• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.14 no.10
• /
• pp.985-995
• /
• 2003

In this paper, a study on optimization of three dimensional multi-layered metallic disk array structure(MDAS) excited by circular waveguides was performed to shape efficient flat-topped element patterns(FTEP) of ${\pm}$20$^{\circ}$ beam width. Each radiating element of the MDAS is composed of input, transition and radiation circular waveguides and finite metal disks stacked on radiation circular waveguide. It has an array structure of a hexagonal lattice appropriate for the conical beam scanning. The analytic algorithm for the MDAS was proposed and the code was also programmed using it. Optimal design parameters of the MDAS were determined through the optimal simulation process to obtain ${\pm}$20$^{\circ}$ FTEP. Also, bandwidth characteristics for FTEP and reflection coefficients of the MDAS were investigated and, as the results, it was shown that the MDAS could shape good FTEPs of ${\pm}$20$^{\circ}$ beam width in main planes at least within a 5.6 % frequency band.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.21 no.9
• /
• pp.921-932
• /
• 2010

This paper presents a dual-band array antenna based on a modified Sierpinski fractal structure. Array structure is mirror symmetric, and forms broadside radiation pattern for dual frequency band if the ports are fed with $180^{\circ}C$ phase difference between upper and lower $2{\times}1$ array. To use in-phase corporate feeding circuit, the phase inversion structure is designed by changing the position of patch and ground for upper and lower array. The dimensions of the array antenna is $28{\times}30{\times}5\;cm^3$ and the bandwidth of 855~1,380 MHz(47 %), 1,770~2,330 MHz(27 %) were achieved for -10 dB return loss. The measured gain is 9.06~12.44 dBi for the first band and 11.76~14.84 dBi for the second band. The half power beam width is $57^{\circ}$ for x-z plane and $46^{\circ}$ for y-z plane at 1,100 MHz and $43^{\circ}$ and $28^{\circ}$ at 2,050 MHz, respectively.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.18 no.8
• /
• pp.922-929
• /
• 2007

In this paper, a rectangular loop array antenna for beam scanning is designed. A program using RWG MoM(Rao Wilton Glisson Method of Moment) is developed for SEP(Scan Element Pattern) theoretically. Simulation results obtained by using a commercial software tool, MWS are compared with the MoM results to confirm the validity of the program. Also these results are compared with the measured ones for the case of an $8{\times}5$ subarray. The fabricated $8{\times}5$ subarray showed a flat gain characteristic in the elevation scan range of ${\pm}45^{\circ}$ in the E-plane.

• Korean Journal of Optics and Photonics
• /
• v.14 no.4
• /
• pp.466-472
• /
• 2003

In this paper, we proposed an optical true time-delay (TTD) feeder system for phased array antennas (PAAs). The system possesses high-speed beam scan capability since, in this scheme, different lengths of fiber delay-lines are selected by optical 2${\times}$2 MEMS switches at high speed. An optical TTD capable of beam scanning in one of eight different directions has been built for 10 GHz linear PAA systems. Experimental results on time delay measurements show that the maximum time delay error is less than 0.2 ps corresponding to a scan angle error of less than 0.84o. We have also designed a 10 GHz linear PAA composed of eight micro-strip patch antenna elements driven by the proposed TTD, and the radiation patterns of this PAA have been analyzed by simulation.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.16 no.3
• /
• pp.407-416
• /
• 2021

An active phased array antennas can not only electrically steer the beam by controlling the weighting of the excitation signal, but can also form a pattern null in the direction of the interference source. The weight of the excitation signal to steer the main beam can be easily calculated based on the position of the radiating element. In addition, the weight of the excited signal for pattern null formation can also be calculated by setting the required radiation pattern and using WLSM(Weighted Least Squares Method). However, in a general wireless communication network environment, the location of the interference source is unknown. Therefore, an adaptive pattern null synthesis is needed. In this paper, it was confirmed that pattern null synthesis according to the required radiation characteristic was possible. And based on this, adaptive pattern null synthesis into the direction of an interference source was studied using a binary search algorithm based on observation area. As a result of conducting a simulation based on the presented technique, it was confirmed that adaptive pattern null forming into the direction of an interference is possible in efficient way.

