• Journal of the Optical Society of Korea
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• v.14 no.4
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• pp.438-443
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• 2010

In this paper, behaviors of photonic crystal (PC) radiative structures and antenna arrays have been compared for two types of uniform and binomial excitations. Appropriate duality has been shown between them. These results can be generalized to other types of excitation and arrangement of photonic crystal radiative arrays such as linear, planar and circular arrays of three dimensional (3D) photonic crystal termination resonators. Using these results in designing photonic circuits has some advantages for shaping a particular radiative beam at the photonic crystal exit, for instance reducing the divergence angle of the main lobe in order to enhance the directivity, for better coupling, or for splitting the emitted beam, for dividing the output beam to the next devices in photonic integrated circuits (PIC). For analysis and simulation of the photonic crystal structures, the finite difference time domain (FDTD) method has been employed.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.43 no.4 s.346
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• pp.31-37
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• 2006

Strongly motivated by the need for significant reduction in the optics-to-antenna interface circuitry used in a Photonically controlled array, it has proposed the design development of a novel 'true photonic antenna' consisted of optical fiber and micro-strip antenna. To clarify the design capability of the geometry, modal transmission-line theory including the discontinuity property between circular i,nd planar guiding structures is defined, md the optical power coupling of a slot-coupled microstrip antenna directly fed from an optical fiber using photoconductive effect is evaluated numerically. The numerical results reveal that the maximum power transfer between the two different guiding structures occurs at a new point in which the guiding powers of two rigorous modes are equally partitioned.

• Journal of the Microelectronics and Packaging Society
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• v.11 no.1
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• pp.13-19
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• 2004

This paper demonstrates the detailed study of a microstrip Yagi-Uda antenna with and without PBG structure at wireless LAN(5725∼5825 MHz) frequency band. The impedance bandwidth of the antenna with the PBG holes is greater than (about 30 MHz) that of its counter part without PBG holes. The measured gains of the antenna at the frequency band are 7 dB and 6 dB respectively for antenna with and without PBG. The improvement of gain of about 1 dB is likely due to the suppression of surface wave.

• Korean Journal of Optics and Photonics
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• v.19 no.1
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• pp.9-14
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• 2008

In this paper, a new type of Yagi-Uda antenna that operates in the terahertz frequencies is designed. The proposed Yagi-Uda antenna can obtain high input resistance of approximately $2000{\Omega}$ at the resonance frequency by using a full-wavelength dipole instead of a half-wavelength dipole as the driver element. The current leakage into the bias line was minimized by applying the photonic bandgap structure to the bias line. By designing the antenna on a thin substrate, the impedance lowering of an antenna caused by the relative dielectric constant of the substrate was prevented and the end-fire radiation pattern which is the original radiation characteristic of the Yagi-Uda antenna could be obtained. We expect that the proposed Yagi-Uda antenna can achieve increased terahertz output power by improving the impedance mismatching problem with the photomixer.

• Journal of electromagnetic engineering and science
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• v.12 no.1
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• pp.85-93
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• 2012

We propose a new expression of the near-field gain correction to calculate the on-axis far-field gain from the onaxis near-field gain for a directive antenna. The new expression is represented by transversal vectorial transmitting characteristics of two antennas that are measured by planar near-field equipment. Due to the advantages of the photonic sensor, the utilization of the new expression realizes the measurements of the on-axis far-field gains for two kinds of double ridged waveguide horn antennas within 0.1 dB deviation from 1 GHz to 6 GHz without calibrating the photonic sensor system.

• Journal of electromagnetic engineering and science
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• v.10 no.4
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• pp.282-289
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• 2010

A simplified, practical vector network analyzer (VNA) that uses mature radio-over-fiber technology has been designed and demonstrated. The measurement concept allows the full S-parameters of a microwave device (or antenna) to be obtained while minimizing the detrimental effects of electrical cables, which are replaced with a photonic link. A variety of high-frequency light modulation schemes with frequency sweeping capabilities are presented to realize a one-path (single, forward), frequency-multiplied optical link for VNA applications. Using the photonic one-path link, full two-port S-parameters have been extracted based on five-term error modeling, which has half the error terms compared with the standard duplex configuration. The S-parameters of a microwave filter and antenna measured using frequency-multiplied optical links are found to be in good agreement with those obtained using a conventional VNA.

• Journal of the Optical Society of Korea
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• v.18 no.4
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• pp.406-413
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• 2014

An optical true-time delay beam-forming system using a tunable dispersion compensating module (DCM) for dense-wavelength division modulation (DWDM) and a multiwavelength fiber ring laser for a phased array antenna is proposed. The multiwavelength fiber ring laser has one output that includes four wavelengths; and four outputs that include only single-wavelength. The advantage of such a multiwavelength fiber ring laser is that it minimizes the number of devices in the phased array antenna system. The time delays according to wavelengths, which are assigned for each antenna element, are obtained from the tunable DCM. The tunable DCM based on a temperature adjustable Fabry-Perot etalon is used. As an experimental result, a DCM could be used to obtain the change of the beam angle by adjusting the dispersion value of the DCM at the fixed lasing wavelengths of the fiber ring laser in the proposed optical true-time delay.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.11 s.102
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• pp.1067-1074
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• 2005

Studied antenna's basic structure was circular micro-strip patch antenna. Bandwidth was broaden and back-radiation pattern was decreased because studied antenna had PBG on a ground for improvement in its defect which is skin-effects. And character of antenna according to different shape of PBG was observed. Finally, air-gap whose dielectric constant is lower than substrates was added between substrates sc respond frequency was higher despite small size antenna.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.23 no.4
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• pp.65-71
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• 2023

In this paper, the design, fabrication and verification steps of an electronically scanned array antenna(AESA) for a photonics-based Ku-band FMCW radar system is described. The presented system consists of a transmitter and a receiver respectively, which has a same antenna in the transceiver. The designed antenna has 2×8 array configuration and operates at Ku-band. The VSWR(Voltage Standing Wave Ratio) of each 16-radiators and the coupling power between radiators is measured. Also, in order to minimize the radar system damage because of handover power from the transmitter antenna to the receiver antenna when the transmitter works, the isolation between the transmitter antenna and the receiver antenna is optimized by test. As a result, beamwidth, side lobe level and beam steering characteristic are obtained by synthesizing each radiator pattern measurement data after each beam pattern of 16-radiators is measured in the near-field chamber.

• Journal of electromagnetic engineering and science
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• v.10 no.1
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• pp.18-24
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• 2010

A Ka-band microstrip array antenna for wide-range detection of moving targets is analyzed through a photonicassisted reactive-near-field characterization technique. The antenna array employs a 3-dB-tapered feed network to suppress the sidelobe level while retaining a wide azimuth beamwidth for a wide detection range. The relative nearelectric field patterns of the array and its 3-dB-tapered feed lines have been measured using an electro-optic fieldmapping technique for minimally invasive millimeter-wave sensing. A number of typical limitations on the technique, involving bandwidth, low signal-modulation depth, and high laser-induced noise in high-frequency applications, have been overcome by suppressing the carrier portion of the optical interrogation beam.