• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.5
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• pp.413-420
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• 2009

We propose a novel feed network for a $2{\times}2$ array antenna to form a sectoral conical beam. The proposed feed network, which is a symmetrical structure, consists of four $90^{\circ}$ hybrids, a crossover, and four $90^{\circ}$ delay lines. To verify the performance of the feed network a $2{\times}2$ array antenna and the feed network are fabricated on a microstrip structure, and the radiation patterns are measured at the center frequency of 2.57 GHz. The maximum radiation is measured at the $45^{\circ}$ elevation angle and at the $45^{\circ}$, $135^{\circ}$, $225^{\circ}$, and $315^{\circ}$ azimuth angles depending on the choice of the input port of the feed network.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.4
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• pp.351-356
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• 2009

A dual-mode annular ring antenna for both global positioning system(GPS) and satellite digital multimedia broad-casting(DMB) is designed. The proposed antenna consists of a coupling feed line and four slots on the annular ring patch. The gap between the feed line and the annular ring patch is used for an input impedance matching, and the slot length is used for adjusting the resonant frequency of the $TM_{21}$ mode at the DMB frequency. The antenna was fabricated and measured. The experimental results show that the antenna resonants at the GPS and DMB frequencies with suitable bandwidths, and had a broadside radiation pattern at the GPS band and a conical beam radiation pattern at the DMB band.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.4
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• pp.363-368
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• 2003

In this paper, the characteristics of the horn antenna for the high power transfertation system is stuided and several kinds of a horn antenna are compared and finally a conical hem antenna using multi-mode is proposed. In the high power system, the efficiency of power transfer is very important. Therefore the feeding hem of a reflector must have a circular symmetric radiation pattern. And the side lobe must be suppressed to reduce a spillover power loss and interference. By using multi-mode in a circular hem antenna, the whole length can be shorter and the radiation pattern can be adjusted according to the shape and direction of a reflector. This is confirmed by the experiments.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2001.10a
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• pp.222-225
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• 2001

This paper describes design and performance test of dual-mode horn antenna for HAPS (High Altitude Platform Station) in 47.2 - 47.5 GHz and 47.9 - 48.2 GHz bands. To obtain the optimal geometry parameters of it. the conical section is represented by a stepped transition composed of a set of cylindrical waveguide sections. For each step. the corresponding generalized scattering matrix is calculated. The elements of the matrices at the open end of the horn, are calculated by the rigorous formulas of the factorization method. To verify the theoretical results, a horn breadboard was manufactured for the medium frequency of 47.7 GHz and its radiation beam patterns were measured. The calculated and theoretical results are in good agreement.

• Journal of Species Research
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• v.10 no.3
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• pp.287-300
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• 2021

Three new species of Myzomolgus are described as associates of sipunculans from a tidal flat in Phuket, Thailand. As diagnostic features, Myzomolgus leptocercosus n. sp. has elongate caudal rami which are 10.7 times longer than wide, 5 setae and a conical process on the first antennular segment, an armature formula 1, 0, 1+sucker, and 6 of antenna, and an inner coxal seta on all swimming legs. Myzomolgus spatulatus n. sp. lacks a rostrum, but bears 4 setae and a spatulate process on the first antennular segment, an armature formula 0, 0, 2+sucker, and 6 of the antenna, the inner coxal seta on legs 1-3, and 5 armture elements on the third endopodal segment of legs 1-3. Myzomolgus cucullatus n. sp. has short caudal rami which are 1.60 times longer than wide, a broad, hood-like tergite of fouth pedigerous somite, 4 setae only on the first antennular segment, the armature formula 0. 0. 2+sucker, and 6 of the antenna, and no iiner coxal seta on the swimming legs.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.3 s.94
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• pp.260-269
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• 2005

In this paper, we propose a microstrip line fed printed monopole antenna which has an ultra-wideband characteristic. Proposed antenna can improve the bandwidth characteristic with the taper structure formed by modified ground plane and radiating element. Measured impedance bandwidth ratio of the antenna is more than 30:1; from the lower frequency of 0.89 GHz to the upper frequency of more than 30 GHz for VSRW$\leq$2. The antenna has conical radiation pattern that has low radiation gain to $\theta$=0$^{\circ}$ direction and higher radiation gains as $\theta$ increases.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.44 no.3
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• pp.39-44
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• 2007

In this paper, satellite searching and tracking method for the satellite antenna in naval vessels system are proposed. For fast searching satellite, Wide Range Search(WRS) algorithm is proposed where the signal strength of side-lobe is utilized as well as that of main-lobe. Satellite tracking algorithm to stabilize satellite antenna is based on conical-scanning which is accomplished by the use of the sub-reflector located in front of the focus of the reflector. The sub-reflector rotates about a slightly tilted axis by means of a motor and shapes the antenna beam to utilize stabilization. To show the validity of the proposed method, an experimental example is represented.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.11 s.114
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• pp.1096-1104
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• 2006

In this paper, the broadband antenna for the combined base station of Cellular/PCS/IMT-2000/Wibro and S-DMB services is designed and the proposed antenna allows having sufficient coverage for each service band. In order to get the broadband impedance matching, the tapered sections are applied on the both terminus of hi-conical respectively. The design parameter is calculated and simulated by using FDTD method. As a result, the measured bandwidth of the proposed antenna is $0.79GHz{\sim}2.93GHz$ and the gain is distributed from 5.5 dBi up to 8.19 dBi.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.9 no.3
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• pp.330-337
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• 1998

In this paper, we fabricated a pair of circulaly polarized conical horn antennas for evaluating the scattering characteristics of a hemispherical reflector and of propagation characteristics in in-building environments, which is required for constructing a new wireless in-building communication system of microwave band consisted of a hemispherical reflector installed on the ceiling. The measurements show the fairly good features such that cross-polarization discremination more than 27 dB and axial-ratio less than 1.25 dB.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.42 no.12
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• pp.165-170
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• 2005

In this paper, influences of a ultra wideband (UWB) antenna on impulse channel measurement are investigated in time domain (TD) and frequency domain (FD) as well. Firstly, impulse response of an UWB antenna is obtained and then using the result of impulse response of the UWB antenna, influences of the antenna on impulse radio channel is analyzed. Furthermore, using the impulse response of the UWB anenna, method of impulse radio channel analysis is presented by excluding the effect of the antenna from an impulse radio channel. For verifying the theory, a modified conical monopole antenna is designed for measuring impulse radio channel and its impulse response is obtained. After that, in order to investigate the effects of the UWB antenna on an impulse radio channel, multipath environments are set up in an anechonic chamber and transmission coefficient for each multipath environment is measured with an aid of vector network analyzer. Data measured in frequency domain is transformed into those in time domain by way of signal processing. Measurement shows that such properties of the antenna as dispersion and ringing affect impulse radio channel. Moreover, using the impulse response of the antenna, impulse response of only multipath channel is obtained.