Bandwidth Improvement Research Articles

Dual-band polarization-controlled metasurface with independent amplitude-phase coding for versatile beam forming.

Digital coding metasurfaces have gained considerable attention for their potential to bridge physical and information sciences. However, existing metasurfaces are often restricted to either phase-only or amplitude-only control and typically operate within a single frequency band or polarization, limiting their functionality in advanced electromagnetic applications. This study proposes a dual-band metasurface with independent amplitude-phase coding for polarization-controlled beam manipulation, addressing these limitations. The designed metasurface features a three-layer structure that integrates resistive films and optimized geometries, allowing simultaneous and independent control of amplitude and phase for linearly polarized (LP) waves in the X-band and circularly polarized (CP) waves in the Ku-band. Through digital coding, it achieves simultaneous 1-bit control over amplitude and phase, facilitating flexible beam steering and complex wavefront manipulation across distinct polarizations and frequencies. A functional prototype was designed, simulated, fabricated, and experimentally tested. The results show close alignment between simulations and experimental measurements, confirming the metasurface's versatile modulation capabilities. This advancement provides a robust platform for applications in wireless communication, radar systems, and adaptive electromagnetic wave engineering, offering significant improvements in design flexibility and operational bandwidth.

Bandwidth Improvement for Patch Antenna via Knowledge-Based Deep Reinforcement Learning

Bandwidth Improvement for Patch Antenna via Knowledge-Based Deep Reinforcement Learning

Design and analysis of a fabricated modified elliptical patch antenna with slots and partial ground plane techniques for UWB applications

This study presents a novel elliptical microstrip antenna (EMSA) design method for enhanced bandwidth. The proposed EMSA offers versatile polarization control, generating both linear and circular polarization. Wider impedance bandwidths compared to some other patch antennas make it suitable for broadband communication. Its compact size facilitates integration into space-constrained devices. Additionally, it provides polarization diversity for MIMO systems, reducing signal fading. The fabricated EMSA, operating at 7.05 GHz, achieves a simulated bandwidth of 5.7% and a measured bandwidth of 4.28%. It exhibits a return loss of -42 dB, 50 Ω impedance matching, 8.57 dB radiation gain, and a VSWR of 1.016. Two bandwidth enhancement techniques were investigated: reducing the ground plane size and incorporating slots within the patch. The partial ground plane achieved simulated and measured bandwidth improvements of 146% and 167%, respectively. The slotted patch yielded 160% and 180% improvements, respectively.

The Causal Nexus Between Different Feed Networks and Defected Ground Structures in Multi-Port MIMO Antennas.

Multiple input multiple output (MIMO) antennas have recently received attention for improving wireless communication data rates in rich scattering environments. Despite this, the challenge of isolation persists prominently in compact MIMO-based electronics. Various techniques have recently emerged to address the isolation issues, among which the defected ground structure (DGS) stands out as a cost-effective solution. Additionally, selecting the appropriate feed mechanism is crucial for enhancing the key performance indicators of MIMO antennas. However, there has been minimal focus on how different feed methods impact the operation of MIMO antennas integrated with DGS. This paper begins with a comprehensive review of diverse antenna design, feeding strategies, and DGS architectures. Subsequently, the causal relationships between various feed networks and DGSs has been established through modeling, simulation, fabrication, and measurement of MIMO antennas operating within the sub-6 GHz spectrum. Particularly, dual elements of MIMO antennas grounded by a slotted complementary split ring resonator (SCSRR)-based DGS were excited using four standard feed methods: coaxial probe, microstrip line, proximity coupled, and aperture coupled feed. The influence of each feed network on the performance of MIMO antennas integrated with SCSRR-based DGSs has been thoroughly investigated and compared, leading to guidelines for feed network selection. The coaxial probe feed network provided improved isolation performance, ranging from 16.5 dB to 46 dB in experiments.The aperture and proximity-coupled feed network provided improvements in bandwidth of 38.7% and 15.6%, respectively. Furthermore, reasonable values for envelope correlation coefficient (ECC), diversity gain (DG), channel capacity loss (CCL), and mean effective gain (MEG) have been ascertained.

