Phased Array Radar Systems Research Articles

M2CS: A Microwave Measurement and Control System for Large-scale Superconducting Quantum Processors

Abstract As superconducting quantum computing continues to advance at an unprecedented pace, there is a compelling demand for the innovation of specialized electronic instruments that act as crucial conduits between quantum processors and host computers. Here, we introduce a Microwave Measurement and Control System (M2CS) dedicated for large-scale superconducting quantum processors. M2CS features a compact modular design that balances overall performance, scalability and flexibility. Electronic tests of M2CS show key metrics comparable to commercial instruments. Benchmark tests on transmon superconducting qubits further show qubit coherence and gate fidelities comparable to state-of-the-art results, confirming M2CS’s capability to meet the stringent requirements of quantum experiments run on intermediate-scale quantum processors. The compact and scalable nature of our design holds the potential to support over 1000 qubits after upgrade in stability and integration. The M2CS architecture may also be adopted to wider range of scenarios, including other quantum computing platforms such as trapped ions and silicon quantum dots, as well as more traditional applications like microwave kinetic inductance detectors, phased array radar systems.

Design and Simulation Analysis of Antenna Structure for Active Phased Array Radar

Abstract This article adopts a modular design concept to design an active phased array radar antenna system structure and elaborates on its structural layout design and thermal design content. A finite element model of the antenna structure framework was established, and the rationality of its structural and thermal design was verified through static and thermal simulation analysis.

Application of generalized aurora computed tomography to the EISCAT_3D project

Abstract. EISCAT_3D is a project to build a multi-site phased-array incoherent scatter radar system in northern Fenno-Scandinavia. We demonstrate via numerical simulation how useful monochromatic images taken by a multi-point imager network are for auroral research in the EISCAT_3D project. We apply the generalized aurora computed tomography (G-ACT) method to modelled observational data from real instruments, such as the Auroral Large Imaging System (ALIS) and the EISCAT_3D radar. G-ACT is a method for reconstructing the three-dimensional (3D) distribution of auroral emissions and ionospheric electron density (corresponding to the horizontal two-dimensional (2D) distribution of energy spectra of precipitating electrons) from multi-instrument data. It is assumed that the EISCAT_3D radar scans an area of 0.8° in geographic latitude and 3° in longitude at an altitude of 130 km with 10 × 10 beams from the radar core site at Skibotn (69.35° N, 20.37° E). Two neighboring discrete arcs are assumed to appear in the observation region of the EISCAT_3D radar. The reconstruction results from G-ACT are compared with those from the normal ACT as well as the ionospheric electron density from the radar. It is found that G-ACT can interpolate the ionospheric electron density at a much higher spatial resolution than that observed by the EISCAT_3D radar. Furthermore, the multiple arcs reconstructed by G-ACT are more precise than those by ACT. In particular, underestimation of the ionospheric electron density and precipitating electrons' energy fluxes inside the arcs is significantly improved by G-ACT including the EISCAT_3D data. Even when the ACT reconstruction is difficult due to the unsuitable locations of the imager sites relative to the discrete arcs and/or a small number of available images, G-ACT allows us to obtain better reconstruction results.

A tristatic phased array radar system in China

A tristatic phased array radar system in China

A wideband and low-power mm-wave variable-gain phase shifter based on a source-switching scheme

This article presents a low-power and wideband variable-gain phase shifter (VGPS) designed and simulated in a CMOS 65 nm technology. It introduces a source-switching scheme for designing a variable gain amplifier (SSVGA) characterized by invariant linearity, impedance, and phase characteristics, showcasing improved gain and bandwidth compared to conventional VGAs. The current-reuse and staggered-tuning techniques are used to reduce power consumption and extend the bandwidth, respectively. The proposed VGPS enables gain tuning without the need for an additional gain tuning block, resulting in reduced chip area and sidelobe levels in phased array radar systems. The proposed VGPS, with a 5-bit resolution, achieves a 3-dB bandwidth of 18 GHz (53.5–71.5 GHz) and exhibits RMS gain error range from 0.23 to 0.5 dB and RMS phase error range from 0.54° to 2.65° with phase calibration based on simulation results. It achieves a peak average gain of 1.2 dB at 58.5 GHz while consuming a DC power consumption of only 5 mW with a 1.2 V power supply voltage. Moreover, it demonstrates a wide gain tuning of 20.6 dB, allowing for flexible gain adjustments.

