• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.27 no.3
• /
• pp.261-268
• /
• 2016

In this paper, dual-polarized monopulse cassegrain antenna for W-band millimeter-wave seeker was proposed and the performances were verified by the measured results of the fabricated antenna. Dual-polarized monopulse Cassegrain antenna consists of main/subreflector, dual-polarized feed horn and monopulse comparator. The proposed feed horn has $2{\times}2$ array square waveguide feeding structure to make monopulse signals and it was designed using 90 degree rotational symmetric structure to receive dual-polarized signals. At the sum and difference channel, the measured vertical and horizontal polarization radiation pattern were similar. Measurement gains are 35.1 dBi for v-pol. and 35.6 dBi for h-pol. at the center frequency with 0.5dBi difference between each polarization and the side lobe level is below -21.6 dB.

• Aerospace Engineering and Technology
• /
• v.6 no.2
• /
• pp.211-218
• /
• 2007

Dual-polarization means to use two orthogonal polarizations, namely two independent channels in communication. This can be used to deal with high datarate caused by large amount of observed data in future LEO satellite. However, when two orthogonal polarizations are not perfectly independent to each other in practical, interference is probably raised in each channel, meaning that noise level in passband increases. XPD (Cross-Polarization Discrimination) is the ratio of the signal level at the output of a receiving antenna that is nominally co-polarized to the transmitting antenna to the output of a receiving antenna of the same gain but nominally orthogonal polarized to the transmitting antenna. In this paper, the influence of XPD on the communication between satellite and ground station was analyzed under the assumption that X-Band dual-polarization was applied to KOMPSAT-2 (KOrea Multi-Purpose SATellite-2). Through analysis, it was shown that more than 3dB of link margin was still achievable despite of worst axial ratio, 2.5dB, at ground station antenna when axial ratio of satellite antenna was about 0.5dB under 99% of environmental availability.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.11 no.10
• /
• pp.3880-3884
• /
• 2010

In this paper, circularly polarized micro-strip GPS antenna has been designed and fabricated. In order to improve of frequency properties, patch size, corner truncated size and feed positions were simulated using HFSS simulation program. Micro-strip GPS antenna was fabricated on the FR4 substrate of dielectric constant 4.4. The fabricated GPS antenna has that center frequency is 1.575GHz and insertion loss is -34.50dB.

• Proceedings of the KAIS Fall Conference
• /
• 2007.05a
• /
• pp.226-229
• /
• 2007

본 논문에서는 사각형 링을 갖는 UHF대 RFID 리더기용 소형 원편파 패치 안테나를 설계 제작하였다. 정사각형의 패치 안테나를 설계하고, 원편파를 위한 Truncated 패치 안테나를 설계한 후, 소형화를 위해 사각형의 링을 갖는 Truncated 패치 안테나를 설계하였다. 주파수 대역은 UHF대역인 902928MHz이며, 설계를 위하여 HFSS simulation올 사용하였다. 비유전율 4.3, 두께 1.6mm, 손실탄젠트 =0.019의 epoxy 기판을 사용하여 실현하였다. VSWR, 방사이득, RHCP, LHCP의 큰 변화없이 사각형의 링을 이용하여 기본 Truncated 안테나보다 6.37% 소형화시켰다.

• The Bulletin of The Korean Astronomical Society
• /
• v.37 no.2
• /
• pp.217.2-217.2
• /
• 2012

저궤도위성 관제용 소형안테나시스템의 송수신채널은 저궤도위성의 특성상 안테나구동부의 물리적인 제약조건을 갖으며 이러한 제약조건은 Rotary Joint 포트 수에 의존한다. 다목적 실용위성 5호와 같이 RH 및 LH 편파를 동시 사용하는 위성의 경우 지상안테나의 RF채널은 물리적으로 4포트가 필요하게 된다. 이러한 물리적 채널을 구현하기위해서는 안테나구동부가 대형화될 뿐만 아니라 고비용의 소요된다. 이와 같이 대형화 및 고비용의 단점을 극복하기위하여 Channel Combine Filter를 적용하여 채널이중화를 구현하였으며 단일채널을 갖는 저궤도위성 지상안테나시스템을 RH 및 LH 편파를 동시수신 가능하도록 성능을 개선하였다. 금번 개발된 Channel Combiner는 하나의 물리적 채널을 이용하여 위성으로부터 수신되는 수신신호 및 지상에서 송신하는 송신신호를 동시에 전송하도록 설계한 것으로서 수신되는 신호대비 송신신호의 크기가 상대적으로 고출력이기 때문에 송수신신호간의 간섭영향을 최소화할 수 있도록 설계하였다. 따라서 본 논문에서는 채널이중화를 위하여 개발된 Channel Combiner의 설계방법 및 성능 시험결과에 대하여 상세하게 기술하였으며, 최종적으로 RH 및 LH 편파를 동시에 사용하는 저궤도 위성을 이용한 수신결과에 대하여 기술하였다.

