• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.6
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• pp.525-532
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• 2015

In this paper, we propose an equivalent model of array antennas that use open-ended waveguides for effective EM simulation. We first investigate an individual element that consists of an open-ended waveguide and square ground plane. The waveguide length, aperture size, and ground size of the individual element are adjusted to give a similar radiation pattern to that of the individual element of the original antenna. We then apply the designed equivalent model to two different types of array antennas, such as a microstrip patch array and a waveguide array antenna. Comparison of the simulation results using the equivalent model with the results obtained with the original antenna reveals a difference in gain of less than 0.2 dB and a difference in half power beam width(HPBW) of less than $1^{\circ}$. The designed equivalent model is then mounted on a simple aircraft, and the simulation results are again compared to results from the original antenna. We find a 60 % reduction in simulation resources and time when compared with the original antenna model.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.10
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• pp.1071-1078
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• 2003

In this paper, the planar, compact, and broadband phased array antenna system for IMT-2000 applications has been investigated. Two methods far designing a low-cost and low-complex beam-farming network are proposed. First, a new compact and broadband phase shifter with continuously controlled phase bits is designed by using parallel coupled lines. Second, its equivalent phase delay line is suggested to be capable of replacing the complex phase shifter with a reference phase bit on a phased array antenna. For the purpose of achieving the broadband system, in addition to the broadband phase shifter, a wide-slot antenna with a ground reflector is utilized as an element antenna. Therefore, the phased array antenna system has achieved compact size, broad bandwidth, and wide steering angle, although it has low complexity and low fabrication cost. The 3${\times}$1 phased array antenna system has a compact size of 1.6 λ${\times}$ l.6 λ, which is the sufficient ground plane of the wide-slot antenna. Experimental results present that the S$\_$11/ has less than 15 dB within the band and its radiation patterns on an E-plane have the capability of steering an antenna beam from -29$^{\circ}$to +30$^{\circ}$.

• Journal of IKEEE
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• v.24 no.2
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• pp.372-377
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• 2020

This paper is based on the triangular inset patch antenna as the basic structure, and the array structure is the twin tree form to improve the antenna's main lobe gain and reduce the side lobe gain. A twin tree structure was implemented by placing two identical trees of 2-4-6 arrays of triangular inset patches side by side. The parametric analysis confirmed that the gap between tree structures arranged side by side is most effective for impedance matching. The fabricated antenna has a gain of 16.74 dBi at 24.15 GHz, and the beam width of the main lobe is 22° in the E-plane and 6° in the H-plane. The antenna size was 125 mm × 50 mm, and a Taconic TLC substrate with a dielectric constant of 3.2 was used. Although the main lobe gain is improved over the twin tree structure, The directivity in the beam pattern due to the mutual interference of the two tree array structure can be improved.

• Journal of IKEEE
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• v.26 no.1
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• pp.137-140
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• 2022

In this paper, we proposed a new W-band monopulse tracking system based on reflectarray antenna structure. The proposed reflectarray antenna monopulse tracking system consists of four feed horn antennas and a planar reflector using a microstrip reflectarray. The four feed horn antennas have a gain of 10 dBi and a half-power beam-width of 56 degrees symmetrically in the E/H plane. It was confirmed that the reflectarray antenna using one feed horn antenna has a size of 41.8 × 41.8 mm², a gain of 26.8 dBi, and a half-power beam-width of about 5.6 degrees. The reflectarray monopulse tracking system using 4 feeding horn antennas is well matched from 75 GHz to 90 GHz, and the isolation is secured by more than 10 dB. Finally, the proposed system shows the tracking range of 5.98 degrees and the tracking error range was 0.02 degrees.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.18 no.2
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• pp.177-184
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• 2018

In this paper, we analyze the characteristics of the antenna by changing the structure of the radiator and the angle of the branch of the array patch antenna. First, the structure of the radiator was changed from the rectangular patch to a hexagonal patch, a triangular patch. Secondly, we changed the angle of the feeder branch to $5^{\circ}$, $10^{\circ}$, $15^{\circ}$, $20^{\circ}$. When the branch angle is $10^{\circ}$, the measured 10dB frequency band is 23.38 GHz-24.19GHz and the bandwidth is 810MHz. The fabricated antenna has a gain of 9.65-10.06dBi at 24.05 GHz. The beam width of the main lobe is $12^{\circ}$, and the antenna size is $70{\times}36mm^2$. In addition to the rectangular patch, it is possible to maintain the performance by using patches of other shapes, and it is confirmed that by changing the feeder branch at various angles, it is possible to reduce the substrate size and contribute to diversity in the fabrication of the array antenna.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.11 no.8
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• pp.1455-1461
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• 2000