Ultra-wideband high gain low group delay variation amplifier for phased-array radar system

This paper describes a ultra-wideband (UWB) three-stage cascaded high gain amplifier with low group delay variation for phased-array radar system. The shunt inductor at the input not only provides an electrostatic discharge (ESD) path to ground, but also introduces a new notch for S11, thus extending the matching bandwidth. Staggered tuning of load impedance peaks at each stage facilitates a balance between flat gain and low group delay variation. The output stage further enhances the overall gain while reinforcing bandwidth and stability through resistive feedback, and employs an adaptive bias circuit for linearity improvement. Implemented in SMIC 40-nm CMOS technology, the proposed amplifier achieves good input impedance matching, flat gain and low group delay variation of ±73.5 ps over 4.7–16 GHz. The whole power consumption is 198.3 mW and the output 1 dB compression point (OP1dB) is greater than 9 dBm. After careful design, the chip size is 0.64 mm2.

Spin dynamics of room temperature van der Waals (vdW) ferromagnets and their usage in microwave devices

Quasi-two-dimensional van der Waals (vdW) materials exhibiting room-temperature (RT) long-range ferromagnetic nature have emerged as a significant research field to explore fundamental condensed matter physics due to their intriguing physical properties. These vdW materials enable a futuristic platform for implementing novel spintronics devices. Here, we examined the spin dynamics of polycrystalline Fe5GeTe2 and Fe4.8Co0.2GeTe2 vdW materials using ferromagnetic resonance (FMR) spectroscopy. Vibrating Sample Magnetometer (VSM) study reveals that both materials have a soft ferromagnetic character at room temperature. From room temperature FMR measurements, the effective magnetization of Fe5GeTe2 and Fe4.8Co0.2GeTe2 derived ∼0.54 ± 0.056 and 0.50 ± 0.017 kOe, respectively. These results are consistent with reported VSM data. Fe5GeTe2 and Fe4.8Co0.2GeTe2 exhibit broad FMR linewidths of 0.697 ± 0.036 and 0.748 ± 0.056 kOe, respectively, which can be due to inhomogeneous line broadening. Besides its intrinsic contribution to linewidth, it is also affected by extrinsic Gilbert damping (αext). The value of αext is influenced by conflicting intra-band and inter-band electronic transitions, according to Modified Kambersky's theory. Furthermore, the effective Gilbert damping constant (α) obtained is 0.0513 ± 0.0046 for Fe5GeTe2 and 0.0526 ± 0.0031 for Fe4.8Co0.2GeTe2 at RT. Additionally, we developed microwave signal processing devices using these materials and evaluated their functionality both as a microwave band-reject filter and an adjustable phase shifter. The stop-band response was studied across the 5 to 25 GHz frequency range under an applied magnetic field as high as 7 kOe. For these flip-chip-based devices, attenuation is −5 dB/cm for the Fe5GeTe2-based filter and −3.2 dB/cm on sample Fe4.8Co0.2GeTe2 at 6.95 and 5.37 kOe, respectively. The same micro-strip filter was used as a tunable phase shifter in the off-resonance region. The optimal differential phase shift studied for Fe5GeTe2 and Fe4.8Co0.2GeTe2-based phase shifters in the high-frequency region (22 GHz for Fe5GeTe2 and 18 GHz for Fe4.8Co0.2GeTe2) is 23°/cm and 14°/cm, respectively, at high magnetic fields. These versatile devices find integration across a wide spectrum of applications, such as phased-array antennas, radar systems, and wireless communication systems, offering their benefits to diverse fields.

