• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.9
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• pp.933-939
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• 2010

In this paper, modified spiral monopole printed antenna for dual band operation in GPS(1.57~1.577 GHz) and WiBro(2.3~2.4 GHz), WLAN(2.4~2.48 GHz) is proposed. To control the frequency ratio of the antenna for dual band operation freely, distance between inner lines of the spiral is diversified by using the different current distribution between basic resonance frequency of spiral monopole antenna and harmonic resonance frequency$(3\lambda_H/4)$. And also the branch line is inserted. Bandwidth(-10 dB) of the antenna is measured 140 MHz(1.47~1.61 GHz) in basic resonance frequency and 420 MHz(2.29~2.71 GHz) in harmonic resonance frequency$(3\lambda_H/4)$. The peak antenna gains are measured 2.825 dBi in GPS(1.57 GHz), and 3.65 dBi in WiBro(2.35 GHz), and 4.564 dBi in WLAN(2.44 GHz).

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.39 no.9
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• pp.883-888
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• 2011

The UAV tracking antenna system based on GPS has a characteristic of update of position information which can occurs a position error. To reduce the position error, UAV tracking antenna system separates period of GPS update-rate and predicts the position of UAV using divided time points. These process improves the tracking performance of UAV. To predict the position of UAV by divided time points, we used a linear kalman filter based on the velocity and acceleration. Using this system, we measured velocity and acceleration according to the change of position. Finally, we can predict the change of position on divided time points.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.4
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• pp.343-350
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• 2003

Circularly polarized-dual band antenna for GPS(Global Positioning System) and satellite radio system is developed and measured. Both circular polarization and overall antenna dimension reduction are achieved by placing a partially filled high-permittivity substrate under radiating edges. The bandwidth is also improved by choosing an optimal geometric configuration with a partially filled high permittivity substrate. The proposed antenna can be installed on moving vehicles or ships.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.42 no.4
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• pp.723-730
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• 2017

In this paper, we consider an online compensation algorithm considering the mutual coupling and suggest a new GPS antenna array to apply. To evaluate the anti-jamming performance for the proposed antenna array, ULA and URA, we divide direction finding of multiple jamming signals into environments. 1. there is no mutual coupling. 2. there is mutual coupling but no compensation. 3. mutual coupling is compensated. RMSE analysis showed that the online compensation algorithm works and that peak detection is possible for multiple jamming signals.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.43 no.2
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• pp.133-140
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• 2015

In this paper, a roll angle estimation method of a rolling airframe using a low grade GPS and a roll rate gyro is proposed. The strength of the received signal of the GPS antenna attached on the rolling airframe is maximized when the GPS satellite is placed on the plane determined by the x-axis of the rolling airframe and the GPS antenna axis. Under the assumption that the x-axis of the rolling airframe is coincident with its velocity vector, the roll angle of the rolling airframe is calculated from the relative position vector of the satellite to the GPS when the GPS signal strength becomes maximum. The Kalman filter combined with a roll rate gyro is introduced to increase the determination accuracy of the roll angle. The performance of the proposed method is verified via 6-DOF simulations.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.41 no.10
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• pp.103-108
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• 2004

In this paper, a compact patch antenna with four T-slits fed by crossed aperture coupling is proposed for miniaturized Portable GPS handsets. The mechanism for compact size antenna is investigated with the behavior of the currents on the radiating patch. The equivalent surface current path due to the slits is lengthened, reducing the resonant frequency at a fixed patch size. The results of embedded T-slits for compact antenna size show that the resonant frequency is significantly lowered from 2.545GHz to 1.575GHz, corresponding to a 44.65% antenna size reduction compared to reference design. Experimental results show that good CP radiation patterns are obtained and impedance bandwidth (VSWR $\leq$ 2), 3dB axial ratio are about 21MHz, 19MHz at the center resonant frequency, respectively.

• Journal of electromagnetic engineering and science
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• v.17 no.2
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• pp.108-110
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• 2017

The global positioning system (GPS) is a useful system in civilian and military applications. However, because of the weak signal, GPS receivers are vulnerable to interference caused by unwanted signals or intentional jammers. To alleviate this issue, a controlled reception pattern antenna (CRPA) array can be employed to adaptively place radiation pattern nulls toward the direction of the signal interference. The performance of the CRPA array improves as the number of antenna elements increases. Therefore, antenna miniaturization is highly desirable for CRPA applications. We designed a compact CRPA array based on seven electrically miniaturized microstrip patch antennas (MPAs) on a 5-inch ground platform. We used a non-Foster matching circuit to match efficiently miniaturized MPAs on an FR-4 substrate. Experimental results show that the non-Foster matching circuit significantly improves such elements of antenna performance as return loss and antenna gain. In addition, we confirmed that the mutual coupling of the proposed CRPA array is less than -45 dB.

• Journal of the Institute of Convergence Signal Processing
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• v.16 no.4
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• pp.156-161
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• 2015

In this paper, a dual-polarized multi-band multi-layer antenna for a vehicle, which operates in the GPS, bluetooth, and DSRC bands, was implemented. The antenna was designed as a multi-layer structure, and a FR4-epoxy substrate with =4.4 and =1.6mm was used. GPS and DSRC antennas have circular polarized characteristics, and a single probe feeding method was applied. Simulated results by Ansys HFSS v11 was compared with the measured ones. The size of the optimally designed antenna is $67mm{\times}67mm{\times}4.8mm$, -10dB bandwidth of the anatenna was measured to be 820MHz, 127MHz, and 862MHz in each band, and 3dB AR bandwidth of the antenna was simulated to be 19MHz and 110MHz in GPS and DSRC bands. The results confirmed that suggested system satisfies the system requirements.

• The Journal of the Korea institute of electronic communication sciences
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• v.5 no.6
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• pp.563-567
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• 2010

In this paper, circularly polarized micro-strip GPS of 1.57 GHz and DMB of 2.63~2.65GHz antenna have been studied. In order to improve of frequency properties, parameters such as patch size, corner truncated type, and feed positions were simulated using HFSS program. GPS and DMB antenna were fabricated and characteristics were measured using network analyzer.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.24 no.4
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• pp.319-326
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• 2006

To get the highly-accurate and precise position of a GPS receiver, they should consider the state-of-the-art GPS force and measurement models. Especially, the phase center variations (PCV) of a GPS antenna can cause several centimeters of positioning errors in the vertical direction. In this study, we implemented four different models of PCV and evaluated their impact on the computed coordinates. The test data were taken from the 14 National Geography Information Institute permanent GPS stations and 30 Minisry of Government Administration and Home Affairs sites. For different combinations of calibration methods, an average of 1.3-2.6cm of height difference was observed. Also, we found a maximum error of ${\sim}4mm$ in the estimates of the precipitable water vapors.