Transcript Preliminary Design Review Presentation: Transmitter

Overview
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Exciter
Receiver
Oscillators
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High-Powered Amplifier
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Calibration
HPA: Extended Interaction Klystron
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EIK-based amplifier appears to
be the best suited
Conduction cooled unit was
developed for CloudSat
Mounted in a pressure vessel in
the pod with modulator and RF
front-end electronics
EIK Specifications
Center Frequency
94 GHz
Bandwidth (1 dB)
> 200 MHz
Peak Power
1.7 kW
Gain
50 dB
CloudSat Flight Model EIK
HPA: Extended Interaction Klystron
EIK Passband versus Temperature
2200
(3 % duty cycle)
Peak Power (W)
2000
1800
1600
1400
1200
1000
0ºC
11ºC
50ºC
800
93.84 93.88 93.92 93.96 94.00 94.04 94.08 94.12 94.16 94.20 94.24 94.28
Frequency (GHz)
HPA: Extended Interaction Klystron
EIK Passband versus Duty Cycle
2200
(Heatsink at 25ºC)
Peak Power (W)
2000
1800
1600
1400
1200
1000
3.00%
1.40%
0.10%
800
93.84 93.88 93.92 93.96 94.00 94.04 94.08 94.12 94.16 94.20 94.24 94.28
Frequency (GHz)
HPA: Modulator
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Requirements
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Options
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5 % duty cycle
Up to 20 kHz pulse repetition rate
Pulse lengths from 200 ns to 2 µs
Aircraft ready (vibration, attitude changes)
Communications & Power Industries (CPI)
• Expensive modulator
• Reports of bad experiences
Pulse Systems
• Cheap
• Largely untested
Applied Systems Engineering (ASE)
• Very expensive
• Good engineering support
Looking for advice and comments
HPA: Waveguide
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Peak Power Considerations
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WR-10 can handle around 8 % (1.34 kW at 94 GHz) of the waveguide
theoretical peak power (Ciavolella, 1972)
Pressurize the front-end electronics waveguide with nitrogen
Average Power Considerations
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Maximum rated average power of WR-10 is 18 W at 94 GHz
At 1 µs pulse length and a 10 kHz PRF, the average power out of the EIK is
17 W assuming no standing waves in the waveguide
May need to use heat-sinks and forced-air cooling to remove heat from the
waveguide walls