• Journal of IKEEE
• /
• v.26 no.1
• /
• pp.129-132
• /
• 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 the Acoustical Society of Korea
• /
• v.34 no.2
• /
• pp.117-129
• /
• 2015

A parametric array is a nonlinear phenomenon that generates a narrow beam of low-frequency sound using the nonlinearity of the medium. The low-frequency sound so generated has a low sound pressure compared with that of sound generated directly. Consequently, a transducer that can generate a primary wave with high directivity and level is required. This study designed, fabricated, and evaluated a multi-resonance transducer as a parametric array source. The designs of the unit transducers and array transducer were based on an analysis model. The design process was repeated to fabricate the optimum transducer. The fabricated transducer array can generate a 189 dB, 190 dB primary wave level at 6.3 m and a 134 dB difference frequency wave using the parametric array phenomenon. The difference frequency wave has a frequency of 15 kHz and high directivity with an $8^{\circ}$ half power beam width in a $12{\times}18{\times}10m$ water tank.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
• /
• v.2 no.2
• /
• pp.69-77
• /
• 2009

Small size and low profile antenna for mobile vehicular-top-mounted is needed in satellite communication services such as DBS, Satellite Internet and VSAT. In middle latitudes, the development of an array antenna which has the conformal, low profile and 45 degree beam tilted configuration, and has the high gain with sharp beamwidth, low sidelobe and low loss is required for Ka band satellite communication. In this paper, in order to meet with these performances, an array antenna consisting of the vertical polarized waveguide longitudinal slots based on the leaky-wave mode of traveling wave antenna is proposed. Especially, for the lower sidelobe level the radiation power control using a design method of the different slot width is proposed. An array antenna consisting of 32 leakywave elements is showing 34.4 dBi of gain, 3.6 degree of beamwidth, below than -25 dB of sidelobe level, 43 degree of beam tilt angle in center frequency 20.0 GHz. Feed network designed by waveguide cooperated feed shows good performance of wideband and low loss.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.39 no.3
• /
• pp.140-149
• /
• 2002

This paper describes the characteristics of beam-tilting slot away waveguide antennas for mobile DBS reception. As a basic study of slotted waveguide array, design for 16 slot elements located on a broad-wall waveguide is considered. Design parameters such as slot length, space between each slot and cross slot angle of antennas with the beam-tilting characteristics are calculated by method of moments. Based on these results, the radiation waveguide antennas with 16-element $\times$16-array are designed and fabricated. The measured main beam direction angles of the fabricated antennas are 48$^{\circ}$to 50$^{\circ}$depending on the measured frequencies and it shows good agreement with prediction. The measured 3 dB beam width of elevation pattern is about 13$^{\circ}$, and the axial ratio and the gain measured at DBS band are observed 2.8 dB below and 24 dBi above, respectively. In order to evaluate a performance of the fabricated waveguide planar antenna, it is combined with the satellite tracking control system and the field performance test of antenna mounted on a mobile vehicle is carried out at highway. During the measurement, it was possible to watch television without a break signal in a driving vehicle and an excellent performance of the proposed antennas was demonstrated.

• Journal of information and communication convergence engineering
• /
• v.9 no.5
• /
• pp.483-486
• /
• 2011

In this study, a fan-beam microstrip array antenna for an X-band radar was designed and fabricated using a novel technique. A microstrip array structure was used to obtain a high-gain and narrow horizontal beam-width. The feeding point is located at the center of the antenna because of its $360^{\circ}$ rotational characteristic. The measured results indicate a gain of 23dBi, and a horizontal and vertical beamwidth of $3.57^{\circ}$, $26.12^{\circ}$, respectively. The proposed antenna performed adequately and managed to meet the specifications.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.14 no.2
• /
• pp.72-78
• /
• 1981

