected into the desired direction at an operation frequency close to 1 THz. The radiation patterns of the reflectarray in TM and TE polarizations are also obtained at different frequencies. This work presents an attractive concept for developing components able to efficiently manipulate terahertz radiation for emerging terahertz communications.
128 citations
TL;DR: In this paper, a 32-element symmetrical TX/RX 60 GHz RF integrated circuit (RFIC) with built-in self-test is presented, which achieves record size and power consumption.
Abstract: Fully integrated 32-element symmetrical TX/RX 60-GHz RF integrated circuit (RFIC) with built-in self-test is presented. The RF bidirectional power-combining architecture with shared blocks and less than 1-dB millimeter-wave transmit/receive (T/R) switch loss achieves record size and power consumption. The RFIC features an 8-dB noise figure and - 28-dBm IP1 dB in RX mode, 10-dB power gain, and Psat of +3.5 dBm per chain in TX mode. Further included are a 2-bit phase shifter, an IF converter to/from 12 GHz, and an integrated frac-N synthesizer with push-push voltage-controlled oscillator having a-93 dBc@1-MHz phase noise at 48-GHz local oscillator port. A novel high dynamic range phase and power detector is presented with 2° and ±1-dB accuracy over PVT in phase and power. A detailed analysis of both phase quantization and power distribution is presented. Array impairments such as mismatch and coupling were compared for different topologies. The RFIC is packaged on alumina for testing and on low-temperature co-fired ceramic (LTCC) for antenna integration. The 6 × 6 patch antenna on LTCC including four dummies achieves a gain of 19 dBi with scanning of ± 30°. The total root mean square amplitude and phase error of the array is 0.8 dB and 6° , respectively, resulting in a maximum array beam degradation of 1.4 dB for 2-bit quantization. The RFIC area is 29 mm2 and it consumes 1.2 W/0.85 W at TX/RX, with a 29-dBm effective isotropic radiated power at -19-dB error vector magnitude.
128 citations
TL;DR: A transmitter and receiver phased array chipset is demonstrated in the range between 70 and 100 GHz using a 0.18 µm SiGe BiCMOS process with $f_{T}/f_{MAX}$ of 240/270 GHz.
Abstract: A transmitter and receiver phased array chipset is demonstrated in the range between 70 and 100 GHz using a 0.18 µm SiGe BiCMOS process with $f_{T}/f_{MAX}$ of 240/270 GHz. Each chip comprises four phased array elements with distributed calibration memory and calibrated direct up- and down-conversion mixer chain. Each receive channel has a conversion gain of 33 dB and noise figure of 5 dBm between 70 and 100 GHz. Both transmitter and receiver arrays operate from 1.5 V and 2.5 V power supplies and consume 1 W each. Using a die-on-PCB prototype with integrated antennas, a wireless link operating at 10 Gb/s (using 16-QAM) or 8.75 Gb/s (using 32-QAM) is demonstrated at a distance of 1-meter with a carrier frequency of 88 GHz.
119 citations
TL;DR: In this article, a novel millimeter-wave phased array with four linearly-arranged pattern reconfigurable elements is presented in order to extend the scanning range of a phased array and maintain the scanning gain flatness.
Abstract: In order to extend the scanning range of a phased array and maintain the scanning gain flatness, a novel millimeter-wave phased array with four linearly-arranged pattern reconfigurable elements is presented in this communication. The phased array has been designed, fabricated, measured and analyzed. The active patterns of each reconfigurable element are measured at different reconfigurable modes and the pattern scanning performance of the phased array is synthesized by using these active patterns. Furthermore, a genetic algorithm is used to lower the level of side lobes of the proposed phased array. The results show that the phased array can scan its main lobe from -75° to +75° in the elevation plane with a gain fluctuation less than 3 dB.
118 citations
TL;DR: A new phased-MIMO radar with frequency diversity for range-dependent beamforming is proposed, to divide the frequency diverse array transmit array into multiple subarrays, each subarray coherently transmits a distinct waveform with a small frequency increment across the array elements.
