• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.6
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• pp.602-612
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• 2013

In this paper, a design and fabrication of miniaturized 5.3 GHz reflection type $360^{\circ}$ analog phase shifter with branch line coupler and $360^{\circ}$ variable reactance load. In order to miniaturize phase shifter, novel branch line coupler is proposed. The novel branch line coupler is miniaturized using transformation of transmission line to T and ${\pi}$ type equivalent circuit. The miniaturized branch line coupler has small size of above 50 % compared with conventional branch line coupler. For wide phase shift range, $360^{\circ}$ variable reactance load structure is adopted. Especially, the structure was improved for linear phase shift by adding transmission line which acts as an impedance transformer. The improved structure was miniaturized using the equivalent lumped-element of transmission line. The fabricated phase shifter with $15{\times}15mm^2$ shows wide phase shift of above $480^{\circ}$, the insertion loss of -4~-6 dB and the reflection loss of below -20 dB at 5.3 GHz under 0~10 V control voltage range.

• Journal of Advanced Navigation Technology
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• v.21 no.3
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• pp.287-293
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• 2017

This paper describes an unequal Bagley divider using uniform transmission lines with adjustment electrical lengths between output ports. To obtain an arbitrary dividing ratio of Bagley divider, we have only adjusted the electrical lengths of the transmission line between output ports. All the transmission lines have the same characteristic impedance value. This design method does not require an impedance transformer for port matching. For verification, we simulated and fabricated a 3-way, 1:2:1 and 5-way, 2:3:4:3:2 ratio Bagley divider with an operating frequency of 2 GHz. The experimental results are in agreement with the simulated results.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2003.11a
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• pp.347-351
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• 2003

본 논문에서는 전력 분배비를 변화시킬 수 있는 전력 분배기/합성기를 설계하였다. 전력 분배기/합성기의 ${\lambda}/4$ 전송선로 특성 임피던스를 결합선로 또는 하이브리드로 변환하여 설계하였다. 결합 선로나 하이브리드의 결합포트와 격리포트를 동시에 On/Off시킴으로써 변화하는 임피던스를 이용하여 전력 분배비가 1:1에서 1:0으로 즉 전력이 두개의 포트에 같은 크기로 전달되다가 모든 입력이 하나의 출력포트로 모두 전달되는 전력 분배기를 설계하였다.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.14 no.2
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• pp.147-152
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• 2014

A longitudinal modal transmission-line theory(L-MTLT) to analyze the static and dynamic behavior of two-section distributed feedback (DFB) lasers is used. The characteristic impedance and equivalent propagation constant of DFB structure with active layer are derived from L-MTLT. A two-section DFB laser is analogous to a transmission-line network, in which each section is described by transmission-line block corresponding to the equivalent factors. The longitudinal resonant condition of DFB laser based on equivalent transmission-line network is used to reformulate the rate equations so that static and dynamic behavior of two-section DFB lasers with active layer is demonstrated and analyzed accurately.

• Journal of Advanced Marine Engineering and Technology
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• v.32 no.8
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• pp.1248-1256
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• 2008

In this paper, basic characteristics of transmission line employing PPGM (periodically perforated ground metal) were investigated using theoretical and experimental analysis.According to the results, unlike the conventional PBG (photonic band gap) structures, the characteristic impedance of the transmission line employing PPGM structure showed a real value, which exhibited a very small dependency on frequency. The transmission line employing PPGM structure showed a loss (per quarter wave length) higher by $0.1{\sim}0.2\;dB$ than the conventional microstrip line. According to the investigation of the dependency of RF characteristic on ground condition, the RF characteristic of the transmission line employing PPGM structure was hardly affected by the ground condition in the frequency lower than Ku band, but fairly affected in the frequency higher than Ku band, which indicated that coplanar waveguide employing PPGM structure was optimal for RF characteristic and reduction of size. Considering above results, impedance transformer was developed using coplanar waveguide with PPGM structure for the first time, and good RF characteristics were observed from the impedance transformer. In case that {\lambda}/4$ impedance transformer with a center frequency of 9 GHz was fabricated for a impedance transformation from 20 to10 {\Omega}$, the line width and length were 20 and $500\;{\mu}m$, respectively, and its size was only 0.64 % of the impedance transformer fabricated with conventional microstrip lines. Above results indicate that the transmission line employing PPGM is a promising candidate for a development of matching and passive elements on MMIC.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.3
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• pp.259-269
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• 2013