Design and Performance of a Fully-polarized Tightly-coupled Patch Antenna for Advanced Phased Array Radar Systems

Design and Performance of a Fully-polarized Tightly-coupled Patch Antenna for Advanced Phased Array Radar Systems

Quantum-enhanced angle-of-arrival pre-estimation of radio-frequency signals

Quantum metrology with quantum effects, gives remarkable possibility to increase the precision of estimated parameter. Here, we demonstrate a quantum-enhanced angle-of-arrival pre-estimation protocol, which conduces to predict a target orientation for modern phased-array radar and sonar systems. Taking edge sensor as reference, we estimate the first, second, and third derivatives of radio-frequency (RF) phase via only four-sensor network arranged in linear topology. Combining the quantum technology with high-order derivatives, the receiving angle-of-arrival at arbitrary sensor can be pre-estimated with enhanced sensitivity of nearly 49.5%.

Two-dimensional phased array antenna beamforming system based on mode diversity.

In this paper, a two-dimensional phased array antenna beamforming system based on mode diversity is demonstrated for the first time. The system uses few-mode long-period fiber gratings to excite different modes, and utilizes few-mode fiber Bragg gratings and 2 × 2 optical switches to control the propagation paths of optical signals, so as to realize the true time delay control of optical signals of different mode channels and complete the two-dimensional scanning of the beam. In order to prove the feasibility of the two-dimensional phased array antenna beamforming system based on mode diversity, we conduct experimental verification and performance testing of the system using optical switches to select the loop structures composed of the optical circulators. The far-field radiation patterns of 2 × 3 phased array antenna system of different frequencies are tested at different beam pointing angles. The experimental results are compared with the simulation results to demonstrate that the beam pointing angles have no squint. The beamforming system based on mode diversity takes modes as independent channels for the transmission of signals, and excites and processes signals of different modes in a single few-mode fiber core, which effectively reduces the volume and complexity of the optically controlled phased array radar system.

Pareto-based bi-objective optimization for robust power allocation in hybrid MIMO phased-array radar system under air defense maneuvering tracking

Recently, Hybrid MIMO phased-array (H-MIMO-PA) radar systems have been demonstrated to offer enhanced target tracking capabilities. In practice, an effective radar resource allocation (RA) strategy can ensure the quality of service (QoS) of subtasks and improve the system resource utilization in multiple target tracking (MTT) applications. In this paper, a robust power allocation strategy is developed with the objectives of enhancing target tracking accuracy (TTA) and low probability of intercept (LPI) performance in H-MIMO-PA radar. Firstly, in order to accurately grasp the air defense battlefield situation and improve the QoS for MTT, we propose a threat assessment model based on the intuitionistic fuzzy entropy (IFE) to calculate the comprehensive threat degree of each target in real time. Next, since the predicted conditional Cramér-Rao lower bound (PC-CRLB) is based on the most recently realized measurement and provides an accurate lower bound, the PC-CRLB in clutter is derived and utilized to formulate the task utility function for TTA. In addition, the probability of intercept is derived and adopted as the performance metric for LPI. Due to power allocation process may become conflicting for achieving better TTA and LPI performance at the same time, the Pareto-based bi-objective optimization scheme is adopted, which formulates a non-convex optimization problem. Finally, to solve the formulated model, we propose the modified bi-objective particle swarm optimization (MBOPSO) algorithm. Simulation results are provided to verify the effectiveness of the proposed power allocation algorithm.

