• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.5 no.1
• /
• pp.166-172
• /
• 2001

A RF wideband receiver for INMARSAT-B satellite communications system was composed of low noise amplifier and high gain amplifier, The low noise amplifier used to the resistive decoupling circuit for input impedance matching and self-bias circuits for low noise. The high gain amplifier consists of matched amplifier type to improve receiver gain. The active bias circuit can be used to provide temperature stability without requiring the large voltage drop or relatively high-dissipated power needed with a bias stabilization resistor. The bandpass filter was used to reduce a spurious level. As a result, the characteristics of the receiver implemented here show more than 60 dB in gain and less than 1.8:1 in input and output voltage standing wave ratio(VSWR), especially the carrier to noise ratio which is input signal level -126.7 dB m at 1537.5 MHz is a 45.23 dB /Hz at a 1.02 kHz.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.19 no.1
• /
• pp.61-70
• /
• 2008

This paper presents the flexible MEMS transmitter based on flexible printed circuit board or FPCB, which can be transformed to arbitrary shape. The FPCB is suitable to fabricate light weight and small size modules with the help of its thin thickness. Moreover a module based on FPCB can be attached on the arbitrary curved surface due to its flexible enough to be lolled up like paper. In this paper, the flexible MEMS transmitter integrated on FPCB for a short-distance sensor network which is based on orthogonal frequency division multiplexing(OFDM) communication system is proposed. The active device of the proposed flexible MEMS transmitter is fabricated on InGaP/GaAs HBT process which has been used for power amplifier design to take advantages of high linear and high efficient characteristics. Moreover, the passive devices such as the filter and signal lines are integrated and fabricated on the FPCB board. The performance of the fabricated flexible MEMS transmitter is analyzed with EVM characteristics of the output signal.

• Journal of Satellite, Information and Communications
• /
• v.2 no.2
• /
• pp.41-47
• /
• 2007

The first geostationary satellite made by Korea, COMS, has the three different payload ; Meteorological sensor, Oceanographic sensor and Ka-band communication payload. There are Meteorological & Ocean Data Communication Subsystem(MODCS) and Telemetry, Command and Ranging Subsystem(TC&R) as other RF radiation sources. MODCS transmits and receives Meteo and Ocean measurement data from/to earth using L-band and TC&R using S-band. The Ka-band communication payload will provide high-speed multimedia services and communication services for natural disaster such as prediction, prevention, and recovery services in the government communications network.Ka-band beacon is for the earth antenna pointing and the experiment of rain fading. This paper gives the analysis results about the mutual radiation effect on Ka-band communication payload, Ka-band beacon, MODCS and TC&R. Up/Down link power and coupling factor including the geometrical position and distance of antenna, filter rejection and degradation factor due to the different polarization are considered. The results show MODCS and TC&R are compatible for Ka-band communication payload and Ka-band beacon does not interfere with MODCS and TC&R normal operation.

• Journal of the Institute of Electronics Engineers of Korea TE
• /
• v.39 no.3
• /
• pp.59-64
• /
• 2002

In the RFID system using ISM-band, The tag mounted at the object has used the DC power by rectifying the RF signals of the small antenna for operating the micro-controller and memory. The performance of the tag would be reduced because of the second harmonics generated by the nonlinearity of the semiconductor and the spurious signal excited the high order mode of the antenna. This paper has realized the novel type low-pass filter with "the Stub-I type DGS slot structure" to improve the efficiency of the tag by suppressing the harmonics. The optimized frequency character at the pass-band/stop-band has obtained by tuning the stub width and slit width of I type slot. The measured result of the LPF has the cutoff frequency 3.25 GHz, the insertion loss about -0.29~-0.3 dB at pass-band 2.4 GHz~2.5 GHz, the return loss about -27.688~-33.665 dB at pass-band with a good performance, and the suppression character is about -19.367 dB at second harmonics frequency 4.9 GHz. This DGS LPF may be applied the various application as the RFID, WLAN to improve the efficiency of the system by suppressing the harmonics and spurious signals.