There are many researches to increase bandwidth of the microstrip patch antenna for wireless LAN. In spite of broad bandwidth, Bow-Tie antenna has disadvantages that are low gain and big size. In this paper, stacked Bow-Tie microstrip patch antenna for wireless LAN is designed in 5.725 ~5.825 GHz band. This antenna has characteristics that are broadband bandwidth, high gain and small size compared with microstrip patch antenna. In simulated results, the return loss is -34.2 dB at 5.78 GHz and bandwidth is 11.345% for VSWR 2:1 and 7.75%for VSWR 1.5:1. In measured results, the return loss is -38.45 dB at 5.78 GHz and bandwidth is 13% for VSWR 2:1 and 5.6% for VSWR 1.5:1. It has 73.16$^{\circ}$ -3dB beam width and 6.5dB gain.

• International Journal of Internet, Broadcasting and Communication
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• v.16 no.1
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• pp.330-338
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• 2024

In this paper, a Ka-band high-output active phased array antenna device applicable to small radars and seekers was designed, and the improved performance was studied. The radiation device assembly consists of 1x8 arrangements, and the step flared notch antenna type. It shows low active reflection loss characteristics in broadband, and low loss characteristics by applying the air-strip feeding structure, and is designed to enable beam steering up to 45 degrees. The TRM(transmit receive module) output power is more than 2.0W per channel using GaN HPA in the transmitting path, and satisfies more than 25.0 dB gain and less than 6.0 dB noise figure in the receiving path. Accordingly, the Effective Isotropically Radiated Power(EIRP) of the antenna unit shows the performance of 0.00 dB or more and the receive gain-to-noise temperature ratio(G/T) of 0.00 dB/k or more. For demonstration, we have designed aforementioned planar array antenna which consists of 64 radiating elements having a size within 130 mm x 130 mm x 300 mm and weight of less than 4.9 kg..

• Journal of Sensor Science and Technology
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• v.27 no.5
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• pp.311-316
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• 2018

An antenna-coupled bolometer-type terahertz sensor was designed, fabricated, evaluated, and utilized to obtain terahertz transmission images. The sensor consists of a thin film bowtie antenna that resonates accordingly in response to an incident terahertz beam, a heater that converts the applied current in the antenna into heat, and a microbolometer that converts the rise in temperature into a change in resistance. The device is fabricated by a bulk micromachining process on a 4-inch silicon wafer. The fabricated sensor chip has a size of $2{\times}2mm$ and an active area of $0.1{\times}0.1mm^2$. The temperature coefficient of resistance (TCR) of the bolometer film (VOx) is 2.0%, which is acceptable for bolometer applications. The output sensor signal is proportional to the power of the incident terahertz beam. Transmission images were obtained with a 2-axis scanning imaging system that contained the sensor. The small active area of the sensor will enable the development of highly sensitive focal plane array sensors in terahertz imaging cameras in the future.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.5
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• pp.428-434
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• 2009

In this paper, we propose an U-slot microstrip antenna with the U-shaped parasitic patches. U-slot and parasitic patches make two resonant frequencies and one additional resonant frequency, respectively, so that the impedance band-width of the antenna is expanded. The size of radiator part is $64{\times}53\;mm^2$ and the entire size of the antenna is $150{\times}150{\times}11.5\;mm^3$. The measured bandwidth is $1.85{\sim}2.40\;GHz$. Thus, our antenna can be used for DCS1900, WCDMA and WiMax services. The radiation characteristic is almost same in the bandwidth, the beam width is about $60^{\circ}$, and the gain is more than 7 dBi.

• Journal of the Korean Institute of Telematics and Electronics
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• v.19 no.2
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• pp.14-22
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• 1982

The design and manufacfure technology of the large aperture cassegrain antenna was first studied in the country, and its performances in a trial manufactured product are measured and compared. In order to design this cassegrain antenna with reference to several literatures, the schemed order was decided. Especially, for the cassegrain antenna of 4.6m diameter which is becoming the television receiving antenna directly from satellite, in advanced countries, the 1/12 sized small section of its parabolic curved surface is made primarily with the precision of less difference than 1/16λ depth. Cares are taken also on the computer program so that the size and position of primary radiator may satisfy the minimum blocking with the given sub-reflector. The preformances of the designed antenna are shown as being 43dB in gain, 1.15 or less in VSWR, 1.1$^{\circ}$ of beam angle etc., and found to be not worse than those of foreign productions with similar type and size.