Joint Polarization-Space-Time Processing for Mainlobe Jamming via CP Decomposition

This paper deals with the problem of mainlobe jamming suppression for polarization sensitive phased-array radar system via a joint polarization-space-time processing method resorting to tensor decomposition. Firstly, a radar model accounting for one target and multiple mainlobe jammers in the far field is considered, which is equipped with a polarized transmitted antenna and a uniform linear dual-polarization receiving array. Then, exploiting the polarization-space-time characteristics, tensor CANDECOMP/PARAFAC (CP) decomposition is introduced to recast the received signal as a third order tensor consisting of three factor matrices. Further, the target echo and the jamming signal can be obtained via minimizing the Frobenius norm of the approximation error between the tensor and the outer product of the factor matrices. Finally, the effectiveness of the proposed method by numerical simulation is verified, showing its capability to combat various types of mainlobe jamming as well as their compound forms compared with the art competing method.

A Software-Defined Radar for Low-Altitude Slow-Moving Small Targets Detection Using Transmit Beam Control

Low-altitude slow-moving small (LSS) targets are defined as flying at altitudes less than 1000 m with speeds less than 55 m/s and a radar crossing-section (RCS) less than 2 m2. The detection performance of ground-based radar using the LSS target detection technique can be significantly deteriorated by the diversity of LSS targets, background clutter, and the occurrence of false alarms caused by multipath interference. To address the LSS target detection problem, we have devised a novel two-dimensional electronic scanning active phased array radar system that is implemented in the software-defined radar architecture and propose a transmit beam control algorithm based on the low peak-to-average ratio (PAPR). Meanwhile, we devised a flexible arbitrary radar waveform generator to adapt to complex environmental situations. Field experiment results effectively demonstrate that our radar can be used to detect LSS targets. Moreover, an ablation experiment was conducted to verify the role played by transmit beam control and adaptive waveform optimization and generation in improving the system performance.

A 6–18 GHz bulk CMOS three-stage gain-compensation amplifier for phased-array radar system

A fully integrated 6–18 GHz bulk CMOS ultra-wideband (UWB) gain-compensation amplifier for phased-array radar system based on SMIC 40-nm CMOS process is presented in this paper. Combined with dual-branch input matching network, three-stage cascaded amplification and both the inductive series- and shunt-peaking techniques, the gain 3-dB bandwidth (BW) is further extended. The fabricated UWB amplifier achieves a flat gain of 8.7–13.3 dB and an averaged noise figure (NF) of 5.75 dB with input return loss better than −15.1 dB. Measured input 1-dB compression point (IP1dB) is −11.9 dBm at 12 GHz. The UWB amplifier totally consumes 33.6 mW from a 1.2-V supply and occupies an area of 0.337 mm2.

Pseudo-Label Guided Sparse Deep Belief Network Learning Method for Fault Diagnosis of Radar Critical Components

Effective fault diagnosis of critical components is essential to ensure the safe and reliable operation of the entire system. This paper deals with the fault diagnosis of transmitter/receiver module, which is a critical component in the phased array radar system, by proposing a novel deep belief network learning method. A sparse deep belief network based on Gaussian function is first constructed to automatically learn the relationship between monitoring data and component health conditions. With the trained sparse deep belief network, the pseudo-labels are produced for unlabeled samples, while the information entropy is employed to calculate the confidence levels reflecting their certainty to reduce the effect of pseudo-label noise. The pseudo-labeled samples with high confidence levels are added to the training set to retrain the network. Optimal model configuration parameters are obtained through a chaos game optimization algorithm. The effectiveness of the proposed method is verified on a real-world dataset from a certain type of phased array radar. The experiments show that the mean identification rate of this method can reach 96.33%, which not only exceeds some deep belief network-based modeling methods, but also exceeds other intelligent methods.

Explicit Joint Resolution Limit of Range and Direction of Arrival Estimation for Phased-Array Radar

Phased-array technology can greatly enhance radar surveillance strategies and has become an attractive candidate for the next generation radar. Resolution limit is a critical performance indicator in phased-array radar systems. However, when it comes to estimating multiple parameters, the resolution limit has not been fully explored. This paper uses information theory to establish joint resolution limits (JRL) for range and direction of arrival (DOA) estimation in phased-array radar. In Swerling 1 model, we obtain the explicit scattering information of the duo-target whose amplitudes are the same. A threshold condition is picked in which the scattering information’s quadrature part equals one bit, and relevant parameters separations are determined to be the JRL. The explicit JRL is obtained by Taylor expansions, which illustrates that the JRL depends on several key parameters, including the number of elements, the signal-to-noise ratio, and the ratio of signal bandwidth to carrier frequency. Moreover, we demonstrate that the JRL degrades to the range/DOA resolution limit if the separation of DOA/range is zero. Finally, we validate the JRL through numerical simulations.