Optimized Graph Sample and Aggregate‐Attention Network‐Based High Gain Meta Surface Antenna Design for IoT Application

ABSTRACTThis paper presents a High Gain Metasurface (HGM) antenna design optimized for IoT applications. The antenna operates at a 5.8 GHz frequency and utilizes a quarter‐wavelength unit cell structure. The design employs a Graph Sample and Aggregate‐Attention Network (GSAAN) to enhance the transmission characteristics of the metasurface. To optimize the performance of GSAAN, the Giza Pyramids Construction Algorithm (GPCN) is applied to adjust the weight parameters, leading to significant improvements in radiation efficiency, bandwidth, gain, directivity, and return loss. The proposed HGM antenna is simulated in MATLAB 2023b, where it demonstrates substantial performance gains over existing methods. Specifically, the proposed design achieves 28.34% higher gain compared to the MSA‐RHCOA method, 24.47% improvement over HGM‐AD‐MATCS, 26.34% better gain than BR‐HGA‐PGM, and a 32.12% gain increase relative to MSA‐Hyb‐ADSA‐HMSOA. These enhancements make the proposed antenna design a competitive solution for high‐gain applications in wireless communication, satellite communication, and radar systems. The integration of GSAAN with GPCN optimization in the HGM antenna design enables the creation of highly directive radiation patterns, making it well‐suited for IoT applications that require high performance and reliability. The results of this study demonstrate the effectiveness of the proposed approach in achieving superior antenna performance, positioning it as a strong alternative to existing metasurface antenna designs.

Cryogenic optical-to-microwave conversion using Si photonic integrated circuit Ge photodiodes

Integrated circuit technology enables the scaling of circuit complexity and functionality while maintaining manufacturability and reliability. Integration is expected to play an important role in quantum information technologies, including in the highly demanding task of producing the classical signals to control and measure quantum circuits at scales needed for fault-tolerant quantum computation. Here, we experimentally characterize the cryogenic performance of a miniaturized photonic integrated circuit fabricated by a commercial foundry that downconverts classical optical signals into microwave signals. The circuit consists of waveguide-integrated germanium PIN photodiodes packaged using a scalable photonic wire bonding approach to a multi-channel optical fiber array that provides the optical excitation. We find the peak optical-to-microwave conversion response to be ∼150 ± 13 mA/W in the O-band at 4.2 K, well below the temperature the circuit was designed for and tested at in the past, for two different diode designs. The second diode design operates to over 6 GHz of 3 dB bandwidth, making it suitable for controlling quantum circuits, with improvements in bandwidth and response expected from improved packaging. The demonstrated miniaturization and integration offers new perspectives for wavelength-division multiplexed control of microwave quantum circuits and scalable processors using light delivered by optical fiber arrays.

Integrated Pockels Modulators on Silicon Photonics Platform

AbstractElectro‐optic (EO) modulators are essential components in various fields, including optical communication, free‐space communication, microwave photonics, sensing, and light detection and ranging. The EO modulation enables the fast conversion of electric signals into optical signals, facilitating the precise manipulation of light. With advancements in fabrication processing techniques, next‐generation integrated EO modulators have demonstrated substantial improvements in modulation efficiency, bandwidth, and footprint. Here, the latest research progress in integrated EO modulation, focusing on the principle of the Pockels effect, key modulation metrics, novel EO thin‐film material platforms, and innovative device architectures is overviewed. Finally, it is evaluated different schemes and provide perspectives on future trends in developing integrated EO modulators, highlighting both the advantages and challenges of integrated EO modulation, including waveguide and electrode engineering, integrated methods, and other applications for large‐scale photonic integrated circuits.

Modulation transfer protocol for Rydberg RF receivers

We propose and demonstrate a modulation transfer protocol to increase the detection sensitivity of a Rydberg RF receiver to fields out of resonance from the transition between Rydberg levels. This protocol is based on a phase modulation of the control field used to create the Electromagnetically Induced Transparency signal. The nonlinear wave mixing of the multi-component coupling laser and the probe laser transfers the modulation to the probe laser, which is used for the RF-field detection. The measurements compare well with semi-classical simulations of atom–light interaction and show an improvement in the RF bandwidth of the sensor and an improved sensitivity of the response to weak fields.

SSA-over-array (SSoA): A stacked DRAM architecture for near-memory computing

Aiming to enhance the bandwidth in near-memory computing, this paper proposes a SSA-over-array (SSoA) architecture. By relocating the secondary sense amplifier (SSA) from dynamic random access memory (DRAM) to the logic die and repositioning the DRAM-to-logic stacking interface closer to the DRAM core, the SSoA overcomes the layout and area limitations of SSA and master DQ (MDQ), leading to improvements in DRAM data-width density and frequency, significantly enhancing bandwidth density. The quantitative evaluation results show a 70.18 times improvement in bandwidth per unit area over the baseline, with a maximum bandwidth of 168.296 Tbps/Gb. We believe the SSoA is poised to redefine near-memory computing development strategies.

