• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.11
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• pp.2121-2126
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• 2007

In this paper, the performance improvement of ultra-wideband(UWB) communications system to achieve high-data-rate using spatial diversity provided by multiple receive antennas is investigated. We derive the expression for the received SINR after spatially combining through multiple receive antennas and evaluate the bit error rate(BER) performance by numerical simulation. We also compare the performance results in the case of 2PPM systems with the theoretical performance results in the case of 2PAM THMA UWB systems. The impacts of spatial diversity on the performance of 2PPM and 2PAM THMA UWB systems are analyzed. It is shown that the BER performance is improved as the number of receive antennas increases. Also, it is observed that in the presence of multiple user interference signals, the performance of 2PAM THMA UWB systems is considerably superior to that of 2PPM THMA UWB systems.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.12
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• pp.52-58
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• 2009

We propose a folded monopole antenna with loads, and analyze the roles of design parameters which affect the return loss of the proposed antenna. VSWR < 3 bandwidth of the antenna is 30 ~ 2000 MHz, ranging from the HF/VHF/UHF bands. For operating travelling antenna, we connect six loads at the end of the antenna. The reflected wave is drastically reduced due to the six loads. For improved return loss properties, we use Klopfenstein tape that determine positions and values of six loads. The propose antenna has omni-directional radiational patterns like that of conventional monopole antennas. For wideband impedance transformation, we use the balun which operating frequency region is 10 ~ 1900 MHz. We expect the proposed antenna has important role for the wideband and multi-rold multi-functional communication systems.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.6 no.3
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• pp.162-167
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• 2013

The variation of S11 depending on the ground sizes of circular planar monopole UWB antenna was studied. And optimal ground structure and size in UWB application devices are proposed. Radius R of circular monopole UWB antenna as a reference antenna was designed for UWB frequency band, and the measured results of this antenna on the horizontal ground plane was good agreed with the simulated results. When radius R is small, optimal size of ground plane is proposed, and when radius R is more large, minimum size of ground plane is proposed.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.05a
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• pp.49-50
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• 2014

In this paper, a wideband loop antenna for UWB applications is studied. The proposed wideband loop antenna consists of a circular loop and circular sectors. Circular sectors with a ultra-wideband characteristic are used to connect the circular loop and the center feed points. Optimal design parameters are obtained by analyzing the effects of the gap between the circular sectors and the radius of the circular loop on the input reflection coefficient and gain characteristics. The optimized wideband loop antenna is fabricated on an FR4 substrate with a dimension of $41mm{\times}41mm$. Experimental results show that the antenna has a desired UWB characteristic with a frequency band of 3.1-11.0 GHz for a VSWR < 2.25.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.42 no.11
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• pp.101-106
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• 2005

A ground penetrating image radar (GPR) using an ultra wideband (UWB)impulse waveform is developed for non destructive detection of metallic pipelines buried under the ground. Dielectric constant of test field is measured and then a GPR system is designed for better detection up to 1 meter deep. By considering total path loss, volume of complete system, and resolution, upper and lower frequencies are chosen. First, a UWB impulse for the frequency bandwidth of the impulse is chosen with rising time less than 1 ns, and then compact planar UWB dipole antenna suitable for frequency bandwidth of a UWB impulse is designed. Also, to receive reflected signals, a digital storage oscilloscope is used. For measurement, a monostatic technique and a migration technique are used. For visualizing underground targets, simple image processing techniques of A-scan removal and B-scan average removal are applied. The prototype of the system is tested on a test field in wet clay soil and it is shown that the developed system has a good ability in detecting underground metal objects, even small targets of several centimeters.

