• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.37 no.9
• /
• pp.38-48
• /
• 2000

This paper presents the photonic bandgap structure that has a defect mode within a broad stopband. In order to create a broad stopband, we eliminated one of periodic stopbands of PBG structure by using a quarter-wavelength transformer and cascaded another PBG structure having a center frequency corresponding to the eliminated stopband. We have demonstrated that it is a simple and effective method that can solve an overlapping problem of periodic stopband in two cascaded PBG structures.

• Journal of the Korean Institute of Telematics and Electronics D
• /
• v.34D no.10
• /
• pp.45-52
• /
• 1997

An analysis method for the electromagnetic scattering of a gaussian beam wave by finite periodic conducting strip grating on a groudned dielectric slab is considered. The intergral equation for the unknown current induced on the conducting strip surface is derived and solbed numerically by use of the method of moment. From knowledge of the strip current, the quantities of interest such as radiation pattern, the space wave power radiated into the free space, and the coupled surface wave power propagating along the dielectric slab are computed for the appropriately chosen parametes Some similarity between scattering behaviours of the present geometry and the infinite geometry is examined by observing the Off-bragg as well as bragg blaxing penomena in both geometries.The validity of the numerical results are assured by a check of the power conservation relations.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.43 no.5 s.347
• /
• pp.147-155
• /
• 2006

In this paper, we propose a new Mushroom-like PBG concepts for designing with forbidden frequency band-gap at low frequency. These design rules are based on enhancing the capacitance per unit area using modified top-patch of mushroom PBG with no increase on the overall thickness of the substrate board. Also, in this paper, a new approach to suppress the surface wave from antenna is proposed by embedding compact mushroom PBG in the substrate. Comparisons between the results from a conventional patch antenna to a patch antenna on a PBG substrate show that the reduction in the surface wave level is remarkable. This can be observed in the radiation pattern and the maximum gain. The maximum gain for reference patch antenna is $6.43dB{\imath}$ at 5.37 GHz, while the maximum gain for the patch antenna with normal mushroom and vane mushroom PBG is $7.24dB{\imath}\;and\;7.53dB{\imath}$at 5.14 GHz. The back radiation is also considerably reduced; this will lead, of course, to an increase in the antenna efficiency.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.46 no.8
• /
• pp.67-78
• /
• 2009

Radiation characteristics of microstrip patch antennas integrated with mushroom-like EBG structures in all directions and length direction on a substrate with the relative dielectric constant of 10 are systematically analyzed. As the substrate thickness increases, the effect of the surface wave on the input impedance and radiation pattern of a patch antenna increases. The effect of EBG structures on the input impedance of a patch antenna is negligible when the distances between EBG structures and the center of a patch antenna are 0.4 ${\gamma}_0$, 0.2 ${\gamma}_0$ and 0.1 ${\gamma}_0$ for the substrate thickness of 3.2 mm, 1.6 mm and 0.8 mm, respectively. The forward radiation is improved due to the suppression of surface wave when the periods of EBG structures integrated are larger than 2, 2, 3 periods for the substrate thickness of 3.2 mm, 1.6 mm and 0.8 mm, respectively. The effects of EBG structures on the radiation characteristics of a patch antenna integrated with EBG structures in all directions and length direction are similar.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.8 no.2
• /
• pp.161-172
• /
• 1997

In this paper, electromagnetic scattering by a perfectly conducting strip grating on dielectric multilayers is analyzed for the normalized reflected and transmitted power by applying the Fourier-Galeakin moment method. The induced current density is expanded in a series of multiplication of chebyshev polynomials of the first kind and functions with appropriate edge boundary condition, the continuous condition of electromagnetic field is applied in the boundary planes. The confirm the validity of the proposed method, the nor- malized reflected and transmitted power obtained by varying the relative permittivity and thickness of each dielectric layers are evaluated and compared with those of the existing numerical method and a paper, and then the numerical results in this paper are in good agreement with those of the existing numerical method and the paper. The sharp variation position in the geometrically normalized reflected and transmitted power can be moved by the incident angle, grating period, and the relative permittivity and thickness of the dielectric multilayers, these sharp variation points which are called the Wood's anomaly of the Geome- trically normalized reflected power are observed as a main factor when the reflected powers of the higher order mode are transitted between propagating and evanescent modes, and the local minimum positions are slightly moved to the left hand direction in which grating period is getting small according to the increase of the relative permittivity of dielectric layers.

