• Journal of Satellite, Information and Communications
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• v.10 no.2
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• pp.24-29
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• 2015

Recently, with developments of various networks, devices and various services, energy efficiency has become one of the most crucial issues with respect to sustainability of mobile devices. For connecting to networks seamlessly to offer services, a scenario of RF energy harvesting which supplies energy to wireless devices with RF signals is assumed. To increase the efficiency of RF energy harvesting, this paper proposes a RF energy harvesting algorithm which is based upon a frequency selective fading map. Through the algorithm, a receiver of mobile device can get fading information at each frequency and select a frequency which has the best quality. At the end, the simulation result demonstrates its superiority by showing a 4.45dB improvement in comparison to a deep fading frequency point.

• Journal of electromagnetic engineering and science
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• v.4 no.4
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• pp.143-149
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• 2004

This paper describes characteristics of the single-balanced low IF resistive FET mixer for the digital beam forming(DBF) receiver. This DBF receiver based on the direct conversion method is designed with Low IF I and Q channel. A radio frequency(RF), a local oscillator(LO) and an intermediate frequency(IF) considered in this research are 1950 MHz, 1940 MHz and 10 MHz, respectively. Super low noise HJ FET of NE3210S01 is considered in design. The measured results of the proposed mixer are observed IF output power of -22.8 dBm without spurious signal at 10 MHz, conversion loss of -12.8 dB, isolation characteristics of -20 dB below, 1 dB gain compression point(PldB) of -3.9 dBm, input third order intercept point(IIP3) of 20 dBm, output third order intercept point(OIP3) of 4 dBm and dynamic range of 30 dBm. The proposed mixer has 1.0 dB higher IIP3 than previously published single-balanced resistive and GaAs FET mixers, and has 3.0 dB higher IIP3 and 4.3 dB higher PldB than CMOS mixers. This mixer was fabricated on 0.7874 mm thick microstrip $substrate(\varepsilon_r=2.5)$ and the total size is $123.1\;mm\times107.6\;mm$.

• Journal of electromagnetic engineering and science
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• v.2 no.2
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• pp.117-123
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• 2002

This paper describes the design for the resistive FET mixer with low If for the 4-Ch DBF(Digital Beam Forming) receiver This DBF receiver based on the direct conversion method is generally suitable for high-speed wireless mobile communications. A radio frequency(RF), a local oscillator(LO) and an intermediate frequency(If) considered in this research are 2.09 GHz, 2.08 CHz and 10 MHz, respectively. This mixer is composed of band pass filter, a low pass filter and a DC bias circuit. Super low noise HJ FET of NE3210S01 is considered in design. The RE input power, LO input power and Vcs are used -10 dBm, 6 dBm and -0.4 V, respectively. In the 4-Ch resistive FET mixer, the measured If and harmonic components of 10 MHe, 20 MHz and 2.087 CHz are about -19.2 dBm, -66 dBm and -48 dBm, respectively The If output power observed at each channel of 10 MHz is about -19.2 dBm and it is higher 28.8 dBm than the maximum harmonic component of 2.087 CHz. Each If output spectrum of the 4-Ch is observed almost same value and it shows a good agreement with the prediction.

• Journal of Electrical Engineering and Technology
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• v.7 no.1
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• pp.81-85
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• 2012

This paper presents a wideband and low-noise direct conversion front-end receiver supporting VHF and UHFbands simultaneously. The receiver iscomposed of a low-noise amplifier (LNA), a down conversion quadrature mixer, and a frequency divider by 2. The cascode configuration with the resistor feedback is exploited in the LNA to achieve a wide operating bandwidth. Four gainstep modesare employed using a switched resistor bank and a capacitor bank in the signal path to cope with wide dynamic input power range. The verticalbipolar junction transistors are used as the switching elements in the mixer to reduce 1/f noise corner frequency. The proposed front-end receiver fabricated in 0.18 ${\mu}m$ CMOS technology shows very low minimum noise figureof 1.8 dB and third order input intercept pointof -12dBm inthe high-gain mode of 26.5 dBmeasured at 500 MHz.The proposed receiverconsumeslow current of 20 mA from a 1.8 V power supply.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.3
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• pp.371-379
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• 2011

Active phased array antenna structure is used for modern multi-function radars. To search targets in high clutter environment, the radar receiver needs high dynamic range performance. Though active phased array antenna structure lead to increase of SNR, the SFDR is not increased. In this paper, high SFDR receiver of X-band active phased array radar was designed and manufactured. One channel digital receiver is connected to 32 T/R modules and one PCB assembly is composed to 2 channel digital receivers with RF part, ADC part, LO distribution part and digital down conversion part. A commercial FIFO board was used for digital receiver measurement about major performance in digital output signal condition. The measured digital receiver gain and SFDR is 33 dB and more than 81 dBc each.