Abstract: Phased-multiple-input and multiple-output (MIMO) radar is a flexible technique which enjoys the advantages of MIMO radar without sacrificing the main advantage of phased-array radar. However, the phased-MIMO radar is limited to range-independent directivity; this limits the radar performance to mitigate non-desirable range-dependent interferences. In this paper, we propose a new phased-MIMO radar with frequency diversity for range-dependent beamforming. The essence of the proposed technique is to divide the frequency diverse array transmit array into multiple subarrays, each subarray coherently transmits a distinct waveform with a small frequency increment across the array elements. Each subarray forms a directional beam and all beams are independently steerable by tuning the frequency increment. The subarrays jointly offer flexible operating modes and range-dependent beamforming. The beamforming performance as compared to phased-MIMO radar is examined by analyzing the transmit-receive beampatterns and the output signal-to-interference-plus-noise ratio. The effectiveness of the proposed technique is verified by numerical simulation results.
TL;DR: In this article, a comprehensive review of the methods that model and mitigate the mutual coupling effect for different types of arrays is discussed, and the techniques for optimization of the antenna characteristics in the presence of coupling are also included.
Abstract: The mutual coupling between antenna elements affects the antenna parameters like terminal impedances, reflection coefficients and hence the antenna array performance in terms of radiation characteristics, output signal-to-interference noise ratio (SINR), and radar cross section (RCS). This coupling effect is also known to directly or indirectly influence the steady state and transient response, the resolution capability, interference rejection, and direction-of-arrival (DOA) estimation competence of the array. Researchers have proposed several techniques and designs for optimal performance of phased array in a given signal environment, counteracting the coupling effect. This paper presents a comprehensive review of the methods that model and mitigate the mutual coupling effect for different types of arrays. The parameters that get affected due to the presence of coupling thereby degrading the array performance are discussed. The techniques for optimization of the antenna characteristics in the presence of coupling are also included.
TL;DR: In this article, the A-projection algorithm is used to correct for all DDE, including individual antennas, projection of the dipoles on the sky, beam forming, and ionospheric effects.
Abstract: The required high sensitivities and large fields of view of the new generation of radio interferometers impose high dynamic ranges, e.g., ~1:106 to 1:108 for the Square Kilometre Array (SKA). The main problem for achieving these high ranges is the calibration and correction of direction dependent effects (DDE) that can affect the electro-magnetic field (antenna beams, ionosphere, Faraday rotation, etc.). It has already been shown that the A-Projection is a fast and accurate algorithm that can potentially correct for any given DDE in the imaging step. With its very wide field of view, low operating frequency (~30–250 MHz), long baselines, and complex station-dependent beam patterns, the LOw Frequency ARray (LOFAR) is certainly the most complex SKA pathfinder instrument. In this paper we present a few implementations of the A-Projection in LOFAR which can deal nondiagonal Mueller matrices. The algorithm is designed to correct for all DDE, including individual antennas, projection of the dipoles on the sky, beam forming, and ionospheric effects. We describe a few important algorithmic optimizations related to LOFAR’s architecture that allowed us to build a fast imager. Based on simulated datasets we show that A-Projection can dramatically improve the dynamic range for both phased array beams and ionospheric effects. However, certain problems associated with the calibration of DDE remain (especially ionospheric effects), and the effect of the algorithm on real LOFAR survey data still needs to be demonstrated. We will be able to use this algorithm to construct the deepest extragalactic surveys, comprising hundreds of days of integration.
Patent•
12 Aug 2013TL;DR: In this article, a microwave communication system consisting of a remote station, a phased array antenna (2), phase shifters (Ψ1 to ΨN), and a software unit (5) is presented.
Abstract: A microwave communication system comprising a remote station, a phased array antenna (2), phase shifters (Ψ1 to ΨN) and a software unit (5), wherein the phased array antenna (2) is emitting a microwave signal beam, wherein the phased array antenna (2) is pointing the beam in a direction of alignment with the remote station, wherein the received signal level at the remote station is maximum in the direction of alignment, wherein the phase shifters (Ψ1 to ΨN) are connected to the antenna (2), wherein the software unit (5) is connected to the phase shifters (Ψ1 to ΨN), wherein the system comprises first means to detect an antenna (2) misalignment, wherein said first means to detect an antenna (2) misalignment are connected to the software unit (5).
