Security Paper Design with Frequency-Selective Structure for X-Band Electromagnetic Detection System

This study designed and fabricated a frequency-selective structure-based security paper for the electromagnetic detection system of a security gate, which aims to prevent leakage of confidential documents. When a functional paper embedded with a frequency-selective pattern that selectively reflects a specific frequency is being leaked out of a security zone, the electromagnetic detection system receives and detects the intensity of the electromagnetic wave reflected from the security paper passing through an antenna gate, which transmits/receives RF signals. A stable detection performance of the security paper can be ensured by improving the incidence angle stability for incident waves and reducing the reflection loss. This study designed a frequency-selective structure with stable frequency reflection properties at the X-band by utilizing a Jerusalem cross structure. The proposed design was realized using the screen printing technique, which could implement a circuit, to print silver ink on a plain paper. To verify the applicability of the frequency-selective structure-based security paper, an RF detection system with a multiple antenna array was constructed and the intensity of the received signals was measured. The measurement was performed for various scenarios, and the result showed that the proposed security paper was well detected.

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Design of Security Paper with Selective Frequency Reflection Characteristics

Sensors ◽

10.3390/s18072263 ◽

2018 ◽

Vol 18 (7) ◽

pp. 2263

Author(s):

Sang-Hwa Lee ◽

Min-Sik Kim ◽

Jong-Kyu Kim ◽

Ic-Pyo Hong

Keyword(s):

Angle Of Incidence ◽

Patch Type ◽

Band Frequency ◽

Detection Range ◽

Screen Printing Method ◽

Detection Systems ◽

Silver Ink ◽

X Band ◽

Frequency Selective ◽

Reflection Characteristics

In this research, a security paper based on frequency selective structure technologies was designed and fabricated using selective wave reflection characteristics to prevent the offline leakage of confidential documents. Document leakage detection systems using security papers detect security papers using transceiving antenna gates. For the application of such systems, the structure must be designed with excellent reflection performance and stability at the angle of incidence. For this purpose, a loop and patch-type frequency selective structure based on a four-legged element structure was designed to have X-band frequency reflection characteristics. This design was based on optimized variables and was realized through the screen printing method using silver ink on A4 paper. It was verified that both the design and simulation results matched well. To verify its actual applicability, a detector module operable at 10 GHz was manufactured to observe both the security paper detection range in relation to distance with a signal strength of −10 dBm and the detection area in relation to the number of times that the security paper had been folded.

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C-Band and X-Band Switchable Frequency-Selective Surface

Electronics ◽

10.3390/electronics10040476 ◽

2021 ◽

Vol 10 (4) ◽

pp. 476

Author(s):

Umer Farooq ◽

Adnan Iftikhar ◽

Muhammad Farhan Shafique ◽

Muhammad Saeed Khan ◽

Adnan Fida ◽

...

Keyword(s):

Bottom Layer ◽

Frequency Selective Surface ◽

Transverse Magnetic ◽

Unit Element ◽

Angular Stability ◽

Band Spectrum ◽

Pin Diode ◽

Pin Diodes ◽

X Band ◽

Frequency Selective

This paper presents a highly compact frequency-selective surface (FSS) that has the potential to switch between the X-band (8 GHz–12 GHz) and C-band (4 GHz–8 GHz) for RF shielding applications. The proposed FSS is composed of a square conducting loop with inward-extended arms loaded with curved extensions. The symmetric geometry allows the RF shield to perform equally for transverse electric (TE), transverse magnetic (TM), and 45° polarizations. The unit cell has a dimension of 0.176 λ0 and has excellent angular stability up to 60°. The resonance mechanism was investigated using equivalent circuit models of the shield. The design of the unit element allowed incorporation of PIN diodes between adjacent elements for switching to a lower C-band spectrum at 6.6 GHz. The biasing network is on the bottom layer of the substrate to avoid effects on the shielding performance. A PIN diode configuration for the switching operation was also proposed. In simulations, the PIN diode model was incorporated to observe the switchable operation. Two prototypes were fabricated, and the switchable operation was demonstrated by etching copper strips on one fabricated prototype between adjacent unit cells (in lieu of PIN diodes) as a proof of the design prototypes. Comparisons among the results confirmed that the design offers high angular stability and excellent performance in both bands.

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Fluctuation of magnitude of wave loads for a long array of bottom-mounted cylinders

Journal of Fluid Mechanics ◽

10.1017/jfm.2019.195 ◽

2019 ◽

Vol 868 ◽

pp. 244-285 ◽

Cited By ~ 1

Author(s):

Xiaohui Zeng ◽

Fajun Yu ◽

Min Shi ◽

Qi Wang

Keyword(s):

Incidence Angle ◽

Local Maximum ◽

Destructive Interference ◽

Horizontal Distance ◽

Wave Loads ◽

Wave Load ◽

Intrinsic Mechanism ◽

Fluctuation Phenomenon ◽

Analytical Formulae ◽

Incident Waves

For wave loads on cylinders constituting a long but finite array in the presence of incident waves, variations in the magnitude of the load with the non-dimensional wavenumber exhibit interesting features. Towering spikes and nearby secondary peaks (troughs) associated with trapped modes have been studied extensively. Larger non-trapped regions other than these two are termed Region III in this study. Studies of Region III are rare. We find that fluctuations in Region III are regular; the horizontal distance between two adjacent local maximum/minimum points, termed fluctuation spacing, is constant and does not change with non-dimensional wavenumbers. Fluctuation spacing is related only to the total number of cylinders in the array, identification serial number of the cylinder concerned and wave incidence angle. Based on the interaction theory and constructive/destructive interference, we demonstrate that the fluctuation characteristics can be predicted using simple analytical formulae. The formulae for predicting fluctuation spacing and the abscissae of every peak and trough in Region III are proposed. We reveal the intrinsic mechanism of the fluctuation phenomenon. When the diffraction waves emitted from the cylinders at the ends of the array and the cylinder concerned interfere constructively/destructively, peaks/troughs are formed. The fluctuation phenomenon in Region III is related to solutions of inhomogeneous equations. By contrast, spikes and secondary peaks are associated with solutions of the eigenvalue problem. This study of Region III complements existing understanding of the characteristics of the magnitude of wave load. The engineering significances of the results are discussed as well.

