arXiv subjects

Negin Shariati

Publications and source records attributed to Negin Shariati.

At least 19 recordsLinked to original sources

arXiv2025

Soil Salinity Frequency-Dependent Prediction Model Using Electrical Conductivity Spectroscopy Measurement

Soil salinity is a critical factor influencing agricultural productivity and environmental sustainability, requiring precise monitoring tools. This paper focuses on developing a frequency-dependent model to predict soil salinity based on electrical conductivity (EC) and volumetric water content (VWC). A dataset of 40 soil samples with varying levels of salinity and moisture, consisting of two soil types (sandy and clayey), was experimentally measured for EC in the frequency range of 10 to 295 MHz using electrical conductivity spectroscopy (ECS) measurement with the DAK-VNA (Dielectric Assessment Kit - Vector Network Analyzer) system. A new, more comprehensive frequency-dependent model is proposed, surpassing previous models that lacked frequency considerations. This modelling approach was conducted in stages: initially, a frequency-independent model for electrical conductivity as a function of salinity and moisture was developed. Next, a frequency-dependent model was introduced. Finally, a comparison between pure sandy soil and a sandy-clay mixture led to the final model, which also incorporates effective porosity. The results of the proposed model, comparing measured and predicted values, provide a robust approach to accurately predict soil salinity. Findings demonstrate that the model can enhance salinity prediction accuracy, extending its applicability beyond agriculture to geological and hydrological applications in real-world scenarios.

hep-ex↗

arXiv2024

A Data-Driven Review of Remote Sensing-Based Data Fusion in Precision Agriculture from Foundational to Transformer-Based Techniques

This review explores recent advancements in data fusion techniques and Transformer-based remote sensing applications in precision agriculture. Using a systematic, data-driven approach, we analyze research trends from 1994 to 2024, identifying key developments in data fusion, remote sensing, and AI-driven agricultural monitoring. While traditional machine learning and deep learning approaches have demonstrated effectiveness in agricultural decision-making, challenges such as limited scalability, suboptimal feature extraction, and reliance on extensive labeled data persist. This study examines the comparative advantages of Transformer-based fusion methods, particularly their ability to model spatiotemporal dependencies and integrate heterogeneous datasets for applications in soil analysis, crop classification, yield prediction, and disease detection. A comparative analysis of multimodal data fusion approaches is conducted, evaluating data types, fusion techniques, and remote sensing platforms. We demonstrate how Transformers outperform conventional models by enhancing prediction accuracy, mitigating feature redundancy, and optimizing large-scale data integration. Furthermore, we propose a structured roadmap for implementing data fusion in agricultural remote sensing, outlining best practices for ground-truth data selection, platform integration, and fusion model design. By addressing key research gaps and providing a strategic framework, this review offers valuable insights for advancing precision agriculture through AI-driven data fusion techniques.

cs.LG↗

arXiv2024

Efficient Dual-Band Single-Port Rectifier for RF Energy Harvesting at FM and GSM Bands

This paper presents an efficient dual-band rectifier for radiofrequency energy harvesting (RFEH) applications at FM and GSM bands. The single-port rectifier circuit, which comprises a 3-port network, optimized T-matching circuits and voltage doubler, is designed, simulated and fabricated to obtain a high RF-to-DC power conversion efficiency (PCE). Measurement results show PCE of 26% and 22% at -20 dBm, and also 58% and 51% at -10 dBm with a maximum amount of 69% and 65% at -2.5 dBm and -5 dBm, with single tone at 95 and 925 MHz, respectively. Besides, the fractional bandwidth of 21% at FM and 11% at GSM band is achieved. The measurement and simulation results are in good agreement. Consequently, the proposed rectifier can be a potential candidate for ambient RF energy harvesting and wireless power transfer (WPT). It should be noted that a 3-port network as a duplexer is designed to be integrated with single-port antennas which cover both FM and GSM bands as a low-cost solution. Moreover, based on simulation results, PCE has small variations when the load resistor varies from 10 to 18 k$\Omega$. Therefore, this rectifier can be utilized for any desired resistance within the range, such as sensors and IoT devices.

eess.SY↗

arXiv2024

Internet of Things Networks: Enabling Simultaneous Wireless Information and Power Transfer

The number of sensors deployed in the world is expected to explode in the near future. At this moment, nearly 30 billion Internet of Things (IoT) devices are connected and this number is expected to double in the next four years. While not all of these are battery powered, as technology becomes smaller and mobility becomes more important to consumers, soon a larger portion will be. This forecast predicts that the number of machine to machine (M2M) devices will have the largest increase, representing nearly 50% of all devices in 2023.

