• 전기전자학회논문지
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• 제24권2호
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• pp.536-542
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• 2020

본 논문에서는 광대역 지향성 방사패턴을 가지는 자연에서 영감을 얻은 새싹 모양 안테나를 제안한다. 모션감지 센서 응용을 위해 넓은 빔폭을 가지는 새싹 모양의 기울어진 방사체를 설계하였다. 확장된 잘려진 접지면을 반사기로 작용하도록 하여 지향성 방사패턴을 가지도록 하였다. 평형 방사체를 급전하기 위하여 우수한 진폭 및 위상 평형도를 가지는 광대역 발룬을 활용하였다. 제안된 안테나는 8.5에서 14.5 GHz의 넓은 주파수 대역폭과 넓은 빔폭을 가졌으며, 방사 효율은 90% 정도이었다. 측정된 이득은 4에서 5dBi이며, 전후방비는 10~20dB이었다. 제안된 안테나는 광대역 넓은 빔폭과 지향성 방사패턴을 요구하는 이미징 센서, 위상 배열 시스템 및 레이더 등에 활용될 수 있음을 보였다.

• 마이크로전자및패키징학회지
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• 제16권1호
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• pp.21-25
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• 2009

Si CMOS 공정을 사용하여 소형의 RFID 태그 안테나를 Si 기판위에 구현하고 그 전기적 특성을 평가하였다. HFSS 전자계 시뮬레이터를 사용하여 13.56 MHz 주파수 대역에서 마이크로스트립 선폭 및 선간격을 $50{\sim}200{\mu}m$ 영역에서 조절하면서 안테나 패턴을 설계하였다. S 파라메터, 자기공진주파수 및 Q 값을 시뮬레이션으로부터 도출하였다. 마이크로스트립 선폭 및 선간격이 각각 $100{\mu}m$ 인 10턴의 안테나에서 자기공진주파수는 80 MHz 정도이며 Q 값은 9 정도로 계산되었다. Si 기판 태그의 마이크로스트립 안테나는 DC 스퍼터링 공정에 의해 Al $2{\mu}m$를 증착하여 구현하였다. 리더-태그를 밀착시킨 조건에서 태그 안테나 루프에서는 약 4.3 V의 전압이 검출되었다.

• Journal of Positioning, Navigation, and Timing
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• 제12권2호
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• pp.101-111
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• 2023

Many spoofing detection studies have been conducted to cope with the most difficult types of deception among various disturbances of GPS, such as jamming, spoofing, and meaconing. In this paper, we propose a spoofing detection scheme based on elevation masked-relative received power between GPS L1 and L2 signals in a system using a multi-band array antenna. The proposed scheme focuses on enabling spoofing to be normally detected and minimizes the possibility of false detection in an environment where false alarms may occur due to pattern distortion among elements of an array antenna. The pattern distortion weakens the GPS signal strength at low elevation. It becomes confusing to detect a spoofing signal based on the relative power difference between GPS L1 and L2, especially when GPS L2 has weak signal strength. We propose design parameters for the relative power threshold including beamforming gain, the minimum received power difference between L1 and L2, and the patch antenna gain difference between L1 and L2. In addition, in order to eliminate the weak signal strength of GPS L2 in the spoofing detection process, we propose a rotation matrix that sets the elevation mask based on platform coordinates. Array antennas generally do not have high usefulness in commercial areas where receivers are operated alone, but are considered essential in military areas where GPS receivers are used together with signal processing for beamforming in the direction of GPS satellites. Through laboratory and live sky tests using the device under test, the proposed scheme with an elevation mask detects spoofing signals well and reduces the probability of false detection relative to that without the elevation mask.