TL;DR: This paper presents the first 16-element wafer-scale phased array transmitter with scanning in both the E-and H-planes, and leads the way to millimeter-wave waferscale phased-array integration.
Abstract: This paper presents a W-band wafer-scale phased- array transmitter with high-efficiency on-chip antennas. The 4 × 4 array is based on an RF beamforming architecture with an equiphase distribution network and phased shifters placed on every element. The differential on-chip antennas are implemented using a 100 μm thick quartz superstrate and with a simulated efficiency of ~ 45% at 110 GHz. The phased array is designed with low mutual coupling between the elements and results in a stable active antenna impedance versus scan angle. The phased array is built in the Jazz SBC18H3 SiGe BiCMOS process, and is 6.5 × 6.0 mm2. Measurements show two-dimensional pattern scanning capabilities with a directivity of 17.0 dB, an array gain of ~26.5 dB at 110 GHz, and an EIRP of 23-25 dBm at 108-114 GHz. The power consumption is 3.4 W from a 1.9 V supply. To our knowledge, this work represents the first W-band wafer-scale phased array to-date. The application areas are in point-to-point communication systems in the 100-120 GHz range.
TL;DR: Fundamental expressions of the FDA operation and its typical implementation schemes are reviewed, and an ultimately useful scheme for implementing and FDA is introduced based on linear frequency modulated continuous waveform (LFMCW).
Abstract: Frequency diverse arrays (FDA) are recently introduced. Not only the phased array and frequency scanning arrays, but also FDA provides electronic beam scanning ability. Moreover, electronic beam scanning is provided without the use of phase shifters or vector modulators. Nevertheless, reported studies on this concept do not provide practically implementable results. In this paper, fundamental expressions of the FDA operation and its typical implementation schemes are reviewed, and an ultimately useful scheme for implementing and FDA is introduced based on linear frequency modulated continuous waveform (LFMCW). The mathematical foundations of LFMCW FDA are developed and used to design a basic proof of concept structure. This structure is also implemented and the measurements related to the implementation are presented with discussions on the results.
TL;DR: In this article, a 4 × 4 SiGe BiCMOS phased array chip at 90-100 GHz with vertical and horizontal polarization capabilities, 3-bit gain control (9 dB), and 4-bit phase control is presented.
Abstract: This paper presents a 4 × 4 transmit/receive (T/R) SiGe BiCMOS phased-array chip at 90-100 GHz with vertical and horizontal polarization capabilities, 3-bit gain control (9 dB), and 4-bit phase control. The 4 × 4 phased array fits into a 1.6×1.5 mm2 grid, which is required at 94 GHz for wide scan-angle designs. The chip has simultaneous receive (Rx) beam capabilities (V and H) and this is accomplished using dual-nested 16:1 Wilkinson combiners/divider with high isolation. The phase shifter is based on a vector modulator with optimized design between circuit level and electromagnetic simulation and results in 1 dB and gain and phase error, respectively, at 85-110 GHz. The behavior of the vector modulator phase distortion versus input power level is investigated and measured, and design guidelines are given for proper operation in a transmit (Tx) chain. The V and H Rx paths result in a gain of 22 and 25 dB, respectively, a noise figure of 9-9.5 (max. gain), and 11 dB (min. gain) measured without the T/R switch, and an input P1 dB of -31 to -26 dBm over the gain control range. The measured output Psat is ~ -5 dBm per channel, limited by the T/R switch loss. Measurements show ±0.6- and ±0.75-dB variation between the 4 × 4 array elements in the Tx mode (Psat) and Rx mode, respectively, and 40-dB coupling between the different channels on the chip. The chip consumes 1100 mA from a 2-V supply in both the Tx and Rx modes. The design can be scaled to >10 000 elements using polyimide redistribution layers on top of the chip and the application areas are in W-band radars for landing systems.
TL;DR: A 3-D imaging system using capacitive micromachined ultrasonic transducer (CMUT) technology that addresses many of the challenges in building such a system and demonstrates two approaches in integrating the transducers and the front-end electronics.