eess.SY↗

arXiv2024

Highly Sensitive Differential Microwave Sensor Using Enhanced Spiral Resonators for Precision Permittivity Measurement

This paper presents a highly sensitive microwave sensor for dielectric sensing. One of the main disadvantages of microwave resonant-based sensors is cross-sensitivity originated by time-dependent uncontrolled environmental factors such as temperature that affect the material under test (MUT) behavior, leading to undesirable frequency shifts and, hence, lower accuracy. However, this work eliminates the unwanted errors using the differential measurement technique by comparing two transmission resonance frequencies during a unit test setup to measure the permittivity of MUT over time. The proposed structure comprises a spiral resonator with an extended horizontal microstrip line (EH-ML) coupled to a microstrip transmission line (MTL). Creating EH-ML within the structure comprises two primary contributions: enhanced sensitivity resulting from stronger fringing fields generated by increasing the effective area and improved resolution due to higher resonance frequencies caused by a lower total capacitive coupling effect. The proposed sensor is fabricated and tested using MUTs with a permittivity of less than 80 to verify the performance. In this regard, a frequency detection resolution (FDR) of 44MHz and a sensitivity of 0.85% are achieved at a maximum permittivity of 78.3. The results of theoretical analysis, simulation, and measurement are in relatively good agreement. Consequently, the proposed highly sensitive microwave sensor offers significant advantages, such as low complexity in design and fabrication. It also offers high resolution and precision in a wide range of permittivity, which can be an attractive candidate for dielectric sensing in health, chemical and agriculture applications.

eess.SP↗

arXiv2024

Software-defined Programmable Metamaterial Lens System for Dynamic Wireless Power Transfer Applications

A software-defined 2-bit Programmable Transmit Metamaterial (PTM) array surface with beam steering capabilities is proposed for indoor dynamic Wireless Power Transfer (DWPT) applications. The novel metamaterial unit cell structure is designed based on transmission phase, amplitude, and electric field response to model DWPT using PTM. Theoretical analysis of the electric field (e-field), coupling effect, and current distribution at the metamaterial interface enhances the intelligence and reconfigurability of the PTM lens. The modeled 2-bit 6x6 array PTM is designed to operate at a frequency of 4 GHz. The reconfigurable architecture comprises a fixed system with a single-layer PTM lens capable of 60{\deg} beam scanning. The PTM lens, along with a distribution board, is fabricated and experimentally tested. The results between simulation and measurements are in good agreement. The system enables dynamic optimisation of the beam pattern to track the positions of mobile users with minimal software-hardware complexity. This novel work presents a low-cost experiment achieving an average 90.7% beamforming accuracy throughout the analytical and measurement processes of DWPT for movable users, utilizing a programmable transmit metamaterial array.

eess.SP↗

arXiv2024

Compact Multi-Service Antenna for Sensing and Communication Using Reconfigurable Complementary Spiral Resonator

In this paper, a compact multi-service antenna (MSA) is presented for sensing and communication using a reconfigurable complementary spiral resonator. A three turns complementary spiral resonator (3-CSR) is inserted in the ground plane of a modified patch antenna to create a miniaturized structure. Two Positive-Intrinsic-Negative (PIN) diodes (D1, D2) are also integrated with the 3-CSR to achieve frequency reconfiguration. The proposed structure operates in three different modes i.e., dual-band joint communication and sensing antenna (JCASA), dual-band antenna, and single-band antenna. The required mode can be selected by changing the state of the PIN diodes. In mode-1, the first band (0.95-0.97 GHz) of the antenna is dedicated to sensing by using frequency domain reflectometry (FDR), while the second band (1.53-1.56 GHz) is allocated to communication. The sensing ability of the proposed structure is utilized to measure soil moisture using FDR. Based on the frequency shift, permittivity of the soil is observed to measure soil moisture. In mode-2 and mode-3, the structure operates as a standard dual and single band antenna, respectively, with a maximum gain of 1.5 dBi at 1.55 GHz. The proposed planar structure, with its simple geometry and a high sensitivity of 1.7%, is a suitable candidate for precision farming. The proposed structure is versatile and capable of being utilized as a single or dual-band antenna and also measuring permittivity of materials within the range of 1-20. Hence, it is adaptable to a range of applications.

