• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.8
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• pp.873-879
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• 2007

We have implemented a highly efficient 2.14-GHz class-F amplifier using Freescale 4-W peak envelope power(PEP) RF Si lateral diffusion metal-oxide-semiconductor field effect transistor(LDMOSFET). Because the control of the all harmonic contents is very difficult, we have managed only the $2^{nd}\;and\;3^{rd}$ harmonics to obtain the high efficiency with simple harmonic control circuit. In order to design the harmonic control circuit accurately, we extracted the bonding wire inductance and drain-source capacitance which are dominant parasitic and package effect components of the device. And then, we have fabricated the class-F amplifier. The measured drain and power-added efficiency are 65.1 % and 60,3 %, respectively.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.12
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• pp.1402-1409
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• 2008

In this paper, a low temperature co-fired ceramic cavity backed antenna in order to improve the performances of radiation and bandwidth for the antenna with high relative dielectric constant is proposed. Low temperature co-fired ceramic cavity consisted of several ground planes with closely spaced metallic vias connected. It is shown that the size of a low temperature co-fired ceramic cavity has the effects on the performances of radiation and bandwidth for the antenna. The proposed 2x4 low temperature co-fired ceramic cavity backed antenna is $10{\times}20\;mm^2$ in size. Measured results show antenna gain of $11.8{\sim}14.1\;dBi$ and bandwidth of 13 %(7.9 GHz) in the $57{\sim}64\;GHz$ band.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.11
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• pp.1156-1163
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• 2014

In this work by measuring transfer impedance of communication cables using EN50289 its Shielding effect is analyzed. transfer impedance measurement triaxial method using EN50289 is defined in CENELEC, it is unlike triaxial method prescribed in IEC Standard 96-1, can be measured regardless of diameter of coaxial cable and outer conductor. in this paper, transfer impedance measurement device of coaxial cable is designed and made according to EN50289 standard, The analysis determines the reliable working frequency range of coaxial cable and examined the impact of different shielding methods on coaxial cable. The transfer impedance measurements show considerable variations in results with various shielding methods. also the measurement procedure is verified through comparison of calculated and measured transfer impedance of RG-58 cable.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.7
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• pp.720-728
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• 2011

In this paper, development of the monopulse secondary surveillance radar antenna which can be used for IFF system is presented. This antenna that is passive linear array is comprised of the row-feeder and several array-elements. The row-feeder provides sum, different and SLS(Sidelobe Supression) channels which are optimized the distribution of the power and phase ratio. The azimuthe sidelobe level of the sum channel beam pattern is -20 dBc or less. The SLS channel covers the sidelobe of the sum-chanel in the whole azimuth angle range. And the difference channel is used to perform the mono-pulse function, improves the detection accuracy in the azimuth direction. Meanwhile, the arrayelement makes shaped beam in the elevation angle, in order to eliminate the clutter and multipath effects from the ground. Performance of the antenna developed is verified by the measurement of S-parameters and far-field beam pattern, and satisfies all of the development specifications well.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.10
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• pp.1166-1172
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• 2012

In this paper, by using a commercial EM simulator, we could obtain the array manifold which are phase responses of an array antenna for the incident plane wave and then verified the effectiveness of methodology after comparing with the measurement. The result shows that the array manifold can be calculated including not only the phase response of the ideal point sources but also the influences of the mutual coupling between antennas and the installed platform. Also it can exclude the interference of strong broadcasting signal and the disturbance of the multipath in the calibration process. Finally, to predict the performances of direction finding systems, a novel method using both the EM simulation-based receiving signal and the sparsely sampled array manifold with the parabolic estimation is proposed. This method can be utilized in the various fields of direction-finding since it shows the superior predictive performance even in low SNR conditions.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.7
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• pp.675-682
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• 2011

This paper presents two ground plane effects due to the size of two rectangular apertures for two-wire transmission line with equal line length crossing the changeable rectangular apertures in infinite ground planes. The CST MWS is used to determine the characteristics of the insertion loss of the transmission line from the load section in accordance with the ground plane aperture size. The results show that the insertion gain and the insertion loss are periodically observed for the multiple frequency of the half wavelength resonance by the wire length when the transmission line is nearby to horizontal side or vertical side of the aperture. The measurements of the insertion loss are performed to verify the theoretical analysis.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.8
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• pp.790-796
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• 2011

The system which is exposed in the impact range of High-altitude Electromagnetic Pulse(HEMP) may get serious damage because HEMP has a very large electric field value, a very fast rise-time, and so on. Electromagnetic analysis should be performed for signals coupled to the opening or cables of the system prior to derive the system design specifications in order to protect the system against HEMP adequately. In this paper, we analyzed the HEMP coupled signals for the coaxial cable which is generally used to transmit and receive video or RF signals and compared the coupled signal of the one wire with that of the inner conductor of a coaxial cable to confirm the decreased effect of HEMP by the shield. The coaxial cable is analyzed by the external and internal region of the shield separately. For the external region of the coaxial cable, general scattered equation was applied to calculate currents on the surface of the shield and for internal region of the coaxial cable, chain matrix algorithm is used. To verify this paper the analyzed results were compared the results of the existing paper and the two results have good agreements.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.5
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• pp.560-567
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• 2011

In this paper, we reduced the optical noise interference using polarizers in a visible light communication system. In a transmitter, two light-emitting diodes(LEDs) are modulated synchronously by the original and the reversed signals of the transmitted data, and the two LED lights are radiated through orthogonal polarizers. In a receiver, two optical signals are detected through orthogonal polarizers and differentially amplified to remove the optical noise. In an environment that noise light from a fluorescent lamp is much stronger than the signal, the receiver with orthogonal polarizers removed the 120 Hz noise, and synchronous light transmission of the original and the reversed signals using two LEDs reduced the illumination flickering to about one-eighth that using one LED.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.8
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• pp.776-783
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• 2011

In modern warfare, jamming for neutralizing the enemy electronic equipments is as important as destroying them by common weapon systems. Noise jamming is a base technique of EA(Electronic Attack) and it is one of the effective jamming techniques. Noise jamming is effective regardless of enemy electronic equipment receiver types. For increasing jamming efficiency using the same output power, noise jamming bandwidth has to be similar to target receiver's bandwidth. Radar jamming source like DRFM(Digital Radio Frequency Memory) requires noise bandwidth changing immediately for time sharing multiple jamming. In this paper, we developed bandwidth changable noise jamming signal for phase sampling type DRFM and do simulation using Matlab for showing the jamming signal output.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.7
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• pp.728-736
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• 2014

Due to the recent development of mobile wireless telecommunication, RRHs(Remote Radio Heads) are widely being utilized to expand the cell coverage. Wire-link, an existing connection between DU(Digital Unit) and RRH through fiber cables, is considered to have limitations in relation to cost for a wide range of applications. This paper focuses on replacing the wire-link by wireless transmission using millimeter-wave, and implementing cellular network system through RRH from a remote location. After an influence element analysis on millimeter-wave wireless link transmissions, a comparative analysis between wireless link and an existing fiber link method will be made by utilizing currently commercialized LTE(Long Term Evolution), to prove the compatibility of millimeter-wave wireless link RRH method in replacing fiber link method without a significant decline in data transmission performance.