• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.18 no.10
• /
• pp.1107-1116
• /
• 2007

In this paper, a broadband open stubs band pass filters which can suppress the second harmonics using Z-transform technique, is designed, fabricated and characterized. The proposed broadband filters integrate the band stop filter with the FSCS structure and ${\lambda}_g/4$ open stub in order to suppress the second harmonics. Due to insertion of BSF at input and output terminal, the size of the filter was increased in the conventional filter, however, in the proposed structure, the position of inverter that connects the stubs can be integrated between those stubs, thereby decreasing the size. So, it can be fabricated in the size of $18.7{\times}16.9mm^2$ which is smaller size than conventional one. The measured results of the proposed filters have center frequency of a 5.8 GHz with bandwidth of 95 %, insertion loss of 0.6 dB, return loss of 14 dB. The simulation results are consistent with measurement results. The filter is designed far X-band satellite communication and ITS applications.

• Journal of Advanced Navigation Technology
• /
• v.27 no.3
• /
• pp.281-286
• /
• 2023

This paper proposes a design of a wideband array antenna involving the downlink bands of fixed satellite service (FSS) and broadcasting satellite service (BSS) by applying two mixed patch sets. The proposed antenna is implemented on FR4 substrate by arranging rectangular patches in 6 by 2. To design a wideband antenna (10.7~12.75 GHz) covering both FSS downlink bands (10.7~10.95 GHz, 11.2~11.45 GHz) and BSS downlink bands (11.7~12.5 GHz, 12.2~12.75 GHz, 11.7~12.2 GHz), rectangular patches working at 11.5 GHz and 12.5 GHz are arranged alternately, and thus the proposed antenna can obtain a wide bandwidth equivalent to 30.8% of the center frequency. The proposed antenna was fabricated and measured, and the results are well matched with the simulated ones. From the performances, the proposed antenna can be applied to the receiving antenna for FSS and BSS downlinks.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.22 no.11
• /
• pp.1034-1046
• /
• 2011

In this paper, a design and fabrication of 40 W power amplifier for the X-band using load-pull measurement of GaN HEMT chip are presented. The adopted active device for power amplifier is GaN HEMT chip of TriQuint company, which is recently released. Pre-matched fixtures are designed in test jig, because the impedance range of load-pull tuner is limited at measuring frequency. Essentially required 2-port S-parameters of the fixtures for extraction optimal input and output impedances is obtained by the presented newly method. The method is verified in comparison of the extracted optimal impedances with data sheet. The impedance matching circuit for power amplifier is designed based on EM co-simulation using the optimal impedances. The fabricated power amplifier with 15${\times}$17.8 $mm^2$ shows the efficiency above 35 %, the power gain of 8.7~8.3 dB and the output power of 46.7~46.3 dBm at 9~9.5 GHz with pulsed-driving width of 10 usec and duty of 10 %.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.6 no.5
• /
• pp.621-627
• /
• 2011

In this paper, we analysed performance for on-wafer GaN HEMT using load-pull in X-band, and studied optimum impedance point based on analysis result. We suggested method of optimum performance device by analysis of optimum impedance for solid state device on-wafer condition before packaging. The measured device is gate length 0.25um, and gate width is 400um, 800um. device 400um is performed $P_{sat}$=33.16dBm, PAE=67.36%, Gain=15.16dBm, and device 800um is performed $P_{sat}$=35.91dBm, PAE=69.23%, Gain=14.87dBm.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.9 no.11
• /
• pp.1215-1220
• /
• 2014

In this paper, a local oscillator for X-band radar system is designed and fabricated with GaAs MESFET. GaAs MESFET is good for microwave oscillators because of very low noise figure and high electron mobility. Oscillator design methods in this paper are used the characteristic of negative resistance of active component and impedance matching technique without RF resonator. So, oscillator is designed in compact size because space of RF resonator is reduced and can be applied MMIC technique. Designed oscillator has characteristic of the output power of 2.30 dBm and center frequency of 10.545GHz.

