mmWave Phased Array Research Articles

Shared Aperture Wideband Endfire/Broadside mm-Wave Phased Array With Enhanced Scanning Range Integrated With Metal Frame for Mobile Terminals

Shared Aperture Wideband Endfire/Broadside mm-Wave Phased Array With Enhanced Scanning Range Integrated With Metal Frame for Mobile Terminals

Estimation of Power Density in mm-wave Phased Array Antenna for 5G Cellular Handset

Estimation of Power Density in mm-wave Phased Array Antenna for 5G Cellular Handset

Gradient-Based Beam Peak Search for Over-the-Air Testing of Mmwave Phased Arrays

Gradient-Based Beam Peak Search for Over-the-Air Testing of Mmwave Phased Arrays

Optimizing Multiple Beam Patterns for 5G mmWave Phased Array Applications

In this paper, a new technique for shaping multiple beam patterns antenna arrays for 5G and beyond wireless massive MIMO communication systems is introduced. The technique aims to concentrate the radio energy in specific coverage areas with a desired shape by optimizing the excitation amplitudes and phases of the array elements. To assess the proposed technique, both genetic algorithm and particle swarm optimization are utilized to optimize the excitation amplitudes and phases of the array elements such that the required number of the beams, their shapes, their directions, their power magnitudes, and the desired sidelobe pattern can be achieved. Simulation results fully confirm the effectiveness of the proposed technique in generating optimized shaped patterns that can be suitably used for distributing the radiation powers over the coverage areas in the mobile communication base stations.

Chip-to-Chip Interfaces for Large-Scale Highly Configurable mmWave Phased Arrays

This article presents a chip-to-chip (C2C) interface for constructing reconfigurable phased arrays to be used in fifth-generation (5G)/sixth-generation (6G) wireless systems. The C2C interface further facilitates building phased array panels by allowing the use of grid-based PCB routing, thus providing flexibility in the system design. An eight-element RFIC capable of handling two independent data-streams is fabricated using 45-nm CMOS technology. The RFIC incorporates four C2C interfaces operating at 27 GHz, two C2C interfaces operating at 9 GHz, and a complex baseband (BB) with single-sided bandwidth in excess of 400 MHz. The architecture is tested by flip-chip bonding two fabricated RFICs on an eight-layer Megtron 7 PCB. In this article, only the receiver path of the RFIC and the phased array is described. Performance of both the single RFIC and the combination using the 27-GHz C2C interface is demonstrated using conductive and over-the-air (OTA) measurements. OTA measurements are conducted using 5GNR FR2 OFDM waveforms with a signal bandwidth of up to 800 MHz. The measured RF to BB conversion gain for a single element is larger than 23 dB and the minimum measured noise figure (NF) is 6.2 dB. The nominal dc power consumed by the receiver per element per stream is 116.5 mW. The RFIC occupies a normalized area per element per data stream of 2.7 mm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^2$</tex-math> </inline-formula> . The RFIC is capable of supporting dual-polarized antennas or in a large-scale panel utilizing the same antenna elements to two independently weighted data streams as part of the hybrid beamforming architecture.

Impact of dielectric substrate on the performance of an 8 × 8 magneto-electric dipole phased array antenna for 5G mmWave applications

The impact of the substrate dielectric material on the performance of a wideband magneto-electric dipole (MED) phased array antenna is systematically studied in this article. Four commercially available dielectric substrates for mmWave applications, i.e., Rogers RO 5880, RO 3003, RO 4350B, and Panasonic Megtron-6, are considered in the design investigation of the proposed MED phased array antenna. First, the influence of the dielectric constant on the operating frequency of the unit cell MED antenna is explored in the broadside direction (θ = 0°). Second, the scanning impedance is assessed at various scanning angles for both E- and H-plane scanning. Finally, the radiation performance of the proposed design of a finite 8 × 8 MED phased array antenna is examined. This study gives a foundational understanding of the impact of dielectric characteristics on the performance of MED phased arrays. The analysis revealed that the MED phased array antenna based on substrates with a higher dielectric constant exhibited a smaller scanning angle than the substrate with a lower dielectric constant. The findings may serve as practical guidelines for selecting the dielectric substrates for the 5G mmWave phased array antenna in order to adapt their design to an application’s specifications.