• Journal of electromagnetic engineering and science
• /
• v.19 no.1
• /
• pp.13-19
• /
• 2019

This paper proposes a systematic method for estimating detection performances of a frequency-modulated continuous wave radar using electromagnetic simulations. The proposed systematic method includes a radar system simulator that can obtain range-Doppler images using the electromagnetic (EM) simulations in conjunction with a test setup employed for performance evaluation of multiple targets at different velocities in a traffic environment. This method is then applied for optimizing the half-power beamwidths of the antenna array using an evaluation metric defined to improve the detection strengths for the multiple targets. The optimized antenna has vertical and horizontal half-power beam widths of $10^{\circ}$ and $60^{\circ}$, respectively. The results confirm that that the proposed systematic method is suitable to improve the radar detection performance with the enhanced radar-Doppler images.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.17 no.7
• /
• pp.334-341
• /
• 2016

In this paper, the study of a waveguide aperture-coupled feed-structured antenna has been conducted for the purpose of applying it to a wireless back-haul system sufficient for high-capacity gigabits-per-second data rates. For this study, a $32{\times}32$ waveguide slot sub-array antenna with a corporate-feed structure was designed and produced. Also, this antenna is used at 57 GHz to 66 GHz in the V-band. The construction of the antenna is a laminated form with radiating parts (outer groove and slot, cavity), a coupled aperture, and feeds in each. The antenna was designed with HFSS, which is based on 3D-FEM, produced with aluminum processed by a precision-controlled milling machine, and assembled after a silver-plating process. The measurement result from analysis of the characteristics of the antenna shows that return loss is less than -12 dB, VSWR < 2.0, and a wide bandwidth ranges up to 16%. An overall first side lobe level is less than -12.3 dB, and a 3 dB beam width is narrow at about $1.85^{\circ}$. Also, antenna gain is 38.5 dBi, offering high efficiency exceeding 90%.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.21 no.12
• /
• pp.1380-1393
• /
• 2010

This paper presents a design, fabrication and the test results of planar active electronically scanned array(AESA) radar prototype for airborne fighter applications using transmit/receive(T/R) module hybrid technology. LIG Nex1 developed a AESA radar prototype to obtain key technologies for airborne fighter's radar. The AESA radar prototype consists of a radiating array, T/R modules, a RF manifold, distributed power supplies, beam controllers, compact receivers with ADC(Analog-to-Digital Converter), a liquid-cooling unit, and an appropriate structure. The AESA antenna has a 590 mm-diameter, active-element area capable of containing 536 T/R modules. Each module is located to provide a triangle grid with $14.7\;mm{\times}19.5\;mm$ spacing among T/R modules. The array dissipates 1,554 watts, with a DC input of 2,310 watts when operated at the maximum transmit duty factor. The AESA radar prototype was tested on near-field chamber and the results become equal in expected beam pattern, providing the accurate and flexible control of antenna beam steering and beam shaping.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.13 no.5
• /
• pp.500-506
• /
• 2002

This paper presents a design of wide angle steering microstrip Rotman lens operating over broadband frequency range for Electronic Warfare equipments. It has a compact and simple structure which it is easy to manufacture repetitively. The lens is modelled as a 2-dimension planar circuit, the contour integral method is performed over entire lens contour and the transmission coefficients from 8 beam ports to 8 array ports are found. The measured results are well agreed with those of analysis. Prediction of the multibeam array pattern fed by linear array antenna shows $\pm$65$^{\circ}$ of beam steering and $\pm$5 dB insertion loss deviation over 3:1 frequency range.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.13 no.2
• /
• pp.137-142
• /
• 2013

Direction of arrival is estimating for desire signal direction among received signal on antenna in spatial. In this paper, we were an estimation a receiving signal direction of arrival using multi beam forming in radar. We proposed, by signal direction of arrival estimation method, an algorithm which combine spatial correlation matrix weight value and beam steering algorithm in this paper. Through simulation, we were analysis a performance to compare general algorithm and proposal algorithm. In direction of arrival estimation, proposed algorithm is effectivity to decrease processing time because it is not doing an eigen decomposition. We showed that proposal algorithm improve more target estimation than general algorithm.