• The Journal of the Korea institute of electronic communication sciences
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• v.15 no.5
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• pp.849-856
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• 2020

The Angle-of-Arrival(AOA) information for an array antenna receiver is one of the important factors for estimating the location of specific signals and detecting signals efficiently, in various situations. The AOA estimator in the satellite environment can rapidly calculate the AOA information in the wide area, utilizing a planar (grid, circular) array antenna mounted on the satellite. Since the satellite receiver has the limitation of the array antenna size, the concentric circular (ring) array (CCA or CRA) antenna structure with comparatively small size but with multiple antenna elements is more efficient than the uniform circular array (UCA) structure, for the satellite environment. In this paper, we introduce a cascade AOA estimation algorithm based on CRA, consisting of CAPON and Beamspace MUSIC. In addition, we provide computer simulation examples for verifying the estimation performance of the cascade AOA estimation algorithm based on CRA and compare it to the case of UCA.

• 한국정보통신설비학회:학술대회논문집
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• 2007.08a
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• pp.427-431
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• 2007

Applications in present-day mobile communication systems particularly require miniaturized dimensions and low-profiles of antenna in order to meet the mobile units. Thus, size reductions and bandwidth enhancements are becoming crucial design considerations for practical applications of microstrip antennas. The motivation of further experiments have been stepped to follow those studies for achieving compact and broadband, even multiplied operation modes, which are greatly increased with much attentions recently. To obtain broadband, single-feed, circularly polarized characteristics of microstrip antennas, a design with feed-line ought to be a factor of two. Usually, diagonally balanced-line feeds with hybrid coupler are employed to attain circular polarizations. We firstly formulated DGS (Defected Ground Structures) based operation principles of the entire microstrip components and therefore were able to derive impedance variance of feed-lines. After verifying corresponding experimental results, we targeted the frequency bands of UHF RFID (Ultra High Frequency Radio Frequency IDentification) and approximately of 0.4-2.4GHz have exhibited remarkable two resonance amplitudes as a dual band antenna. Our secondary researches were aimed to design quad band microstrip antenna which represents four resonance characteristics within the identical frequency bands as well. Microstrip patch has been meandered to lengthen the electrical paths, and the other design criteria with respecting physical parameters including radiation patterns and impedance bandwidths measurements will be described for verification. Advisable applications of these antennas can be GSM850, GSM900, GPS (L1-1575 and L2-1227) and UMTS-2110 of cellular systems, which extremely desire multiband and minimum size.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.12 no.1
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• pp.58-65
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• 2013

It's introduced a BLA(Branch Loop Antenna) that is modified from conventional loop, and verified antenna performances for applying to mobile handset. Branch elements are added to a rectangular loop, and low resonance is obtained by the length of the branch line. When resonance frequency of a single loop is 2.5GHz, BLA had near 900 MHz under the same antenna size. Multiple resonances are established by the locations of branch connection and their lengths. By the implementation and measurement for the dual band BLA, it's showed 75MHz -10dB bandwidth and -3.03~-1.46dBi average gains with 49.73~71.39% efficiencies at GSM900 band, and 90MHz -6dB bandwidth and -8.14~-2.17dBi average gains with 15.34~60.62% efficiencies at DCS1900 band. And H-plane radiation patterns were omni-directional. These performances are good for the mobile handset antenna.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.23 no.7
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• pp.1677-1688
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• 1998

In this paper, we analyze the performance of a DS-CDMA system employing adaptive adaptive array antenna technology at base-station. For the analysis the receiving architecture of a multiple team adaptive base-station array antenna is proposed as a major system omponent, and signal to interference and noise ratio(SINR) on the proposed architecture is developed. We show that the perfomance enhancement of the CDMA system is represented as great reduction of interfreence by employing an array antenna capable of resolving the angular distribution of the mobile users as seen at the ase-station. The energy associated with each mobile or a group of mobiles is thus confined within the addressed volume, greatly reducing the amount of co-channel interference experienced from and by neighboring co-channel cells. In order to ascertain the benefits of such an antenna, a theoretical approach, which eis based on the conventional and proposed antenna systems in a typical mobile radio environment, is adopted. Finally computer simulation results show the insight into how the adaptive array antenna operates when used in conjunction with DS-CDMA and illustrate the potential benefits in the SINR point of view.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.45 no.5
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• pp.409-416
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• 2017

