• Proceedings of the KSRS Conference
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• 2002.10a
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• pp.581-586
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• 2002

The development of 2-D radiometer is a new technical challenge for space borne remote sensing area. The Y-type antenna array has been proposed as a most efficient configuration because a large alias free FOV and a small-synthesized beam-width can be achieved compared to L-, T-type under the fixed antenna spacing. New configuration of antenna array, which is called sub-Y type configuration, is proposed to obtain a higher angular resolution than the case of Y-type array in the paper. The sub-Y type array is consisted of basic arrays, which are the Y-type array of four antenna elements. To analyze characteristics of the proposed configuration, the synthesized beam pattern is simulated through simulation. The secondary effect of the sub-Y-type is that the reconstructed image is suffered from the alias effect is appeared around the real target. The ghost targets in the reconstructed image can be reduced by the alias suppression algorithm introduced in this paper. In conclusion, the performance evaluation by use of array factor simulation shows more than 37.5% improvement in average for angular resolution and almost similar performance for temperature resolution.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.4
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• pp.353-359
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• 2004

In this paper, the single-layer slotted waveguide array antenna is designed, which consists of two par the slot plate and the structure of waveguide. The key difficulty in mass production is the realization of perfect electrical contact between the two parts. Therefore the single-layer slotted waveguide array antenna is presented with a dumbbell patch and a choke. The choke can prevent from the leakage between the slot plate and waveguide, while the choke in the adjacent waveguide incurs space dissipation. To reduce the spacing of antennas about a dumbbell patch is utilized. the 16${\times}$16 array antenna gain of 27.2 ㏈ with 45 % aperture efficiency is obtained.

• Journal of IKEEE
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• v.26 no.1
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• pp.129-132
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• 2022

In this paper, a technique for optimizing the sub-array system structure that can minimize the side lobe level of the phased-array antenna is proposed. Optimization of the proposed array antenna structure is to adjust the spacing between sub-arrays and sub-arrays by using a hexagonal array structure of one sub-array and a hexagonal sub-array for six hexagonal arrays, and thus the entire phased array antenna system of the radiation pattern was optimized. Compared to the 2-dimensional planar antenna system, the proposed technique maintains a gain of 24.3 dBi and a half-power beam-width of 8.46 degrees without change, and only reduces -3.4 dB and -6.5 dB in the x-axis and y-axis directions, respectively.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.8
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• pp.806-812
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• 2009

In this paper, the omnidirectional circularly polarized(CP) antenna using arc-shaped mushroom structure with curved branch is proposed. To obtain a vertical polarization and an omnidirectional radiation pattern, the CP antenna uses zeroth-order resonance(ZOR) mode of composite right and left handed(CRLH) transmission line. The horizontal polarization is achieved by the curved branches. Also, the spacing between curved branch and arc-shaped mushroom structure gives the $90^{\circ}$ phase difference between vortical and horizontal polarization. The proposed antenna, therefore, has an omnidirectional CP radiation pattern In the azimuthal plane. The electrical size of the proposed antenna is reduced by 38%, compared with that of the previously presented omnidirectional CP antenna. In addition, the CP antenna is simply designed without $90^{\circ}$ phase shifter and dual feed line. The proposed antenna uses a Bazooka balun for good impedance matching and radiation pattern. To improve 3 dB axial ratio in XY plane, the designed antenna is optimized. After optimization, the measured 3 dB axial ratio in XY plane is observed in $86{\sim}282^{\circ}$.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2000.11a
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• pp.345-349
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• 2000

A microstrip polarized 8${\times}$2 linear phased array antenna with four 4-bit phase shifters is designed at 10 GHz. The 180$^{\circ}$and 90$^{\circ}$ sections of the phase shifter are of the switched line type, and the rests are of the loaded line type. A 2${\times}$2 sequential sub-array is adopted for a broad axial ratio bandwidth. The construction of the array antenna is of the tile type placing the phase shifters on the same layer containing the feed network. The element spacing is chosen to be 0.45λ$\sub$0/ to exclude the grating lobe. Measurement results show a gain 9.69 dB at broadside and 8.3 dB at the beam-tilt angle of 16$^{\circ}$ by imposing a progressive phase of 90$^{\circ}$.

