• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.2
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• pp.495-504
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• 1996

In this paper, series-fed mirostrip array anteenas with coupling-slots are prposed and their operating characteristics are analyzed based on analyzed based on analytical and experimental results. An accurate analysis method for the slot-coupled feed structure is based on using both circuit coupling between anteenas and full-wave analysis which use travling wave mode and non-traveling wave mode on feed line. The basis functions that used for the numerical analysis bas been determined depending upon the accuracy, convergence properties of the solution, and the computation time:The patch uses 3 EB mode, the slot uses 1PWS mode, and feeders use 5 PWS mode. Series-fed array antennas have been designed, built, and tested in a standing-wave configuration. Using the results of the full-wave analysis, the chebyshev array antennas consisting of 8 elements are designed and fabricated changing the amount excited to each array element by adjusting slot length and by the slot position relative to the feeder. Experiment results show that the series-fed array antenna designed by adjusting the slot position relative to the feeder is superior to that designed by slot length.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.11 no.1
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• pp.26-36
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• 2000

A circularly polarized $12\times12$ array with application in the satellite communications is designed at 10 GHz. The radiator is an aperture-coupled ring patch, which is suitable of large arrays. The element spacing of the array is chosen to be $0.7\lambda_0$to maintain the main beam in the broadside direction. The array is a sequential array constructed on a series-parallel feed network to obtain high gain and low axial ratio. Measurement results for the array, acquired by experiments in the compact range of POSTECH, showed a directivity of 27.88 dB, a high gain of 25.55 dB, an efficiency of 60%, an axial ratio of 1.74 dB, and a side-lobe level of -13 dB. The bandwidth of the array was 43% when the VSWR was 2, and the bandwidth of the axial ratio was 16%.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.12 no.1
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• pp.92-98
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• 2001

When analyzing the scatting problem of multi-layered planar structures using closed-form Green's function, one of the main difficulties is that the numerical integrations for the evaluation of diagonal matrix elements converge slowly and are not so stable. Accordingly, even when the integration fur the singularity of type $e^{-jkr}/{\gamma}$, corresponding to the source dipole itself, is performed using such a method, this difficulty persists in the integration corresponding to the finite number of complex images. In order to resolve this difficulty, a new technique based upon the Gaussian quadrature in polar coordinates for the evaluation of the two-dimensional generalized exponential integral is presented. Stability of the algorithm and convergence is discussed. Performance is demonstrated for the example of a microstrip patch antenna.

• Korean Journal of Optics and Photonics
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• v.17 no.1
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• pp.7-17
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• 2006

In this paper, we proposed an optical true time-delay (TTD) for planar phased array antennas (PAAs), which is composed of a wavelength-dependent optical true time delay (WDOTTD) followed by a wavelength-independent optical true time delay (WIOTTD). The WDOTTD is a fiber Bragg gratings (FBGs) Prism and the WDOTTD is a fiber delay-lines matrix of which each component consists of a certain length of fiber connected to cross-ports of a 2${\times}$2 MEMS switch. A 10-GHz 2-bit${\times}$4-bit two-dimensional optical TTD has been fabricated by cascading a WDOTTD with a maximum time delay of 810 ps to a WIOTTD of $\pm$50 ps. Time delay and insertion loss for each radiation angle have been measured. Time delay error for the WIOTTD has been measured to be less than $\pm$1 ps. We have also designed a two-dimensional 10-GHz PAA composed of 8${\times}$8 microstrip patch antenna elements driven by the proposed TTD. The radiation patterns of this PAA have been obtained by simulation and analyzed.