Circulant Shift-Based Beamforming for Secure Communication With Low-Resolution Phased Arrays

Millimeter wave (mmWave) technology can achieve high-speed communication due to the large available spectrum. Furthermore, the use of directional beams in mmWave system provides a natural defense against physical layer security attacks. In practice, however, the beams are imperfect due to mmWave hardware limitations such as the low-resolution of the phase shifters. These imperfections in the beam pattern introduce an energy leakage that can be exploited by an eavesdropper. To defend against such eavesdropping attacks, we propose a directional modulation-based defense technique where the transmitter applies random circulant shifts of a beamformer. We show that the use of random circulant shifts together with appropriate phase adjustment induces artificial phase noise (APN) in the directions different from that of the target receiver. Our method corrupts the phase at the eavesdropper without affecting the communication link of the target receiver. We also experimentally verify the APN induced due to circulant shifts, using channel measurements from a 2-bit mmWave phased array testbed. Using simulations, we study the performance of the proposed defense technique against a greedy eavesdropping strategy in a vehicle-to-infrastructure scenario. The proposed technique achieves better defense than the antenna subset modulation, without compromising on the communication link with the target receiver.

A mm-Wave Signal Generation and Background Phase Alignment Technique for Scalable Arrays

This work presents a mm-wave signal generation method that provides background phase tuning and self-alignment between adjacent sources. This technique is based on direct monitoring of the mm-wave signal and provides phase tuning through a baseband feedback loop. We present the theory of the concept, provide the design methodology, and validate the proposed method with a two-element prototype in a 65-nm CMOS process. The prototype has a chip area of 1.3 mm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times $ </tex-math></inline-formula> 2 mm and consumes a total dc power of 258 mW. Chip measurements demonstrate a phase tuning range of 140° at 35 GHz with 20°/step and 3.5° of rms phase error. The measured phase switching time is 20 ns. The measured phase noise at 1-MHz offset is below –117 dBc/Hz across phase settings, and the accumulated jitter is 86 fs. These results are consistent with theory and simulation. This work provides a phase alignment technique for large-scale mm-wave phased arrays.

Development and Validation of Testing System for Automated Millimeter-Wave Phased Array Multibeam Near-Field Measurement

To ensure millimeter-wave (mmWave) radio system performance, multiple beam-steered radiation patterns of phased arrays are required to be measured in conventional antenna measurement ranges. This is typically done by sequentially measuring the radiation pattern of phased array under test (AUT) with the AUT mechanically rotating in a far-field setup for each steered beam in a beam-lock mode. However, the conventional pattern measurement procedure for mmWave phased arrays with multiple beams is time-consuming and costly due to the repetitive mechanical rotation and the use of far-field anechoic chamber. The problem becomes even more pronounced for mmWave phased arrays with large-scale antenna configuration due to many more beam states and more directive beam patterns. To address this issue, this paper proposes a novel near-field multi-beam measurement system for mmWave phased arrays, which offers unique advantages in terms of short measurement time, support for full automation, no need for mechanical rotation, compact measurement setup and low system cost. For the pattern with its beam steered to any given direction can be reconstructed based on the AUT element patterns retrieved from a few sparse measurement samples. In this work, the principle and effectiveness of the proposed measurement system have been firstly validated by electromagnetic simulations with CST Studio Suite. Besides, a practical system prototype has been built and experimentally validated where the near-field reconstructed multi-beam patterns are shown to match well with the far-field target patterns in terms of beam direction, beam gain, and pattern similarity percentage.