• Journal of the Korean Institute of Telematics and Electronics
• /
• v.19 no.6
• /
• pp.80-83
• /
• 1982

A quarter-wavelength open circuited microstripline slot array is realized at X-band froquency. The optimal feeding point is experimentally determined. The input impedance of the slot array for various frequencies and its radiation pattern are measured. The bandwidth of the slot array is increased by using the 4$\times$4 elements which are slightly different in length and feeding network which is suggested in this papers.

• Information and Communications Magazine
• /
• v.14 no.5
• /
• pp.128-146
• /
• 1997

정보통신서비스의 멀티미디어화, 실시간화가 보편적 요구조건으로 자리잡으면서 인프라의 광대역화, 고속화가 당면 과제로 되고 있다. 현존하는 가입자망이 집선 혹은 다중화 기능을 이용한 페어게인 시스템을 기반으로 하고 있으나, 규제완화와 정보통신서비스 고도화에 의해 새로운 가입자망의 탄생이 예고되고 있다. 이에 따라 기존 동선을 사용하여 전송 대역을 확장하는 xDSL(x Digital Subscriber Line)기술, 광케이블을 사용하여 광대역 전송능력을 지원할 뿐 아니라 가입자 배선능력을 획기적으로 개선하는 FTTx(Fiber To The x)기술, 광대역 전송 능력을 지원하는 광휘더와 배선 순기비용을 원천적으로 삭감시키는 무선 배선을 결합하여 새로운 비지니스 기회를 제공하는 HFR(Hybrid Fiber Radio)기술, 댁내 배선상의 병목을 제거하기 위한 WHAN(Wireless Home Area NetWork) 기술등이 가입자 접속능력을 초고속화하기 위한 기반이 될 것으로 예상된다. 본고에서는 정보통신서비스의 발전이 가입자 접속방식과 가입자망의 구성방식에 미치는 영향을 분석하고, 초고속 가입자 접속 기술의 전개 방향과 가입자망의 진화 전망을 기술한다.

• Proceedings of the KIEE Conference
• /
• 1987.11a
• /
• pp.377-382
• /
• 1987

To obtain a high resolution microwave images, back scattering microwave fields from one, two, four poles on a rotating object is measured. A computation algorithm to reconstruct these poles images from measured data is programed. The program is tested for these poles on a rotating object for different frequency intervals in the X-Band. The more frequency data yield the reduction of side lobe level. The reconstructed image for the two pole objects having the diameter of 1cm and separated by 1 lamda, 2 lamda (lamda-3.75 cm) from the measured data is shown. And, the image of two objects having the different reflectivity coefficient from the measured data is also shown and it assumes that this reconstructing algorithm from the measured angular spectrum provides quite accurate images.

• Proceedings of the IEEK Conference
• /
• 2002.06a
• /
• pp.455-458
• /
• 2002

Design methods are presented for an X-band traveling-wave slot array realized on a rectangular waveguide. An array of 21 longitudinal slots is realized on the broad wall of a rectangular waveguide. The squint of the antenna main beam is adjusted using the element spacing and the waveguide broad wall dimension. The excitation of the array is controlled by the slot offset from the waveguide center line Multiple I-plane steps are placed around last slot elements so that the second-order beam due to tile reflected wave Is minimized A waveguide-to-coaxial adapter Is designed for feeding the array antenna from a coaxial system. Results of the design show an outstanding performance of the antenna 17.1 dB gain. 36"beam 1111, and -21 dB maximum sidelobe level.evel.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.11 no.4
• /
• pp.92-98
• /
• 2008

A beam steering system of X-band 2-D phased array antenna for radar application is developed. The beam steering system consists of real-time command generator, beam steering unit, control PCB of array module and power supply. It plays a role of beam steering and on-line check of phased array antenna. The performance of beam steering system is verified with pulse timing of current control in phase shifters and measurement of far-field of phased array antenna. The developed beam steering system offers basic technology to develop full-scale beam steering system of multi-function radar.