Abstract: Real-time volumetric ultrasound imaging systems require transmit and receive circuitry to generate ultrasound beams and process received echo signals. The complexity of building such a system is high due to requirement of the front-end electronics needing to be very close to the transducer. A large number of elements also need to be interfaced to the back-end system and image processing of a large dataset could affect the imaging volume rate. In this work, we present a 3-D imaging system using capacitive micromachined ultrasonic transducer (CMUT) technology that addresses many of the challenges in building such a system. We demonstrate two approaches in integrating the transducer and the front-end electronics. The transducer is a 5-MHz CMUT array with an 8 mm × 8 mm aperture size. The aperture consists of 1024 elements (32 × 32) with an element pitch of 250 μm. An integrated circuit (IC) consists of a transmit beamformer and receive circuitry to improve the noise performance of the overall system. The assembly was interfaced with an FPGA and a back-end system (comprising of a data acquisition system and PC). The FPGA provided the digital I/O signals for the IC and the back-end system was used to process the received RF echo data (from the IC) and reconstruct the volume image using a phased array imaging approach. Imaging experiments were performed using wire and spring targets, a ventricle model and a human prostrate. Real-time volumetric images were captured at 5 volumes per second and are presented in this paper.
TL;DR: It is shown that the MMSE method is appropriate to this fast-scanning phased array weather radar concept and compared with traditional beam-forming methods, Fourier and Capon methods, to observe distributed targets such as precipitation.
Abstract: A fast-scanning phased array weather radar (PAWR) with a digital beam forming receiver is under development. It is important in beam forming for weather radar observation with temporally high resolution to form a stable and robust main lobe and adaptively suppress sidelobes with a small number of pulses in order to accurately estimate precipitation profiles (reflectivity, mean Doppler velocity, and spectral width). A minimum mean square error (MMSE) formulation with a power constraint, proposed in this paper, gives us adaptively formed beams that satisfy these demands. The MMSE beam-forming method is compared in various precipitation radar signal simulations with traditional beam-forming methods, Fourier and Capon methods, which have been applied in atmospheric research to observe distributed targets such as precipitation, and it is shown that the MMSE method is appropriate to this fast-scanning PAWR concept.
TL;DR: In this paper, a tunable sampled-grating distributed Bragg reflector laser has been monolithically integrated and 2D beam steering has been demonstrated with this on-chip tunable laser source.
Abstract: Two-dimensional optical beam steering using an InP photonic integrated circuit has been demonstrated. Lateral beam steering controlled by a 1-D phased array has been made easier through on-chip interferometer monitors. Longitudinal beam steering controlled by the input wavelength has demonstrated an efficiency of 0.14 °/nm. Very fast beam steering (>107 °/s) in both dimensions has been demonstrated as well. As the latest development, a widely tunable sampled-grating distributed Bragg reflector laser has been monolithically integrated and 2-D beam steering has been demonstrated with this on-chip tunable laser source.
TL;DR: In this paper, a 16-element phased-array receiver with built-in self-test (BIST) capabilities is presented for 76-84 GHz applications with BIST capabilities.
Abstract: This paper presents a 16-element phased-array receiver for 76-84-GHz applications with built-in self-test (BIST) capabilities. The chip contains an in-phase/quadrature (I/Q) mixer suitable for automotive frequency-modulation continuous-wave radar applications, which is also used as part of the BIST system. The chip achieves 4-bit RF amplitude and phase control, an RF to IF gain of 30-35 dB at 77-84 GHz, I/Q balance of and at 76-84 GHz, and a system noise figure of 18 dB. The on-chip BIST covers the 76-84-GHz range and determines, without any calibration, the amplitude and phase of each channel, a normalized frequency response, and can measure the gain control using RF gain control. System-level considerations are discussed together with extensive results showing the effectiveness of the on-chip BIST as compared with standard S-parameter measurements.
01 Oct 2013
TL;DR: In this article, a 4×4 transmit/receive SiGe BiCMOS phased array at 90-100 GHz with vertical and horizontal polarization capabilities, and 3-bit amplitude and 4-bit phase control is presented.
Abstract: This paper presents a 4×4 transmit/receive SiGe BiCMOS phased array at 90-100 GHz with vertical and horizontal polarization capabilities, and 3-bit amplitude and 4-bit phase control. The 4×4 phased array fits into a 1.6×1.5 mm2 grid, which is required at 94 GHz for wide scan-angle designs. This is accomplished using dual-nested 16:1 Wilkinson combiners/divider with > 40 dB isolation between the dual-receive beams. Measurements show ±0.6 dB and ±0.75 dB variation between the array elements in the transmit (Psat) and receive mode, and <; -40 dB coupling between the elements for transmit, receive and dual-receive modes. The application areas are in W-band radar systems.
