Wideband Phased Array Research Articles

Wideband patch antenna through introducing co‐plane terminal

AbstractWideband operation is a crucial topic in patch structure research. Various wideband methods have been developed for patch antennas. However, some of the key benefits of patch antennas, such as semi‐space radiation and easy fabrication, are degraded. In this study, we refer to the planar inverted‐F antenna (PIFA) and propose a co‐plane terminal loading strategy, resulting in an antenna model termed the co‐plane terminal loaded antenna (CTLA). It transforms the dipole‐to‐background metallic via in PIFA to a dipole‐to‐feed gap in CTLA. Because the gap is a coupling connection, the impedance‐match and resonant‐frequency performance improve, resulting in a wider bandwidth. Based on the proposed approach, three CTLAs, including an original CTLA, an improved CTLA, and a multi‐path CTLA, were constructed and simulated, with relative bandwidths of 63.5%, 55%, and 62%, respectively. The radiation pattern is typically patch‐like, radiating in semi‐space, and hybrid polarisation over the working band. Finally, the improved and multi‐path CTLAs are fabricated and measured to validate this method and ensure that the results are consistent with the simulation results accurately. This study proposes a terminal‐loading method for patch structures, which results in wideband radiation. It can be used in wideband phased arrays, communication systems etc.

Low-Profile Circularly Polarized HF Helical Phased Array: Design, Analysis, and Experimental Evaluation

This paper presents the design, development, and performance evaluation of a compact wideband phased array active helical antenna for monitoring HF interference. Traditional multi-element HF antenna designs are often subjected to size restrictions. The front-to-back ratio of the proposed circularly polarized phased array exceeds 20 dB across the operating range. This array enables the simultaneous monitoring of vertically and horizontally polarized signals, offering a practical alternative to larger antennas, particularly in space-constrained scenarios. Through advanced low-noise amplifier design, efficiency and bandwidth are optimized while mitigating mutual coupling effects. Optimal beamformer design enhances array performance with respect to more traditional array design approaches. The test results verify exceptional performance with an average axial ratio of 2 dB and a high front-to-back ratio beyond the desired frequency range. This study offers valuable insights into the design and deployment of compact wideband phased array antennas, providing an effective solution for monitoring HF interference.

A Low-Cost Wideband Digital Array Antenna Based on Stretch Processing Technique

Wideband digital phased array radar offers the advantages of high range resolution, which improves the recognition ability for multiple targets, group targets, and high-speed targets. Traditional wideband phased arrays use true time delay to compensate for aperture fill time; however, the cost increases significantly. In this paper, a wideband elemental digital array architecture based on the stretch processing method is proposed. By utilizing the time-domain and frequency-domain translation equivalence of the LFM (Linear Frequency Modulation) signal waveform, the equivalent aperture fill time is compensated for through frequency shift and phase shift after stretch processing. Compared to traditional wideband digital arrays, this method can dramatically reduce the required sampling rate and lower the requirements on antenna hardware, thereby reducing the manufacturing cost of system. A comprehensive analysis of the signal processing process and stretch processing method is provided. And an antenna array prototype is developed to verify the T/R channel compensation and wideband beamforming. Measured results show that the antenna is capable of ±60° scanning in azimuth plane and ±40° scanning in elevation plane, with a bandwidth of 500 MHz in S-band. The results demonstrate excellent wideband beam performance and accurate lobe scanning, which confirms the validity of the proposed wideband architecture for stretch processing, frequency shift, and phase shift. This method can be widely applied to the low-cost design and wideband performance improvement of wideband digital array radar.

Performance analysis of scanning gain for irregular ultra wideband phased array antennas based on subarrays

Performance analysis of scanning gain for irregular ultra wideband phased array antennas based on subarrays

Wideband and Wide Beam Scanning Dual-Polarized Phased Array Antenna-in-Package Design for 5G Applications

Wideband and Wide Beam Scanning Dual-Polarized Phased Array Antenna-in-Package Design for 5G Applications

Design of True Time Delay Line Based Octal Transmit Receive Module for Wideband Phased Arrays

Design of True Time Delay Line Based Octal Transmit Receive Module for Wideband Phased Arrays

Wideband phased array design using hairpin ring resonator (HRR) and DGS for double band-notched performance

In this paper, a wideband Vivaldi phased array with double band-notched performance for radio astronomy is proposed. To address the issues of radio frequency interference from 5 G mobile communication (4.8–5 GHz) and C-band satellite communication (5.9–6.5 GHz) in radio astronomy system, the hairpin ring resonator (HRR), defected ground structure and λ/2 shorted-circuit stub are utilized together to realize the double notched bands with different bandwidth. The resonate mechanism of the proposed HRR is widely investigated, which exhibits independent and controllable resonances. Meanwhile, λ/2 shorted-circuited stub is adopted for the band notched performance. As the current on the stub is induced along the shorted via to the ground, without participating in radiation, thus the notched frequency is not affected by the scan angle. With these novel and dedicated design, the proposed phased array performs double band-notched performance with high skirt selectivity and deep suppression, within the notched band the maximum rejection level is better than 22.7 dB. This is the first work to implement double notched bands in phased array to the authors’ best knowledge. Finally, a prototype composed of 8 × 9 elements is fabricated and measured. The measurements agree well with the simulated ones.

