Subarray Module Research Articles

Analysis, Design, and Experimental Validation of a High-Isolation, Low-Cross-Polarization Antenna Array Demonstrator for Software-Defined-Radar Applications

In a software-defined radar (SDR) system, most of the signal processing usually implemented in hardware is implemented by software, thus allowing for higher flexibility and modularity compared to conventional radar systems. However, the majority of SDR demonstrators and proofs of concept reported in the open literature so far have been based on simple antenna systems. As a result, the full potentialities of an SDR approach have not been completely exploited yet. In this work, we propose a flexible antenna module to be integrated into an active electronically scanning array (AESA) with controlled sidelobe level over a wide angular range, exhibiting polarization reconfigurability with a low cross-polarization level and high isolation. For this purpose, analytical and numerically efficient techniques for the synthesis of the aperture distribution and the correct evaluation of the radiating features (e.g., beamwidth, pointing angle, sidelobe levels, etc.) are presented in order to grant real-time control of the digital beamforming network. A sub-array module demonstrator is fabricated and measured to corroborate the concept.

Design of a phased array antenna with scan loss reduction and gain enhancement by using reconfigurable subarrays

In order to reduce the scan loss and also obtain higher scanning gain for a phased array, a subarray design is proposed in this study. Different from the prior works, the number of active phase shifters utilised in this topology is identical to its counterpart without subarrays, which makes it more cost-effective. To achieve this valuable characteristic, a reconfigurable beam-former is proposed to enable the radiation pattern of a subarray to be switchable to different modes for different scanning regions. The proposed beam-former is based on substrate-integrated waveguide (SIW) and featured by extremely low-loss, due to its unique working mechanism. For validation, a fully integrated subarray module consisting of a beam-former and two Yagi-Uda antennas is designed and analysed. Furthermore, in order to show the effectiveness, five subarray modules with uniform spacing are utilised to construct a complete prototype operating at 15 GHz. Measurement results of the entire array indicate that the achieved gain is 2∼3 dB higher than its counterpart without the subarray, from −45° to +45° in the beam-scanning plane. Meanwhile, the scan loss is decreased from ±1.45 dB to smaller than ±0.9 dB. Meanwhile, sidelobe levels are also improved for scanning angles between ±45°. It should be pointed out that the proposed approach is also applicable to broaden the scanning angle of phased arrays with properly selected antenna elements. Since there is no need to increase the number of active phase shifters, this subarray-based approach can be considered more economic, and is very attractive for a variety of phased array systems.

An X-Band CMOS Digital Phased Array Radar from Hardware to Software.

Phased array technology features rapid and directional scanning and has become a promising approach for remote sensing and wireless communication. In addition, element-level digitization has increased the feasibility of complicated signal processing and simultaneous multi-beamforming processes. However, the high cost and bulky characteristics of beam-steering systems have prevented their extensive application. In this paper, an X-band element-level digital phased array radar utilizing fully integrated complementary metal-oxide-semiconductor (CMOS) transceivers is proposed for achieving a low-cost and compact-size digital beamforming system. An 8–10 GHz transceiver system-on-chip (SoC) fabricated in 65 nm CMOS technology offers baseband filtering, frequency translation, and global clock synchronization through the proposed periodic pulse injection technique. A 16-element subarray module with an SoC integration, antenna-in-package, and tile array configuration achieves digital beamforming, back-end computing, and dc–dc conversion with a size of 317 × 149 × 74.6 mm3. A radar demonstrator with scalable subarray modules simultaneously realizes range sensing and azimuth recognition for pulsed radar configurations. Captured by the suggested software-defined pulsed radar, a complete range–azimuth figure with a 1 km maximum observation range can be displayed within 150 ms under the current implementation.