• Journal of electromagnetic engineering and science
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• 제14권1호
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• pp.31-35
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• 2014

An ultra-wideband (UWB) circular monopole antenna with a multiband-notched characteristic is proposed. The multiband-notched filter consists of three different sized folded slots, which are distinctly assigned for the notched band at the 3.5-GHz WiMAX, 5-GHz WLAN, and 8-GHz ITU bands. The proposed antenna results in a measured ${\mid}S_{11}{\mid}$ < -10 dB, which completely covers the UWB band (3.1 10.6 GHz) with three notched bands at 3.5, 5.5, and 8.0 GHz. The antenna yields an omnidirectional radiation pattern and high radiation efficiency.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 ITC-CSCC -1
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• pp.519-522
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• 2002

An active phased array antenna consists of many channels. Each channel has a different initial phase shift and gain because of the inequality in the active circuits themselves, interface between radiators and active circuits, and beam-forming circuits and other antenna system configurations. This raises an inherent problem in active phased array antennas. To compensate for this problem the initial phase and gain of each channel should be calibrated. This paper presents an efficient calibration method for an initial phase variation of each channel in active phased array antennas. We tested our method in an active phased array antenna, and obtained good results in the radiation pattern and beam direction of antenna.

• Journal of Electrical Engineering and Technology
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• 제11권6호
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• pp.1777-1782
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• 2016

A compact and broadband balun is designed using a conventional right-handed transmission line (RHTL) and a left-handed transmission line (LHTL) with lumped elements only. The proposed balun maintains a phase difference of $180^{\circ}{\pm}12^{\circ}$ at the output ports for the frequency range of 1.27 GHz-2.69 GHz. Nevertheless, the circuit size is merely $9.5mm{\times}12.7mm$. To verify the performance of the proposed balun, we attached it to a dipole-type antenna and observed that the return loss is greater than 10 dB for the frequency range between 1.86 GHz and GHz. The radiation pattern and peak gain are similar to those of the dipole antenna with a conventional balun.

• Journal of electromagnetic engineering and science
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• 제10권3호
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• pp.171-174
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• 2010

In the paper, a printed dual-dipole array antenna is presented. A 4-way planar SIW power divider is adopted for feeding the array antenna. The dual-dipole is adopted as radiation elements which greatly improves the impedance band. The measured bandwidth larger than 31 % for VSWR$\leq$1.5 operating near 14 GHz is achieved and in agreement with the simulated results. The radiation E-plane and H-plane radiation pattern is presented in the paper. The radiation gain is also presented in the paper.

• Journal of Electrical Engineering and Technology
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• 제10권4호
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• pp.1738-1745
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• 2015

Radiation characteristics of a probe-fed rectangular microstrip patch antenna printed on a finite grounded high permittivity substrate are investigated systematically for various square grounded dielectric substrate sizes with several thicknesses and dielectric constants by experiment and full wave simulation. The effect of the substrate size on the radiation characteristics of a rectangular patch antenna is mainly determined by the effective dielectric constant of surface waves on a grounded dielectric substrate. As the effective dielectric constant of surface waves increases, the substrate sizes for the maximum broadside gain and the required onset for a large magnitude of squint angle decrease, while the variations of the broadside gain, the front-to-back ratio, and the magnitude of squint angle versus the substrate size increase due to the increase of the power of the surface wave.

• 한국항행학회논문지
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• 제15권6호
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• pp.1008-1014
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• 2011

본 논문에서는 WLAN 대역과 WiMax 대역에서 통신을 가능하게 하기 위한 다중대역 프랙탈 마이크로스트립 패치 안테나를 설계 및 제작하였다. 제안된 안테나는 다중공진을 위해 공진주파수, 임피던스정합, 극성 및 방사패턴을 훌륭히 제어할 수 있으며 다중 독립 주파수를 만족시키기 위한 세 개의 반원의 프랙탈 패치를 삽입하였다. 제안된 구조는 반원의 프랙탈 구조가 연속적으로 이루어져 있는 형태의 안테나로써 하나의 반원이 하나의 대역을 나타내고 있다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2008년도 하계종합학술대회
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• pp.209-210
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• 2008

We have proposed a bow-tie UWB antenna using a U-shaped stub. The proposed antenna covers the entire ISM frequency (2.45 GHz) and DS-OFDM UWB band ($3.1\;{\sim}\;5\;GHz$). Simulated and measured results are found to be in good agreement with each other. The designed antenna has the figure-of-eight radiation pattern, wide bandwidth, dual-band, and negligible dispersion over the operating frequency band.