A Multioutput and Highly Efficient GaN Distributed Power Amplifier for Compact Subarrays in Wideband Phased Array Antennas

This article presents the design, implementation, and measurement results of a multioutput distributed power amplifier (MODPA) in 100-nm AlN–GaN–AlGaN high-electron-mobility transistor (HEMT) on a silicon substrate. The proposed MODPA improves power-added efficiency (PAE) in distributed amplifiers (DAs) by not wasting reverse traveling waves and delivering all forward and reverse waves to the output ports. Utilizing MODPA in implementing a subarray-based phased-array transceiver reduces the number of power splitters and PAs, significantly reducing the subarray’s chip area and power loss. A design methodology for broadband, efficient amplifier implementation by optimizing load/source impedances at the fundamental and harmonic frequencies is presented based on comprehensive source/load—pull simulations and class-J dynamic load lines. The presented broadband design methodology addresses an ambiguity for picking optimum load/source impedance at a single frequency caused by higher order harmonics of operating frequencies dropping in the band. The fabricated MODPA occupies 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> 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">$^{2}$</tex-math> </inline-formula> chip area. In 0.01–25-GHz frequency, MODPA delivered 37–41-dBm power to the four outputs, with a 17–21-dB total power gain and 22%–73% total PAE. The power gain and phase variation between the four matched-output ports are less than 1.5 dB and 3 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{\circ}$</tex-math> </inline-formula> , respectively, making MODPA an attractive design for implementing subarrays.

Analysis of tightly-coupled dipole phased array antennas with metasurface superstrate

Tightly coupled dipole arrays, including connected arrays, and capacitively coupled arrays, are one of the best solutions for wideband phased array antenna designs. However, to increase bandwidth and maximum scan angle, we can use a metasurface superstrate. We propose an analytical model to compute the scan impedance of a tightly coupled dipole array loaded with a metasurface. This analytical model helps us to simplify the calculation of the scan impedance of the array and speeds up the design process of these array antennas. It is shown that the metasurface superstrate improves the bandwidth and beam scanning angles of the array. Using the proposed general transmission line model, the computation of the scan impedance of tightly coupled dipole arrays is done very fast with minimum error. The semi-analytical model is about 7 times faster than a full-wave simulation.

Millimeter-Wave Wideband ±45° Dual-Polarized Phased Array Antenna Based on Compact Wideband Widebeam Dipole Element Antenna

To meet the requirements of a millimeter-wave (mmWave) communication system prototype complying with 5G (24.25-29.5GHz) and B5G/6G (30-33GHz) standards, this letter presents a compact wideband widebeam ±45° dual-polarized dipole element antenna to form a wideband phased array antenna (PAA) covering the entire 24-33GHz (∼31.6%) band. First, by placing two orthogonal coupling feeding baluns over a dual-polarized dipole to excite the dipole's two pairs of orthogonal arms and employing four parasitic patches, a ±45° dual-polarized dipole element antenna is developed, showing a compact size (0.34λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> ×0.34λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> @24GHz), wide -14-dB impedance bandwidth (24-33GHz, 31.6%), wide 3-dB beamwidth (>100°), high polarization isolation (>25dB), and high cross-polarization discrimination (XPD) (>25dB) within the -14-dB impedance bandwidth. Then, based on the element antenna, a 4×4-element ±45° dual-polarized PAA is designed, fabricated using the LTCC process, and measured. The measurements show that, within the entire 24-33GHz band, the broadside scanning gain of the PAA is up to 14dBi, and the 3-dB gain variation scanning range is >±41° with a peak up to ±60º.

Integrated contra-directionally coupled chirped Bragg grating waveguide with a linear group delay spectrum

Due to the advantages of low propagation loss, wide operation bandwidth, continuous delay tuning, fast tuning speed, and compact footprints, chirped Bragg grating waveguide has great application potential in wideband phased array beamforming systems. However, the disadvantage of large group delay error hinders their practical applications. The nonlinear group delay spectrum is one of the main factors causing large group delay errors. To solve this problem, waveguides with nonlinear gradient widths are adopted in this study to compensate for the nonlinear effect of the grating apodization on the mode effective index. As a result, a linear group delay spectrum is obtained in the experiment, and the group delay error is halved.Graphical

The Design of a Novel 2-42 GHz MEMS True-Time Delay Network for Wideband Phased Array Systems.

