• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.22 no.12
• /
• pp.1155-1164
• /
• 2011

In this paper, we proposed the transmit beam measurement method of active phased array antenna, which is installed in Korea's first developed naval medium range radar, using near-field measurement facility. The pulse-mode high power characteristics of active phased array antenna's trasmit-beam make it difficult to measure with general near-field measurement facilities where low power continuous RF signals are used. Thus, in this paper, the measurement method of active phased array antenna's transmit beam in conjunction with the near-field measurement facility, which is suitable for the high-power transmit beam measurement, and PNA-X network analyzer(Agilent Technologies), which can support pulse-mode measurement, was proposed and measured by near-field measurement techniques. And the EIRP(Effective Isotropic Radiated Power), the transmit characteristic of active phased array antenna, was measured by the near field measurement techniques and compared to numerical estimation which was nearly equal with small difference of 0.1 dB.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.44 no.4
• /
• pp.88-94
• /
• 2007

This paper deals with the performance analysis of 3-dimensional array antenna by DOA estimation and beamforming in GPS receiver for performance improvement by interference elimination. The array antenna in GPS receiver can improve the system performance by estimating DOA of arriving signal direction, making the main beam for desired direction and elimate the jammer signal by nulling while keeping the GPS signal direction by spatial filtering. In this paper, we propose five types of 3-dimensional array antenna and analyze the estimation error via MUSIC algorithm which is used for the estimation of DOA of arrived signal and beamforming performance. In analyzing DOA performance, we measure DOA estimation error, while in analyzing beamformig performance, we measure BER. In beamforming performance analyzing, we use various jammer power and the existence of GPS signal and angle spread. By performing through the computer simulation, Curved (B) 7-element antenna in proposed 3-dimensional array antenna exhibits the superior performance in the DOA estimation, estimation error, BER characteristic and angle spread compared to the rest four array antenna types.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.11 no.4
• /
• pp.514-522
• /
• 2000

In this thesis, a two-dimensional active phased array antenna without phase shifter is studied for two-dimensional beam scanning. A designed two-dimensional oscillator-type active array antenna, radiation elements and the oscillator circuits were combined with via-hole and coupled by slot on the opposite ground plane. The operating characteristics are analyzed and experimentally demonstrated , The two-dimensional $4\times4$ elements were designed for the proper coupling strengths and coupling phases by adjusting the width, length and offset position of slot-lines. The fabricated active phased array antenna shows the beam shift characteristics capable of scanning from $-17^{\circ}$ to $18^{\circ}$ with respect to broadside in one dimension, from $-5^{\circ}$ to $10^{\circ}$ in two dimension. The experimental results show that it is possible to use the oscillator-type active phased array antenna as a two-dimensional planar array antenna.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.27 no.2
• /
• pp.138-146
• /
• 2016

This paper proposes an optimum beam forming of conformal array antenna by using LSM(Least Squares Method) and GA(Genetic Algorithm). The weights which approximate conformal array antenna beam pattern to linear array antenna beam pattern have been evaluated by applying LSM. Also, the optimum locations of conformal array antenna which form wideband optimum beam pattern have been obtained by using GA. The proposed method is applied to a problem of Bezier platform array antenna for a verification purpose.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.24 no.1
• /
• pp.23-30
• /
• 2024

This paper dedcribes the design. verification, and analysis techniques for an advanced phased array antenna. When applying an active phased array antenna to an aircraft or missile, miniaturization of the array antenna and wide-angle beam steering characteristics can be unavoidable antenna design considerations. In particular, the active reflection coefficient characteristics when electronically steering a wide-angle beam is a design parameter that must be minimized in terms of system survival and system performance. As a radiator suitable for broadband characteristics and wide-angle beam steering, this paper designed an array structure using SFN and minimized the active reflection coefficient according to beam steering of up to 40° based on the spherical coordivate system angle. The bandwidth of the radiator was confirmed to be 3GHz based on active reflection in the Ka-band. In addition, the performance of the actually manufactured 8by8 array antenna wsa analyzed by measuring the single pattern of the radiator through a near-field test, mathematically synthesizing it, and predicting the Tx/TRx beam used in the seeker system.