In order that multiple wideband RF transmitters which have mission to deliver essential information to aircraft operate at the same time, RF transmitter has a variable sub-carrier frequency to modulate the signal. In case of exposure to weak environment, Wide-band RF transmitter is designed to check component of transmitter that includes antenna BIT to increase system reliability. Normally, Antenna BIT measure the reflection RF power of antenna to check system condition. However, Antenna BIT has a difference that depends on testing frequency to use the long RF cable which is located between the power amp and the antenna. The periodic phenomenon of the reflected antenna power are theoretically explained about dependence on the RF cable length. Based on presented result, suggested measurement methods is effectively able to be applied to diagnosis system condition.

• Journal of Advanced Navigation Technology
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• v.25 no.5
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• pp.384-389
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• 2021

An optimal ground station (GS) antenna pattern design method for network-based UAV command and control communication systems considering complexity and performance is presented. The GS antenna consists of multiple side sectors and one upward sector. The antenna gain for each vertical/horizontal angle of the GS antenna according to the change of antenna design parameters such as the number of sectors, horizontal and vertical beam-width, and tilt-angle is modeled, and the effect of the parameter changes on the signal-to-noise ratio (SNR) distribution in the virtual three-dimensional space is analyzed. It is observed that the tilt-angle of the side sectors has the greatest effect on the performance, and the longer the distance between GSs, the higher the maximum altitude and the smaller the number of side sectors, the tilt-angle should be lower. In addition, it is observed that the wider vertical beam-width of the side sector is advantageous in maximizing the lowest SNR, but narrow vertical beam-width is advantageous in maximizing the average SNR.

• Journal of Mechanical Science and Technology
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• v.16 no.11
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• pp.1367-1378
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• 2002

This paper investigates observability properties of strapdown INS aided by a GPS antenna array. The motivation to consider a GPS antenna array is that the lever-arms between the GPS antennas and IMU play an important role in the estimation of vehicle attitude and biases of IMU. It is shown that time-invariant INS error models are observable with measurements from at least three GPS antennas. It is also shown that time-varying error models are instantaneously observable with measurements from three antennas. Numerical simulation results are given to show the effectiveness of multiple GPS antennas on estimating vehicle attitude and biases of IMU when IMU has considerable magnitude of biases.

• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.123-126
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• 2005

In this paper, we propose a multiple slotted dual-band square patch antenna with CP(Circular Polarization) characteristic. And we present the simulation and measurement results of the design example. We designed a slotted patch antenna by using computer simulation program, Zeland IE3D, and then some tuning followed with measurements. Measured -10dB bandwidths of $S_{11}$ characteristic are 127MHz($2.346GHz{\sim}2.473GHz$) for the low-band, and 122MHz($3.379GHz{\sim}3.501GHz$) for the high-band, respectively. And measured maximum gains and half-power beamwidths are 6.94dBi, $72.95^{\circ}$ for the low-band at 2.30GHz, 5.78dBi, $76.51^{\circ}$ for the high-band at 3.45GHz, respectively.

• Journal of IKEEE
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• v.13 no.2
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• pp.220-223
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• 2009

A simple measurement system is built to estimate the dual-antenna diversity gain at 2.4GHz easily in open lab environment. To obtain multipath fading propagation channel, the system consists of two transmission horn that placed on opposite direction and a rotating stage mechanically changing the position of test dual-antenna with time over distance greater than one wavelength. Estimated diversity is nearly same as theoretical value such that measured diversity gain of 30mm separated is about 6dB similar to theoretical value of 5.7dB and increases monotonically with the increasing separation distance as predicted by the theory. Proposed measurement system that is simple enough to fit in a small space can evaluate the performance of various dual-antennas with a reasonable accuracy with lower 5% difference between the ten sets of measured waveform distribution and theoretical Rayleigh cumulative distribution.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.8
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• pp.1626-1631
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• 2004

OFDM are digital modulation techniques where a single data symbol is transmitted at multiple subcarriers which are orthogonal to each other. With this technique, frequency diversity can be achieved. The performance of OFDM systems with various antenna structure are analyzed, where data is transmitted over multi-path Rayleigh fading channel. The performance of this technique, gauged by the average bit error rate, is analyzed for the OFDM systems dependent upon the various antenna diversities.