• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.14 no.4
• /
• pp.413-420
• /
• 2003

In this paper, the correction method of antenna beam direction errors is introduced which caused by frequency scan effect in active Phased may antenna for satellite communications. The antenna makes the beam directional error from frequency scan effect when it has dual beam may structure with asymmetrical series connection, their frequencies are different and for from each other, their 3dB beamwidth is narrow, and scan range is wide. By proposed equations, estimated beam direction error angles can be calculated and active phase shifter control values also can be calculated to compensate them. In this paper, the active phased array antenna system was fabricated to measure beam direction errors both before and after correction, which has dual beam from 32${\times}$4 main level array and 4${\times}$2 second level array, frequency deviation 500 MHz max.(6.7 %) at 7.25 GHz∼7.75 GHz ranges, 0$^{\circ}$∼${\pm}$35$^{\circ}$nm ranges, and 35.6 dBi gain with 2.2$^{\circ}$3 dB beam width. Its beam direction error by frequency san effect which was 2.5$^{\circ}$max., was reduced to 0.2$^{\circ}$max. after correction. This was 7 dB improvement of signal loss. The active phased array antenna can accurately track the target satellite for communications by this proposed correction method.

• Journal of the Korean Institute of Telematics and Electronics
• /
• v.26 no.5
• /
• pp.32-37
• /
• 1989

The design method of the center-fed resonant type slotted waveguide antenna using the Dolph-Tschebyscheff array is presented. Slot admittances are obtained by empirical and theoretical method since the effect of mutual coupling between slots is included. We design a slotted waveguide antenna which has 1.8ft. length and operates on 9.4GHz. The experimental results of the antenna show that its gain, maximum sidelobe level and half power beam-width are 25.5dB, -22dB and 3.6deg., respectively.

• Land and Housing Review
• /
• v.3 no.4
• /
• pp.433-449
• /
• 2012

An experimental investigation was conducted to study the behavior of RC wide beam-column joints with slab subjected to reversed cyclic loads under constant axial load. Six half scale interior wide beam-column assemblies representing a portion of a frame subjected to simulated seismic loading were tested, including three specimens without slab and three specimens with slab. The primary variables were the ratio of column-to-beam flexural capacity ($M_r={\Sigma}M_c/{\Sigma}M_b$ ; 0.77~2.26), ratio of the column-to-beam width (b/H ; 1.54, 1.67). Test results are shown that (1) the current design code and practice for interior joints(type 2) are apply to the wide beam-high strength concrete column. (2) the presence of a slab have an effect on the performance of the wide beam-high strength concrete column interior joints(type 2). therefore in the design of the wide beam-high strength concrete column interior joints(type 2), the width of slab effective as a T beam flange should be considered. It was show that the case of the ratio of column-to-beam flexural capacity is more than 2.0, the effective width of slab are 2 times of an effective depth of wide beam, however if the ratio of column-to-beam flexural capacity is 1.4~2.0, the effective width of slab are not able to be considered.

• The Journal of the Acoustical Society of Korea
• /
• v.40 no.4
• /
• pp.391-399
• /
• 2021

The conformal array sensor has different sub-array depending on different beam steering directions. According to the method to effective the sensor, the performance of the conformal array sensor can be different, where the sub-array selects an effective sensor. Also, due to the figure of the conformal array sensor, the figure of the sub-array can be different each other, which results in different performance on directivity index, beam width and etc. In this paper, two methods to select sub-array which is the criteria for each sensors position vector and directive vector were proposed. For two sub-array selection methods, the performance of the directivity index, horizontal and vertical beam width were compared with the average and variance. In addition, this comparison was conducted when the number of sensors was fixed. When the number of sensors was not fixed, the directional vector method mainly results in high performance, but the performance of vertical beam width was lower or equal. When the number of sensors was fixed, the performance of two methods is similar, but the performance of variance was deteriorated.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.37 no.2
• /
• pp.83-90
• /
• 2000

In this paper, a stacked circular-disk microstrip 1${\times}$4 array antenna was designed and manufactured and tested to apply in next generation mobile communication, on IMT-2000 system(up-link: 1.885 GHz∼2.025 GHz, down-link: 2.11 GHz∼2.2 GHz) base station which has dual frequency, broadband and high-gain characteristics. The experimental results are as follows : resonant frequency of 1.885 GHz and 2.178 GHz VSWR (1.064 , 1.432), return loss (-30.19 dB , -24.99 dB), band width (VSWR<2) are 402 MHz, -3dB beam width at radiation pattern are ${\alpha}$E-16.8$^{\circ}$, ${\alpha}$H-69$^{\circ}$(1.885 GHz) and ${\alpha}$E-l5.2$^{\circ}$, ${\alpha}$H-51.5$^{\circ}$(2.178 GHz), gain(13.7 dBi∼15.21 dBi).

