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Optical and RF Atmospheric Propagation

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A special issue of Sensors (ISSN 1424-8220). This special issue belongs to the section "Optical Sensors".

Deadline for manuscript submissions: closed (30 June 2022) | Viewed by 14170

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Special Issue Editors

Prof. Dr. Natan Kopeika

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Guest Editor

Department of Electrical and Computer Engineering, Ben Gurion University of the Negev, P.O. Box 653, Beer Sheva 84105, Israel
Interests: imaging through the atmosphere; MMW/THz imaging; optical-MMW communication through the atmosphere; interaction of EM waves with plasma; optogalvanic effect
Special Issues, Collections and Topics in MDPI journals

Prof. A.A. Bazil Raj

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Guest Editor

Electronics Engineering, Defence Institute of Advanced Technology, Pune-411025, India
Interests: atmospheric Optics; free space optical communication; optical/RF channel modeling; active/passive optical/RF imaging; optical signal processing; RF-Photonics

Special Issue Information

Dear Colleagues,

This special issue aims to create collections of research papers on Optical and RF atmospheric Propagation and their applications. This special issue attracts the papers of latest research works and system developments in the field of optical and RF propagation sensing, propagations/effects/channel molding, advancements in applications, signal far-field measurements, application specific new theoretical/measurement methods for beam handling/processing, military applications, and next-generation network formations etc. An intensive survey papers in any suitable/relevant topics of this special issue is also invited.

The sensing and measurements are the primary requirements for all the above fields; thus, this proposed topic falls within the scope of the journal “Sensors”.

Topics:

Short/Medium/Long range free space optical communication
Atmospheric optical channel modeling
Space/Deep-space optical communication
Satellite/UAVs/mobile-platform optical interlinks
Optical camera communication
Optical weather sensing/measurement/imaging
Quantum channel modeling
Quantum key-distribution (QKD)
Quantum communication/Computing
Quantum random number generation (QRNS) and distribution
FSO for energy harvesting
AI for FSO applications
Advances in adaptive optics
Atmospheric optical/RF data analyses
Automated optical targets detection/tracking
Directed energy systems and applications
Passive optical imaging
Automated atmospheric optical beam correction optics
Hybrid (FSO-RF) communication technology
RF atmospheric propagation and applications
Optical/RF remote sensing
RF sensing for low-RCS targets detection/classification/imaging
RF underground/surface scanning and detections/Target Acquisition

Prof. Natan Kopeika
Prof. A.A. Bazil Raj
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

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Keywords

imaging
RF remote sensing
optical communication
atmospheric optical channel modelling
optical camera communication
optical weather sensing
quantum communication

Published Papers (7 papers)

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Editorial

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4 pages, 172 KiB

Open AccessEditorial

Editorial—Special Issue on “Optical and RF Atmospheric Propagation”

by Natan Kopeika and A Arockia Bazil Raj

Sensors 2023, 23(7), 3644; https://doi.org/10.3390/s23073644 - 31 Mar 2023

Viewed by 751

Abstract

This Special Issue presents the latest research and developments in the field of optical and RF propagation sensing, propagation/effects/channel molding, advancements in applications, signal far-field measurements, theoretical/measurement methods for beam handling/processing, military applications, and next-generation network formations, amongst others [...] Full article

(This article belongs to the Special Issue Optical and RF Atmospheric Propagation)

Research

Jump to: Editorial

13 pages, 2829 KiB

Open AccessArticle

Fast and Enhanced MMW Imaging System Using a Simple Row Detector Circuit with GDDs as Sensor Elements and an FFT-Based Signal Acquisition System

by Arun Ramachandra Kurup, Daniel Rozban, Amir Abramovich, Yitzhak Yitzhaky and Natan Kopeika