Research on Quantization Error Influence of Millimeter-Wave Phased Array Antenna

The millimeter-wave phased array antenna is a higher integration system that is composed of different subarray modules, and in actual engineering, the existing amplitude, phase errors, and structural errors will change the performance of the array antenna. This paper studies the influence of the random amplitude and phase errors of the antenna array in the actual assembly process and the actual position errors between the subarrays on the electrical performance of the antenna. Based on the planar rectangular antenna array-electromagnetic coupling model, we propose a method of verifying the effect of random errors on the phased array antenna. The simulation result shows that the method could obtain the critical value of the error generated by the antenna subarray during processing and assembly. To reduce the error factor, it is necessary to ensure that the random phase and amplitude error should not exceed 10 ° , 0.5 dB . The error in the X-direction during assembly should be ≤ 0.05 λ , and the error in the Y-direction should be ≤ 0.1 λ . When symmetrical deformation occurs, the maximum deformation should be less than 0.05 λ .

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

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

Hybrid Beamforming Transmitter Modeling for Millimeter-Wave MIMO Applications

Hybrid digital and analog beamforming is an emerging technique for high-data-rate communication at millimeter-wave (mm-wave) frequencies. Experimental evaluation of such techniques is challenging, time-consuming, and costly. This article presents a hardware-oriented modeling method for predicting the performance of an mm-wave hybrid beamforming transmitter. The proposed method considers the effect of active circuit nonlinearity as well as the coupling and mismatch in the antenna array. It also provides a comprehensive prediction of radiation patterns and far-field signal distortions. Furthermore, it predicts the antenna input active impedance, considering the effect of active circuit load-dependent characteristics. The method is experimentally verified by a 29-GHz beamforming subarray module comprising an analog beamforming integrated circuit (IC) and a 2 2 subarray microstrip patch antenna. The measurement results present good agreement with the predicted ones for a wide range of beam-steering angles. As a use case of the model, far-field nonlinear distortions for different antenna array configurations are studied. The demonstration shows that the variation of nonlinear distortion versus steering angle depends significantly on the array configuration and beam direction. Moreover, the results illustrate the importance of considering the joint operation of beamforming ICs, antenna array, and linearization in the design of mm-wave beamforming transmitters.

A Lightweight Planar Ultrawideband UHF Monopole Mills Cross Array for Ice Sounding

An electrically large ultrawideband ultrahigh frequency (UHF) monopole antenna array has been designed to sound up to 3 km of ice and meet the logistical requirements of transportation to arctic regions. The monopole array is comprised of 16 planar subarray modules, which in combination form a 16 m by 17 m Mills cross array configuration to maximize sensitivity and spatial selectivity in both cross-track and along-track directions. Each planar subarray module is 1 m by 2 m in size with a 6.35 cm thick rigid insulation foam panel separating the individual monopole elements from metal foil ground plane on the top such that the maximum radiation is directed to nadir. Each subarray panel consists of 4 by 8 circular monopole antenna elements with a spacing of 0.25 m. Each monopole element is printed on a 130 mm by 80 mm 62 mil FR4 board. The total weight of each subarray panel is 9 kg, making for very lightweight and low-profile antenna construction. The antenna array together with the radar system was deployed to the East Greenland Ice-coring Project site in August 2018 for demonstrating surface-based ice sounding at the UHF band.

A Ka-Band Scalable Hybrid Phased Array Based on Four-Element ICs

In this article, a scalable hybrid phased-array system is presented through synchronization, analog complex weighting, and digital beamforming of numerous fully integrated Ka-band four-receiver (RX)/four-transmitter (TX) phased-array transceiver integrated circuits (ICs). A 1.09-GHz clock synchronizes the local oscillator (LO) and a 50-MHz clock synchronizes analog-to-digital (A/D)/digital-to-analog (D/A) converters for all array elements. Phase shifting is first accomplished in the analog domain using optimal intermediate frequency (IF)/LO complex weighting and signal summing in the 4RX/4TX IC to reduce the number of signals by a factor of four, followed by A/D sampling and digital beamforming in field-programmable gate arrays (FPGAs) and central processing units (CPUs). Phase-shifting properties, programmable gain variations, and antenna patterns of each RTX channel are measured and tabulated to calculate the optimal channel weights. The long-term phase stability is enhanced through temperature control by monitoring all ICs’ temperatures in real time and adaptively adjusting the duty cycle of the TX mode of each IC to limit instantaneous temperature variations to ±0.5 °C over each calibration session. This reduces random phase errors from 13.3° to 4.8° in the TX mode. After each Vivaldi antenna is located on a 2-D rectangular grid, an $8 \times 4$ subarray module with synchronized digital output is demonstrated. With the boresight pointing along the $\hat {x}$ -axis, the eight-element dimension pointing along the $\hat {y}$ -axis, and the four-element dimension pointing along the $\hat {z}$ -axis, this subarray steers radiation patterns with the $\overrightarrow {E}$ -field polarized to the $\hat {y}$ -axis between ±40° in both azimuth and elevation with 13.4° and 26.4° measured 3-dB beamwidths, respectively.

