• Journal of the Korean Institute of Telematics and Electronics A
• /
• v.29A no.10
• /
• pp.24-28
• /
• 1992

A new design method of microstrip wide band VHF tunable bandpass filters using varacter diodes is presented. In the proposed filter both the input and output ports are coupled through capacitors, and an open micro-strip line is inserted between the coupled line in order to obtain the desired degree of coupling. The optimized filter responseses for the frequency range of 220-404MHz by TOUCH-STONE are compared with the measured ones.

• Journal of the Korean Institute of Telematics and Electronics A
• /
• v.33A no.5
• /
• pp.65-74
• /
• 1996

in this paper, the propagation characteristics of the dominant modes in multiple coupled microstrip lines on a magnetized ferrite substrate are analyzed. The propagation constants and characteristic impedances are calculated by using the spectral domain method. With the numerical results, multi-port impedance parameters as well as scattering parameters are derived from nonreciprocal transmission line equations which are consistent with conventional transmission line theory. In additon, the numerical resutls of nonreciprocal characteristics for various values of structural, material parameters, and external magnetic fields are also presented.

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.40 no.10
• /
• pp.63-67
• /
• 2003

This paper proposes a new BLSA(Bit Line Sense Amplifier) for MRAM. Current BLSA employs a latch-type circuit to amplify a signal from the selected memory cell. The proposed BLSA simplifies the circuit by amplifying the signal using cross-coupled PMOS transistors. It shows the same operation speedas the latch-type BLSA in simulation and occupies only 85% of the area taken by the latch-type BLSA.

• The Transactions of the Korean Institute of Electrical Engineers C
• /
• v.53 no.3
• /
• pp.175-181
• /
• 2004

In order to increase the coupling efficiency of the Power and Phase of the active Phase way antenna, we have fabricated the active phased-array antenna which is coupled by the transmission line, and investigated the relationship between the length of the coupling transmission line and coupling power and phase. The following three types of driving method -(1) giving the frequency difference between the two active antenna, (2) applying the input signal to the one side of the two antennas, and changing the eigen frequency of the other side antenna, (3) appling the different phase inputs to the active antennas was investigated. The experimental results showed that the interval of the antenna elements has not affected the power and the phase of the antenna.

• Journal of electromagnetic engineering and science
• /
• v.9 no.2
• /
• pp.85-97
• /
• 2009

As operating frequency is raised and as more integration with active and passive elements is required, it becomes difficult to fabricate more than 120 ${\Omega}$ characteristic impedance of a mierostrip line. To solve this problem, an equivalent high impedance transmission-line section is suggested, which consists mainly of a pair of coupled-line sections with two shorts. However, it becomes a transmission-line section only when its electrical length is fixed and its coupling power is more than half. To have transmission-line characteristics(perfect matching), independently of coupling power and electrical length, two identical open stubs are added and conventional design equations of evenand odd-mode impedances are modified, based on the fact that the modified design equations have the linear combinations of conventional ones. The high impedance transmission-line section is a passive component and therefore should be perfectly matched, at least at a design center frequency. For this, two different solutions are derived for the added open stub and two types of high impedance transmission-line sections with 160 ${\Omega}$ characteristic impedance are simulated as the electrical lengths of the coupled-line sections are varied. The simulation results show that the determination of the available bandwidth location depends on which solution is chosen. As an application, branch-line hybrids with very weak coupling power are investigated, depending on where an isolated port is located, and two types of branch-line hybrids are derived for each case. To verify the derived branch-line hybrids, a microstrip branch-line hybrid with -15 dB coupling power, composed of two 90$^{\circ}$ and two 270$^{\circ}$ transmission-line sections, is fabricated on a substrate of ${\varepsilon}_r$= 3.4 and h=0.76 mm and measured. In this case, 276.7 ${\Omega}$ characteristic impedance is fabricated using the suggested high impedance transmission-line sections. The measured coupling power is -14.5 dB, isolation and matching is almost perfect at a design center frequency of 2 GHz, showing good agreement with the prediction.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.65 no.7
• /
• pp.1193-1203
• /
• 2016

This paper proposes a droop control scheme to compensate the unbalanced line-to-line voltage of unbalanced 3-phase load which is coupled with two inverter-based distributed generations through unequal impedance lines. Unbalanced line-to-line load voltages occur due to using single-phase loads, which brings about bad effects on the coupled inverters and the distributed generations. In order to compensate the unbalanced line-to-line voltages, a positive sequence voltage control was used for sharing the active and reactive power and a negative sequence control was used for reducing the negative sequence voltage. The feasibility of the proposed scheme was first verified by computer simulations, and then experiments with a hardware set-up built in the lab. The experimental results were compared with the simulation results to confirm the feasibility of the proposed scheme.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.20 no.4
• /
• pp.333-343
• /
• 2009

The BPF designed by the formula based on strip line shows the center frequency shift and distortion in filter response and this becomes more significant with higher frequency. In this paper, the novel design based on EM simulation is proposed. In the design, the filter is decomposed into individual resonators and, for each resonator, the reactance slope and the inverter values are measured and tuned to desired design values for a inverter BPF prototype. The filter composed with such resonators shows the desired filter response without further tuning. This is because possible effects of discontinuities and dispersion are included in the filter parameter extraction. The method can generally apply to all filters that can be transformed into inverter BPF prototype. The procedure is verified by designing a 5th-order SIR filter and quite general to adapt into the design of a parallel coupled line filter, and hair-pin filter.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.20 no.7
• /
• pp.1237-1242
• /
• 2016

In this paper, the low pass filter with harmonics suppression and rejection using parallel coupled-line and radial type open stub is presented. And the resultant characteristic of the proposed low pass filter is that the harmonics are suppressed and rejected in wide bandwidth due to the parallel coupled-line structure. The open stub of a low pass filter is constructed in radial type which can be used to adjust the size of filter. The size of the proposed low pass filter is $6.98{\times}7.60mm2$ and the cut off frequency is 2.45 GHz. And the filter is economical in unit cost and can be constructed easily and has the merit of mass product because the filter is composed of distributed element. Also, the widely rejected harmonics is 128 % in the bandwidth and the insertion and return losses of the low pass filter are 1.07 dB and 19.5 dB, respectively.

• Journal of Electrical Engineering and Technology
• /
• v.6 no.1
• /
• pp.111-118
• /
• 2011

In recent years, various types of partial discharge (PD) methods such as capacitive, inductive, electromagnetic, and acoustic coupling techniques have been developed for diagnosing rotating machines. An electromagnetic (EM) probe, which is an inductively coupled type of sensor, is required for detecting corona and internal discharges during off-line tests. In this study, a new technique for enhancing the measurement sensitivities for corona and internal discharge based on an EM inductive position sensor is proposed. An EM probe that winds wires around horseshoe-shaped and cylindershaped ferrites as helices is designed and optimized for the implementation of off-line PD monitoring of the stator winding of a rotating machine. The measurement system based on this design is implemented, and it is verified from the results of the experiment performed in this study that the probe provides similar performance as existing commercial products.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.11 no.6
• /
• pp.388-395
• /
• 1986

Dispersion characteristics of shielded single, coupled and edge-offset microstrip structures are investigated by using hybrid mode analysis with Galerkin's method in the spectral domain. Two new basis functions for the longitudinal strip current are proposed and convergence rates of the solutions for the basis functions are compared. Current distribution of the coupled line is obtaind from that of the single line by using shift theorem of the Fourier transform. In addition, effects of off-centered inner strip conductor on dispersion are also discussed Numerical results include various structual parameters and are compared with other available data and good agreements are observed.