• Journal of the Institute of Electronics Engineers of Korea TC
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• v.37 no.5
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• pp.10-16
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• 2000

This paper presents new double-sided 3-dB branch-line coupler using CPW-to-Microstrip via-hole transitions for the multi-layer applications. The characteristic impedance is obtained using the even-odd mode method, and the circuit performance Is accurately estimated by the Finite Difference Time Domain(FDTD) method. The fabricated double-sided 3-dB branch-line coupler has less than 0.3 dB power dividing imbalance and 1。 phase imbalance, greater than 30 dB isolation, and 25 dB return loss over a 20% bandwidth centered at 2 GHz. Calculated and fabricated results show that this coupler provides better performance as compared to the conventional microstrip branch-line couplers.

• The Journal of the Korea institute of electronic communication sciences
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• v.12 no.3
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• pp.445-450
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• 2017

In this paper, the directional coupler with half-power division is designed and fabricated by using the vertical coupling structure based on the CPW transmission-line. Even-mode and odd-mode of the vertical coupling structure can be analyzed by the conventional CPW-line and the CBCPW-line, respectively, with half thickness of the substrate. The directional coupler is designed by using the tefron substrate with the dielectric constant of 2.55 and the thickness of 0.76mm. Manufactured directional coupler has the center frequency of 2.45 GHz and the bandwidth of 66.1%. Also, the return loss and isolation are 19.52dB and 19.47dB, respectively, at the center frequency.

• Journal of Advanced Navigation Technology
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• v.14 no.6
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• pp.909-915
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• 2010

In this paper, the unequal power divider based on CRLH (Composite Right/Left-Handed) transmission line with dual-band characteristic is proposed. They consist of dual-band branch line hybrid coupler, the connection between input and isolation port of hybrid coupler and ${\lambda}/4$ impedance transformer. When the transmission line between input and isolation port of hybrid coupler is asymmetrical connected, the divider is obtained the output results of the equal phase and unequal power dividing ratio. The simulation results of the divider represent the power ratio of 0 dB ~ 20 dB. To validate a function of divider, the hybrid coupler and transformer with 880 MHz and 1850 MHz is implemented. As a result, the proposed unequal divider obtains the power ratio of 3.2 dB ~ 8.8 dB at 880 MHz and 2.5 dB ~ 14.0 dB at 1850 MHz.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.5
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• pp.3139-3145
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• 2014

This paper describes the design of a size-reduced ring hybrid coupler for microwave band using an artificial dielectric substrate(ADS). ADS structure adopts the second substrate on which has lots of the metalized via-holes. The effective capacitance and effective dielectric constant per unit length of ADS increases compared to the normal substrate due to the via-holes. This enables the physical length of microstrip transmission line to be reduced by adopting ADS instead of the normal substrate. In order to present an example of size-reduction of microwave wireless circuit by ADS, a size-reduced 3GHz ring hybrid coupler is designed, fabricated and measured in this work. The designed coupler has the smaller size from the normal one by 65% due to the ADS, while no critical degradation from ideal performances is observed. The measured power division ratio at two output ports are -3.05dB and -3.135dB, respectively. In addition, the phase differences are 3o for in-phase division and 176o for out of phase split. The measured performances are so similar to ideal ones, and prove the design of size-reduced ring hybrid coupler using ADS is successful.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.31A no.8
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• pp.7-15
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• 1994

In this paper, the directional coupler for Ku-band, which is designed is of the crossguide type with a coupling value of about 3-dB. The apertures chosen for this design are crosses. We used polynomial approximations of rounded end slot to obtain the electric and magnetic polarizability of crossed-slot and compared the results with Cohn's experimental results. The optimized dimensions and positions of the cross aperture are obtained by a trial-and-error reiteration of the program. This paper presents the measurement results for the designed coupler. The very flat coupling shows a total variation of only 29.80$\pm$0.04dB for the design frequency ranges of 12.25GHz-12.75GHz. The measured minimum directivity is 25dB. The aperture attenuation for the finite diaphragm thickness is about 2dB pr 0.5mm, which is in agreement with the theoretical value. The transmission loss and input return loss at center frequency are 0.0564dB and 48.16dB respectively. We obtained the measured minimum directivity of the coupler. Whose apertures are both circles is better than that containing holes in the performance of directivity.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2001.11a
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• pp.180-183
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• 2001