Sensors 2023, 23(3), 1578; https://doi.org/10.3390/s23031578 - 01 Feb 2023

Cited by 1 | Viewed by 1608

Abstract

The relatively high atmospheric propagation of millimeter-waves (MMW) was found to be one of the most critical reasons for the development of reliable sensors for MMW detection. According to previous research works, it has been already shown that incident MMW radiation on a glow discharge detector (GDD) can increase the discharge current. Hence, the electrical mode of detection can be employed to detect the presence of MMW radiation. In this article, a new design of a row detector using GDDs as pixel elements, and the influence of MMW incidence on GDD’s discharge current, were acquired using an elementary data acquisition (DAQ) platform. The DAQ system computes the averaged Fast Fourier Transform (FFT) spectrum of the time signal and returns the FFT results as magnitude based on the level of detection. An FFT-based signal acquisition proved to be a better alternative to the lock-in detection that was commonly used in MMW detection systems. This improved detection circuit provides enhanced noise filtering, thereby resulting in better MMW images within a short time. The overhead expense of the entire system is very low, as it can avoid lock-in amplifier stages that were previously used for signal enhancement. A scanning mechanism using a motorized translation stage (step motor) is involved to place and align the row detector in the image plane. The scanning can be carried out vertically to perform the imaging, by configuring the step motor after selecting the desired step size and position. A simplified version of the MMW detection circuit with a dedicated over-voltage protection facility is presented here. This made the detection system more stable and reliable during its operation. The MMW detection circuit demonstrated in this work was found to be a milestone to develop larger focal plane arrays (FPA) with very inexpensive sensor elements. Full article

(This article belongs to the Special Issue Optical and RF Atmospheric Propagation)

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15 pages, 3298 KiB

Open AccessArticle

A Simple Model for Assessing Millimeter-Wave Attenuation in Brownout Conditions

by Arkadi Zilberman and Natan Kopeika

Sensors 2022, 22(22), 8889; https://doi.org/10.3390/s22228889 - 17 Nov 2022

Cited by 2 | Viewed by 1176

Abstract

Flying helicopters in adverse environmental conditions, such as low heights in arid regions, can be dangerous, especially during landing and take-off, since during hovering, the rotors produce a dust cloud of particles. This phenomenon is known as the “brownout” condition. Unlike visible and infrared systems, the radar devices in the microwave or millimeter wave region offer the capability of sufficient transmission through atmospheric obscurants, such as fog, smoke, sand/dust storms, and brownout. In this work, we present a theoretical evaluation of mm-wave (85–100 GHz) attenuation/scattering and power transfer in brownout conditions. The model includes attenuation/scattering prediction and radiant flux, or power collected by the receiver. We are considering the case of sand grain clouds created by helicopter rotor airflow during landing in arid areas. The evaluated scenarios are brownout environments over ranges up to 50 m. The predicted values from the mathematical model are compared with findings in the field and the literature. A simple model for mm-wave power transfer estimation shows satisfactory agreement with the measured values. Full article

(This article belongs to the Special Issue Optical and RF Atmospheric Propagation)

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12 pages, 21354 KiB

Open AccessArticle

Sensing and Analysis of Greenhouse Gas Emissions from Rice Fields to the Near Field Atmosphere

by Panneerselvam Rajasekar and James Arputha Vijaya Selvi

Sensors 2022, 22(11), 4141; https://doi.org/10.3390/s22114141 - 30 May 2022

Cited by 5 | Viewed by 3222

Abstract

Greenhouse gas (GHG) emissions from rice fields have huge effects on climate change. Low-cost systems and management practices to quantify and reduce GHGs emission rates are needed to achieve a better climate. The typical GHGs estimation processes are expensive and mainly depend on high-cost laboratory equipment. This study introduces a low-cost sensor-based GHG sampling and estimation system for rice fields. For this, a fully automatic gas chamber with a sensor-integrated gas accumulator and quantifier unit was designed and implemented to study its performance in the estimation efficiency of greenhouse gases (CH₄, N₂O, and CO₂) from rice fields for two crop seasons. For each crop season, three paddy plots were prepared at the experimental site and then subjected to different irrigation methods (continuous flooding (CF), intermittent flooding (IF), and controlled intermittent flooding (CIF)) and fertilizer treatments to study the production and emission rates of GHGs throughout the crop growing season at regular intervals. A weather station was installed on the site to record the seasonal temperature and rainfall events. The seasonal total CH₄ emission was affected by the effects of irrigation treatments. The mean CH₄ emission in the CIF field was smaller than in other treatments. CH₄ and N₂O emission peaks were high during the vegetative and reproductive phases of rice growth, respectively. The results indicated that CIF treatment is most suitable in terms of rice productivity and higher water use efficiency. The application of nitrogen fertilizers produced some peaks in N₂O emissions. On the whole, the proposed low-cost GHGs estimation system performed well during both crop seasons and it was found that the adaption of CIF treatment in rice fields could significantly reduce GHG emissions and increase rice productivity. The research results also suggested some mitigation strategies that could reduce the production of GHGs from rice fields. Full article

(This article belongs to the Special Issue Optical and RF Atmospheric Propagation)