eess.SY↗

arXiv2024

Compact Pixelated Microstrip Forward Broadside Coupler Using Binary Particle Swarm Optimization

In this paper, a compact microstrip forward broadside coupler (MFBC) with high coupling level is proposed in the frequency band of 3.5-3.8 GHz. The coupler is composed of two parallel pixelated transmission lines. To validate the designstrategy, the proposed MFBC is fabricated and measured. The measured results demonstrate a forward coupler with 3 dB coupling, and a compact size of 0.12 {\lambda}g x 0.10{\lambda}g. Binary Particle Swarm Optimization (BPSO) design methodology and flexibility of pixelation enable us to optimize the proposed MFBC with desired coupling level and operating frequency within a fixed dimension. Also, low sensitivity to misalignment between two coupled TLs makes the proposed coupler a good candidate for near-field Wireless Power Transfer (WPT) application and sensors.

eess.SY↗

arXiv2024

Multitone PSK Modulation Design for Simultaneous Wireless Information and Power Transfer

Far-field wireless power transfer, based on radio frequency (RF) waves, came into the picture to fulfill the power need of large Internet of Things (IoT) networks, the backbone of the 5G and beyond era. However, RF communication signals carry both information as well as energy. Therefore, recently, simultaneous wireless information and power transfer (SWIPT) has attracted much attention in order to wirelessly charge these IoT devices. In this paper, we propose a novel N -tone multitone phase shift keying (PSK) modulation scheme, taking advantage of the non-linearity of integrated receiver rectifier architecture. The main advantage of the proposed modulation scheme is the reduction in ripple voltage, introduced by the symbol transmission through phases. Achievable power conversion efficiency (PCE) and bit error rate (BER) at the output are considered to measure the efficacy of the proposed modulation scheme. Simulation results are verified by the measurements over the designed rectifier circuitry. The effect of symbol phase range, modulation order, and the number of tones are analyzed. In the future, this transmission scheme can be utilized to satisfy the data and power requirements of low-power Internet of Things sensor networks.

eess.SY↗

arXiv2024

Miniaturized Patch Rectenna Using 3-Turn Complementary Spiral Resonator for Wireless Power Transfer

A miniaturized linearly-polarized patch antenna is presented for Wireless Power Transfer (WPT) at 1. 8 GHz. The proposed antenna consists of a patch element and a 3-turn Complementary Spiral Resonator (3-CSR) with antenna dimension of 50 mm x 50 mm. 3-CSR is inserted in the ground plane to reduce the antenna size. This modification also increased the impedance bandwidth from 43 MHz (1.78-1.83 GHz) to 310 MHz (1.69-2.0 GHz) . Moreover, antenna is fabricated and simulated and measured results are in good agreement. Additionally, a rectifier and matching circuits are designed at -10 dBm to realize a rectenna (rectifying antenna) for WPT application. Rectenna efficiency of 53.6 % is achieved at a low input power of -10 dBm.

eess.SY↗

arXiv2024

Enabling Wireless Communications, Energy Harvesting, and Energy Saving by Using a Multimode Smart Nonlinear Circuit (MSNC)

In this paper, a multimode smart nonlinear circuit (MSNC) for wireless communications (Tx and Rx modes) as well as energy harvesting (EH) and power saving is presented. The proposed MSNC is designed at 680 MHz and has three ports, which are connected to an antenna, and T/R (transceiver) and power-saving modules. According to the input/output power level, the proposed MSNC has three modes of operations; Receiving (Rx), power saving and transmitting (Tx), for low (<-25 dBm), mid (>-25 dBm and <0 dBm) and high (>5 dBm) power ranges, respectively. In the power-saving mode, when the received power is greater than the sensitivity of the Rx module, the excess power is directed to the energy harvesting load (power storage), while the receiving direction is still in place. The fact that the proposed MSNC can manage the received power level smartly and without any external control, distinguishes the proposed MSNC from other EH circuits. The proposed MSNC operates within a power range from -50 dBm to +15 dBm, demonstrates an efficiency of more than 60% in the power-saving mode, and has acceptable matching over a large frequency range. The design procedure of the proposed MSNC along with the theoretical, simulation and measurement results are presented in this paper. Good agreement between theory, simulation and measurement results confirms the accuracy of design procedure.

eess.SY↗

arXiv2024

Real-Time Discrete Fractional Fourier Transform Using Metamaterial Coupled Lines Network

