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Filter Retuning DemonstrationD i l F ll S RF E i
COMPANY CONFIDENTIAL
GLOBAL INFRASTRUCTURE X PROCESS EQUIPMENT X DIAGNOSTIC TOOLS
1
Daniel Fallon, Sr. RF Engineer
Filter Tuning
• Retune 150 Watt Filter from ch 42 to ch 30
• Uses Agilent Time Domain Tuning Technique
• Agilent AN1287-8 “Simplified Filter Tuning Using Time Domain”
• Requirements
• VNA with time domain option (8753ES / )EN5071…)
• 7/8” deep socket wrench
• ½” wrench (deep socket preffered)
• 1/16” Allen Wrench
COMPANY CONFIDENTIAL
GLOBAL INFRASTRUCTURE X PROCESS EQUIPMENT X DIAGNOSTIC TOOLS
7/28/2012 2
Sequence• Capture memory trace of tuned filterp y
• Set frequency of new channel and recalibrate
• Preset all coupling loop depthsPreset all coupling loop depths
• Set input coupling and resonator 1 (each side)
• Rough tune resonators 2 and 3 (each side)• Rough tune resonators 2 and 3 (each side)
• Time domain fine tune res 1 to 3 (each side)
• S21 fine tune cross coupling• S21 fine tune cross coupling
• Time domain fine tune all
F d i fi i hi t h t i /• Frequency domain finishing touches – centering / bandwidth / frequency
• Lock down
COMPANY CONFIDENTIAL
GLOBAL INFRASTRUCTURE X PROCESS EQUIPMENT X DIAGNOSTIC TOOLS
7/28/2012 3
• Lock down
100/150/200 Watt Filter
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Resonators, Fine matchers and Loops
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Initial Channel Measurement
• Span 30 MHz• Full two Port Cal
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Full two Port Cal• Shown with limits – LPTV Stringent Mask
Coupling Presets
• All coupling loops and Cross coupler position pre-set to height off case from chart
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Coupling Heights
• Cross Coupler Height
• Coupling Loop Height
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Loosen all resonators
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Resonator # 1 and input coupling tune
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Rough In Resonator #2
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Rough In Resonator #3
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Initial Time Domain Tune
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Adjust Cross Coupling
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Bandwidth Adjust
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• All loops deeper = wider filter
Frequency Adjust
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• All fine matchers into cavity= tune down
Fine Tune in Time Domain
• S11 Log Mag display data and memory
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S11 Log Mag, display data and memory• Band-pass time domain transform• Start time -20 ns, stop time ~650 ns
Polar Plot Centering
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• Input coupling and resonator 1
Lock Down Tuned Filter
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• Put tuned filter into memory, do one screw at a time
CONCLUSIONS
• Tuned filter can serve as a template for new channel
• Time domain option on VNA makes tuning much easierTime domain option on VNA makes tuning much easier
• Dielectric offers one time re-tuning with low power filters
COMPANY CONFIDENTIAL 20