A novel microstrip lowpass filter utilizing defected ground structure (DGS) units is presented in this paper. A DGS unit is simulated with different physical dimensions in order to show variation of effective inductance and capacitance. Next, a lowpass filter using proposed DGS unit is designed. A method for determining dimensions of microstrip structure and DGS units is proposed. Influence of dimensions of the microstrip structure on filter characteristics is investigated and simulated. Filters of various orders are simulated as well. Selected filter is simulated and experimentally verified.

Design of Microstrip Lowpass Filter Using Defected Ground Structure

This paper focuses on the design and implementation of a front-end for a Vinasat satellite receiver with auto-searching mechanism and auto-tracking satellite. The front-end consists of a C-band low-noise block down-converter and a L-band receiver. The receiver is designed to meet the requirements about wide-band, high sensitivity, large dynamic range, low noise figure. To reduce noise figure and increase bandwidth, the C-band low-noise amplifier is designed using T-type of matching network with negative feedback and the L-band LNA is designed using cascoded techniques. The local oscillator uses a voltage controlled oscillator combine phase locked loop to reduce the phase noise and select channels. The front-end has successfully been designed and fabricated with parameters: Input frequency is C-band; sensitivity is greater than -130 dBm for C-band receiver and is greater than -110dBm for L-band receiver; output signals are AM/FM demodulation, I/Q demodulation, baseband signals.

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Design of a Front-End for Satellite Receiver

During changing sun activity, the ionosphere is responding accordingly and therefore it is interesting to observe the propagation behavior of shortwave bands. For the above mentioned purpose we are designing a monitoring payload for an experimental cubesat satellite called PSAT. The payload consists of a receiver, which is able to receive SSB modulated narrowband signals in 28 MHz uplink band and a transmitter with FM modulation in UHF downlink frequency band. The receiver frequency is selected to be at the center of radio amateur activity with low data rate digital modulations.

/pdf/experimental-band-monitor-for-psat-satellite-1st4760i22.pdf

Experimental band monitor for PSAT satellite

Since early nineties we are involved into program of international organization AMSAT. We have participated on several satellite projects as well as these satellites control and telemetry gathering. For this purposes we built up an automatic tracking system with high gain antennas and radio electronics for advanced spacecraft application. A number of graduate and postgraduate student projects became hardware and software application for this station. It has also been a good opportunity for students to meet spacecraft technology. Several of our activities in this field are described in this paper.

Experimental satellite laboratory but education and research

During changing sun activity, the ionosphere is responding accordingly and therefore it is interesting to observe the propagation behavior of shortwave bands. For the above mentioned purpose we have designed a bandmonitoring payload for an experimental CubeSat satellite. The payload consists of a receiver, which is able to receive SSB modulated narrowband signals in 28 MHz uplink band, and a transmitter with FM modulation in UHF downlink band. The receiver frequency is selected to be at the center of radio amateur activity with low data rate digital modulations.

Band-monitoring Payload for a CubeSat Satellite

In this paper, a new developed satellite receiver for very slow data operation and an experimental SSB/spl rarr/FM transponder is described. The receiver is an uplink part of the transponder that is based on a new unconventional method for Doppler shift rejection by the help of FM downlink and low SSB uplink frequency with an application of FDMA. The base advantages of the slow rate PSK31 operation, the design and measurements of the receiver with respect to high reliability and low power consumption, the transponder and a practical simulation of Doppler shift influence on a transmitted message error rate is presented. This project is apart of PCSAT2 satellite project of US Naval Academy that has to be placed on ISS.

PSK slow rate data transmission in satellite communication

A novel method for the optimization of the active frequency multiplier utilizing the harmonic terminating impedances with the defected ground structures (DGS) has been developed. Furthermore, a new type of the low-pass filter with DGS for the higher harmonic suppression will be reported. Experimental conversion gains (14.52 dB for the doubler, 5.56 dB for the tripler and 0.43 dB for the quadrupler) and real power-added efficiency (32.76 % for the doubler, 10.15 % for the tripler and 1.42 % for the quadrupler) have been attained. To our knowledge, in the considered frequency range, these results represent the best performance reported up to date for the active frequency multipliers utilizing the low-cost BJTs.

/pdf/novel-optimization-method-of-active-frequency-multiplier-fk9chisa05.pdf

Novel Optimization Method of Active Frequency Multiplier Utilizing Harmonic Terminating Impedances with DGS

The design, simulation and experiments of an L-band front end for the new AMSAT Phase 3E satellite are presented here. The double conversion receiver for the transponder and command unit is based on the double PLL frequency synthesizer synchronized by an ultra stable oscillator positioned on-board the satellite.

/pdf/satellite-l-band-front-end-design-3ck3dbovdb.pdf

Satellite L-band front end design

A novel method for the optimization of the active frequency multiplier utilizing the harmonic terminating impedances with the defected ground structures (DGS) has been developed. Furthermore, a new type of the low-pass filter with DGS for the higher harmonic suppression will be reported. Experimental conversion gains (14.52 dB for the doubler, 5.56 dB for the tripler and 0.43 dB for the quadrupler) and realpower-added efficiency (32.76 % for the doubler, 10. 15 % for the tripler and 1.42 % for the quadrupler) have been attained. To our knowledge, in the considered frequency range, these results represent the best performance reported up to date for the active frequency multipliers utilizing the low-cost BJT.

Petr Kutin

Papers

PSK slow rate data transmission in satellite communication

Novel Optimization Method of Active Frequency Multiplier Utilizing Harmonic Terminating Impedances with DGS

Satellite L-band front end design

Advanced Technique for Optimization of Active Frequency Multiplier Utilizing Harmonic Terminating Impedances with DGS