• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.9 s.100
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• pp.941-948
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• 2005

In this paper, we have proposed a Ultra-Wideband slot notch antenna by using a semi-circular extension. The proposed antenna cover the entire UWB band(3.1${\~}$10.6 GHz) and notch out the IEEE 802.1la frequency band(5.15${\~}$5.825 GHz) by inserting a $\lambda$/4 length slot into the patch. A prototype antenna was fabricated on FR-4( ${\epsilon}_r$ =4.4, substrate thickness=0.8 mm) and measured for VSWR characteristics. The measured notched frequency variations versus frequency for different slot length. The path loss and group delay were measured. The proposed antenna also show a good gain flatness(1.9 dBi) except the IEEE 802.1la frequency band.

• Proceedings of the KSRS Conference
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• 2008.10a
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• pp.441-444
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• 2008

This paper describes the development of a circularly polarized microstrip antenna, as a part of the Circularly Polarized Synthetic Aperture Radar (CP-SAR) sensor which is currently under developed at the Microwave Remote Sensing Laboratory (MRSL) in Chiba University. CP-SAR is a new type of sensor developed for the purpose of remote sensing. With this sensor, lower-noise data/image will be obtained due to the absence of depolarization problems from propagation encounter in linearly polarized synthetic aperture radar. As well the data/images obtained will be investigated as the Axial Ratio Image (ARI), which is a new data that hopefully will reveal unique various backscattering characteristics. The sensor will be mounted on an Unmanned Aerial Vehicle (UAV) which will be aimed for fundamental research and applications. The microstrip antenna works in the frequency of 1.27 GHz (L-Band). The microstrip antenna utilized the proximity-coupled method of feeding. Initially, the optimization process of the single patch antenna design involving modifying the microstrip line feed to yield a high gain (above 5 dBi) and low return loss (below -10 dB). A minimum of 10 MHz bandwidth is targeted at below 3 dB of Axial Ratio for the circularly polarized antenna. A planar array from the single patch is formed next. Consideration for the array design is the beam radiation pattern in the azimuth and elevation plane which is specified based on the electrical and mechanical constraints of the UAV CP-SAR system. This research will contribute in the field of radar for remote sensing technology. The potential application is for landcover, disaster monitoring, snow cover, and oceanography mapping.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.8
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• pp.899-905
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• 2008

In this paper, we propose a dual-spiral line loaded monopole antenna having a vertical ground plane for quadband applications. The antenna occupies a volume of $38{\times}12{\times}7\;mm^3$ with a $40{\times}92\;mm^2$ ground plane. The measured impedance bandwidths of the antenna based on $VSWR{\le}2$ are approximately of 11.7 % and 24.8 % in the first and second frequency band, respectively. The operating frequency can simultaneously cover Cellular($0.824{\sim}0.894\;GHz$), PCS($1.750{\sim}1.870\;MHz$), UMTS($1.920{\sim}2.170\;MHz$), and IMT-2000($1.885{\sim}2.200\;GHz$) bands. The maximum gains of the antenna are -0.99 dBi, 4.07 dBi, 2.72 dBi, and 4.33 dBi at the center frequencies of the Cellular, PCS, UMTS, and IMT-2000 bands, respectively. Good radiation patterns are experimentally obtained.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.29 no.10
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• pp.752-757
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• 2018

This study presents the performance evaluation results of a 77-GHz waveguide slot array antenna that was fabricated by attaching a patterned printed circuit board(PCB) on a metal block. The 77-GHz waveguide was divided into a top plate and a bottom structure. The top plate was fabricated using a patterned PCB that can implement a fine slot at low cost. The top cover was then bonded to the bottom metal structure with a waveguide trough using anisotropic conductive film. For evaluating the antenna performance, a $1{\times}16$ slot array antenna was fabricated using our proposed method and the gain and pattern were measured and compared with the simulation results. Though the measurement results demonstrate a reduction in gain of around 2.3~3.5 dB compared to the simulation results assuming ideal bonding conditions, the pattern hardly changed and the slot antenna with a gain of approximately 17 dBi at 77 GHz can be easily manufactured at a low cost using the proposed method.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.12C
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• pp.759-763
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• 2011

In this paper, a dual-band T-shaped microstrip monopole antenna with a pair of slits for 2.4/5.2/5.8-GHz wireless local area networks (WLANs) is proposed. A pair of T-shaped slits is loaded on a T-shaped monopole antenna fed by microstrip line in order to obtain dual-band operation as well as to reduce the antenna size. It is demonstrated from experimental results that the proposed antenna can cover all the required bands for WLAN. The measured impedance bandwidth for VSWR<2 is about 5.7% (2.37-2.51GHz) in the lower frequency band and about 28.8% (4.76-6.35GHz) in the higher frequency band. The measured peak gains are about 1.33 dBi to 1.66 dBi in the 2.4GHz band, 3.50 dBi to 3.95 dBi in the 5.25GHz band, and 2.06 dBi to 2.34 dBi in the 5.8GHz band.

