arXiv subjects

Negin Shariati

Publications and source records attributed to Negin Shariati.

24 records · Page 2Linked to original sources

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↗

arXiv2024

Autonomous Nonlinear Passive Transmit-Receive Switch for Compact IoT Devices: A Three-Port Agile Network

Recent advancements in RF technologies, especially Internet of Things (IoT) devices, require compact and integrated RF circulators or transmit-receive (TR) switches for efficient resource use. Although conventional techniques are crucial in managing signal flow to prevent signal interference to sensitive receiver components, they have some drawbacks, such as limited isolation, low switching speed, complex circuitry, bulkiness, and high cost. This work presents a smart, miniaturized, nonlinear TR switch capable of operating over a wide frequency range (0.8 - 1.3 GHz), making it suitable for IoT frequency bands. The switch achieves high isolation, low insertion loss, and intelligent transitions between transmitter and receiver without requiring external control or bias pins.

eess.SY↗

arXiv2024

Terahertz Digital Reconfigurable Metamaterial Array for Dynamic Beamforming Applications

A novel digital reconfigurable 2_bit metamaterial, equipped with a substrate integrated feeding system, is designed for industrial quality control applications within the terahertz frequency range. The proposed feeding mechanism facilitates azimuthal beam steering, spanning from negative 90 degree to positive 90 degree, thereby enabling the reconfiguration of beam patterns within the digital metamaterial. Utilizing the phase distribution concept and comprehensive analysis of coupling and the e_field effect on individual unit cells, the metamaterial array spacing is meticulously designed. Operational at 0.7 THz, the system offers versatile reconfigurability, supporting single, dual, and multibeam modes. Through meticulous optimization, the system demonstrates an impressive negative 138 degree to positive 138 degree beam steering capability. This dynamic beamforming ability, transitioning seamlessly from a singular beam to multibeam configurations, requires minimal software-hardware integration for scanning and inter_satellite links, thus presenting significant potential for enhancing product quality within industrial environments and satellite communication.

physics.optics↗

arXiv2023

Intelligent Spatial Interpolation-based Frost Prediction Methodology using Artificial Neural Networks with Limited Local Data

The weather phenomenon of frost poses great threats to agriculture. As recent frost prediction methods are based on on-site historical data and sensors, extra development and deployment time are required for data collection in any new site. The aim of this article is to eliminate the dependency on on-site historical data and sensors for frost prediction methods. In this article, a frost prediction method based on spatial interpolation is proposed. The models use climate data from existing weather stations, digital elevation models surveys, and normalized difference vegetation index data to estimate a target site's next hour minimum temperature. The proposed method utilizes ensemble learning to increase the model accuracy. Climate datasets are obtained from 75 weather stations across New South Wales and Australian Capital Territory areas of Australia. The results show that the proposed method reached a detection rate up to 92.55%.

cs.LG↗