• Journal of Advanced Navigation Technology
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• v.22 no.1
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• pp.31-36
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• 2018

In this paper, we designed and implemented an ultra wideband(UWB) antenna with band rejection characteristics. The proposed antenna consists of a planar radiation patch with slots and ground planes on both sides. Due to the slots in the radiation patch, the antenna shows band rejection characteristics. U-type slot contributes for wireless local area network(WLAN, 5.15~5.825 GHz) band rejection and n-type slot contributes for X-Band(7.25~8.395 GHz) band rejection. To make voltage standing wave ratio(VSWR) less than 2.0 for UWB frequency band except rejection bands, the shapes of planar radiation patch and ground plane was modified. The Ansoft 's high frequency structure simulator(HFSS) was used for the design process and simulations of the proposed antenna. The simulated antenna showed VSWR less than 2.0 for all UWB band excepts for dual rejection bands of 5.15 ~ 5.94 GHz and 7.02 ~ 8.45 GHz. And measured VSWR for the implemented antenna is less than 2.0 for all UWB band of 3.10~10.60 GHz excluding dual rejection bands of 5.12~5.95 GHz and 7.20~8.58 GHz.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.16 no.1
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• pp.215-220
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• 2016

In this paper, a wideband antenna accomplished by adding a double sleeve of a rectangular planar monopole structure is proposed. In order to impedance matching of proposed antenna, the antenna performance was improved by adding two gap sleeves and outer sleeve for double sleeve structure. HFSS simulator of ANSYS corp. was used in order to confirm the antenna parameter characteristic. According to the simulation results, the VSWR was less than 2 for the range of 2.5GHz~10.5GHz. The frequency bandwidth is 8GHz. The frequency range of the actual fabricated antenna was 2.92GHz~10.32GHz, the frequency bandwidth is 7.4GHz. The measured radiation pattern frequency is 3GHz, 6GHz and 9GHz. The results are similar with dipole antenna pattern in all frequency. The antenna size is $40{\times}40mm^2$. The utilization possibility of the ultra-wideband planar monopole antenna could be confirmed according to compare and analyze the simulation and measurement data.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.6
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• pp.553-563
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• 2010

This paper presents a tapered slot-antenna(TSA) for optimal impulse-signal transmission in ultra-wide band(UWB). The proposed TSA provides radiates in end-fire direction, which meets an impulse-radio UWB(IR-UWB) system demands(e.g., low loss, thus less error throughout the UWB band). In order to minimize the pulse distortion, we used an wideband impedance transformer and a microstrip slotline. The pulse fidelity characteristics was evaluated with finite-difference time-domain(FDTD) analysis technique and pulse fidelity correlation equation. Approximately 93.89 % pulse fidelity was obtained between the two antennas in 0.5 m range. Additionally, derived chirp Z-transform algorithm enables us to utilize the zoom-in option on the pulse signal in few nano-seconds below. Thus, it is possible to analyze the pulse signal distortion, delay or dispersion characteristics.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.10a
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• pp.484-487
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• 2014

In this paper, We describe antenna characteristics for efficiently detecting human signs using small, planar and low power antenna. Then we can measure biological signals including respiration, heart rate, blood pressure, and blood sugar, using UWB (Ultra Wide Band) pulses, while does not contact the human body. The antenna need stable and wideband impedance characteristic, because it use gaussian pulse signal. Usually it has trade-off between wideband impedance and gain. But we don't considered array type antennas because we want to need small size. Generally the antennas that classified as frequency independent satisfy our requirements. Frequency independent antennas include spiral, log-periodic, sinuous, and etc. These antennas are possible to have shape planar type. In this paper, We tested these kind antenna's characteristics in center frequency 5 GHz, Especially circular patch and sinuous antenna designed and analyzed.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.6
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• pp.1057-1062
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• 2016

In this paper, a design method for a compact log-perio dic half-bow-tie dipole array antenna for an operation in a UWB band(3.1-10.6 GHz) is studied. The proposed antenna is miniaturized by using half-bow-tie shaped dipole elements instead of strip-type dipole elements, which are commonly used in a general log-periodic dipole array(LPDA) antenna, and by reducing the element spacing. The effects of the flare angle of the half-bow-tie elements and the spacing factor on input reflection coefficient and realized gain characteristics of the proposed log-periodic antenna are analyzed. The optimized antenna is fabricated on an FR4 substrate, and the experiment results show that the antenna has a frequency band of 2.95-11.31 GHz for a VSWR < 2, which assures the operation in the UWB band. In addition, the length and width of the proposed antenna are reduced to 32.1 % and 18.3 %, respectively, compared to the LPDA antenna.