Joint probabilistic modeling approach for harmonic and three-phase unbalanced disturbance sources

Harmonics and three-phase imbalance are two common disturbances in power systems that interact with and affect each other, leading to more complex impacts on power system performance. To comprehensively and accurately analyze the distribution and interaction mechanisms of harmonics and three-phase imbalance, this study investigated the joint emission level of harmonic and three-phase unbalanced disturbance sources (H-TU-DS). This paper proposes a joint probabilistic emission level modeling approach. The power, harmonic, and three-phase unbalanced data of H-TU-DS are multidimensional, and the feature dataset is filtered by calculating multiple correlation coefficients to achieve dimensionality reduction without losing data information. Considering the different operating characteristics of the H-TU-DS, an improved fuzzy C-means (FCM) algorithm is applied to classify operating conditions, enabling a comprehensive and accurate analysis of the joint emission level. Based on the nonparametric kernel density function, joint probability modeling of H-TU-DS is performed using an adaptive bandwidth improvement method, effectively enhancing the accuracy of the modeling process. Finally, the effectiveness and accuracy of the proposed methods for feature dataset filtering, operating condition classification, and joint probability modeling are demonstrated through comparisons with both simulated and actual data. The proposed model facilitates the prediction and assessment of the impact of H-TU-DS on power quality after grid connection, enabling the effective prevention of power-quality problems through advanced treatment.

Broadband low radar cross section frequency selective surface radome based on phase cancellation and spatial filtering

AbstractThis letter introduces a novel design approach for broadband radar cross section (RCS) reduction of frequency selective surface (FSS) radomes. The approach integrates the principles of phase cancellation and spatial filtering together through a hybrid design method. The phase cancellation is obtained through the checkerboard arrangement of units, and the spatial filtering characteristics is achieved by the slot etched on the ground plane. Experimental and simulation results demonstrate that etching slots on the ground plane maintains broadband in‐phase reflection and bandpass characteristics, thereby extending the bandwidth of RCS reduction through a combination of two operation bands. Theoretical analysis of the working mechanism is also provided using equivalent circuit models. In comparison to the conventional radomes, the proposed FSS radome achieves significant bandwidth improvement for RCS reduction, indicating that it has promising prospects in future low‐RCS radome applications.

PHOTONIC INTEGRATED CIRCUITS: GIANT LEAP IN COMPUTING TECHNOLOGY

There is a continued demand for increase in computing requirements from sensor, smartphones, to servers. However, the technology improvements in clock speed, power, and memory bandwidth from traditional electronic integrated circuits (EIC) has started to saturate. This has triggered further research in exploration of photon integrated circuits (PIC) that utilize photons (or particles of light) as opposed to electrons to form a functioning circuit. Research suggests that by integrating the benefits of EIC and PIC, one is able to harness the best of both worlds. The inherent advantages of photonics technology such as speed, energy-efficiency, and density, coupled with the advances in material technology, make them suitable to address the challenge of designing heterogeneous chips. This paper presents the fundamentals of the photonic technology, applicability to solving digital computing problems, ability to integrate into PICs, and its capability to complement electronic integrated circuits for powering the computing demands of emerging applications.

Bandwidth and Gain Improvement of a Circularly Polarized Slot Antenna Using Nonuniform Metasurface

This paper presents a novel design of a circularly polarized antenna based on a nonuniform metasurface (NMS). The original antenna comprises a uniform metasurface (UMS) layer and a slot antenna below. In order to achieve circularly polarized (CP) radiation, an oblique slot is etched on the center patch, and the size ratio between the center patch and the surrounding patches is adjusted to create the NMS. To further enhance the CP properties, an improved NMS (INMS) is proposed, consisting of four units with corners removed, building upon the original NMS design. Simulation results demonstrate that the proposed antenna design offers an S11 bandwidth ranging from 4.39 to 7.21 GHz, with a 3 dB axial ratio (AR) bandwidth spanning from 5.43 GHz to 6.76 GHz. Compared to the original UMS-based antenna, the INMS design shows an average gain increase of 1.21 dB, with a peak gain of 9.49 dBic. Furthermore, utilizing characteristic mode analysis (CMA), this paper explores the modal behaviors when applying the NMS to the antenna. The results indicate that this configuration excites two orthogonal modes, leading to CP radiation and the emergence of an additional AR minimum point. These factors contribute to the broader bandwidth observed in the proposed antenna design. The outstanding radiation performance of the proposed antenna design makes it suitable for various applications, including military and civilian communication, as well as point-to-point links.