Shaped beam from multiple beams using planar phased arrays

ABSTRACT This paper proposes a synthesis and optimization procedure to generate user-specific shaped and multiple beams in any arbitrary 3D space. The synthesis method generates independently controllable multiple beams over different azimuth and elevation angles with variable peak powers. These multiple beams can form any user-defined shaped pattern with an optimum number of beams, their power, and placement in the angles using the proposed direct synthesis method. Different evolutionary algorithms are employed to optimize the beam peak parameters to mitigate the ripple, side lobe level, and beam spread. The synthesis method is validated on a fully functional integrated 5G mmWave phased array for various shaped beam patterns. Measured sector, isoflex beams between , , and dual beams with unequal powers are presented and compared with the shaped beam synthesis method.

An Indoor Environment Sensing and Localization System via mmWave Phased Array

In this paper, an indoor layout sensing and localization system with testbed in the 60-GHz millimeter wave (mmWave) band, named mmReality, is elaborated. The mmReality system consists of one transmitter and one mobile receiver, both with a phased array and a single radio frequency (RF) chain. To reconstruct the room layout, the pilot signal is delivered from the transmitter to the receiver via different pairs of transmission and receiving beams, so that multipath signals in all directions can be captured. Then spatial smoothing and the two-dimensional multiple signal classification (MUSIC) algorithm are applied to detect the angle-of-departures (AoDs) and angle-of-arrivals (AoAs) of propagation paths. Moreover, the technique of multi-carrier ranging is adopted to measure the path lengths. Therefore, with the measurements of the receiver in different locations of the room, the receiver and virtual transmitters can be pinpointed to reconstruct the room layout. Experiments show that the reconstructed room layout can be utilized to localize a mobile device via the AoA spectrum.

Digital Predistortion for Dual-Linearly Polarized Millimeter-Wave Phased Array User Equipment

To accommodate the ongoing user’s data explosion, many approaches like polarization multiplexing are proposed to increase the uplink communication capacity with limited bandwidth in user equipment (UE). This article proposes a novel dual-linearly polarized digital predistortion (DLP-DPD) scheme for DLP millimeter-wave (mmWave) phased array UE. Different from conventional single-polarized arrays, the DPD here not only aims to deal with the nonlinear distortion caused by power amplifiers (PAs) but also the cross-polarization interference which is a specific distortion in DLP phased array system. Theoretical analysis and system modeling of DLP phased array is presented, and a DLP-DPD model is proposed according to the derivation. Furthermore, in order to reduce the complexity of the DPD module, the proposed DLP-DPD scheme only needs to update a small part of coefficients when the user moves within a beam coverage. To validate the proposed DLP-DPD scheme, experiments were carried out on a 1 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times $ </tex-math></inline-formula> 4 DLP mmWave phased array at 26.5 GHz. The experimental results show that DLP-DPD scheme can achieve good performance in DLP phased array dynamic scenario, dealing with the nonlinearity and cross-polarization interference well.

A Fast Multibeam Measurement Method for Millimeter-Wave Phased Arrays

Accurate knowledge of multibeam radiation patterns of millimeter-wave (mmWave) phased arrays is a key to mmWave radio system performance. The multibeam radiation patterns can be measured by conventional antenna test ranges in a sequential manner. However, these tasks can be time-consuming and low efficient in practice, especially for large-scale arrays with many beam-steering states. To address this problem, this letter proposes a multibeam reconstruction method, which can measure all possible steered beams in a fast and efficient manner. In the proposed method, multiple beam patterns are reconstructed synchronously by a fast element pattern retrieving method based on a few sparse measurement samples, which were obtained in a multiprobe setup or with the help of a turntable in a single probe setup. The proposed method is experimentally validated in a compact antenna testing range (CATR) setup at 28 GHz for a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$4\times 4$</tex-math></inline-formula> mmWave phased array with an integrated antenna-in-package design. The experimental results show that the reconstructed array multibeam patterns by the proposed method are comparable to the conventional CATR measurement results but in a faster way, which validates the effectiveness of the proposed method.

