Документ взят из кэша поисковой машины. Адрес оригинального документа : http://www.naic.edu/~phil/hardware/sband/Water_in_the_WG.txt Дата изменения: Wed Aug 19 16:45:14 2015 Дата индексирования: Mon Apr 11 12:56:40 2016 Кодировка:

THIS IS ABOUT A SERIES OF MEASUREMENTS MADE ON MOST OF THE LENGTH OF THE S-BAND WG
IN THE ARECIBO PLANETARY RADAR, ON 18 AUG 2015 IN THE AFTERNOON.

The WG is WR430. If the width is taken as 4.30 inches, then the lowside cutoff
frequency is 1.372 GHz, and the first moding frequency is 2.74 GHz.

for these measurements the VNA was sweeping from 2.0 to 2.5 GHz, encompassing the
range in which the available WG-N transitions worked reasonably well, with a little
bit to spare on the high end.

The top end of the WG section under test was at the top junction of the fixed part
of the rotary joint, and this was terminated with a transition and a coaxial
termination.

The bottom end of the WG section under test was the top end of the WG elbow that
comes from the feed-end coupler under the floor and turns upwards toward the
turnstile junction.

Before measurements were taken, the VNA was given a 1-port calibration over
2.0-2.5 GHz using the Maury mechanical standards.

> The initial test was made with ZA = 11 deg and the SBTX horn at the focus,
thus assuring that the rotary WG joint was aligned in the normal manner.
The following file was captured:

sbwg1.s1p (frequency domain table)

sbwg1.xls (freq domain spreadsheet)

and the time domain trace was stored as a comparison reference but not
explicitly captured to a file just yet.


> Next the ZA was moved to 1.7 deg. At the end of the transverse the following
two files were captured (note substantial changes from 11 deg ZA):

sbwg1r7.s1p (freq domain table)

sbwg1r7.xls (freq domain spreadsheet)

dana1.png (screen shot of the time domain reflection, from -1 ns to +100 nsec)
blue trace was memory from initial 11 deg ZA, green trace was live
data at 1.7 deg ZA


> Now the ZA was moved to maximum, assumed to be 19.7 deg. Two more traces
were captured:

sbwg19.s1p (freq domain table)

sbwg19.xls (freq domain spreadsheet)

dana19.png (time domain screen shot), again with the blue trace being the
initial 11 deg reference and the green trace being live
at 19.7 deg.


> The ZA was then taken back to 11 deg, and yet two more traces captured:

sbwg1b.s1p (freq domain table)

sbwg1b.xls (freq domain spreadsheet)

dana11.png (time domain screen shot), again with the blue trace being the
initial 11 deg reference and the green trace being live
at 11 deg.


> While holding the ZA constant, the floor was rotated 180 deg. Note that this
should not in principle have changed anything since no antenna was involved,
but in fact things changed a great deal. The following files were captured:

sbwg1b-180.s1p (freq domain table) this showed a seried of distinct sharp
resonances in the freq domain.

sbwg1b-180.xls (freq domain spreadsheet)

dana11_180.png (time domain screen shot, again with the blue trace being the
initial 11 deg reference and the green trace being live
at 11 deg (with 180 deg floor rotation).


> Created composite frequency domain spreadsheet and plot:

sbwg_comp_freq_domain.xls (composite of all the freq domain data)

sbwg_comp_freq_domain.pdf (composite freq domain plot)