• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.10 no.1
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• pp.122-132
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• 1999

In this paper, a shaped small-size ADE(Axially Displaced Ellipse) reflector antenna of 30 cm in diameter operating from 37 to 40 GHz was designed. The experimental antenna was manufactured, and the radiation characteristics evaluated. In the procedure of antenna design, aperture field distribution was assumed to uniform + parabolic distribution. And the variations of beam width, aperture efficiency, and sidelobe level as functions of aperture field distributions were investigated, and these results presented to be used in antenna design. The measured gain and sidelobe level of experimental antenna were found 39.9 dBi(efficiency : 61.9%) and -18.8 dB for 40 GHz. These values show good agreement in design goal of efficiency more than 60% and sidelobe level less than -20 dB.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.40 no.4
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• pp.54-59
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• 2003

In this paper, a cylindrical dielectric antenna with dielectric clad is designed and analyzed. Design parameters of a cylindrical dielectric resonator antenna are calculated from the wave equation of cylindrical dielectric. The variations of characteristics of the antenna are analyzed as varying the thickness and the relative permittivity of its clad. From the results, when the ratio of the outside radius of the dielectric clad to the radius of the cylindrical dielectric is 1.3 and the relative permittivity of the dielectric clad is one-third of the cylindrical dielectric resonator antenna, the relative bandwidth of the antenna is 49%, which is improved by 2.3 times than the cylindrical dielectric resonator antennas. However, the thickness and the relative permittivity of the dielectric clad have not effect on the radiation pattern, beamwidth and gain of the antenna.

• Aerospace Engineering and Technology
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• v.12 no.2
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• pp.140-146
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• 2013

In this study, we discuss about the printed reflectarray antenna design for parabolic reflector volume reduction. For this, we simulated and measured the phase characteristics of the unit array element of reflectarray antenna using waveguide simulator. As a results, the maximum phase variation is $298^{\circ}$ by simulation, the average phase variation is $309^{\circ}$ by measurement in 10GHz. And the printed Reflectarray antenna gain is 28.3dBi, 3dB beamwidth is E-plane $5.1^{\circ}$, H-plane $5.2^{\circ}$, sidelobe level is E-plane -11.4dB, H-plane -17.6dB.

• The Journal of the Acoustical Society of Korea
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• v.23 no.6
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• pp.428-436
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• 2004

Synthetic Aperture Sonar is a technique of extending Physically limited length of an array by signal processing to enhance bearing resolution of a system. The previous techniques estimate most or away shapes as linear. so when towed array shapes are distorted. this can create a deviation from actual situation. In this paper. we estimated perturbed away shapes. and compensated distortion by using estimated array shapes and synthesized arrays in aperture domain. As experimental data, we used the one obtained from towed array in neighboring waters of the Korean peninsula. We extended array by compensating differences in time and spatial position between overlapped subarrays by using SAS techniques. In simulation results. we confirmed that the bearing resolution was enhanced.

• Journal of Advanced Navigation Technology
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• v.10 no.4
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• pp.342-347
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• 2006

In this paper, we have designed 800[MHz] broad band antenna that is improves a narrow bandwidth problem of microstrip antenna and it will be able to integrate GSM, TRS band including the CDMA band. It had L-shaped feeding structure and added the U-slot it used a duplex resonance effect. Also for the improvement of profit the stack it did with the perpendicular. It seems to be good quality that design and manufactured antenna frequency bandwidth(VSWR 2:1) is 789~1086[MHz] with 297[MHz](33%). Also the E-plan and H-plan all profit 9.4[dBi] above, 3[dB] beam width was visible the quality which above $61^{\circ}$ is improved.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.1
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• pp.96-100
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• 2010

In this paper we present a position tracking system that checks the locations of moving targets in real-time. The system confirms that unknown object invades in watch area using 2 infrared sensors and detect the distance from each sensor to object using 4 ultrasonic sensors, and calculate the position of moving object in x-y coordinate. We specially present an algorithm that decide the location of target in case of target is detected in 2 sensors because of radiation beam width of ultrasonic sensor. We established the algorithm to hardware system and tested the system within a laboratory, and confirmed that the designed system tracked an object exactly in real-time.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.39 no.3
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• pp.254-260
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• 2011

Telemetry link is dynamic communication link that antenna gain and polarization are varying with the movement of the airplane. In this paper we calculated the antenna gain, polarization mismatch using the flight trajectory, motion of the airplane and 3D antenna pattern. And we modeled the multipath environment to the 2-Ray spherical earth reflection geometry, estimated the received signal strength when the narrow beam antenna received the RF signal transmitted from the airplane. Also we performed the flight test and after comparing measured value with the estimated value, we confirmed to almost coincide with each other.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.3 s.118
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• pp.315-322
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• 2007

In this paper, active integrated antenna with left hand circular polarization(LHCP) for a transmitter of UHF RFID reader has been described. A novel rectangular ring patch as a radiator of the active antenna is proposed for easier impedance matching, smaller patch size, and LHCP characteristics. An amplification circuit is placed in the opening area of the radiator and is combined with it to work as oscillating circuit around 915 MHz. From the test results, impedance bandwidth of 29 MHz, 3 dB axial ratio bandwidth of 20 MHz, 3 dB beamwidth of 85 degree, and effective radiation power of 8.8 dBm have been obtained.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.12 no.3
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• pp.425-431
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• 2001

In this paper, on aperture-coupled microstrip cylindrical dielectric resonant antenna(DRA) consisting of dielectric material with permittivity ${\epsilon}_{r}$ = 36 is designed and fabricated fir wireless LAN. First of all, the feedline length, width, slot length and width of the feeding element were calculated using the theory of microstrip transmission line. Radiation element is designed using the theory of cylindrical dielectric cavity, Resonant frequency of the fabricated cylindrical DRA is 2.449 GHz and VSWR, return loss and bandwidth is 1.009, -47 dB and 70 MHz, respectively. Front-to-back radiation ratio is about 12 dB and 3 dB beamwidth of E-plane and H-plane is 110$^{\circ}$ and 90$^{\circ}$ , respectively.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.11
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• pp.1216-1224
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• 2003

In this paper Dual Band Log-Periodic Dipole Antenna(DLPDA), which can be used at the Cellular/IMT-2000 band, is proposed. The proposed antenna is composed of 2 of Log-Periodic Dipole Antenna(LPDA) and parasitic elements. To investigate the reliability of the proposed antenna, DLPDA is designed at the cellular/IMT-2000 band and analyzed by using the method of moment, Numerical results are compared with measured results. It is shown that although the antenna length is 70 cm, its radiation characteristics satisfied the design goals of gain, VSWR and beamwidth at the Cellular/IMT-2000 band. From these results, the proposed DLPDA is confirmed as the dual band antenna which can be used at the cellular/IMT-2000 band.