High Gain Planar Segmented Antenna for mmWave Phased Array Applications

A new high-gain antenna structure is proposed for mmWave 5G and potentially for B5G and 6G applications. The proposed antenna is configured by a planar segmented patch structure that has a radiator size comparable to the conventional patch but achieves more than 3 dB gain enhancement without a help of superstrate stack-up layer. The proposed planar segmented antenna (PSA) induces multiple magnetic currents through multiple segmented conductors, resulting in a strong magnetic field circulation around the conductors. Only one conductor requires an excitation port and each segmented conductor has a shorting pin to synchronize resonance currents. To verify the PSA operation, several prototypes were fabricated at 28 GHz with the identical volume of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1.213\,\,\lambda _{0} \times 1.213\,\,\lambda _{0} \times 0.113\,\,\lambda _{0}$ </tex-math></inline-formula> , including the ground plane. The maximum measured impedance bandwidth of the single PSA was 23.1%. Furthermore, the measured maximum antenna gain was 11.5 dBi, whereas the same sized reference patch antenna showed only 6.3 dBi.

Low-Resolution Architectures for Power-Efficient Scaling of mmWave Phased Array Receivers

Low-Resolution Architectures for Power-Efficient Scaling of mmWave Phased Array Receivers

On the Impact of Frequency Discrepancy on Beamforming Performance in Millimeter-Wave Phased Array Antenna Systems

Multiple-input&#x2013;multiple-output (MIMO) is a key technology used to meet the requirements of 5G systems. In millimeter-wave (mmWave) bands, directional beamforming is applied at both the transmitter and the receiver to establish an efficient radio link. The mmWave bands specified in 5G specifications range from 24.25 to 40.0 GHz. Accordingly, different countries may allocate different bands to support 5G services because of the availability of the spectrum and the countries&#x2019; radio management policies. For international roaming, user equipment (UE) must support multiband operations based on a fixed antenna hardware structure that is designed to target a specific operating band. Hence, the frequency discrepancy that results from using different operating bands causes distortion in the achieved beamforming pattern. In this article, we investigate the impact of frequency discrepancy on beamforming performance in mmWave phased array antenna systems at the UE side, considering the resultant beam pattern and interference. In this effort, we studied three major side effects&#x2014;deviation of the beamforming direction, change in the effective array length, and change in the normalized interelement spacing. The numerical results indicate that a large frequency discrepancy causes severe distortion in the resultant beamforming pattern and introduces more interference into the system.

A Ka-Band Antenna Array Based on Wide-Beamwidth Magnetoelectric Dipole

A wide-beamwidth magnetoelectric (ME) dipole antenna for millimeter-wave (mm-wave) phased array applications is proposed in this letter. The antenna is fed by a substrate integrated waveguide. The electric dipole is formed by two patches, while the magnetic dipole consists of two apertures between the two patches. A short strip is introduced to connect the two patches, which can improve the impedance matching performance. The impedance bandwidth with | <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">S</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> | < −10 dB for the antenna element is 19.9% (28.11–34.32 GHz), as shown in the simulated results. And its half-power beamwidth in the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">xoz</i> plane and <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">yoz</i> plane is wider than 82.1° and 81.8° over the operating band. To test the scanning potential of the ME-dipole antenna, a 4 × 4 phased array is constructed in high-frequency simulation software. The simulated scanning range of the phased array is beyond −41°∼41° at two sampling frequencies. Besides, a 4 × 4 antenna array is designed, processed, and measured. The array demonstrates a −10 dB fractional bandwidth of 15.3% (27.7–32.3 GHz) with a peak gain of 17.79 dBi at 30.4 GHz. The proposed ME-dipole antenna demonstrates good potential for 5G mm-wave phased array applications.