• Journal of the Korean Vacuum Society
• /
• v.8 no.1
• /
• pp.43-50
• /
• 1999

We have studied the alignment and the lattice quality of hexagonal rings of h-BN films synthesized by ion beam assisted deposition (IBAD) method. Boron was e-beam evaporated at 1.5 $\AA$/sec and nitrogen gas was ionized using end-hall type ion gun at 60, 80, and 100 eV, respectively. Substrate was either not heated or heated at 200, 400, 500, and $800^{\circ}C$, respectively. As nitrogen ion energy increases, c-axes of hexagonal rings tend to align parallel to the substrate, which is explained by larger compressive stress at higher ion energies. Alignment of c-axis increases with temperature and shows maximum around $400^{\circ}C$. The lattice quality of hexagonal rings improves with temperature. Such behaviors can be understood from two counter trends of increasing the atomic mobility and decreasing compressive stress with temperature. Hardness of h-BN films shows the same trend with the alignment of c-axis. Ion beam assisted deposition method seems to be effective for aligning hexagonal rings and optimizing h-BN properties.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.8 no.6
• /
• pp.363-644
• /
• 1997

This paper presents the design and fabrication of a shaped-beam array antenna which will be used for a PCS basestation using structure that is coupled to a microstrip line by an aperture on the interening ground plane. The shaped-beam pattern is obtained by an antenna synthesis method. An array antenna considering the mutual coupling between array elements patches) and a feeding network are designed by CAD tools. The feeding network is designed by using the Wilkinson power divider to obtain the optimized shaped-beam. The designed results are compared with the measured data.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.14 no.6
• /
• pp.1031-1036
• /
• 2019

This study describes the technique of the beam pattern measurement of array antenna for VHF band radar using drone and active beam pattern measuring device. There is no anechoic chamber for measuring the beam pattern of a large size antenna in the country. In this study, to test the antenna beam pattern characteristics of the developed VHF band radar, the antenna beam pattern characteristics were tested by Drone mounting an Active Beam Pattern Measuring Device. By comparing the results of the pre-simulation analysis with the measured results for the antenna, we could confirm that the beamwidth and side-lobe characteristics are satisfactory. Through the antenna beam pattern measurement technology using Drone and Active Beam Pattern Measuring Device, the beam pattern measurement technology of array antenna of low frequency band and large antenna for low band radar will be used.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.22 no.4
• /
• pp.59-65
• /
• 2022

In this paper, a digital active phased array antenna is briefly introduced and beam forming method for a dual-channel side-lobe blanking applied to blank the side-lobe of the main beam is described. Next, the antenna performance was verified from results of design and antenna near-field measurement for the antenna main beam and side-lobe blanking beam. Then, a single-channel side-lobe blanking beam forming method was proposed to reduce the number of channels than the existing system operating dual-channel side-lobe blanking beam and weight distribution for each element of the side-lobe blanking antenna was designed with the proposed method. Finally, the designed single-channel side-lobe blanking beam pattern and blanking ability were verified and compared with the dual-channel side-lobe blanking beam. In addition, by comparing/verifying the conventional dual-channel and the proposed single-channel side-lobe blanking beam patterns measured through the receiving near-field test of the digital active phased array antenna and their ability to blank side-lobe of the main beam, validity of the proposed method for forming single-channel side-lobe blanking beam was confirmed.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.25 no.8
• /
• pp.864-871
• /
• 2014

In this paper, we propose an optimization method for obtaining beam curve which minimize the phase errors of Rotman lens. This method is based on idea that 3 path lengths from a beam port through equal phase points, which consist of the center point of array antenna and two points placed symmetrically or asymmetrically along array antenna, to the corresponding phase front are equal. According to this method, the optimal locations of beam ports can be obtained directly by finding each equal phase point set on array antenna to minimize the phase errors for each beam direction. Simulation results show that the proposed method is the most optimal and effective method for determining the beam curve of Rotman lens with low phase errors.