The purpose of this study is to find directivity characteristics and relative gain of directivity of the wedge horn in conjunction with a projector with varing horn length, horn angle and frequency. The horns are constructed with aluminum plate covered with styrofoam. By using hinges the horn angle could be varied with wide range. Measurements were made over the frequency range of 25 KHz-100 KHz by varing the horn lengths from 5cm to 21cm and the horn angles up to 90 degrees. The followings were the results obtained from the study, 1. As the horn angle increased, the beam width for tile major lobe initially decreased and then increased. At 80 KHz with horn length 21cm the minimum beam widths were obtained with 16 degrees in horizontal plane and 36 degrees in vertical plane. 2. The maximum relative gains of directivity were 4.4 dB in horizontal plane and 3.4 dB in vertical plane when the horn length was 21cm. 3. Beam width was decreased with increasing of frequency. 4. When the mouth apertures were small the major lobes obtained by the experiment agreed with the computed ones, and when the mouth apertures were wide the major lobes by the observed were wide than the computed ones.

• The Transactions of the Korean Institute of Electrical Engineers P
• /
• v.63 no.3
• /
• pp.200-205
• /
• 2014

In this paper, 5.8GHz band $4{\times}4$ Butler matrix is designed using easily accessible commercial $90^{\circ}$ hybrid coupler and semirigid coaxial cable as a transmission line. This Butler matrix is very flexible to changes of antenna system specification like a frequency band because $90^{\circ}$ hybrid coupler changing is all to do. The result of design is the distance of $2{\times}2$ array antenna element is $\sqrt{2}{\lambda}/4$, the 4 beam directions are diagonal of array antenna and phase shifter is not necessary. The beam width is roughly $25^{\circ}$ narrower because of array antenna geometry and the side lobe is about 10dB higher partially than theoretical beam pattern. But the overall beam pattern is similar with theoretical beam. This Butler matrix can be applied to switching beam antenna of 5.8GHz band Wi-Fi and WAVE system.

• Proceedings of the KSRS Conference
• /
• 2004.10a
• /
• pp.467-470
• /
• 2004

In early 2004, KARI developed 5ft S-Band TT&C antenna for especially KOMPSAT-2 operation in LEOP phase. This paper shows system features of 5ft S-Band antenna and its test result with KOMPSAT-l. Tracking test, command uplink test and telemetry downlink test were performed. Through tests, 5ft antenna was verified to be operational in uplink and downlink with KOMPSAT series. Due to its inherent wide 3dB beam-width of about 7deg at S-Band, this antenna system can be used very effectively even though orbital information is less accurate like LEOP and spacecraft safe mode.

• Korean Journal of Optics and Photonics
• /
• v.14 no.3
• /
• pp.224-229
• /
• 2003

We realized a depolarizer based on two 2$\times$2 directional couplers and single mode optical fiber. A reduction method for the degree of polarization is demonstrated by using computer simulation, which is verified experimentally. The degree of polarization is -20 dB for the polarized input beam of spectral width less than 0.05 nm. The experimental results verify that the polarization noise, which is due to the change of the input polarization state, can be reduced by making the fiber-ring delay-line length greater thanthecoherencelengthofthesource.

• Korean Journal of Optics and Photonics
• /
• v.11 no.6
• /
• pp.423-428
• /
• 2000

We have demonstrated a -8 dB additional reduction in the intensity sidelobe of an apodized-interaction-strength guide-wave acousto-optic filter with a center passband of 1551.6 nm. Acoustic-intensity weighting was achieved by launching a surface acoustic wave (SAW) beam in a straight acoustic waveguide, and gradually transferring this SAW intensity to the active device, and back out, by evanescent-wave coupling across a 50 !lm barrier over a 19 rom interaction length. The intensity sidelobe was -4.27 dB for an unapodized filter with abmpt onset and cutoff of the interaction, but sidelobes were reduced to at most -12.68 dB for a SAW intensity with raised-cosine weighting. The RF driving power was 17.78 mW. A linear tuning rate of 8.86 nmIMHz and a spectral width of -1.7 nm were demonstrated. rated.