Performance Enhancement of mm-Wave Phased Arrays for Mobile Terminals Through Grounded Coplanar Waveguide Feeding Networks With via Fences

This paper presents a design methodology focused on feeding networks that can improve the insertion loss and coverage efficiencies of millimeter-wave (mm-Wave) phased arrays in mobile terminals. This enhancement is accomplished by using a grounded coplanar waveguide (GCPW) transmission line (TL) withviafences fabricated on single-layer FR-4 PCB. The exemplified 8-element phased arrays incorporating a compact one-dimensional electromagnetic bandgap (1-D EBG) antenna are fed through a 1 × 8 T-junction power divider, which includes the predetermined phased delay lines. To achieve high radiation performance with minimum leakage power or spurious waves in the T-junction power divider, an island-shape GCPW TL topology withviafences featuring high-impedance surfaces (HIS) is devised and fabricated. For further investigation on the radiation performance and spherical coverage of the mm-Wave mobile antenna, a mobile device prototype equipped with two sets of the 8-element phased arrays is prepared and studied. Through extensive simulation and experimental studies, it can be ascertained that the proposed GCPW TL topology withviafences can improve the realized gain at a coverage efficiency of 50% by more than 3 dB, between 26 and 36 GHz.

Shape and Weighting Optimization of a Subarray for an mm-Wave Phased Array Antenna

This paper discusses how to optimize the weighting of individual subarrays to derive the low sidelobe level (SLL) based on quadratic programming (QP) and how to derive QP parameters to ensure that the objective function is composed of the quadratic function form, with the actual number identical to the standard objective function of QP. Next, in order to analyze the SLL, a 24 × 24 phased array antenna was compared with 96 transmit–receive modules (TRMs) attached only to the subarray stage and a phased array antenna with 576 TRMs attached to all radiating elements without a subarray. Optimized weighting was applied to the array antennas with a subarray, and Taylor weighting was applied to the array antennas without a subarray. The number of TRMs used in the phased array antenna with the optimized weighting was reduced by 83.3% compared to the phased array antenna in which TRMs were attached to all radiating elements. The SLL and the half-power beamwidths (HPBWs) of the two antennas were practically identical in a narrow beam-scanning environment. Finally, an array pattern (AP) in which mutual coupling between the radiating elements was considered was calculated to verify the optimized weighting. Moreover, the optimized weighting was applied to CST Microwave Studio (an EM full-wave simulation) to compare the results from the AP calculation and a simulation. It was confirmed that the two results above are largely indistinguishable. The analysis found that the HPBW is 3.6∘ × 3.6∘ and the SLL is −26.18 dB from AP calculations in the boresight direction. When each 5∘ beam was scanned at the azimuth and elevation, the corresponding HPBW values were 3.7∘ × 3.7∘ and 3.7∘ × 3.7∘ and the SLLs were −22.70 dB and −24.44 dB according to the AP calculations.

Over-the-Air Array Calibration of mmWave Phased Array in Beam-Steering Mode Based on Measured Complex Signals

Accurate knowledge of initial complex excitation coefficients for phased-array elements is essential to ensure accurate array performance. In the literature, many array calibration algorithms have been proposed for this purpose, which generally requires customized phase setting for individual phase shifters connected to array elements. In this article, a new array calibration method is proposed for phased array operating in beam-steering mode only, that is, phase shifts of elements are only simultaneously set according to the beam-steering directions, and therefore, there is no need for dedicated individual element phase tuning. The proposed method requires a minimum number of complex-signal measurements in principle, which enables fast measurement. Furthermore, it is found that the performance of the proposed method is determined by the beam-steering matrix, whose condition number is mainly ruled by the beam-steering angle interval. The proposed method is numerically simulated and experimentally validated in a millimeter-wave (mmWave) phased-array antenna-in-package (AiP) platform at 28 GHz. The proposed method presents good agreement with the well-known rotating element electric field vector (REV) array calibration method, with an amplitude error and phase error within ±0.5 dB and ±5°, respectively. Furthermore, the reconstructed array pattern with the proposed method offers excellent match with the measured array pattern.