• Journal of Advanced Navigation Technology
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• v.26 no.6
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• pp.464-473
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• 2022

In this paper, about a lightweight design that satisfies the performance of UHF-GPS Antenna used in autonomous underwater vehicle is proposed. Structural analysis, watertight external pressure test and non-destructive testing used in the design process are decided in consideration of structural safety for operating external forces in the underwater environment. First, the material of radome is selected for the performance of the UHF-GPS Antenna for communication with the carrier on the underwater operation in consideration of the 20 bar pressure generated. And the material of radome as PA-GF is selected by conducting electromagnetic field analysis and structural analysis and by considering high strength, rigidity and high dielectric constant. Electromagnetic field analysis and structural analysis by the thickness of radome are additionally performed in order to satisfy the required weight of UHF-GPS antenna. After selecting the final model, its structural safety is verified through watertight external pressure test and non-destructive testing.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.38 no.1
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• pp.11-21
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• 2020

This paper deals with the impact of a GNSS (Global Navigation Satellite System) antenna radome on the PCV (Phase Center Variations) and the estimated kinematic coordinates. For the Trimble and Leica antennas, specially set up CORS (Continuously Operation Reference Stations) in Korea, the PCC (Phase Center Corrections) were calculated and compared for NONE, SCIS, SCIT, and TZGD radome from the PCV model published by the IGS (International GNSS Services). The results revealed that the PCC differences compared to the NONE were limited to about 1mm in the horizontal component while those of the vertical direction ranged from a few millimeters to a maximum of 7mm. Among the radomes of which PCV were compared, the SCIT had the most significant influence on the vertical component, and its GPS (Global Positioning System) L2 and L2 PCC (Phase Center Corrections) had opposite direction. As a result of comparing the kinematic coordinates estimated by the baseline processing of 7 CORSs with an application of the PCV models of the various radomes, the SCIS which was actually installed at CORS in Korea showed 3.4mm bias, the most substantial impact on the ellipsoidal height estimation whereas the SCIT model resulted in relatively small biases.

• Journal of the Korea Institute of Military Science and Technology
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• v.17 no.3
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• pp.311-317
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• 2014

In this paper, the flexible and reconfigurable frequency selective surface for C-band was designed using patch array and grid structure for radome and other curved surface applications. Frequency reconfigurability was obtained by varying the capacitance of varactor diode and flexibility is implemented by using flexible PCB. For the validity of the proposed structure, we fabricated the flexible and reconfigurable frequency selective structure and measured the frequency reconfigurability for different bias voltages and different curvature surfaces from the optimized design parameters. From the measurement results, we know that the proposed structure has the wideband reconfigurable frequency bandwidth of 6.05-7.08GHz. We can apply this proposed structure to the curved surface like as radome of aircraft or warship.

• Composites Research
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• v.20 no.3
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• pp.25-30
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• 2007

This paper describes the basic design and fabrication of smart skin antenna for phased array applications. The smart skin phased array antenna, of which radiation pattern can be electrically steerable without mechanical rotation, has to meet the both mechanical and electrical performance. The smart skin antenna is a honeycomb sandwich structure to enhance the mechanical performance such as strength, weight and so on. The example of smart skin antenna integrated with radome is designed with the resonant frequency of 5 GHz, circular polarization, 2 by 2 subarray, and a coaxial probe-fed excitation. In addition, the performance of raw microstrip patch antenna uncovered radome is investigate. The fabricated smart skin antenna shows a reasonable performance with gain of 12.2 dBi and frequency bandwidth of 6.4 %.

• Journal of Advanced Navigation Technology
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• v.27 no.5
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• pp.546-551
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• 2023

In this study, a beam steering measurement system was developed to perform functions such as far-field beam steering and near-field beam focusing for TX/RX modes in the near file of the AESA radar. The beam steering measurement system consists of a spherical near-field scanner, an antenna positioner, a near-field controller, a network analyzer, a radar control system, a verification radar, a simulated radio, and an AESA radar. Using the developed system, the characteristics of TX/RX patterns before and after installation of radome to AESA radar were measured, and the beam pattern was analyzed through conversion to far field-after near-field measurement.The boresight error of the radar antenna device was measured, and it was confirmed that the main lobes were formed the same before and after the simulated radar dome was mounted.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.4B
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• pp.388-396
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• 2002