Discrete Fractional Fourier Transforms (DFrFT) are universal mathematical tools in signal processing, communications and microwave sensing. Despite the excessive applications of DFrFT, implementation of corresponding fractional orders in the baseband signal often leads to bulky, power-hungry, and high-latency systems. In this paper, we present a passive metamaterial coupled lines network (MCLN) that performs the analog DFrFT in real-time at microwave frequencies. The proposed MCLN consists of M parallel microstrip transmission lines (TLs) in which adjacent TLs are loaded with interdigital capacitors to enhance the coupling level. We show that with proper design of the coupling coefficients between adjacent channels, the MCLN can perform an M-point DFrFT of an arbitrary fractional order that can be designed through the length of the network. In the context of real-time signal processing for realization of DFrFT, we design, model, simulate and implement a 16x16 MCLN and experimentally demonstrate the performance of the proposed structure. The proposed innovative approach is versatile and is capable to be used in various applications where DFrFT is an essential tool. The proposed design scheme based on MCLN is scalable across the frequency spectrum and can be applied to millimeter and submillimeter wave systems.

eess.SY↗

arXiv2024

Ultra-Fast and Efficient Design Method Using Deep Learning for Capacitive Coupling WPT System

Capacitive coupling wireless power transfer (CCWPT) is one of the pervasive methods to transfer power in the reactive near-field zone. In this paper, a flexible design methodology based on Binary Particle Swarm Optimization (BPSO) algorithm is proposed for a pixelated microstrip structure. The pixel configuration of each parallel plate (43x43 pixels) determines the frequency response of the system (S-parameters) and by changing this configuration, we can achieve the dedicated operating frequency (resonance frequency) and its related |S21| value. Due to the large number of pixels, iterative optimization algorithm (BPSO) is the solution for designing a CCWPT system. However, the output of each iteration should be simulated in electromagnetic simulators (e.g., CST, HFSS, etc.), hence, the whole optimization process is time-consuming. This paper develops a rapid, agile and efficient method for designing two parallel pixelated microstrip plates of a CCWPT system based on deep neural networks. In the proposed method, CST-based BPSO algorithm is replaced with an AI-based method using ResNet-18. Advantages of the AI-based iterative method are automatic design process, more efficient, less time-consuming, less computational resource-consuming and less background EM knowledge requirements compared to the conventional techniques. Finally, the prototype of the proposed simulated structure is fabricated and measured. The simulation and measurement results validate the design procedure accuracy, using AI-based BPSO algorithm. The MAE (Mean Absolute Error) of prediction for the main resonance frequency and related |S21| are 110 MHz and 0.18 dB, respectively and according to the simulation results, the whole design process is 3629 times faster than the CST-based BPSO algorithm.

eess.SY↗

arXiv2024

Low Profile Metamaterial Band-Pass Filter Loaded with 4-Turn Complementary Spiral Resonator for WPT Applications

In this paper, a very compact and low insertion loss metamaterial band-pass filter (MBPF) at the center frequency of f0=730 MHz is proposed, based on the rectangular-shape 4 turn complementary spiral resonators (4 CSR). The proposed MBPF consists of an interdigital capacitor as a series capacitance in the top layer, leading to improve the stopband performance in the pass band range of 700 to 760 MHz, which makes it suitable for wireless power transfer (WPT) systems by rejecting unwanted signals. In order to validate the performance of the proposed technique, the MBPF is fabricated on the RO-4003 substrate and great agreement is achieved between simulated and measured results. The stop band attenuations of greater than 52 dB and 20 dB are obtained around the 0.8xfcl (lower cutoff frequency) and 1.2xfcu (upper cutoff frequency), respectively.

eess.SY↗

arXiv2024

High-Sensitivity and Compact Time-domain Soil Moisture Sensor Using Dispersive Phase Shifter for Complex Permittivity Measurement

This paper presents a Time-Domain Transmissometry Soil Moisture Sensor (TDT-SMS) using a Dispersive Phase Shifter (DPS), consisting of an interdigital capacitor that is loaded with a stacked 4-turn Complementary Spiral Resonator (S4-CSR). Soil moisture measurement technique of the proposed sensor is based on the complex permittivity sensing property of a DPS in time domain. Soil relative permittivity which varies with its moisture content is measured by burying the DPS under a soil mass and changing its phase difference while excited with a 114 MHz sine wave (single tone). DPS output phase and magnitude are compared with the reference signal and measured with a phase/loss detector. The proposed sensor exhibits accuracy better than +-1.2 percent at the highest Volumetric Water Content (VWC=30 percent) for sandy-type soil. Precise design guide is developed and simulations are performed to achieve a highly sensitive sensor. The measurement results validate the accuracy of theoretical analysis and design procedure. Owning the advantages of low profile, low power consumption, and high sensitivity makes the proposed TDT-SMS a good candidate for precision farming and IoT systems.