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The InflateSAR Campaign: Testing SAR Vessel Detection Systems for Refugee Rubber Inflatables

Remote Sensing ◽

10.3390/rs13081487 ◽

2021 ◽

Vol 13 (8) ◽

pp. 1487

Author(s):

Peter Lanz ◽

Armando Marino ◽

Thomas Brinkhoff ◽

Frank Köster ◽

Matthias Möller

Keyword(s):

Water Surface ◽

Operating Characteristic ◽

Incidence Angle ◽

Roc Curves ◽

Synthetic Aperture ◽

Moving Window ◽

Threshold Selection ◽

Detection Systems ◽

Experimental Campaign ◽

X Band

Countless numbers of people lost their lives at Europe’s southern borders in recent years in the attempt to cross to Europe in small rubber inflatables. This work examines satellite-based approaches to build up future systems that can automatically detect those boats. We compare the performance of several automatic vessel detectors using real synthetic aperture radar (SAR) data from X-band and C-band sensors on TerraSAR-X and Sentinel-1. The data was collected in an experimental campaign where an empty boat lies on a lake’s surface to analyse the influence of main sensor parameters (incidence angle, polarization mode, spatial resolution) on the detectability of our inflatable. All detectors are implemented with a moving window and use local clutter statistics from the adjacent water surface. Among tested detectors are well-known intensity-based (CA-CFAR), sublook-based (sublook correlation) and polarimetric-based (PWF, PMF, PNF, entropy, symmetry and iDPolRAD) approaches. Additionally, we introduced a new version of the volume detecting iDPolRAD aimed at detecting surface anomalies and compare two approaches to combine the volume and the surface in one algorithm, producing two new highly performing detectors. The results are compared with receiver operating characteristic (ROC) curves, enabling us to compare detectors independently of threshold selection.

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Ultrasound detection using optical interferometry

10.32920/ryerson.14651565 ◽

2021 ◽

Author(s):

Nusrat Jahan Surovy

Keyword(s):

Thin Film ◽

Ultrasound Imaging ◽

Detection System ◽

Incidence Angle ◽

Low Cost ◽

3D Ultrasound ◽

Attractive Alternative ◽

Simulation Results ◽

Exerted Pressure ◽

Piezoelectric Devices

Ultrasound imaging is a widely used noninvasive imaging technique for biomedical and other applications. Piezoelectric devices are commonly used for the generation and detection of ultrasound in these applications. However, implementation of two-dimensional arrays of piezoelectric transducers for 3D ultrasound imaging is complex and expensive. Optical Fabry-Perot interferometry is an attractive alternative to the piezoelectric devices for detection of ultrasound. In this method a thin film etalon is constructed and used. Light reflected from the two surfaces of this thin film produces an intensity which depends on the film thickness. When ultrasound is incident on the film, it changes the thickness of the film and consequently modulates the light intensity on the film. In our work, we made two types of etalon (Finesse 2) for our experiment. We detected lower frequency ultrasound (0.5 MHz or 1 MHz) using the build etalon. We determined a linear relationship between the strength of the optical signals and the exerted pressure on a film by the ultrasound. The dependence of the etalon performance on the light wavelength was demonstrated indirectly by measuring the signal at various light incidence angle. Simulation results are also presented. Lastly, we proposed the optimum design of this detection system based on the simulation results. This method of ultrasound detection can be a potential low-cost approach for 3D ultrasound imaging.

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Multiband and Miniaturized dual layer Antenna incorporated with FSS and DGS

Advanced Electromagnetics ◽

10.7716/aem.v7i1.534 ◽

2018 ◽

Vol 7 (1) ◽

pp. 1-6 ◽

Cited By ~ 2

Author(s):

S. Sah ◽

M. R. Tripathy ◽

A. Mittal

Keyword(s):

Wireless Communication ◽

Frequency Selective Surfaces ◽

Printed Antenna ◽

Defected Ground Structure ◽

Patch Area ◽

Ground Structure ◽

X Band ◽

Type Frequency ◽

Frequency Selective

A novel dual layer rectangular printed Antenna based on loop type Frequency selective surfaces with five concentric rings and I shaped defected ground structure (DGS) is designed and investigated. The deigned antenna is tested for application in C band, WiFi devices and some cordless telephones and X band radiolocation, airborne and naval radars as multiband operational frequencies are at 5.5GHz, 6.81GHz, 9.3GHz and thus covers two wireless communication band C Band (4 to 8GHz ) and X band (8 to 12 GHz) The bandwidth is 200MHz, 300MHz and 1GHz respectively and measured gain of this designed antenna are 2.42dBi against 5.5GHz, 2.80dBi against 6.81GHz, 6.76dBi against 9.3GHz. The proposed antenna in addition to multiband operation also exhibits minituarization.The Floquet port technique is used to analyse concentric rings. The Results comparison of proposed structure with the basic dual layer antenna resonaing at 5.5GHz shows the patch area is reduced by 58.15% while the volume of the antenna is reduced by 81.5%.

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