A Hierarchical PHM Framework for Phased Array Radar Systems

A Hierarchical PHM Framework for Phased Array Radar Systems

Periodic template compensation phase feeding method for phased array antenna

To minimise the beam-pointing error caused by the digital phase shifter in phased array antenna systems, a periodic template compensation (PTC) phase feeding algorithm is proposed in this study. In the PTC, the phase quantisation error period of the rounding method in the u-v dimension is derived as Pu and Pv. Then, the beam-pointing area is divided into multiple regions with a size of Pu × Pv. In the phase quantisation error period of {u,v}∈{[0,Pu), [0,Pv)}, a sequential phase feeding method is derived to minimise the beam-pointing error and a compensation matrix template is constructed. The phase feeding code of the PTC is the summation of that of the rounding method and corresponding compensation vector selected periodically from the compensation matrix template. Simulation results show that the maximal beam-pointing error of the PTC method is 26% of that of the rounding method for a 16 × 16 rectangular array. Azimuth measurement results from a phased array radar system verify the efficiency of the proposed method. Involving only integer multiplication, addition and shift processing, implementing the PTC algorithm in phased array systems is very easy.

MIMO Radar testbed based on USRP N320/321 software-defined radios

In a conventional phased array radar system (PAR), a transmit beam is slowly steered through a sector to illuminate targets sequentially, leaving the radar blind to threats when the transmit beam is pointed in other directions. On the other, multiple input, multiple output (MIMO) radar systems transmit orthogonal waveforms from each antenna element to illuminate the entire field of view (FOV) of the radar simultaneously, providing uninterrupted situational awareness. However, MIMO radar systems are more challenging to implement because of the added orthogonality requirements between its channels and the drastic increase in the required digital signal processing. This paper uses commercially-available cutting-edge software-defined radios (SDRs) to build a reconfigurable 8 × 8 MIMO radar with a 64-element virtual array operating in C-band (NATO G-band). Measurements indicate that the radar can detect and localize multiple targets in all 3-dimensions, including bearing, range, and Doppler, with an angular resolution of 5.5 and a range resolution of 0.9 m. The MIMO radar operates in real-time with a refresh rate of only 3 s and can switch between TDM and CDM multiplexing modes.

A 7–13 GHz 10 W High-Efficiency MMIC Power Amplifier in 0.25 µm GaN HEMT Process

With the increase in applications of the millimeter wave spectrum for phased array radar systems, mobile 7–13 communication systems, and satellite systems, the demand for a wideband, high-efficiency, high-power monolithic microwave integrated circuit (MMIC) power amplifier (PA) is increasing. In this paper, a 7–13 GHz 10 W high-efficiency MMIC PA is designed. This amplifier consists of a two-stage circuit structure with two high electron mobility transistor (HEMT) cells for the driver stage and four HEMT cells for the power stage. To ensure high efficiency and a certain output power (Pout), both the driver–stage and power–stage transistors use a deep Class–AB bias. At the same time, in order to further improve the efficiency, low-loss and second–harmonic tuning techniques are used in the output and inter-stage matching networks, respectively. Finally, the electromagnetic simulation results show that within a frequency of 7–13 GHz, the amplifier achieves an average saturated continuous wave (CW) Pout of 40 dBm, a small signal gain of 14.5–15.5 dB, a power-added efficiency (PAE) of 30–46%, and the input and output return loss are better than 5 dB and 8 dB, respectively.