• Proceedings of the KAIS Fall Conference
• /
• 2012.05b
• /
• pp.471-473
• /
• 2012

본 논문은 DMS (defected microstrip structure) 선로를 이용한 전력분배기 설계에 대하여 기술하고 있다. DMS 선로는 마이크로스트립 선로의 패턴에 변형을 가하여 설계되는데, 이 때 부가적으로 발생하는 인덕턴스와 커패시턴스 효과에 의하여 선로의 특성 임피던스가 변하고, 또한 종래 주기구조에서의 특징들을 보인다. 이를 이용하면 초고주파 전송선로 구조의 무선회로들을 소형화할 수 있는데, 그 한 예로 본 논문에서는 윌킨슨 전력분배기를 소형화하는 설계에 대하여 기술한다. DMS 구조를 삽입하여 소형화된 전력분배기를 설계한 결과, 소형화된 분배기는 표준형 회로에 비하여 약 82%의 크기를 가지면서도 우수한 성능을 갖는다.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.31 no.3A
• /
• pp.321-327
• /
• 2006

In this paper, when a H-polarized plane wave is incident on the grating consisting of uniform resistive strips, electromagnetic scattering is analyzed using the moment of methods (MoM). The current density of each resistive strip on a grounded dielectric plane is fixed by zero at both edges. To satisfy the condition at both ends of each resistive strip, the induced surface current density is expanded in a series of cosine and sine functions. The scattered electromagnetic fields are expanded in a series of floquet mode functions. The boundary conditions are applied to obtain the unknown current coefficients. According to the variation of the involving parameters such as strip width and spacing and angle of the incident field, numerical simulations are performed by applying the Fourier-Galerkin moment method. The numerical results of the normalized reflected power for resistive strips case for zero and several resistivities are obtained.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.18 no.6 s.121
• /
• pp.656-663
• /
• 2007

In this paper, when a E-polarized plane wave is incident on the grating consisting of tapered resistive strips, electromagnetic scattering is analyzed using the method of moments(MoM). The induced current density of each resistive strip in a grounded double dielectric layer is expected to blow up at both edges. To satisfy this, the induced surface current density is expanded in a series of Chebyshev polynomials of the second kind. The scattered electromagnetic fields are expanded in a series of Floquet mode functions. The boundary conditions are applied to obtain the unknown current coefficients. According to the variation of the involving parameters such as strip width and spacing and angle of the incident field, numerical simulations are performed by applying the Fourier-Galerkin moment method. The numerical results of the normalized reflected power for resistive strips case for several resistivities are obtained.

• Journal of Advanced Marine Engineering and Technology
• /
• v.36 no.1
• /
• pp.149-156
• /
• 2012

In this study, we propose a novel transmission line employing inverted PACD (Periodically Arrayed Capacitive Devices) for application to a development of miniaturized passive components on MMIC. The novel microstrip line employing Inverted PACD structure showed a loss much lower than conventional microstrip line. Using the inverted PACD structure, we fabricated a miniaturized impedance transformer on MMIC. the size of the impedance transformer was 0.012 $mm^2$, which is only 1.7% of conventional one. The impedance transformer showed good RF performances in a frequency range of 2.25~6.5 GHz.

• Journal of The Institute of Information and Telecommunication Facilities Engineering
• /
• v.2 no.1
• /
• pp.52-62
• /
• 2003

In this paper, photonic bandgap(PBG) bandstop filters which are composed of periodically etched circles in the ground plane show good microwave characteristics with the harmonic suppression on stopband. The PBG structures were analyzed using a finite-difference time-domain(FDTD) simulation and experimental measurement. The FDTD technique is used because it can simulate arbitrary 3-D structures and provide broadband frequency response. The analysis results are presented it is the same that only one row of etched circles and 2-dimension three rows of etched circles. And we show the PBG resonator characteristics between etched circles using field pattern and frequency characteristics as functions of etched circle number n, etched circle radius r and period a.