• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.3
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• pp.279-287
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• 2002

In this paper, a symmetric microwave lens to steer wide angle and to operate at broad band frequency range for a linear phased array transmitter was designed. To get accurate beam steering performance far a linear phased array transmitter, uniform amplitude transmission characteristics of microwave lens was focused. The measured result for the insertion loss deviation between Input and output ports of microstrip lens with 8 beam ports and 8 array ports was $\pm$3.1 ㏈ over 6~18 ㎓ band, which was very uniform characteristics. Using 8 elements linear array antenna, it was confirmed the radiation beam could be steered over $\pm$60$^{\circ}$ in azimuth. And the measured lens performance data and multi-beam steering pattern were presented.

• Proceedings of the KSRS Conference
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• 1999.11a
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• pp.456-461
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• 1999

It is very important for monitoring the interannual variability of sea ice extents in the Okhotsk Sea because the global warming has firstly appeared around the Okhotsk Sea, locating around the southernmost region of sea ice cover in the Northern Hemisphere. In order to develop the sea ice concentration algorithm by microwave sensors onboard satellite, electromagnetic properties of sea ice in the Okhotsk Sea, therefore, were observed by airborne microwave radiometer (AMR), which has the same frequencies as AMSR (Advanced Microwave Scanning Radiometer), ADEOS-II, launching on November, 2000. On this study, it is discussed how to make the image of AMR-EFOV and the video image with nadir angle under flight at the same time, and superimpose the brightness temperature data by AMR-EFOV on the video mosaiced images. For comparing SPOT image, it is clearly that the variation of brightness temperature is small in 89GHz V-pol without the sea ice types and increase at the lower frequency-band.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.5
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• pp.863-871
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• 2003

In this paper, we design a high stable Ku-band phase-locked dielectric resonant microwave oscillator with the gate voltage controls of p-HEMT. By adapting the nonlinear equivalent elements which affects phase noise of microwave oscillator, we optimize the nonlinear elements of p-HEMT to have low phase noise operation. Using the scattering parameters according to bias voltages, we designed the gate voltage control microwave dielectric resonant oscillator and phase-locked loop circuits is applied to have the high stable operations. Designed microwave oscillator as a local oscillator of digital microwave communication shows that output power is 9.17dBm at 10.75GHz and it's phase noise is -88dBc/Hz at 10KHz offset frequency.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.3
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• pp.517-522
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• 2004

In this paper, we have analyzed the performance enhancement of Orthogonal Frequency Division Multiplexing/Quadrature Phase Shift Keying Modulation-Digital Microwave Radio(OFDM/QPSK-DMR) system using Band Limited-Pulse Shaping Filter(BL-PSF) over microwave channel environments. For performance enhancement, the one-tap adaptive equalizer is adopted in the OFDM/QPSK-DMR system and than both BER and signature curve performance are compared with those of single carrier DMR system. Computer simulations confirm that the OFDM/QPSK-DMR system using 16 sub-carrier increase the fade margin about 2 dB over microwave channel environments and that of performance using one-tap adaptive equalizer is highly increased the fade margin as the number of sub-carriers is larger.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.4 no.3
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• pp.3-10
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• 1993

As a method to measure the absorbing characteristics of microwave absorber, various microwave measuring method can be used fundamentally. There is, however, a big problem in measuring errors, since the wavelength of microwave such as used for radar is very short. Therefor, this research aimed to design and fabricate a converting adaptor of 20mm .PHI. coaxial tube from a type-N connector to coaxial tube and to use it for evaluating absorption characteristics of microwave absorbor. Furthemore, the measurements of absorbing characteristics and material constants have been perfomed and reviewed, which were carried out by using the coaxial and by using rectangular waveguide, respectively. As a result, the validity of the proposed measuring method has been conformed. In this paper, a preliminary evalua- tion on the characteristics of the electromagnetic wave absorbor for X-band radar designed and fabricated for a laboratory use is performed by reflected power method near to a pratical use. Then for field test by using X-band radar is carried out with real target of $1.2m\times1.2m$ in size. As the result of the above, the usefullness of the designed and fabricated electromagnetic wave absorber in paint type for X-band radar has been confirmed.

• Journal of Magnetics
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• v.2 no.1
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• pp.25-27
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• 1997

Ferrite tile absorber is of great concern for the application to anechoic chambers due to the growing demand of EMI or EMC measurements. This paper investigates the magnetic, dielectric and microwave absorbing properties of a Ni-An ferrite for the purpose. A design chart was constructed with the solutions of impedance-matching equation in the radio frequencies (30 MHz - 1 GHz). The material parameters for zero-reflection are predicted from the chart. The magnetic and dielectric properties of sintered Ni-Zn ferrite is found to be well suited for this requirements. A superior microwave absorbing properties (frequency band and absorber thickness) of the samples are demonstrated.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.31A no.6
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• pp.45-52
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• 1994

A microwave PIN diode 4-bit phase shifter is designed in X-band. A loaded-line type is used for the 22.5$^{\circ}$ and 45$^{\circ}$ bits, and a switched-line type for the 90$^{\circ}$and 180$^{\circ}$bits. The measured results show that the phase error and average insertion loss are less than $\pm$5.4$^{\circ}$and 7.2dB, respectively, over a 9.75~10.25GHz frequency band.

• Journal of the Korean Institute of Telematics and Electronics
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• v.16 no.5
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• pp.42-48
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• 1979

In this paper, it is shown that a microwave frequency discriminator can be realized by use of a simple ring resonator. Its characteristics have been analyzed by employing Green's function and verified experimentally. The maximum frequency bandwidth obtained from the experiments is 45MHz at S-band(center frequency 50=3GHz).

• Journal of the Korean Institute of Telematics and Electronics A
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• v.30A no.3
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• pp.34-42
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• 1993

An analytic approach to wide-band amplification using simplified equivalent MESFET modeling has enabled an ultrabroad-band flat-gain amplifier from DC to microwave. The developed lossy-match ultrabroad-band amplifier operates as a RC coupled circuit in the low-frequency range and lossless impedance matching circuit in the microwave frequency range with gain compensation circuits. The reduced gain caused by external resistors is compensated using 2-stage cascade amplification, and the gain of designed unit is 12.5.+-.1dB from the vicinity of DC to 7GAz. The experimental gain characteristics are good agreement with computer simulated results. The input and output VSWRs are measured under 2:1 over the operating frequency range, and the gain goes down over 15dBrange with various gate bias voltages.

• The Journal of the Korea institute of electronic communication sciences
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• v.9 no.2
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• pp.173-180
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• 2014

The development process of a L-Band microwave radiometer for remote sensing of soil-moisture are described in this paper. Achieving the development aim of the measurement accuracy within 2% for soil moisture content of 0~50%, the requirements and specifications of the microwave radiometer and its receiver are drawn. The receiver with high gain, high sensitivity is designed and implemented to satisfy these requirements and specifications. The receiver has the bandwidth of 40 MHz, the system gain of 50 dB and the sensitivity of average value 0.19 K, maximum value 0.313K at 1390 MHz.