Development of the algorithm of reliability­centered maintenance of phased array antennas

The strategy and algorithm of reliability-centered maintenance of active phased array antennas are developed. The use of this strategy and algorithm makes it possible to determine the time and volumes of corrective replacements of the antenna subarray modules based on the results of predicting the reliability indexes of the array antenna as a whole. This procedure is performed as a result of consistent refinement of statistical estimates of reliability indexes of the modules during the normal operation of the phased array antenna. For processing statistical information on the failures of the array antenna modules and determining the estimates of the sample mean, upper and lower confidence limits, the method of quantiles is used. As the law of distribution of the operating time of the array antenna modules, the combination of exponential and diffusion nonmonotonic distributions is used. The example of implementation of the reliability-centered maintenance strategy and algorithm for the receive phased array antenna including 100 antenna subarrays is presented. The results of the research can allow organizing the APAR condition-based maintenance and minimizing the operating costs. Implementation of the obtained results can ensure failure-free operation of active phased array radars during operation with the timely provision of antenna subarrays with spare modules.

Highly Directional Steerable Antennas: High-Gain Antennas Supporting User Mobility or Beam Switching for Reconfigurable Backhauling

Modern millimeter-wave (mmWave) communication systems for large indoor areas and most outdoor scenarios require high-gain antennas with beam-steering ability to support user mobility or beam switching for reconfigurable backhauling. In this article, two new concepts for the development of highly directional steerable mmWave antennas are proposed and analyzed. The first one is modular antenna array (MAA) technology, which allows the creation of large-aperture, high-gain adaptive antenna arrays in a cost-effective and scalable manner. Two MAA configurations based on the existing phased subarray module are considered and analyzed for mmWave small-cell access and backhauling. The second prospective technology that fulfills the required antenna parameters for mmWave smallcell flexible backhauling is the lens-array antenna (LAA). The combination of the dielectric lens for aperture increasing with only one subarray module with beam-steering capabilities may provide 25?30-dBi total antenna gain with azimuth sector sweeping !45?.

Leveraging Software-Defined Radio Techniques in Multichannel Digital Weather Radar Receiver Design

This paper describes the instrumentation, design, and implementation of an inexpensive nearly all-digital field-programmable gate-array (FPGA)-based radar receiver useful in a variety of applications including single-/dual-polarization weather radar, sidelobe cancellation, subarray modules for a digital beam-forming phased-array radar, and other applications where a compact, low-power, and low-cost receiver is needed. The design of the receiver includes a minimal analog radio-frequency front-end followed by an analog-to-digital converter utilizing a bandpass sampling technique which allows the FPGA to produce baseband in-phase (I) and quadrature (Q) signals without the use of multipliers or lookup tables.

A hybrid tile approach for Ka band subarray modules

A "thin" array construction using tile module architecture is presented in this paper. Several transmit-only tile modules operating at 30 GHz have been fabricated. The tile module involves a layered construction that contributes to reduced array thickness, weight, and cost. In such layered construction, the radiating aperture, active devices, and signal distribution functions are placed in different layers and involve vertical interconnections. The subarray module described involves a hybrid construction in which conventional wire bonding is utilized for interconnecting devices to the signal distribution layers. As in conventional modules, the devices are mounted on the carrier plates and fully tested before insertion in the module. The radiating elements which are integral to the module housing are connected to the devices through electromagnetic coupling. This hybrid construction is a first step towards a fully batch-processed tile module architecture. The construction approach and the performance results at the module and array level are presented.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>