• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.46 no.2
• /
• pp.147-151
• /
• 2009

A wideband correlator, with 45% relative bandwidth is proposed at the frequency range of 3.1-5.1GHz. The structures of the correlator components such as the delay line and the Wilkinson power divider are designed to be realized in transmission line form using the Agilent's Advanced Design System (ADS). The correlator made by using three unique wideband 3-dB couplers, rat-race coupler and one 3-dB wilkinson power divider to reach the required bandwidth. The insertion loss, amplitude imbalance and phase imbalance between ports are presented. The proposed correlator makes compact size better than correlator of conventional structure.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.14 no.6
• /
• pp.110-116
• /
• 2015

In this paper, a compact low-loss reflector-type phase shifter with harmonic suppression using meander T-shaped branch-line coupler is suggested. The compact coupler for the phase shifter has a size of $22.2{\times}14.9mm^2$ while a conventional branch coupler has a size of $32.6{\times}27.8mm^2$. The phase shifter shows insertion losses of 0.19-0.28 dB at the center frequency of 2.1 GHz, and a measured maximum phase shift of $137^{\circ}$.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.45 no.9
• /
• pp.55-59
• /
• 2008

In this paper, the linearity of Doherty amplifier has been improved by applying a compact slow-wave microstrip branch-line coupler on the output of Doherty amplifier. The proposed branch coupler has four microstrip high-low impedance resonant cells periodically placed inside the branch-line coupler to result in high slow-wave effect. The new coupler not only effectively reduces the occupied area to 30% of the conventional branch-line coupler at 1.8GHz, but also has high second harmonic suppression performance. We obtained the 3rd-order intermodulation distortion ($IMD_3$) of -31.16 dBc for CDMA applications with that of maintaining the constant power added efficiency (PAE). The IMD3 performance is improved as much as -7 dBc compared with a Doherty amplifier.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.22 no.5
• /
• pp.510-515
• /
• 2011

In this paper, an artificial transmission line coupler with slotted-triangular patches, which is compact and spacesaving structure, is proposed. The proposed structure has specific features of not only convenience for adjusting the characteristic impedance and the phase of its coupled line by varying the lengths of the slots of the artificial transmission lines in designing a coupler but also the maximized coupling value at less than ${\lambda}$/4 electrical length so that it can be designed in compact and small dimensions, while conventional coupled line couplers are generally limited in compact and miniaturized designs by their ${\lambda}$/4 transmission lines. A fabricated 15 dB test-coupler at 2.4 GHz band by proposed design method shows good agreement with theory and simulation.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.41 no.12
• /
• pp.115-124
• /
• 2004

In this paper, we introduce the advanced compact transmission line with periodic stepped stubs. They are more effective than normal stubs in ATL. The short stepped stubs loading of transmission line work as effective shunt capacitance and that was proved by equivalent circuit based on transmission line theory and quasi-static analysis. And the compact branch-line coupler and the compact rat-race coupler via proposed compact microstrip line were designed at 1.8 ㎓. They have 677 ㎟ and 913 ㎟, respectively, and they are 62% and 45% of normal design.

• Journal of Advanced Navigation Technology
• /
• v.17 no.6
• /
• pp.658-663
• /
• 2013

In this paper, a microstrip line implementation using via transition and its application of multilayer compact ring hybrid coupler are presented. This transition is the sandwich structure with via hole to connect two microstrip lines in different layer. For designing a compact RF/Microwave passive circuit, the microstrip line using via-hole transition is proposed to reduce a size of microwave circuit with long transmission line. For the validation of the microstrip line with via-hole transition, the multilayer ring hybrid coupler is implemented at center frequency of 2 GHz. The measured performances are in good agreement with simulation results and about 50% size reduction compare to conventional ring hybrid coupler.

• Journal of electromagnetic engineering and science
• /
• v.12 no.4
• /
• pp.234-239
• /
• 2012

This paper presents a compact K-band Doppler radar sensor for human vital signal detection that uses a radar configuration with only single coupler. The proposed radar front-end configuration can reduce the chip size and the additional RF power loss. The radar front-end IC is composed of a Lange coupler, VCO, and single balanced mixer. The oscillation frequency of the VCO is from 27.3 to 27.8 GHz. The phase noise of the VCO is -91.2 dBc/Hz at a 1 MHz offset frequency, and the output power is -4.8 dBm. The conversion gain of the mixer is about 11 dB. The chip size is $0.89{\times}1.47mm^2$. The compact Ka-band Doppler radar system was developed in order to demonstrate remote human vital signal detection. The radar system consists of a Ka-band Doppler radar module with a $2{\times}2$ patch array antenna, baseband signal conditioning block, DAQ system, and signal processing program. The front-end module size is $2.5{\times}2.5cm^2$. The proposed radar sensor can properly capture a human heartbeat and respiration rate at the distance of 50 cm.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.22 no.6
• /
• pp.598-604
• /
• 2011

A method of miniaturizing branch line coupler with connected coupled lines is presented. The quarter-wavelength transmission lines in the typical microstrip branch line coupler are replaced with the connected coupled lines with same characteristics of ones for compact size. The connected coupled line is analyzed by T-equivalent circuit and Z parameters based on the even-odd mode analysis. The proposed branch line couplers with connected coupled line are designed and fabricated on FR4 substrate at 2.4 GHz. The measured results show good agreement with theoretical prediction. And the experimental results show that the size of coupler is 37 precent smaller than conventional coupler. This minimized coupler is suitable for Butler Matrix as feeder for mobile communication beam forming antenna.

• Journal of the Korean Institute of Telematics and Electronics D
• /
• v.36D no.3
• /
• pp.1-11
• /
• 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 Navigation Technology
• /
• v.13 no.2
• /
• pp.194-200
• /
• 2009

This paper introduces a ring hybrid coupler using shunt capacitors, high impedance lines and CRLH-TLs (Composite Right/Left-Handed Transmission Lines) with size reduction and bandwidth enhancement. The reduced method of line length uses to combine a short length high impedance line and shunt capacitors. Also, there is combined CRLH meta-material so as to obtain wide bandwidth of transmission line using nonlinear phase characteristic of CRLH-TL that consists of series capacitors and shunt inductors. The implemented ring hybrid coupler shows a novel design with compact size that is smaller than 10% and bandwidth is larger than 60% of conventional ring hybrid coupler.