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19 pages, 4035 KiB

Open AccessArticle

SP-WVD with Adaptive-Filter-Bank-Supported RF Sensor for Low RCS Targets’ Nonlinear Micro-Doppler Signature/Pattern Imaging System

by Harish C. Kumawat and A Arockia Bazil Raj

Sensors 2022, 22(3), 1186; https://doi.org/10.3390/s22031186 - 04 Feb 2022

Cited by 21 | Viewed by 2253

Abstract

In this study, the authors present the accurate imaging of the behavior of simultaneous operations of multiple low radar cross-section (RCS) aerial targets. Currently, the popularity of low RCS targets is increasing day by day, and detection and identification of these targets have become critical issues. Micro-Doppler signatures are key components for detecting and identifying these low RCS targets. For this, an innovative approach is proposed along with the smooth pseudo-Wigner–Ville distribution (SP-WVD) and adaptive filter bank to improve the attenuation of cross-term interferences to generate more accurate images for the micro-Doppler signatures/patterns of simultaneous multiple targets. A C-band (5.3 GHz) radio-frequency (RF) sensor is designed and used to acquire the micro-Doppler signatures of aerial rotational, flapping, and motional low RCS targets. Digital pipelined-parallel architecture is designed inside the Xilinx field-programable gate array (FPGA) for fast sensor data collection, data preprocessing, and interface to the computer (imaging algorithm). The experimental results of the proposed approach are validated with the results of the classical short-term Fourier transform (STFT), continuous wavelet transform (CWT), and smooth pseudo-Wigner Ville distribution (SP-WVD). Realistic open-field outdoor experiments are conducted covering different simultaneous postures of (i) two-/three-blade propeller/roto systems, (ii) flapping bionic bird, and (iii) kinetic warhead targets. The associated experimental results and findings are reported and analyzed in this paper. The limitations and possible future research studies are also discussed in the conclusion. Full article

(This article belongs to the Special Issue Optical and RF Atmospheric Propagation)

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14 pages, 2465 KiB

Open AccessArticle

Refining Atmosphere Profiles for Aerial Target Detection Models

by Robert Grimming, Patrick Leslie, Derek Burrell, Gerald Holst, Brian Davis and Ronald Driggers

Sensors 2021, 21(21), 7067; https://doi.org/10.3390/s21217067 - 25 Oct 2021

Cited by 5 | Viewed by 2340

Abstract

Atmospheric path radiance in the infrared is an extremely important quantity in calculating system performance in certain infrared detection systems. For infrared search and track (IRST) system performance calculations, the path radiance competes with the target for precious detector well electrons. In addition, the radiance differential between the target and the path radiance defines the signal level that must be detected. Long-range, high-performance, offensive IRST system design depends on accurate path radiance predictions. In addition, in new applications such as drone detection where a dim unresolved target is embedded into a path radiance background, sensor design and performance are highly dependent on atmospheric path radiance. Being able to predict the performance of these systems under particular weather conditions and locations has long been an important topic. MODTRAN has been a critical tool in the analysis of systems and prediction of electro-optical system performance. The authors have used MODTRAN over many years for an average system performance using the typical “pull-down” conditions in the software. This article considers the level of refinement required for a custom MODTRAN atmosphere profile to satisfactorily model an infrared camera’s performance for a specific geographic location, date, and time. The average difference between a measured sky brightness temperature and a MODTRAN predicted value is less than 0.5 °C with sufficient atmosphere profile updates. The agreement between experimental results and MODTRAN predictions indicates the effectiveness of including updated atmospheric composition, radiosonde, and air quality data from readily available Internet sources to generate custom atmosphere profiles. Full article

(This article belongs to the Special Issue Optical and RF Atmospheric Propagation)

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14 pages, 3694 KiB

Open AccessArticle

A Simplified Model for Optical Systems with Random Phase Screens

by Malchiel Haskel and Adrian Stern

Sensors 2021, 21(17), 5811; https://doi.org/10.3390/s21175811 - 29 Aug 2021

Cited by 2 | Viewed by 1692

Abstract

A first-order optical system with arbitrary multiple masks placed at arbitrary positions is the basic scheme of various optical systems. Generally, masks in optical systems have a non-shift invariant (SI) effect; thus, the individual effect of each mask on the output cannot be entirely separated. The goal of this paper is to develop a technique where complete separation might be achieved in the common case of random phase screens (RPSs) as masks. RPSs are commonly used to model light propagation through the atmosphere or through biological tissues. We demonstrate the utility of the technique on an optical system with multiple RPSs that model random scattering media. Full article

(This article belongs to the Special Issue Optical and RF Atmospheric Propagation)

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