Fat dipole rfi test, azswings

    Ganesh brought down a pair of fat dipoles to test the rfi. He was interested in the power levels that the ao40 amps would have to handle.

Setup:

• the dipoles/backplane assembly were mounted on a beam under the rotary floor. The turret position used was 180 degrees
• the dipoles were connected to a set of amps whose gain ranged from 25 to 45 db over the freq range).
• The output of the amps was connected to the anritsu spectrum analyzer.
  
• the analyzer was on the turret floor and controlled remotely.
  
• The anritsu spectrum analyzer was used to acquire the data (one polarization at a time).
• 300KHz rbw, 15 sec peak hold, preamp off, ref  lev -30 then -20 dbm, 165MHz span
• we stepped through 300 to 2600 MHz in about 230 seconds. there were about 19 passes through this range for each pol.
  
• had trouble with 480 MHz tv station pointed at utuado.
• When the azimuth pointed in that direction, the peak would occasionally go above the reference level
• This caused the spectrum analyzer to output an err msg, rather than the data. By increasing the ref level, we finally got data in that direction.
• we did azimuth spins 270 to 630 with the dome at 18 degrees.

The plots show the results of the azimuth spins (.ps) (.pdf):

• page1
• top spectrum analyzer power from the output of the dipoles,amps
• Black is polA, red is polB. these were not taken simultaneously
• about 19 passes over the freq range are over plotted covering the 360 deg az swing for polA and polB
• bottom:
• s21 (gain) of amps vs frequency measured by ganesh in the lab.
• Page2: remove the amp gain from the spectrum analyzer data
• top
• i interpolated the gain to each frequency channel and then removed it.
• This should be the power at the output of the dipoles.
  
• the rbw is 300 KHz
• (i need to plot the noise floor of the spectrum analyzer for this rbw.
• Bottom: take peak value from polA,polB all az swings for this spectra
• This is a worse case spectra (since the peaks at each freq don't all occur at the same azimuth position.
• the integrated power is -41 dbm.

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