Investigating the impact of graphene patch width on performance and bandwidth enhancement in nano-patch antennas

This study investigates how varying the width of a graphene patch affects the performance and bandwidth of a nano-patch antenna. High-Frequency Structural Simulator (HFSS) software was employed for simulation, evaluating parameters such as voltage standing wave ratio (VSWR), gain, and return loss. The graphene patch of 0.690nm thick was placed on a silicon dioxide substrate with a thickness of 10 µm, while the patch width was systematically varied at 30 µm, 32 µm, 34 µm, 38 µm, and 42 µm. Surprisingly, the resonating frequency remained unaffected by changes in patch width. The results revealed that the patch widths of 32 µm, 34 µm, and 38 µm produced the highest return losses of -24.5482, -24.4774, and -24.4001, respectively. Additionally, these configurations exhibited impeccable VSWR values of 1.0302, 1.0387, and 1.0480. Notably, a substantial bandwidth improvement exceeding 500 GHz was achieved for these patch widths. This finding underscores the significant relationship between gain, directivity, and patch width in graphene nano-patch antennas. Furthermore, both 32 µm and 34 µm patch widths demonstrated gain and directivity exceeding 7 dB.

Investigation and analysis of design techniques for ultra-wideband CMOS on-chip dipole antennas for 6G sub-THz applications

This article explores different techniques to improve the impedance bandwidth of on-chip dipole antennas in the sub-THz frequency range. Increasing the area of the dipole antenna has shown considerable improvement in bandwidth. However, this violates the design rule checks (DRC) of the foundry. Various topologies, such as squared-slotted dipole, meandered-slotted dipole, and straight-slotted dipole antennas, are introduced and implemented to increase the width of the on-chip antennas and thus the impedance bandwidth while meeting the DRC rules. All three topologies show better performance in terms of providing improved bandwidth. The straight-slotted technique is adopted as it offers less complexity and flexibility. The behavior of the impedances for different widths implemented by the straight-slotted topology has been analyzed in detail. A 6-strip straight-slotted dipole antenna results in an ultra-wide impedance bandwidth ranging from 76–262 GHz with a fractional bandwidth of 110% and a gain of −0.6 dBi at 159 GHz, while occupying a small silicon area of 567μm×112μm. To the best of the authors’ knowledge, this is the highest fractional bandwidth that is reported to date at these frequencies.

Efficient strategy for frequency design and bandwidth extension of curved piezoelectric ultrasonic micromachined transducers

Abstract This article proposes an efficient analytical model and strategy for designing curved piezoelectric micromachined ultrasonic transducers (curved PMUTs). The model is developed based on the Donnell-Mushtari-Vlasov (DMV) theory and the Equivalent Single Layer (ESL) method, and validated through Finite Element Analysis (FEA). Utilizing the model, we further analyze the diaphragm’s vibration modes and key design parameters. The proposed strategy is centered on 2 design equations, facilitating the rapid design of devices at any frequency through parametric sweeps. Furthermore, to minimize bandwidth loss, we employ the merging of adjacent vibration modes to broaden the bandwidth. Using the proposed method for modes merging, we have effortlessly designed devices with operating frequencies of 2.15 MHz, 6.3 MHz, 10.65 MHz, and 18.75 MHz in water. For comparison, we also designed planar PMUTs and general curved PMUTs operating around 6 MHz and 15 MHz. Compared to planar PMUTs, curved PMUTs show exceptional performance improvements in output pressure and sensitivity. Moreover, the proposed strategy for bandwidth extension results in 1.33× and 1.25× bandwidth improvements around 6 MHz and 15 MHz. The proposed design methodology is anticipated to assist engineers in designing high-performance PMUT arrays more efficiently and systematically.