• Proceedings of the IEEK Conference
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• 2002.06a
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• pp.455-458
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• 2002

Design methods are presented for an X-band traveling-wave slot array realized on a rectangular waveguide. An array of 21 longitudinal slots is realized on the broad wall of a rectangular waveguide. The squint of the antenna main beam is adjusted using the element spacing and the waveguide broad wall dimension. The excitation of the array is controlled by the slot offset from the waveguide center line Multiple I-plane steps are placed around last slot elements so that the second-order beam due to tile reflected wave Is minimized A waveguide-to-coaxial adapter Is designed for feeding the array antenna from a coaxial system. Results of the design show an outstanding performance of the antenna 17.1 dB gain. 36"beam 1111, and -21 dB maximum sidelobe level.evel.

• Journal of Positioning, Navigation, and Timing
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• v.9 no.4
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• pp.367-378
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• 2020

This paper introduces the development of the iterative multiple signal classification (MUSIC)-based direction-of-arrival (DOA) estimation system using a rotator that can control the direction of antenna for the global navigation satellite system (GNSS) interference. The system calculates the spatial spectrum according to the noise eigenvector of all dimensions to measure the number of signals (NOS). Also, to detect the false peak, the system adjusts the array antenna's direction and checks the change's peak angles. The phase delay and gain correction values for system calibration are calculated in consideration of the chamber's structure and the characteristics of radio waves. The developed system estimated DOAs of interferences located about 1km away. The field test results show that the developed system can estimate the DOA without NOS information and detect the false peak even though the inter-element spacing is longer than the half-wavelength of the interference.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.11
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• pp.1213-1222
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• 2008

In this paper, the isolation of the IBBD array antenna is analyzed as functions of the element spacing and the height of the flat plate inserted between array elements for the intelligent antenna system. It is found that the isolation between array elements improves with increasing the array spacing. The array configuration with the plate between the elements is enhanced by about 13 dB more In the isolation than the one without the plate. The plate-inserted $4{\times}4$ elements IBBD array antennas are fabricated and the radiation characteristics are measured and analyzed for the various heights of the plate. It is found that the gain decreases slightly with increasing the height of plate but the shape of radiation pattern does not show a remarkable change.

• Journal of Advanced Navigation Technology
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• v.26 no.5
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• pp.344-349
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• 2022

A compact LPDA antenna consisting of right triangle-shaped dipole elements appended with strips is proposed for UWB applications. First, right triangle-shaped dipole elements are used instead of conventional strip dipole elements to reduce the width of the LPDA antenna. Second, the spacing between the LPDA elements is decreased to reduce the length of the LPDA antenna. Finally, strips are appended at the ends of the right triangle-shaped dipole elements in order to further reduce the width of the antenna. A prototype of the proposed antenna with 16 elements and gain > 4 dBi is fabricated on an FR4 substrate with dimensions of 44 mm×30 mm. Measured frequency band of the fabricated antenna is 2.99-14.76 GHz for a VSWR < 2, which ensures UWB operation, and measured gain range is 4.0-5.5 dBi with a front-to-back ratio larger than 10 dB. The length and width of the proposed compact LPDA antenna are reduced by 40.9% and 20.6%, respectively, compared to the conventional LPDA.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.24 no.1
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• pp.103-107
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• 2024

This paper is a study on a triangle patch antenna using a rectangle slot and strip conductor. The length and spacing of the slot were adjusted to confirm the characteristics of the triangle patch antenna with rectangle slot, and the area and shape of the radiation patch were changed to triangle, rectangle, and hexagon for impedance matching. The HFSS simulator was used to check the antenna parameter characteristics, and the antenna size was 26 mm ×26 mm. In this proposed antenna, the simulation frequency range with VSWR of 2 or less was 5.27 to 6.24 GHz. The bandwidth was 970 MHz. The frequency range of the fabricated antenna was 5.24 to 6.38 GHz, and the bandwidth 1140 MHz. The maximum radiation gain is 5.01 dBi. It was confirmed that all radiation patterns had directional characteristics.