Background:

• the output of each klystron window. These are reported on the individual klystron pages as reflected power.
• the waster load. This is between thecombiner and the waster load
• just before the turnstile. This is called antenna reflected power.
• as the 4th port of the turnstile. this is called turnstile power. When power reflects back from the horn, some of it will go back towards the combiner, while some will go to this port of the turnstile. The amount depends on the polarization of the reflected signal

The waveguide path is:

• klystron window. start
• directional coupler to
  
• waveguide switch for dummy load
• to combiner input
• combiner
• combines power from both klystrons.
  
• output to directional coupler, then waster load .,. or
  
• output to antenna direction
• combiner to top of vertical waveguide column down to rotary floor
• rotary coupler attaching fixed to rotating waveguide (at top of column)
• waveguide column down to rotary floor
• waveguide along rotary floor out to turnstile, horn
• directional coupler (antenna reflected power)
• turnstile
• horn
• turnstile directional coupler, turnstile load.
  

aug15 problem   

• the rotary floor is level at 10 deg za.
• When the sb tx horn is at the focus:
  
• at high za, the waveguide along the rotary floor is tilted so the horn side is higher than the other side. Any water in this piece of waveguide would flow away from the antenna reflected power coupler that is next to the horn
• at low za, the waveguide along the rotary floor is tilted so that the horn side is lower than the center of the floor edge. Any water in this piece of waveguide would flow toward the horn directional coupler side.

measuring the waveguide with the network analyzer.

• A termination was put at the top of the vertical column that connects the tx room to the rotary floor room. It was placed on the transition above the rotary coupler (so the rotary coupler was included in the measurement).
  
• A second transition was place where the 90 degree elbow attached the waveguide to the turnstile
• 2000 to 2500 Mhz bw was used for the measurement.
• The measurement was done at:
• sband tx on turret focus
• za=11 degrees
• za=1.07 degrees
• za=19.69 degrees
• za=11 degrees
• za=11 degrees with the turret rotated 180 degrees.

• for the distance axis i used the group velocity at 2380 Mhz: .817
• vgrp[2000,2250,2500Mhz]=[.727,.792,.836]
• Page 1: reflected power vs distance, time.. all measurements
• top: reflected power vs time (usec)
• bottom: reflected power vs distance (feet)
• At za=1.07 deg there is a peak close to the analyzer injection power
• at za=19.69 this peak moves away from the injection point by about 6 more feet.. this
  
• At 11 degrees the waveguide is almost level..
• the layer of water may or may not be evenly distributed (depending on the viscosity).
• With the za= 11 deg and the floor is rotated:
• The peak moves closer to the horn (just like za=1.1).
• This may just be centripetal forces pushing the water out during the rotation.
• Page 2: show 11,1.1 and 19.7 degree traces.
• I averaged the  2 11 degree traces and then displayed the 1.1,11,19.7 deg trace to make comparison easier.

Summary

• water in the horizontal portion of waveguide (on the turret floor) caused reflected power faults
• With lots of water
• low za gives antenna and klystron reflected power
• high za only gives klystron reflected power
• With less water (after the cleanup) we only got klystron reflected power.
• We can see a changed in the reflected power as we go from high to low za (if water in the waveguide) using the network analyzer.
• the null at 25 feet is probably the distance from the turnstile to just beyond the rotary coupler
• Later that day we found water seeping from the elbow at the bottom of the waveguide column. There must be a leak into the waveguide .

Dana's notes on measuring S11 (,txt)

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