SDUS front-end for the Meteosat Satellite System

Transcription

1 SDUS front-end for the Meteosat Satellite System Technical specications - Version 0.2 March 15, 2002 Contents 1 Antenna System 2 2 Low-noise Amplier (LNA) General Specications First stage Second stage PCB microwave laminates Local Oscillator Synthesizer General Specications PLL integrated circuits Voltage controlled oscillators (VCOs) PCB microwave laminates Downconverter General specications MMIC ampliers PCB microwave laminates Microstrip Filters Low-pass lter Band-pass lter PCB microwave laminates

2 1 Antenna System The receiving antenna is based on a primary focous parabolic mesh dish reector and a circular horn feed with a monopole probe. Parameter Value Units Dish Diameter 3.1 m Reector material Al Eciency 55 % f/d ratio? Theoretical Gain at 1.7 GHz (πd/λ) 2 35 db 2 Low-noise Amplier (LNA) The LNA is a two-stage amplier and will be mounted directly on the antenna horn feed to minimize noise gure. Power to the LNA should be supplied via the output RF port but provision of separate power supply terminals should be accounted for. 2.1 General Specications Parameter Symbol Value Units min. typ. max. Frequency range [f L f U ] MHz Gain G db Gain atness G ±0.5 db Output 1dB compression P 1dB 0 dbm Input impedance Z in 50 Ω Output impedance Z out 50 Ω Input VSWR VSWR(in) 1.2:1 Output VSWR VSWR(out) 1.2:1 Noise gure F db RF Connectors SMA or N (female) Supply voltage V DC 6 14 V Supply current I DC 100 ma Estimated cost 50 Euro 2.2 First stage Based on a very low-noise GaAs FET transistor in a common source conguration. The source transistor leads should be directly tied to the ground plane using via through holes as close as possible. 2

3 A variable negative gate bias supply should be provided. This stage should have no less than 10 db of gain. Available GaAs FET transistors Manufacturer Model Type Cost factor Agilent ATF General Purpose GaAs 1.0 Agilent ATF High performance GaAs 2.0 Agilent ATF GaAs Pseudomorphic HEMT 2.0 Agilent ATF GaAs Pseudomorphic HEMT 1.8 NEC NE32984D GaAs Pseudomorphic HEMT 2.0 NEC NE32584 Pseudomorphic HJ GaAs FET 2.0 NEC NE3210S01 HJ GaAs FET Second stage Based on a monolithic amplier integrated circuit (MMIC) The same care should be taken regarding the ground connection of the MMIC ground leads (via holes as close as possible) Available MMIC ampliers Manufacturer Model Process Cost Factor Sirenza Microdevices SGA-4586 SiGe 2.7 Sirenza Microdevices SGA-6586 SiGe 2.7 Mini-circuits ERA-3 GaAs HJ Bipolar 1.3 Mini-circuits Gali-55 InGap HBT 1.0 Agilent INA Si PCB microwave laminates Specications of the PCB laminate should be carefully chosen towards low dissipation factors substrates and low dielectric thicknesses (to minimize ground inductances). Rogers Corp. RT/Duroid Rogers Corp. RT/Duroid Rogers Corp. RT/Duroid GIL Technologies GML GIL Technologies GML

4 3 Local Oscillator Synthesizer The receiver local oscillator is based on a microprocessor controlled PLL synthesizer. The output frequency should be stored on a non-volatile memory (EEPROM) and programmed via a serial interface (EIA-232). 3.1 General Specications Parameter Symbol Value Units min. typ. max. Frequency range [f L f U ] MHz Frequency step f step 100 khz Output power P out 6 8 dbm SSB phase noise (@100 khz oset) P N -120 dbc/hz Output impedance Z out 50 Ω Output VSWR VSWR(out) 1.8:1 RF Connector SMA (female) Supply voltage V DC 24 V Supply current I DC 120 ma Estimated cost 70 Euro 3.2 PLL integrated circuits Manufacturer Model Type Freq. range (GHz) Cost factor National Semiconductors LMX-2326 Integer N National Semiconductors LMX-2353 Fractional N Analog Devices ADF-4112 Integer N Voltage controlled oscillators (VCOs) Manufacturer Model Freq. range (MHz) Output Power Cost factor Mini-circuits POS-2000A dbm 1.0 Mini-circuits ROS-1900V dbm PCB microwave laminates Rogers Corp. RT/Duroid GIL Technologies GML FR-4 or G

5 4 Downconverter The downconverter is based on a double-balanced mixer, the ADE-20 from Mini-circuits, inserted between two MMIC ampliers, providing adequate signal level to demodulator receiver. 4.1 General specications Parameter Symbol Value Units min. typ. max. Frequency range (RF port) [f RFL f RFU ] MHz Frequency range (IF port) [f IFL f IFU ] DC 300 MHz Conversion gain Gc 30 db LO level P LO 7 dbm I/O impedance Z out 50 Ω Input / Output VSWR VSWR 1.8:1 RF Connectors SMA (female) Supply voltage V DC 6 14 V Supply current I DC 100 ma Estimated cost 50 Euro 4.2 MMIC ampliers Manufacturer Model Process Cost Factor Sirenza Microdevices SGA-4586 SiGe 2.7 Sirenza Microdevices SGA-6586 SiGe 2.7 Mini-circuits ERA-3 GaAs HJ Bipolar 1.3 Mini-circuits Gali-55 InGap HBT 1.0 Agilent INA Si PCB microwave laminates Rogers Corp. RT/Duroid Rogers Corp. RT/Duroid GIL Technologies GML GIL Technologies GML

6 5 Microstrip Filters There are two types of microstrip lters to be designed: a low-pass and a band-pass response type lters. 5.1 Low-pass lter Band-pass lter PCB microwave laminates Specications of the PCB laminate should be carefully chosen towards low dissipation factor substrates. Very low strip widths should be avoided as the PCB fabrication process does not ensures tight tolerances. Rogers Corp. RT/Duroid Rogers Corp. RT/Duroid Rogers Corp. RT/Duroid GIL Technologies GML GIL Technologies GML