TL;DR: In this paper, a wideband, wide-scan phased array of connected dipoles has been designed and fabricated, and measured results from a 77 prototype demonstrator are presented for experimental validation.
Abstract: A wideband, wide-scan phased array of connected dipoles has been designed and fabricated. Measured results from a 77 prototype demonstrator are presented for experimental validation. In order to avoid common-mode resonances that typically affect this type of array, loop-shaped transformers are included in the feed network. The common-mode rejection implemented by these transformers allow maintaining the cross-polarization levels to values lower than over a 30% relative bandwidth, for an elevation angle up to 45 in all azimuth planes. The array exhibits a measured voltage standing-wave ratio (VSWR) lower than 2.5 from 3 to 5 GHz for broadside radiation. The VSWR maintains levels lower than 3 within a scan volume of 45 from broadside in all planes.
TL;DR: By controlling the electrical power to the individual integrated phase shifters fixed wavelength steering of the beam emitted normal to the surface of the wafer of 8° is demonstrated for 1 × 8 phased arrays with periods of both 6 and 9 μm.
Abstract: An optical phased array of nanoantenna fabricated in a CMOS compatible silicon photonics process is presented. The optical phased array is fed by low loss silicon waveguides with integrated ohmic thermo-optic phase shifters capable of 2π phase shift with ∼ 15 mW of applied electrical power. By controlling the electrical power to the individual integrated phase shifters fixed wavelength steering of the beam emitted normal to the surface of the wafer of 8° is demonstrated for 1 × 8 phased arrays with periods of both 6 and 9 μm.
TL;DR: In this paper, a more practical alternative for designing UWB tightly coupled phased arrays is proposed, which employs uniform excitation of the central array elements and short-circuits the periphery elements to provide up to 3 dB more gain and 50% higher efficiency than typical resistive termination.
Abstract: Tightly coupled phased arrays (TCPAs) provide UWB performance due to their strong inter-element coupling. However, in finite tightly coupled phased array realizations, mutual coupling is reduced near the array edges, causing the edge elements to become narrowband. To address this issue, a nonuniform array excitation scheme, referred to as “characteristic mode (CM) excitation,” was recently proposed. A more practical alternative for designing UWB tightly coupled phased arrays is proposed here. In this paper, we present a strategy that employs uniform excitation of the central array elements and short-circuits the periphery elements. We report that at least for medium size arrays, this approach provides up to 3 dB more gain and 50% higher efficiency than typical resistive termination. This concept is demonstrated using a 7 × 7 linearly polarized dipole array, 60.96 cm × 60.96 cm (2' × 2') in size, for operation from 200 MHz-600 MHz. Feeding of the active elements is challenging due to several constraints on the feed design, including balanced to unbalanced transitions, impedance transformations, common mode suppression, compact size, low cost, etc. To address these issues we propose a novel array feed using a compact, ultrawideband balun (with 10:1 bandwidth for VSWR ). Simulated and measured data are provided for broadside and 30 scan in the H-plane.
01 Nov 2013
TL;DR: In this article, the design of an 8-element circular phased patch array antenna which can generate radio beams carrying orbital angular angular momentum at 10 GHz is described. But the antenna design issues are discussed, including mutual coupling and the array performance when operating in different OAM states.
Abstract: This paper describes the design of an 8-element circular phased patch array antenna which can generate radio beams carrying orbital angular momentum at 10 GHz. Realistic antenna design issues are discussed, including mutual coupling and the array performance when operating in different OAM states.
IBM1
TL;DR: In this paper, a multi-function, dual-polarization phased array transceiver supporting both radar and communication applications at W-band is presented, which includes two independent 16:1 combining networks, two receiver downconversion chains, an up-conversion chain, a 40GHz PLL, an 80GHz frequency doubler, extensive digital control circuitry, and on-chip IF/LO combining/distribution circuitry to enable scalability to arrays at the board level.
