• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.14 no.2
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• pp.127-134
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• 2014

This paper presents a study on the radiation characteristics of low-VHF band electrically small antenna for direction finding. Firstly, it is simulated the antenna for mounting on flat ground and tank model(in 40MHz), and measured for mounting 1/10 scaled model(in 400 MHz). In case of flat ground feed at ${\phi}=0^{\circ}$, $180^{\circ}$(xz-plane), yz-plane $E_{\phi}$ (H-plane) and xz-plane $E_{\theta}$ (E-plane) radiation patterns are hemispheric omni-direction due to effect of narrow ground side. Then, in case of tank model, it is shown equally in case of the flat ground, yz-plane $E_{\phi}$ (H-plane) and xz-plane $E_{\theta}$ (E-plane) radiation patterns are hemispheric omni-direction nearly without effect of mounting position. Therefore, the suggested electrically small antenna for direction finding, in case of mounting on ground narrow side xz-plane(E-plane), is shown more stable radiation patterns as direction finding antenna.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.1
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• pp.11-19
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• 2013

In this paper, we designed and implemented the planar monopole antenna using the coupling effect for the multi-band characteristic. A parasitic element for the multi-band characteristic based on a rectangular patch with single resonance is inserted. Spiral shaped parasitic element is used for minimizing the antenna size and obtaining the multi-resonance characteristic. The frequency characteristics are modified and optimized by varying specific parameters. By inserting an L-shaped resonator at both sides of the feed line which connected through the via hole to the ground plane, unnecessary frequency bands are eliminated. Proposed antenna dimension is $40{\times}60{\times}1mm^3$. It is fabricated on the FR-4 substrate(${\varepsilon}_r$=4.4) using a microstrip line of $50{\Omega}$ for impedance matching. By measurement results, the characteristic of the return loss under -10 dB are 1.714~2.496 GHz, 2.977~4.301 GHz, and 4.721~6.315 GHz, and the radiation patterns have omni-directional shapes.

• Journal of Advanced Navigation Technology
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• v.21 no.2
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• pp.193-199
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• 2017

In the paper, a dual band-notched monopole antenna is proposed for 2.4 GHz WLAN (2.4 ~ 2.484 GHz) and UWB (3.1 ~ 10.6 GHz) applications. The 3.5 GHz WiMAX band notched characteristic is achived by a pair of L-shaped slots instead of the previous U-shaped slot on the center of the radiating patch, whereas the 7.5 GHz band notched characteristic is achived by C-shaped strip resonator placed near to the microstrip feed line. The measured impedance bandwidth (${\mid}S_{11}{\mid}{\leq}-10dB$) is 8.62 GHz (2.38 ~ 11 GHz) which is sufficient to cover 2.4 GHz WLAN and UWB band, while measured band-notched bandwidths for 3.5 GHz WiMAX and 7.5 GHz bnad are 1.13 GHz (3.15 ~ 4.28 GHz) and 800 MHz (7.2 ~ 8 GHz) respectively. In particular, it has been observed that antenna has a good omnidirectional radiation patterns and higher gain of 2.51 ~ 6.81 dBi over the entire frequency band of interest.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.4 s.95
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• pp.366-372
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• 2005

This paper presents analysis of a slot array antenna having a low side lobe level and high front-to-back ratio for a repeater system of a satellite DMB(Digital Multimedia Broadcasting) service. Antennas for this repeater system require a high gain and enough isolation to reduce interferences between signals in system. Therefore, it is necessary to suppress a side lobe level and to increase front-to-back ratio. Unlike a structure 134 by lossy microstrip lines, in this work a single cavity-backed slot antenna array using a single waveguide feed is proposed to obtain the reliability for high power handling and high radiation efficiency. The side lobe level and front-to-back ratio are enhanced with tapered array technique and an optimized vertical reflector. The measured side lobe levels in H- and E-plane are under $-33.24\;\cal{dB}$ and $-35.78\;\cal{dB}$, respectively. The front-to-back ratio over $37.84\;\cal{dB}$, and the peak gain of over $17\;\cal{dBi}$ are measured.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.12
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• pp.1327-1336
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• 2012

In this paper, the dual-faced monopole antenna, which is arranged by numerous rectangular ring patches in sequence for the multi-bands is proposed. The ring type structure of the patch can be increased the bandwidth. Therefore the bandwidth and beam width are improved by using multiple arrayed patches. When the ring type patches are inserted serially, the resonance frequencies are occurred by the current flow from the first ring patch. It is possible because the gap between the patches is very narrow. In addition, if the patches are composed on the same plane as the feed-line, fabrication could be very difficult because the gap between the patches is extremely narrow. The thickness and permittivity of the antenna, moreover, are very important parameters because both sides of the substrate are used. We finally found the optimal thickness and permittivity to generate the coupling effect by simulation. All patches are consisted of 4-steps which the patch size was decreased 85 % by each step. In conclusion, the resonant frequency bands are 1.75~2.6 GHz(850 MHz), 3.24~3.46 GHz(220 MHz), 3.8~4.0 GHz(200 MHz), and 4.4~4.9 GHz(500 MHz).

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.1
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• pp.136-141
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• 2003

In this paper, S-type transformed MSA and transformed MSA load by a Capacitor not to limit the electric force on the MSA is proposed. Bandwidth of the designed and fabricated S-type transformed MSA is 5.75% at the resonated frequency of 2.24GHz and the resonant frequency and bandwidth versus change of any arbitrary feed point is observed. also, E-plane and H-plane in the Measured radiation pattern characteristic of S-type transformed MSA is compared and analyzed.

• Journal of electromagnetic engineering and science
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• v.4 no.4
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• pp.150-155
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• 2004

Universal design equations are presented for the H-plane T-junction power divider with a circular conducting post in a rectangular waveguide. For a given operating frequency and power split ratio, the post offset from the T-junction center line, the distance between the post and the waveguide wall, and the post diameter can be adjusted to obtain a minimum reflection at the input waveguide. Optimum values of the post offset are given in terms of the normalized frequency and the power split ratio. Corresponding values of the post diameter and the distance of the post from the waveguide wall are given in terms of the normalized frequency and the post offset.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.05a
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• pp.546-550
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• 2003

For dual-band operation, it can be done by loading two pair of narrow slots in the equilateral-triangular patch, one embedded close to the side edges of the patch and the other inserted at the bottom edge of the patch. The obtained two operating frequencies are of same polarization planes. The frequency ratio of the two operating frequencies is turnabled by varing the positions and lengths of the inserted slots at the bottom edge of the patch. In this paper, A single-feed equilateral-triangular microstrip patch with two pairs of narrow slot for dual-frequency operation is printed on the substrate(TMN-4 Rosers Co.) of the 60 miles. the antenna radiation characteristics are calculated by Ensemble ver. 5.0 software, and compared with the experimental results.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2006.07a
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• pp.708-708
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• 2006

• Journal of the Korean Institute of Telematics and Electronics
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• v.20 no.3
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• pp.40-44
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• 1983

A wide band quasi-log periodic microstrip antenna is designed using circular-disc microstrip patches as a basic radiator. The radiating elements are series-fed by a coplanar feeding network which consists of an open circuited feed line with a branch line connected to each radiating element. Experiment results show that the values of VSWR are less than 2.3 over the range of 2.72-3.43 GHz.