This article presents the design method of a compact MEMS switched-line true-time delay line (TTDL) network over a wide frequency range extending from 2 to 42 GHz using TTDL units. The TTDL units, namely the cascading radio frequency micro-electromechanical system (RF MEMS) switches and GCPW, were employed in the proposed TTDL network to improve the delay-bandwidth product (DBW) while maintaining its compact size and low delay variation (DV). For comparison, a theoretical analysis of the RF MEMS switch was performed while observing the switch performance with various top electrodes. The MEMS TTDL network has a compact size of 5 mm × 5 mm, with a maximum delay of 200 ps and a minimum of 30 ps. The maximum insertion loss of 9 states is 10 dB, and the in/out return loss is better than 20 dB across 2-42 GHz. The group delay variations are within ±2.5% for all the delay states over the operating frequency range. To the best of our knowledge, the proposed TTDL network obtains the most control bits among the TTDL networks offered to date.

MmWave Yagi-Uda Element and Array on Liquid Crystal Polymer for 5G

Arrays on personal terminals are feasible using mmWave frequencies, but are limited by mutual coupling. A standard specification for MIMO is −15 dB coupling which can be readily attained over a modest bandwidth, and decoupling modifications can reduce this to less than −20 dB. Such a change has relatively little impact on narrowband MIMO performance but is significant for wideband phased arrays, demonstrated here using simulation and measurement of a new design. For the element, we present a Yagi-Uda structure on PCB with a bandwidth from 22 to 44 GHz to cover a set of standard mmWave bands for 5G. Our prototype uses the RFIC packaging material Liquid Crystal Polymer which is suitable for Antenna-in-Package technology. For the array, the element spacing is set small enough to suppress grating lobes at the highest frequency. At the lowest frequencies, the lowest electrical spacing means the highest mutual coupling, and we apply a decoupling modification for this. The associated improvements in the impedance bandwidth, scan range, gain and radiation efficiency are presented for edge- and corner-mounted arrays designed for a mobile terminal such as a cellphone. Our array combining comprises simulation-based signal phasing and the simpler beam switching using element selection. The edge-mounted array has a 59% TARC bandwidth (24–44 GHz) over which the scan range is between ±60° and ±35°, the gain is 9.5 to 13 dBi with a radiation efficiency better than −0.2 dB. The corner-mounted switched array has peak gains of 6 to 9 dBi, showing the gain penalty associated with the simpler switched beam architecture. Finally, the impact of a cellphone chassis on the antenna performance is assessed by simulation.

Determination of Excitation Amplitude and Phase for Wide-Band Phased Array Antenna Based on Spherical Wave Expansion and Mode Filtering

A new method for solving the excitation amplitude and phase of wide-band phased array antenna is presented, in which spherical wave expansion and mode filtering (SWEMF) techniques are applied for the first time. Different from the previous methods that are required of matrix inversion or optimization iteration, the proposed SWEMF method is a forward calculation process. Thus, the solution is unique, and the result is closer to the true value. On the other hand, the SWEMF method only needs the total radiated field data of the array antenna in a small angular domain to ensure that the operation is simple and efficient. The effectiveness of the SWEMF method is successfully verified by examples of low sidelobe planar and linear arrays. The mean square error of the excitation amplitude can reach −38.88 dB. The range of excitation amplitude error is 0.05 v, and the excitation phase error is within 5.2°. This method takes about 60 s to calculate amplitude and phase at any one time. The feed amplitude and phase can be only calculated with the data in a small angular domain, and when the amount of data is small.

Radar Cross Section Reduction of Wideband Vivaldi Antenna Arrays With Array-Level Scattering Cancellation

Wideband phased antenna arrays always contribute large radar cross section (RCS) to low-observed platforms. Low-scattering wideband phased antenna arrays are thus highly demanded. This article proposes to reduce the RCS of wideband phased antenna arrays through array-level scattering cancellation. Two types of Vivaldi antenna elements that exhibit almost the same scanning performance and operating bandwidth are developed. However, the tapered curves are intentionally designed to be different to achieve a 180° reflection phase difference. With these two types of Vivaldi antenna elements, a low-scattering Vivaldi antenna array ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$16\times16$ </tex-math></inline-formula> ) is developed by array-level scattering cancellation. A reference Vivaldi antenna array with a single type of antenna element is also developed. Simulation and measurement results of the reference and the proposed antenna array are compared to illustrate the effectiveness of the proposed RCS reduction technique. Both antenna arrays operate over the 8–12 GHz frequency band and scan up to ±60° in the E-/H-planes. However, the proposed Vivaldi antenna array achieves an average of 10 dB monostatic RCS reduction over 6–18 GHz. It indicates that the array-level scattering cancellation technique is promising for developing low-scattering wideband phased antenna arrays.