본 논문에서는 N개의 평행 결합선로를 이용한 3dB 결합기를 해석하였으며, 유도된 식에 의하여 최소의 단수와 크기로 3dB 결합기를 설계하였다. 기존의 Spectral Domain상에서 N단 평행 결합선로의 복잡한 관계식 유도를 S 파라미터 관계식으로 간단히 유도 하였으며, 유도된 식의 타당성을 위해 실제 제작 검증하였다. 제작된 결합기는 Loose coupling의 평행 결합 선로의 광대역 특성을 그대로 이용하기 때문에 Lange Coupler와 같은 높은 임피던스와 Tight coupling을 구현 할 필요가 없으며, wire bonding도 용이하게 된다. 최소의 단수로 구현하기 위해 RT/Duroid의 R06006과 같은 높은 유전율과 두꺼운 기판을 사용하여 2단으로 3dB 구현이 가능하게 하였다. 제작결과 3.6GHz에서5.5GHz로 대략 42%(0.5dB imbalance) 정도의 광대역특성을 가지고 위상오차도 1$^{\circ}$내외의 결합기를 구현할 수 있었고 격리도 특성 또한 대역 내에서 15dB 내외의 특성을 보였다.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.40 no.9
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• pp.651-657
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• 2003

We have demonstrated an in-line polarization splitter based on a side-polished fiber coupler including a thin metal intermediate layer. The experimental results revealed that the metal layer with proper thickness prevents TE polarization component from optical coupling between two contacted side-polished fibers, whereas it allows TM polarization component to the coupling. The design and fabrication techniques about the polarization splitter exploiting the side-polished fibers have been presented. The fabricated polarization splitter exhibited 18dB and 23dB of isolation ratio for TE polarization and TM polarization, respectively. The measured insertion loss for TE and TM polarization was 0.7dB and 1.3dB, respectively.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.36D no.3
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• pp.1-11
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• 1999

It is now common practice to utilize the quadrature RF coils to improve the signal-to-noise ratio (SNR) in the Magnetic Resonance Imaging (MRI) System. In addition, to make such an available SNR improvement, it is mandatory to use a well-designed quadrature coupler, which facilitates a perfect 3-dB coupling and quadrature-phase shift. However, the four ports matching condition has to be well considered during the RF excitation and the signal detection period. This work investigates the effects of such a mismatching condition (especially, due to patient) from the analysis, simulation, and real implementation and firstly proposes dynamic loading technique for a quadrature coupler and transmitting/receiving switch module to minimize a patient mismatching and enhance a system reliability. Also, we designed and implemented the quadrature coupler and transmitting/receiving switch module using microstrip. As a result, the SNR of our MRI system using the microstrip quadrature coupler and transmitting/receiving switch module with dynamic load increases 3 dB compared with the old one using USA quadrature switch. Also, the power capability of quadrature coupler and transmitting/receiving switch module is 5-kw peak power. Considering power loss and reduction of size, we used a RT/duroid 6010 substrate with high permittivity and for simulation we use Compact Software.

• Journal of Advanced Marine Engineering and Technology
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• v.32 no.1
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• pp.147-152
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• 2008

This paper has been fabricated the two different type of variable attenuators using a characteristics of a 3 dB directional coupler and pin diodes. One was not analyzed using the conventional even-odd modes but used simple two-port techniques. The resulting scattering parameters described operation characteristics for the general case where the terminating impedances are equal and unequal. After analyzing resistor role of the ${\pi}$ type fixed attenuator. this paper used a pin diode instead of a resistor. The variable attenuators were fabricated using pin diodes for current-controlled attenuation on the coupled ports of a 3 dB branch-line coupler and ${\pi}$ type fixed attenuator. The realized variable attenuators have more than 33 dB attenuation ranges at 2.1 GHz. and the input and output reflection coefficients are less than -13 dB. These results could be applied to mobile communication systems. It can be varied gain of the power amplifier according to change a outdoor environmental temperature and improved linearity.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.34D no.4
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• pp.62-72
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• 1997

The optical power splitter/couplers based on MMI(multimode interference) in GaAs/AlGaAs are studied. We presetn a design of optical power splitter/couplers, which have deeply etched multimode waveguide. The properties and fabrication tolerance on the etching depth, multimode waveguide width are simulatedusing a FD-BPM (finite difference beam propgation method). Proposed 1*N optical of designed device is 0.7dB smaller than the optical power splitter with a shallowly etched MMI section. For 0.5dB excess loss, the predicted fabrication tolerance is 0.6.mu.m on the multimode waveguide width of the 14 optical power splitter with a deeply etched MMI section. Also excess loss and uniformity of poposed 32*32 optical power coupler are below 0.3dB. The excess loss of proposed 32*32 optical power coupler is 2dB smaller than the optical power coupler with a shallowly etched MMI section. It is shown that the optical power splitters/couplers with a deeply etched mMI section have low loss, good uniformity, and improved fabriction tolerance.