• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.61 no.2
• /
• pp.257-262
• /
• 2012

The Ministry of Information-Communication assigned 18~19GHz frequency band for communication of cabins and platform to link between subway/train and it's station. In this paper, we propose wireless transmission devices which are 2 stage hybrid low noise amplifier of 18GHz band and mixer for 18GHz as well to apply for RF receiver. We designed LNA to be noise matched its 1st stage and gain matched for 2nd stage and mixer using $180^{\circ}$ hybrid coupler to suppress the spurious signal. The transistors of 18 GHz LNA and mixer are NE3210S01 of NEC and KMB-N51-1, respectively. As the result of simulation, we get 19.92dB gain and 2.06dB noise figure with LNA and 8.61dB conversion loss with mixer.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.43 no.2 s.344
• /
• pp.88-93
• /
• 2006

In this paper, smaller load has been used compared with the conventional Doherty amplifier and PBG structure have been employed to suppress IMD (Inter-modulation Distortion) and improve PAE (Power Added Efficiency). And The PBG structure has been employed on the output macthing network of Doherty amplifier. The proposed power amplifier has been improved more the IMD3 by 5.5 dBc, and the average PAE by $5\%,$ at peak output power, $18\%$ at 8dB back-off point respectively than the conventional Doherty power amplifier.

• Journal of Satellite, Information and Communications
• /
• v.11 no.1
• /
• pp.1-5
• /
• 2016

In this paper, High Power Pulsed Amplifier with wide-band characteristic is implemented for L-band Navigational Aid(NAVAID). Due to the characteristics of L-Band NAVAID, implemented SSPA is demanded characteristics of high RF power, high linearity and high efficiency. Therefore, in this paper, efficiency characteristic is improved by modified class F technique. And linearity characteristic is improved by balance structure using hybrid coupler, $2^{nd}$ & $3^{rd}$ harmonic trap and anti-phase technique using non-linear characteristics of drive amplifier. Implemented SSPA shows that bandwidth of 300MHz, RF Output power of 1.5KW and efficiency of 55%.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.14 no.1
• /
• pp.1-8
• /
• 2011

In this paper, dual-feed circularly polarized microstrip patch antenna for GPS L1, GPS L2, GLONASS L1 signal was fabricated by using stacked patch. It was fed by dual coaxial probe on the patch at 50ohm impedance, and was simulated to resonate at GPS L1, GPS L2, GLONASS L1. To realize characteristics of right hand circular polarization using dual-feed stacked patch antenna and hybrid coupler for $90^{\circ}$ phase difference. Output of hybrid coupler was contacted input of Low Noise Amplifier(LNA). The LNA using dual band pass filter was designed and fabricated. The measured results of the implemented antenna is VSWR < 1.5 : 1 and the gain of 32dB(Zenith) over at GPS L1, L2, GLONASS L1.

• Korean Journal of Optics and Photonics
• /
• v.15 no.6
• /
• pp.555-562
• /
• 2004

We propose a hybrid method combining the implicit with the explicit methods in order to reduce the calculation time and improve the convergence problem of the 3-dimensional finite-difference beam propagation method. The numerical simulation of a directional coupler is carried out by the proposed method. It is found from the simulation results that the calculation speed of our method is 10 times faster than that of direct solving techniques.

• Journal of Advanced Navigation Technology
• /
• v.14 no.2
• /
• pp.170-175
• /
• 2010

This article proposed polarization selective antenna for UHF RFID system. The proposed antenna is consist of microstrip patch antenna with dual feeding and two SPDT switches and a SP4T switch and 3dB hybrid coupler. Through control of voltage of switches, the proposed reader antenna can select horizontally linear polarization, vertically linear polarization, left-hand circular polarization (LHCP) and right hand circular polarization (RHCP). The proposed reader antenna satisfied 2:1 VSWR at 902MHz ~ 928MHz. and 3dB under AR(axial ratio). And it can select appropriative polarization with user environment and tag polarization. So it minimize PLF and increased reading distance.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.8 no.5
• /
• pp.1076-1081
• /
• 2007

In this paper, we propose a new switch structure for time division duplex(TDD) system. The existing TDD structure utilizes a circulator fur isolation characteristic between ports. However, the circulator produces intermodulation distortion signals which are undesired signal because of its nonlinear properties. The proposed circuit is composed of a modified branch-line hybrid coupler which controls the signal flow while the isolated port is open-/short- terminated. In order to prove the validity of the presented structure, the switch circuit is fabricated and measured at 2.3GHz, the center frequency of Wibro service system.

• Proceedings of the IEEK Conference
• /
• 2005.11a
• /
• pp.925-928
• /
• 2005

In this study, we fabricated the DAMLs using surface micromachining technology as well a low loss coupler for the millimeter-wave band applications using these DAMLs. The structure of DAML is that a signal line is supported on ground plane by dielectric posts. Therefore it has advantages about the loss characteristic and the stable structure. The other advantage of the DAML process is a simple and convenient technique using 4 mask steps, even if it has a micromachining technology. The lowest loss of the fabricated DAML was obtained 2.2 dB/cm at 110 GHz. To obtain the low loss characteristic, couplers were designed and fabricated by using DAMLs. The fabricated ring hybrid coupler has the coupling of 3.58 dB and the thru of 3.31 dB at 60 GHz. We can also obtain the coupling of 3.42 dB, the thru of 3.82 dB from fabricated branch line coupler at 60 GHz.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.17 no.9 s.112
• /
• pp.845-851
• /
• 2006

Folded lines are applied to design a compact microstrip ring hybrid. Using the proposed structure we achieve both significant size reduction and good harmonic suppression with the same results of conventional ring hybrid at 2.41 GHz. Including the third harmonic frequency, up to 11 GHz band harmonics are suppressed to -20 dB. The size of the proposed ring-hybrid is reduced to one forth of the conventional ring hybrid. The measured frequency responses agree well with simulated ones.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.16 no.3
• /
• pp.275-283
• /
• 1991

A design method of the new 7${\lambda}$/6 ring 3dB directional coupler using fundamental /6-sections is proposed and its frequency characteristics are analyzed. Furthermore, the experimental verification has been achieved in microstrip network, and hence, the validity of the design method of a microwave compoennt with the basic ${\lambda}$/6-sections proposed in this paper is confirmed.