Design of a wideband planar printed pattern‐reconfigurable antenna and its application in wideband phased linear array

In this article, a wideband planar printed pattern-reconfigurable antenna built on rotating dipole radiation arms is proposed. Eight PIN diodes and three DC controlling voltages are utilized to switch three working states for generating multi-beam. Two parasitic grounding strips are employed to widen impedance bandwidth and enhance pattern offset directivity. By optimizing rotation angles of the radiation rams, desired wideband characteristics are achieved. Measured results show that the 10-dB impedance operation bandwidth for all modes is 44.5% from 2.05 to 3.23 GHz within a compact size of 0.34 λ × 0.35 λ × 0.007 λ, where λ is the vacuum wavelength at the low frequency. A typical application in phased linear array based on the proposed antenna is investigated and discussed, which shows that it can work in a wide operation band, and the scanning angle in E-plane is more than ±80°.

InFocus: A Spatial Coding Technique to Mitigate Misfocus in Near-Field LoS Beamforming

Phased arrays, commonly used in IEEE 802.11ad and 5G radios, are capable of focusing radio frequency signals in a specific direction or a spatial region. Beamforming achieves such directional or spatial concentration of signals and enables phased array-based radios to achieve high data rates. Designing beams for millimeter wave and terahertz communication using massive phased arrays, however, is challenging due to hardware constraints and the wide bandwidth in these systems. For example, beams which are optimal at the center frequency may perform poor in wideband communication systems where the radio frequencies differ substantially from the center frequency. The poor performance in such systems is due to differences in the optimal beamformers corresponding to distinct radio frequencies within the wide bandwidth. Such a mismatch leads to a misfocus effect in near-field systems and the beam squint effect in far-field systems. In this paper, we investigate the misfocus effect and propose InFocus, a low complexity technique to construct beams that are well suited for massive wideband phased arrays. The beams are constructed using a carefully designed frequency modulated waveform in the spatial dimension. InFocus mitigates beam misfocus and beam squint when applied to near-field and far-field systems.

Low-profile wideband phased array antenna radiator with wide-angle beam scanning

Low-profile wideband phased array antenna radiator with wide-angle beam scanning

Highly non‐linear and wide‐band mmWave active array OTA linearisation using neural network

This paper proposes a neural network (NN)-based over-the-air (OTA) linearisation technique for a highly non-linear and wide-band mmWave active phased array (APA) transmitter and compares it with the conventional memory polynomial model (MPM)-based technique. The proposed NN effectively learns the distinctive non-linear distortions, which may not easily fit to existing MPM solutions, and can, therefore, successfully cope with the challenges introduced by the high non-linearity and wide bandwidth. The proposed technique has been evaluated using a state-of-the-art 4 × 4 APA operating in highly non-linear regions at 28 GHz with a 100-MHz-wide 3GPP base-station signal as input. Experimental results show the pre-distortion signal generated by the NN exhibits the peak-to-average power ratio (PAPR) much lower than the one generated by MPM and consequently superior linearisation performance in terms of adjacent channel leakage ratio (ACLR) and error vector magnitude (EVM) for high non-linearity cases. Using the proposed NN-based linearisation technique, an improvement of 5-dB ACLR and 7% points in EVM are achieved, which demonstrates the promising potential of this technique for emerging broadband communication systems such as 5G/6G and low Earth orbit (LEO) satellite networks.

Fully integrated wideband phased array with large scan range and 5:1 bandwidth

In this work, a fully integrated phased array using multi-layer printed circuit board (PCB) fabrication technologies is presented. This array is directly fed by 50 Ω coaxial cables, without balanced-to-unbalanced transitions. An asymmetric dipole is used to achieve stable input impedance. Furthermore, to broaden the operating bandwidth, a coupling patch is designed beneath the asymmetric dipole , which also eliminates the common-mode resonance and decreases the array profile. In addition, three wide-angle impedance matching (WAIM) layers with different structures are utilised to improve the scan range in all scanning planes. Infinite array simulations indicate that the proposed array can operate over a 5.1:1 bandwidth (2.4 ∼ 12.2 GHz) with an active voltage standing wave ratio below 3 while scanning up to ± 60° in H plane and ±75° in the E plane. Furthermore, the proposed antenna, whose cross-polarization levels remain below −35 and −7.5 dB when scanning up to 75° in the E plane and 60° in the D plane, demonstrates the merits of high polarization purity. Array simulations are verified by the measurements of a 12 × 12 prototype, and good agreement is observed.