• Aerospace Engineering and Technology
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• v.13 no.1
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• pp.55-62
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• 2014

FTSR(Flight Termination System Receiver) is a device that receives a ground command signal to abort a flight mission when abnormal conditions occur in the space launch vehicle. The secure tone command message shall consist of a series of 11 character tone pattern. Each character consists of the sum of two tones which taken from a set of 7 tones defined by IRIG(Inter-Range Instrumentation Group) in the audio frequency range. The MHA(Modified High alphabet) command adds a security feature to the secure tone command by using the predefined difference code. In order to check the function and performance of MHA FTSR, which is under development, for KSLV-II, the testbed should have functions of RF signal generation, receiver's output port monitoring, RS-422 communication and test data management. In this paper, we first briefly introduce MHA command and FTSR interface, and then show the LavVIEW based testbed include its H/W configuration, S/W implementation and test results.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.11 no.2
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• pp.1-6
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• 2011

In this paper, an 1.5Gbit/s wireless data transmission system using the carrier frequency of 300 GHz band was implemented. The RF front-end was composed of schottky diode sub-harmonic mixer, frequency tripler, and horn antennas for transmitter and receiver, respectively. The LO frequencies of sub-harmonic mixer are 150GHz for transmit chain and 156GHz for receive chain. The ASK(Amplitude Shift Keying) modulation was used in the transmitter and the envelope detection method was used in the heterodyne receiver. The conversion loss of sub-harmonic mixer and implementation system loss were measured to be 9.8dB and 1.2dB, respectively. The 1.5Gbit/s video signal with HD-SDI format was transmitted over wireless distance of 40cm without optical lens(4.2m with optical lens) and displayed on HDTV at the transmitted average output power of $20{\mu}W$.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.6
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• pp.630-637
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• 2003

This paper explains the impact of frequency error on the performance of WCDMA mobile communication systems and what brings about the frequency error between the base station and the mobile station, and then presents automatic frequency error correction method in mobile receiver. On the basis of system requirement related to frequency stability, the integration test between the base station and the mobile station was accomplished. After applying automatic frequency error correction to mobile receiver, 4 Hz of frequency error at transmitting frequency was obtained. The result met frequency error requirement of ${\pm}$0.1 ppm(about ${\pm}$200 ㎐). Performance degradation due to frequency error was measured by means of Error Vector Magnitude(EVM) at transmitter and Ec/Io at receiver, respectively and then the interface requirement between Modem control signal and RF was suggested to improve the correctness of frequency error control.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.1
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• pp.70-75
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• 2014

This paper presents a IR-UWB(Impulse Radio Ultra-Wide Band) transceiver circuit for data communication and real time location system. The UWB receiver is designed to OOK(On-Off Keying) modulation for energy detection. The UWB pulse generator is designed by digital logic. And the Gaussian filter is adopted to reject side lobe in transmitter. The measured sensitivity of the receiver is -65 dBm at 4 GHz with 1 Mbps PRF(Pulse Repetition Frequency). And the measured energy efficiency per pulse is 20.6 pJ/bit. The current consumption of the receiver and transmitter including DA is 27.5 mA and 25.5 mA, respectively, at 1.8 V supply.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.3 no.3
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• pp.569-577
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• 1999

A wideband RF receiver for satellite mobile communications system was fabricated and evaluated of performance in low noise amplifier and high gain amplifier. The low noise amplifier used to the resistive decoupling and self-bias circuits. The low noise amplifier is fabricated with both the RF circuits and the self-bias circuits. Using a INA-03184, the high gain amplifier consists of matched amplifier type. The active bias circuitry can be used to provide temperature stability without requiring the large voltage drop or relatively high-dissipated power needed with a bias stabilized resistor. The bandpass filter was used to reduce a spurious level. As a result, the characteristics of the receiver implemented here show more than 55 dB in gain, 50.83 dBc in a spurious level and less than 1.8 : 1 in input and output voltage standing wave ratio(VSWR), especially the carrier to noise ratio is a 43.15 dB/Hz at a 1 KHz from 1537.5 MHz.