• The Journal of the Korea institute of electronic communication sciences
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• v.6 no.5
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• pp.611-620
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• 2011

A planar monopole antenna that was developed for WLAN/WiMAX application is presented in this paper. The proposed antenna with three strips, an asymmetrical ground plane, and a rectangular slit in the ground is designed to cover the popular frequency spectrum of WLAN (wireless local area network) bands and WiMAX (Worldwide Interoperability for Microwave Access) bands. The proposed antenna, which is capable of wideband operation, is fed by a strip line and fabricated on an FR-4 substrate. The obtained numerical results agree well with the experiment data. It was validated that the configuration can meet the demands for the WLAN/WiMAX systems and effectively enhanced the impedance bandwidth to 9.95% for the lower band and 76.05% for the upper band for VSWR < 1 : 2. This paper also presents and discusses the 2D radiation patterns and 3D gains according to the results of the experiment.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.9
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• pp.1019-1024
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• 2012

In this paper, a UWB antenna using a SIR(Step Impedance Resonator) that eliminate signal interference at 5 GHz WLAN as the first rejection band and adjust the second rejection band is proposed. Unlike the unit impedance resonator, the second harmonic of SIR is decided according to step impedance. Therefore, To adjust the second rejection band, SIR is applied to UWB antenna. Also, the equivalent circuit of the antenna at first rejection band is presented and the equivalent modeling values of the SIR and the coupling value is obtained. The proposed antenna is satisfied to cover full UWB band with return losses less than -10 dB and has band rejection characteristic in 5 GHz WLAN band. The radiation patterns show +y directivity characteristics in H-plane and the group delay variations are within 1.0 ns.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.04a
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• pp.817-820
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• 2000

Existence of void or delamination inside building foundation or tunneling lining can cause serious problems in structural safety. Therefore, 0probing of such voids in architectural and civil structures is an important process in evaluating the overall integrity of the structures. In this study, the radar method has been examined in its use in detecting voids inside concrete specimens. The dimensions of the specimens are 1,000 mm(width) $\times$ 600 mm (height) $\times$ 140 mm (thickness). A void is embedded inside concrete specimens with the dimensions of 200 mm(width) $\times$ 600 mm (height) $\times$ 50 mm (thickness). Concrete cover depth of 30 mm, 60 mm is studied for comparison. In both cases, the voids is located with 1 GHz antenna.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.6
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• pp.550-557
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• 2003

In this paper, two dualband internal antennas for GPS/PCS handset are proposed. At first, the monopole antenna with parasitic dipole element is designed to print PCB of handset directly. At second, the antenna with bended loop structure is designed to bend to use internal space of handset maximumly. The proposed dualband internal antennas provide a 2:1 VSWR bandwidth of over 19.1 % which are possible to cover two bands at once. the antennas have a gain between -0.4 and 3.33 ㏈i at all bands and they have almost omni-directional patterns.

• Journal of Advanced Navigation Technology
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• v.20 no.5
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• pp.490-495
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• 2016

In the present study, a microstrip-fed monopole antenna is proposed for wireless local area network (WLAN) operations which cover dual band of 2.4 GHz (2.4 ~ 2.484 GHz) and 5 GHz (5.15 ~ 5.825 GHz). In order to obtain its compact structure and good omnidirectional radiation patterns, a modified inverted L-shaped slot separated from ground for impedance matching in 5 GHz band is etched on 2.4 GHz printed monopole antenna. The proposed antenna is designed and fabricated on a FR4 substrate with dielectric constant 4.3, thickness of 1.6 mm, and size of $30{\times}45mm^2$. The measured impedance bandwidths (${\mid}S_{11}{\mid}{\leq}-10dB$) of fabricated antenna are 270 MHz (2.22 ~ 2.48 GHz) in 2.4 GHz band and 890 MHz (5.08 ~ 5.97 GHz) in 5 GHz band respectively. In particular, high gain of more than about 4 dBi and good omnidirectional radiation patterns have been observed over the entire frequency band of interest.