eess.SY↗

arXiv2024

Dual-Band, Slant-Polarized MIMO Antenna Set for Vehicular Communication

Slant-polarized Multi Input Multi Output (MIMO) antennas are able to improve the performance of mobile communication systems in terms of channel capacity. Especially, the implementation of MIMO configurations for automotive applications requires to consider high gain, wideband, low-profile and affordable antennas in the communication link. In this work design, simulation and measurement of a new dual-band slant-polarized MIMO antenna with HPBW (Half Power Beam Width) of around 900 are presented. Then, four replicas of the proposed antenna set are placed at four different poles (North, South, West and East) to cover 3600 around the vehicle as an omni-directional pattern. In the real world scenario, the proper antenna set is selected to communicate with the intended user. Each slant MIMO antenna set consists of two inclined (450) low band (LB: 700 to 900 MHz) and two inclined high band (HB: 1.7 to 2.7 GHz) log-periodic antennas. The measured gain of LB and HB antennas are 7 dBi and 8 dBi, respectively. Great agreement between simulation and measurement results confirms the accuracy of the design and simulation procedures of antenna system using optimization algorithm (Genetic method). The proposed antenna is also measured in the field for industrial applications.

eess.SY↗

arXiv2024

Highly Sensitive and Compact Quad-Band Ambient RF Energy Harvester

A highly efficient and compact quad band energy harvester (QBEH) circuit based on the extended composite right and left handed transmission lines (ECRLHTLs) technique is presented.The design procedure based on ECRLHTLs at four desired frequency bands is introduced to realize a quad band matching network (QBMN).The proposed QBEH operates at four frequency bands f1=0.75 GHz,f2=1.8 GHz,f3=2.4 GHz and f4=5.8 GHz. The simulations and experimental results of the proposed QBEH exhibit overall (end to end) efficiency of 55percent and 70percent while excited at four frequency bands simultaneously with negative 20dBm (10 microWatt) and negative 10dBm (100 microWatt) input power, respectively.Due to applying multi band excitation technique and radio frequency (RF) combining method in the QBEH circuit, the sensitivity is improved, and sufficient power is generated to realize a self sustainable sensor (S3) using ambient low level RF signals.A favorable impedance matching over a broad low input power range of negative 50 to negative 10 dBm (0.01 to 100 microWatt) is achieved, enabling the proposed QBEH to harvest ambient RF energy in urban environments. Moreover, an accurate theoretical analyses based on the Volterra series and Laplace transformation are presented to maximize the output DC current of the rectifier over a wide input power range.Theoretical, simulation and measurement results are in excellent agreement, which validate the design accuracy for the proposed quad band structure.The proposed new energy harvesting technique has the potential to practically realize a green energy harvesting solution to generate a viable energy source for low powered sensors and IoT devices, anytime, anywhere.

eess.SY↗

arXiv2024

Highly Sensitive Differential Microwave Sensor for Soil Moisture Measurement

This paper presents a highly sensitive differential soil moisture sensor (DSMS) using a microstrip line loaded with triangular two turn resonator(T2 SR) and complementary of the rectangular two turn spiral resonator(CR2 SR),simultaneously.Volumetric Water Content (VWC) or permittivity sensing is conducted by loading the T2 SR side with dielectric samples.Two transmission notches are observed for identical loads relating to T2 SR and CR2 SR.The CR2 SR notch at 4.39 GHz is used as a reference for differential permittivity measurement method.Further, the resonance frequency of T2 SR is measured relative to the reference value. Based on this frequency difference,the permittivity of soil is calculated which is related to the soil VWC.Triangular two turn resonator (T2 SR) resonance frequency changes from 4 to 2.38 GHz when VWC varies 0 percent to 30 percent.The sensor's operation principle is described through circuit model analysis and simulations.To validate the differential sensing concept, prototype of the designed 3 cell DSMS is fabricated and measured.The proposed sensor exhibits frequency shift of 110 MHz for 1 percent change at the highest soil moisture content (30 percent) for sandy type soil.This work proves the differential microwave sensing concept for precision agriculture.

physics.ins-det↗