In this paper, An aperture-coupled microstrip patch antenna operating at WLL frequency range(Rx : 2.3∼2.33Ghz, Tx : 2.37 ∼2.4Ghz) for WLL repeater is designed and fabricated. FR-4 epoxy substrate with 4.7 relative permittivity is inserted between feed-line and patch plane. Aperture-coupled structure is employed for consideration of bandwidth improvement and gain\`s characteristics. Air gap is arranged at each layer for bandwidth extension and radome is used as a protector in the upper patch. In this paper, both 1 port and 2 port are designed as 1$\times$2 array antenna which uses T-junction and λ$\_$g//4 transformer. Here, 1 port is used as transmitting/receiving antenna and 2 port is used as receiving antenna. Functionally independent two antennas using space diversity arrange slots between two antennas in order to be placed at the same place. As a result, we obtained a excellent isolation below -40dB and return loss is reduced by means of slots arrangement between patch and antenna.

• Journal of IKEEE
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• v.16 no.1
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• pp.15-19
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• 2012

The frequency selective surfaces(FSSs) with chessboard patterns are proposed and designed for the first time in this paper. We proposed the design parameters like slot and patch size, gap between slots or patches, and dielectric thickness of FSS chessboard unit cell proposed in this paper. Also, we found that the variation of design parameters can be used to control the frequency transmission characteristics like the resonant frequency or bandwidth of FSS. To validate the proposed FSS, we fabricated the proposed FSS with the use of 1.0mm FR4 for the bandpass operation at X-band and measured the transmission characteristics. From the results, the proposed FSS with chessboard type can be widely applied to application of the frequency controllable radome design because we can use the design parameters selectively.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.27-27
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• 2009

Non-stochiometric CdS:H films grown on polyethersulfon (PES) flexible polymer substrates at room temperature by R.F. sputtering technique. They exhibited a dark- and photo-sheet resistance of $2.7\times10^5$ and $\sim\;50\;{\Omega}$/square, respectively. These values were realized by an optimum control of both hydrogen doping-levels and the surface morphologies of the films. The comparison between the real and the simulated results for the shielding and the transmission by the free space measurement system in the X-band frequency range (8.2 - 12.4 GHz) was also addressed in this study. Samples overlapped with 13 layers of CdS:H/PES were consistent with the transmission results of pure aluminum metal films ($0.1\;{\Omega}$/square) deposited on PES substrates. As a result, by the simples tacking of the CdS:H/PES layers, the perfect control of the shielding and the transmission of the EM wave in the range of X-band frequency is possible by avisible light alone, and their results are especially very outstanding findings in the stealth function of the radome(Radar+Dome) such as aircrafts, ships, and missiles.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.1
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• pp.92-98
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• 2014

In this paper, the reconfigurable frequency selective surface for C-band was designed using patch array and grid structure. Frequency reconfigurability was obtained by varying the capacitance from varactor diode. From the optimized design parameters, we fabricated the reconfigurable frequency selective surface using the FPCB(Flexible Printed Circuit Board) and commercial varactor diode and measured the frequency reconfigurability for different bias voltage. From the measurement results, proposed structure has the wideband operating frequency of 6.6~7.6 GHz. We can applied this proposed structure to the smooth curved surface like as radome of aircraft or warship.

• Journal of the Korea Institute of Military Science and Technology
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• v.21 no.6
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• pp.760-766
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• 2018

The present study investigates the effect of PMMA and BN content on microstructure, mechanical and dielectric properties of silicon nitride($Si_3N_4$) ceramics in $Y_2O_3-Al_2O_3$ additive system. The total additive content was fixed at 8 wt.% and the amount of PMMA varies from 0 to 40 wt.% and BN varies from 0 to 36 wt.%, respectively. The crystalline phases of the samples were determined by X-ray diffraction analysis. All the sintered sample shows complete transformation of ${\alpha}$ to ${\beta}-Si_3N_4$ during the sintering process indicated that the phase transformation was unaffected by the PMMA or BN content. However, the microstructure shows that the residual porosity increased with increasing PMMA and BN content. In addition, the flexural strength and the dielectric constant decrease with addition of PMMA and BN due to the residual porosity. This article provides empirical study of design parameters for $Si_3N_4$-based radome materials.