Abstract: This paper presents a multi-function, dual-polarization phased array transceiver supporting both radar and communication applications at W-band. 32 receive elements and 16 transmit elements with dual outputs are integrated to support 16 dual polarized antennas in a package. The IC further includes two independent 16:1 combining networks, two receiver downconversion chains, an up-conversion chain, a 40GHz PLL, an 80GHz frequency doubler, extensive digital control circuitry, and on-chip IF/LO combining/distribution circuitry to enable scalability to arrays at the board level. The fully-integrated transceiver is fabricated in the IBM SiGe BiCMOS 0.13um process, occupies an area of 6.6×6.7mm2, and operates from 2.7V (analog/RF) and 1.5V (digital) supplies. Multiple operating modes are supported including the simultaneous reception of two polarizations with a 10GHz IF output, transmission in either polarization from an IF input, or single-polarization transmission/reception from/to I&Q base-band signals (2.5W RX, 2.9W TX). Measurement results show 8dB receiver NF and 2dBm transmitter output power per element at 94GHz in both polarizations.
TL;DR: Stroboscopic measurement capabilities are demonstrated which allow for feedforward control to eliminate micromirror ringing and a closed-loop phase-control algorithm results in <π/100 mirror phase accuracy and far field beam steering.
Abstract: We present a high-speed optical beamsteering system based on an 8x8 MEMS phased array. The system incorporates an in situ interferometer that provides a real-time, dynamic measure of the phase of each mirror in the array during beamsteering. A closed-loop phase-control algorithm results in <π/100 mirror phase accuracy and far field beam steering is shown. Stroboscopic measurement capabilities are demonstrated which allow us to show feedforward control to eliminate micromirror ringing.
TL;DR: In this paper, a multi-element matrix ultrasonic probe is driven using the well-known phased array principle, for launching and detecting pure Lamb modes in/from specific directions along the plate, which are arbitrary for isotropic materials and limited to specific directions for anisotropic materials.
Abstract: This article presents a technique for the generation and detection of Lamb waves guided along large plate-like structures made from various types of materials (metal, polymer, fibre-reinforced composite, etc.). A multi-element matrix ultrasonic probe is driven using the well-known phased array principle, for launching and detecting pure Lamb modes in/from specific directions along the plate, which are arbitrary for isotropic materials and limited to specific directions for anisotropic materials, e.g. principal directions or directions for which both phase and group velocities are collinear. The probe is gel-coupled to the tested specimen and allows quick inspection of large area from its fixed position, even of zones with limited access. The technique, which takes into account the frequency dispersive effects, is different than SHM-like (Structural Health Monitoring) inspection, since all transmitting or receiving elements are grouped together in a localized area defined by the active surface of the probe, and not permanently attached to the tested structure. The use of a multi-element probe, for long range Lamb waves-based inspection, is also distinctive from that usually performed, which consists of very local inspection of a material by steering the ultrasonic beam below and nearby the probe. A prototype is presented, as well as measurements of its performances in terms of modal selectivity and directivity. Finally the detection and localisation of a through-thickness hole in a large aluminium plate, of a delamination-like defect in a carbon epoxy composite plate and of an impact damage on a stiffened composite curved plate are shown.
14 Apr 2013
TL;DR: A tactile display which can generate vibrotactile sensation on human skin on which no equipment is mounted is fabricated and its performance evaluation is reported.
Abstract: We fabricated a tactile display which can generate vibrotactile sensation on human skin on which no equipment is mounted. It utilizes focused airborne ultrasound radiation pressure for stimulation. The workspace of our new tactile display is widened to a cube of 1 m × 1 m × 1 m, which allows users free motions in it. In order to widen the workspace, our new prototype integrates multiple ultrasound transducer units and achieves a large aperture airborne ultrasound phased array. As the workspace is widened, it has become possible to stimulate arbitrary regions all over a human body. The amplitude of imposed radiation pressure can be time-variant. The profiles of generated vibrotactile stimuli can be designed with a temporal resolution of 0.5 ms and 320-level quantization of radiation pressure amplitude. It is easy to choose a recorded waveform and reproduce it as vibrotactile stimuli at an arbitrary spatial point. This paper introduces how our new tactile display works and reports its performance evaluation.