Low-loss silica waveguide 1×8 thermo-optic switch based on large-scale multimode interference couplers

Optical switches play key role in signal crossing and interconnection. Low-loss and compact optical switches are highly demanded in on-chip optical routing. A silica waveguide 1 × 8 thermo-optic switch based on cascaded 1 × 8 multimode interference (MMI) and 8 × 8 MMI couplers is experimentally demonstrated. Beam propagation method is adopted in the theoretical design and optimization. Standard CMOS technology fabrication is used in switch preparation. Air trenches are introduced to enhance the thermal modulation. At wavelength 1550 nm, the measured insertion loss and crosstalk of this 1 × 8 switch is less than 3.69 dB and −16.29 dB, respectively. And the extinction ratio is larger than 16.68 dB for all routing states. The rise time and fall time are 1.0 ms and 1.24 ms respectively. Compared with the 8-channel switch based on cascaded stages structure, the size reduces by 30 %. With future bandwidth improvement, this demonstrated switch has good potentials in the application of all-optical network routing.

A low profile high gain concave conformal ring cylindrical dielectric resonator antenna loaded with split ring resonator for ISM and C band applications

SummaryA low profile, concave conformal ring cylindrical dielectric resonator antenna (CDRA) employing frequency selective surface (FSS) using split ring resonator (SRR) for wideband and high gain applications is presented. The ring CDRA loaded with the monopole is designed to excite the TM01δ mode to increase the antenna's bandwidth. The effect of a curved ground plane (GP) on the radiation performance of CDRA is studied. A 5 × 5 array of the SRR is placed above the conformal GP at a far‐field distance optimized to (2n ± 1) λ/4 from the radiating element to enhance the gain of the proposed structure. The planar CDRA with FSS is compared with the conformal CDRA with FSS and a 4.3 GHz improvement in bandwidth is observed due to the multiple reflection and surface reflection leading to a 3.2 dBi improvement in gain. An impedance bandwidth of 51.8% (5 to 8.5 GHz) with a maximum gain of 8.7 dBi at 7.3 GHz resonant frequency and 99% radiation efficiency at 5.9 GHz is offered by the proposed antenna with FSS. Additionally, the proposed CDRA has a low profile of 0.12 λ0 where λ0 is the lower cut‐off frequency's wavelength. A good agreement is observed between the simulated and measured results.

PRAC: Round-Efficient 3-Party MPC for Dynamic Data Structures

We present Private Random Access Computations (PRAC), a 3-party Secure Multi-Party Computation (MPC) framework to support random-access data structure algorithms for MPC with efficient communication in terms of rounds and bandwidth. PRAC extends the state-of-the-art DORAM Duoram with a new implementation, more flexibility in how the DORAM memory is shared, and support for Incremental and Wide DPFs. We then use these DPF extensions to achieve algorithmic improvements in three novel oblivious data structure protocols for MPC. PRAC exploits the observation that a secure protocol for an algorithm can gain efficiency if the protocol explicitly reveals information leaked by the algorithm inherently. We first present an optimized binary search protocol that reduces the bandwidth from O(lg² n) to O(lg n) for obliviously searching over n items. We then present an oblivious heap protocol with rounds reduced from O(lg n) to O(lg lg n) for insertions, and bandwidth reduced from O(lg² n) to O(lg n) for extractions. Finally, we also present the first oblivious AVL tree protocol for MPC where no party learns the data or the structure of the AVL tree, and can support arbitrary insertions and deletions with O(lg n) rounds and bandwidth. We experimentally evaluate our protocols with realistic network settings for a wide range of memory sizes to demonstrate their efficiency. For instance, we observe our binary search protocol provides >27× and >3× improvements in wall-clock time and bandwidth respectively over other approaches for a memory with 2^26 items; for the same setting our heap's extract-min protocol achieves >31× speedup in wall-clock time and >13× reduction in bandwidth.

Effective bandwidth improvement of Travelling-Wave waveguide array antennas using double Parallel-Slot radiating elements

The effective bandwidth of a travelling-wave slotted waveguide array antenna is improved by using a proposed broadband single radiating element based on a pair of longitudinal slots CNC-machined in the broad wall of the waveguide. The TE10 mode excites two resonances generated by each slot, providing an effective bandwidth improvement. As a proof of concept, an array antenna formed by 16 double longitudinal parallel-slot elements is designed. A prototype has been manufactured in printed technology in order to experimentally validate the antenna performance. Measurements show high stability of efficiency, maximum gain and radiation patterns in a broadband higher than 20% in the K-band.