In this paper, we propose an SIW(Substrate Integrated Waveguide) multi-section E-plane transformer using air-holes for an SIW system with variable thicknesses. Air-holes are inserted into a SIW E-plane quarter wavelength transformer for matching an E-plane impedance discontinuity. A PSIW(Punched Substrate Integrated Waveguide) consisted of air-holes has an SIW characteristic impedance tunability because of reducing a equivalent shunt capacitance of the SIW. And, a PSIW multi-section E-plane transformer is implemented for improving a matching bandwidth by using the Chebyshev polynomial. The measurement results of PSIW double-section E-plane transformer show that the insertion loss($S_{21}$) is $1.57{\pm}0.11$ dB and input return loss($S_{11}$) is more than 15 dB from 11.45 GHz to 13.6 GHz.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.49 no.4
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• pp.47-52
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• 2012

We have designed the waveguide to microstrip transition using a probe structure for the center frequency of 200 GHz transceiver. The waveguide to microstrip transition is composed of probe, taper and microstrip transmission line. For design of the transition, we simulated the lengths and width of the probe and the taper to optimize the center frequency and the bandwidth using HFSS simulation tool from Ansoft. The transition is designed back-to-back structure. From the simulation results, the transition exhibits that insertion loss is below - 0.81 dB and the return loss less than -10 dB in range of 186 ~ 210 GHz.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.8
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• pp.904-912
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• 2007

In this paper, a broadband 4-way power divider which can be used from 20 MHz to 500 MHz in the V/UHF band is designed using transmission-line transformer and ferrite toroid. A 4:1 impedance transformer is realized and this 4:1 transformer is connected with bridge-type 2-way dividers to form a 4-way rower divider, Insertion loss of about 6.8dB, isolation of less than -20dB, and return loss of less than -15dB in most band of interest are measured.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.6
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• pp.582-589
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• 2002

This paper presents 12.2 GHz ~ 12.7 GHz frequency band reflection type 5-bit digital phase shifter with constant insertion loss property that was fabricated with relatively low cost's InGaAs HEMT for amplifier. The unavoidable large insertion loss difference between on and off states of HEMT, when it is designed by conventional design theory based on ideal switching device, is removed by transforming the HEMT impedances at on and off states to other proper values connecting a certain length transmission line to HEMT and then applying the conventional design theory. The fabricated 5-bit digital phase shifter shows very good insertion loss properties of less than 1.5 dB insertion loss difference and -4.5 dB ~ -6 dB insertion loss in 35 phase steps at 12.2 GHz ~ 12.7 GHz. These results verify the design method presented in this paper, which is useful to design phase shifter of constant insertion loss with non-ideal switching device.

• Journal of Advanced Navigation Technology
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• v.25 no.3
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• pp.229-235
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• 2021

This paper proposes a method of implementing an unequal power divider for high splitting ratios by using transmission lines connected with open and short stubs. The proposed method is an equivalent circuit analysis of a transmission line with an additional port so that it can be converted to an arbitrary impedance in the center of a 2-port transmission line and a 3-port transmission line with an open or short stub connected in parallel to each port. To prove the validity of this method, a Wilkinson power divider with k² = 20 dB splitting ratio and a Gysel power divider with k² = 17 dB splitting ratio were designed at a center frequency of 1 GHz using a 3-port transmission line equivalent circuit. The experimental results of the electrical characteristics are in good agreement with the simulation.