Development of dual port scanning free space measurement system

Hyun, Jong-Min; Ahmed, Hasan; Lee, Jung-Ryul

doi:10.1088/1361-6501/aac7fd

Cited by 7 publications

(7 citation statements)

References 16 publications

(22 reference statements)

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“…In this study, we used full-field SFM system for the investigation of EM function in whole specimens (Hyun et al, 2018). The SFM system measured EM characteristics automatically according to the position of the specimen using the X-Y transition stage, as shown in Figure 10.…”

Section: Em Performance Evaluationmentioning

confidence: 99%

Nondestructive and electromagnetic evaluations of stealth structures damaged by lightning strike

Jang

Hyun

Son

et al. 2019

Journal of Intelligent Material Systems and Structures

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Stealth technology is very important for the survival of military aircraft. A stealth aircraft structure has both electromagnetic and mechanical functions. Lightning can cause failure on both the points. In this study, we claim that the stealth structure should be evaluated nondestructively and electromagnetically, and we propose a method for full-field evaluations of both the functions. First, a radar absorbing structure was designed and fabricated with stealth capability in the X-band. The radar absorbing structure consisted of a carbon nanotube layer (glass/epoxy dispersed with multiwalled carbon nanotubes), a spacer layer (glass/epoxy) and a perfect electrical conductor layer. A lightning test was performed using an impulse current generator according to standard regulations. Then, nondestructive damage and electromagnetic performance evaluations were performed using a pulse-echo laser ultrasonic propagation imager and a scanning free-space measurement system, respectively. The results showed that neither structural damage nor changes in the electromagnetic properties were observed during the two evaluations. In general, the composites were severely damaged by lightning. However, it turned out that the radar absorbing structure with the carbon nanotube layer could prevent serious damage to stealth function as well as material damage owing to the high conductivity of the carbon nanotubes dispersed in its surface layer.

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Section: Em Performance Evaluationmentioning

confidence: 99%

Nondestructive and electromagnetic evaluations of stealth structures damaged by lightning strike

Jang

Hyun

Son

et al. 2019

Journal of Intelligent Material Systems and Structures

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“…The intrinsic properties of RAS, such as complex permittivity, permeability, reflection coefficient, and reflection loss, can also be calculated from the measured S-parameters for a detailed assessment of specimens. [9][10][11][12] In the conventional FSM system, one point over a specimen is evaluated as a representative value. However, a single point cannot represent the performance of the whole specimen.…”

Section: Introductionmentioning

confidence: 99%

“…The transmitted and reflected waves from the specimen are then recorded in the form of complex scattering parameters (S-parameters) S 21 and S 11 , respectively. 9 The FSM system results are affected by four parameters: the incident angle, specimen curvature, partial illumination at the edges, and standoff distance (SOD) from the calibrated focal point of the antenna, as shown in Figure 1. To reduce the effect of diffraction at the sample edges, focused energy antennas are preferred.…”

Section: Introductionmentioning

confidence: 99%

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Robotic scanning free-space measurement system for electromagnetic performance evaluation of curved radar absorbing structures

Din

Hyun

Son

et al. 2022

International Journal of Advanced Robotic Systems

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Radar absorbing structures are manufactured for stealth missions and total quality inspection applies to evaluate their performances before assembly to stealth weapon systems. This study adopted a six-axis robot arm to move a target specimen in a scanning free-space measurement system for electromagnetic performance evaluation. The six-axis robot arm completely enables the system to maintain the specimen at the focal point of the antenna and solves the issue of curvature effect on the return loss results of the curved specimens, faced in the two- and three-axis scanning free-space measurement systems. The six-axis robotic scanning free-space measurement system uses a RobotStudio to extract the position and orientation of each target point on the specimen to be evaluated and uses a robotic scanning algorithm to transform all the points into a scan path. The system was verified by variable and constant curvature radar absorbing structure specimens with frequency selective surfaces. Return losses ( S 11s) of the nonsymmetrical cambered airfoil specimen and S-shaped double curvature specimen that could not be accurately evaluated with a three-axis stage-based scanning free-space measurement system were measured by the six-axis robotic scanning free-space measurement system. All the specimen results adhere to the theoretical parameters of the specimen. The transition region results of the S-shaped specimen were studied using effective radius of curvature. Finally, the inspected results of the S-shaped specimen were curvature compensated to check the effect of negative and positive curvature on the specimen resonance frequency performance.

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“…There is interest in accurate permittivity measurements due to their importance in the design of radomes [1,2] and electro magnetic susceptor materials [3]. In other applications (e.g.…”

Section: Introductionmentioning

confidence: 99%

Anisotropy of W-band complex permittivity in Al₂O₃

Telmer¹,

Hilario²,

Hoff³

et al. 2019

J. Phys.: Condens. Matter

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The dielectric anisotropy of Al 2 O 3 is studied here by characterizing Wband (75-110 GHz) complex permittivity of four different orientations of sapphire (Al 2 O 3 single crystals). This was done using freespace, focused beam methods. Dielectric polarizability (α D ) of these orientations is then calculated and these values are related to their complex permittivity. Based on this relationship, a framework is developed for rapid and straightforward estimation of dielectric anisotropy using a known crystal structure and a dielectric permittivity measurement performed on one orientation of the material. This framework can be applied to other materials with dielectric anisotropy (e.g. SnO 2 , LiGaO 2 ) to predict permittivity for different orientations, enabling rapid design of highfrequency systems (e.g. radomes, electromagnetic windows). These permittivity measurements were also used to determine the dominant polarization mechanisms leading to dielectric anisotropy of Al 2 O 3 in the Wband; electronic and ionic polarization orthogonal to the direction of the focused beam.

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Development of dual port scanning free space measurement system

Cited by 7 publications

References 16 publications

Nondestructive and electromagnetic evaluations of stealth structures damaged by lightning strike

Nondestructive and electromagnetic evaluations of stealth structures damaged by lightning strike

Robotic scanning free-space measurement system for electromagnetic performance evaluation of curved radar absorbing structures

Anisotropy of W-band complex permittivity in Al₂O₃

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Development of dual port scanning free space measurement system

Cited by 7 publications

References 16 publications

Nondestructive and electromagnetic evaluations of stealth structures damaged by lightning strike

Nondestructive and electromagnetic evaluations of stealth structures damaged by lightning strike

Robotic scanning free-space measurement system for electromagnetic performance evaluation of curved radar absorbing structures

Anisotropy of W-band complex permittivity in Al2O3

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Anisotropy of W-band complex permittivity in Al₂O₃