• The Journal of the Korea institute of electronic communication sciences
• /
• v.12 no.6
• /
• pp.989-996
• /
• 2017

The proposed directional pencil beam antenna consists of a waveguide feeder with bended elliptical conductor plate feed and a parabolic curved reflector. Two rectangular apertures located at the broad wall near the end of the feed waveguide inserted from behind the reflector are located at the focus of the reflector and emit electromagnetic energy with bended elliptical conductor plate. This plate is designed to reflect electromagnetic energy primarily and to face the main reflector. The two rectangular apertures located at the waveguide end have inwardly protruding tabs for impedance matching of the antenna system, the shape of the tabs is a truncated oval. The proposed parabolic reflector antenna has a diameter of 400 mm and a focal length of 134.23 mm. The antenna gain is 33.68 dBi at the center frequency of 16.5 GHz, the beam width is $3.3^{\circ}$ and the reflection loss is -15 dB. Using the HFSS-IE, simulation results are performed to validate the proposed antennas.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.11 no.6
• /
• pp.1006-1014
• /
• 2000

Hemisphere type Luneberg lens antenna with a reflector(frequency : 9.375 GHz, -3 dB beam width 6$^{\circ}$, diameter 30.3 cm(about 10 A), which is miniaturized and lightweightized by attaching a reflector on a section of half the Luneberg lens antenna, is designed and fabricated on the basis of Luneberg lens antenna from which easy beam pointing is acquired only by movement of 1st radiator. Measurement shows -3dB beamwidth is 6.1$^{\circ}$ in case of E-plane and 5.5$^{\circ}$ in case of H-plane. These are good agreements with expected value. Gain of this antenna is 26dBi(Aperture efficiency for uniform distribution : $\pi$ = 44.97%) which is greater than that of 1st radiator(Rectangular microstrip antenna) by 20.4 dB. And, after calculating the approximated pattern of the 1st radiator, far-field pattern, whose source is the second aperture source farmed from the approximated pattern of the 1st radiator is computed. Comparing this far-field pattern with the expected pattern, a (relatively) good agreement is observed. Circular polarization Luneberg lens antenna is also manufactured by making 1st radiator so that it has the characteristics of LHCP and RHCP radiation. The results are as followings : -3 dB beamwidth 5.8$^{\circ}$ , side lobe level -15.3 dB, isolation between LHCP and RHCP radiation 2543, axial ratio 2 dB bandwidth about 1.4 GHz(14.9%).

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.12 no.2
• /
• pp.217-226
• /
• 2001

A small sized ceramic dielectric patch antenna is designed and implemented for GPS/GLONASS combined receiver, and it shows a wideband characteristics with circular polarization. For the miniaturization of the antenna, high-permittivity dielectric material is used, and the wideband characteristics with low axial-ratio is achieved by using dual feed with 90$^{\circ}$ phase difference. The measured data of the manufactured antenna show that the bandwidth is 242 MHz, the axial ratio is less than 3 dB, the half-power beam-width is more than 112$^{\circ}$, and the antenna satisfies the required characteristics of the GPS/GLONASS antenna.

• Journal of Advanced Navigation Technology
• /
• v.11 no.1
• /
• pp.64-71
• /
• 2007

In this paper, we have designed and fabricated microstrip antenna of S-band for the wireless LAN and the ISM. It array $2{\times}2$ circular patch antenna elements at plane instead of conventional rectangular patch antenna elements. It optimized to size calculated of single patch antenna. The radiation elements distance is array $0.24{\lambda}$. The fabricated circular patch antenna decreased 8% of size compared to the conventional rectangular patch antenna. In the E-plane, designed circular microstrip patch $2{\times}2$ array antenna gain is 12.7[dBi], half power beam width is $40^{\circ}$ and in the H-plane, antenna gain is 12.1[dBi], half power beam width is $45^{\circ}$. Bandwidth is 250[MHz] (VSWR < 2).

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.31 no.2A
• /
• pp.201-206
• /
• 2006

A SPST Switch MMIC which used for Microwave Switch Matrix(MSM) of communications satellite payload with multi-beam function has been designed and fabricated. New RE FET switch configuration has been devised to improve power characteristics and isolation. Input and output return losses are better than another switches reported previously for both On and Off states. The MMIC chips were fabricated in 0.15um GaAs pHEMT process and measured insertion loss less than 2.0dB and isolation more than 63dB in the frequency range of 3GHz$\∼$4GHz. Output 3rd order interceptpoint above 32dBm has been recorded and the value is very high even though the unit pHEMT has gate width of 0.2mm and only four pHEMT are used in the MMTC.