• Journal of Advanced Navigation Technology
• /
• v.6 no.3
• /
• pp.251-257
• /
• 2002

Design and characteristic improvement of existing folded dipole antenna is presented to adopt W-CDMA(1.885~2.170 GHz) wideband antenna radiators. The antenna structure has +/- 45 degrees dual polarization. In order to overcome the narrow bandwidth and low gain characteristic typical of the microstrip antenna, double layered structure was employed. The antenna achieved below - 20 dB reflection coefficients each ports, - 20 dB of port isolation, above 7 dBi of gain, providing evidence that the proposed design can be used in the W-CDMA service frequency band antenna.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.13 no.1
• /
• pp.245-252
• /
• 2018

In this paper, the dual band circular polarization patch antenna was designed by using band rejection characteristics of CSRR structure for geostationary satellites. A quadrangular CSRR structure was etched on the ground at the rear of the patch antenna's feed to obtain band rejection characteristics in between the receiving frequency band(1525~1559MHz) and transmission band(1626.5~1660.5MHz), and the corner of the patch antenna was truncated to enable circular polarization. It was confirmed that the resonant frequency of the patch antenna differs according to the size anc location of the CSRR and cirular polarization characteristics with simulation and measurement results. Measurement results shows the gain of about 0.2dB and 1.5dB in the TX and RX band.

• Journal of IKEEE
• /
• v.17 no.2
• /
• pp.140-144
• /
• 2013

This paper presents the novel design of circular polarized Ka-band horn array antenna. The element antenna of the arrya is composed of two parts, microstrip patch and square horn, and the microstrip patch is fed by corner truncated microstrip patch for circular polarization. The patch antenna has the role of a feeder and polarizer of the horn, thus the whole size of the horn antennae can be considerably reduced. The $1{\times}8$ horn array was designed and fabricated by the spacing of $0.9{\lambda}_0$ among the element horn. The element horn has typical gain of 8dBi and axial-ratio bandwidth of 4.9% at 3dB, and the minimum gain and axial-ratio bandwithd of the array is 14dBi and 8.2%.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.11 no.4
• /
• pp.642-648
• /
• 2000

We introduce a new application of the genetic algorithm for design of the coaxial fed circularly polarized rectangular microstrip antenna. The GA shows excellent results for the design of the microstrip antenna which have a very complex objective function including the input impedance, the effective loss tangent and the axial ratio. The objective function is derived from the cavity model, and the size and the feeding point are optimized by the genetic algorithm. The experimental results show good agreement with the simulated results.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.19 no.8
• /
• pp.1759-1764
• /
• 2015

In this paper, we considered a design method of a circular polarization (CP) antenna for UHF (ultra high frequency) RFID (Radio Frequency IDentification) readers. The antenna is a dual-fed circular microstrip patch which produces right-handed CP. Quadrature hybrid coupler is used for dual feeding. The outputs of the coupler and circular patch are connected through copper wires, and the inductive reactance produced by the connecting wires is compensated by a ring-shaped slot inserted inside the circular patch. The effects of the geometrical parameters of the proposed antenna on the antenna performance are examined, and the parameters are adjusted to be suitable for the operation in North American UHF RFID band (902-928 MHz), which includes domestic UHF RFID band. The antenna is fabricated, and the experiment results reveal a frequency band of 854-993 MHz for a voltage standing wave ratio < 2. The fabricated antenna is connected to a commercial RFID reader, and it showed a good performance of tag identification.