Measurements of small losses on 1296 using a HP8712C network analyzer.
(April 6 2013)

The DUTs

  • DUT1 About 30 mm of RG 400 cable. Electrical length 0.284 wavelengths.
  • DUT3 Modified connectors. Electrical length 0.129 wavelengths.
  • DUT8 Modified connectors. Part with high impedance. Electrical length 0.338 wavelengths.

Combinations of the DUTs were also measured. Measurement of DUTs as well as combinations of them gives rise to an overdetermined system of equations from which unknowns can be determined.

DUT18 means DUT1 male connected to DUT8 female and so on.

The test setup.

Figure 1 shows the setup with DUT381 inserted.


Figure 1. The 8753E with DUT381 inserted.


The 8753E was run uncalibrated with "CORRECTION OFF" and "PRESET: FACTORY" The instrument behaves in an odd way after a full 2 port calibration has been performed. When run uncalibrated it behaves as expected.

The electrical length was set for the instrument to show close to the correct phase with the Calibration kit for S11 and S22 and with the direct connection for S21 and S12. There are infinite numbers of different electrical lengths that fullfill this requirement for a single frequency. The length that minimizes the frequency dependency of the phase was selected. These values were selected:

S11 8.3450 ns
S21 4.7700 ns
S22 -2.6803 ns
S21 4.6860 ns

The most critical aspect of S parameter measurements is the impedance stability of the cable. The blue cable in figure 1 is 112 cm of Flexiform 401. The cable is free of mechanical strain and wants to be in the measurement position. It was carefully moved as little as possible and only axially during measurements. The small movement was well within the elastic region which means that impedance variations can be assumed to not have been not very large.

Two types of measurements were performed. First all combinations of the DUTs with all the parts of the calibration kit were used to measure S11 and S22. This series of measurements should allow the determination of a calibration to apply afterwords. After that the full set of S-parameters was measured for all the DUTs.

Measurements were made on 1293, 1296 and 1299 MHz.

Raw data for single port measurements.

Table 1 gives results with links to screen dumps.


                     1293MHz            1296MHz             1299MHz   
Device     Parm.   Zre      Zim        Zre      Zim         Zre      Zim
                  (Ohm)   (Ohm)      (Ohm)    (Ohm)      (Ohm)    (Ohm)  
noneOPEN    S11  374.50  -238.75     360.14  -213.50     356.72  -191.22
noneOPEN    S22  257.63  -1907.7     363.94  -1771.3     460.75  -1667.9 
noneSHORT   S11  3.9598  -3.2278     3.5370  -2.6919     3.1508  -1.9752
noneSHORT   S22  2.3464  -1.2952     2.3236  -1.4130     2.2565  -1.5363
noneLOAD    S11  52.316  -2.5977     52.615  -2.5352     52.912  -2.4199
noneLOAD    S22  51.059   0.6563     51.059   0.6621     51.064   0.6680
DUT1OPEN    S11  3.5317   8.4541     3.2075   9.5474     3.0093   10.805
DUT1OPEN    S22  2.0464   10.266     1.9717   10.400     1.8525   10.539
DUT1SHORT   S11  77.047  -165.57     79.258  -162.36     81.445  -161.12
DUT1SHORT   S22  17.883  -216.80     20.055  -211.96     21.961  -207.94
DUT1LOAD    S11  52.881  -2.7441     53.170  -2.6953     53.463  -2.5840
DUT1LOAD    S22  51.736   0.9883     51.736   0.9941     51.736   1.0020
DUT3OPEN    S11  11.410  -48.900     11.195  -49.223     10.750  -49.469
DUT3OPEN    S22  4.7148  -45.117     4.9355  -45.139     5.0957  -45.229
DUT3SHORT   S11  6.2344   54.730     7.1250   57.020     8.4102   59.027   
DUT3SHORT   S22  0.4297   49.396     0.2754   49.723     0.0859   50.031
DUT3LOAD    S11  51.105  -4.5957     51.367  -4.5313     51.617  -4.4102   
DUT3LOAD    S22  49.766  -1.7520     49.766  -1.7520     49.771  -1.7480 
DUT8OPEN    S11  4.4312  -6.8726     3.9773  -6.2092     3.5500  -5.3435
DUT8OPEN    S22  2.6209  -2.4066     2.5972  -2.3109     2.5236  -2.2214 
DUT8SHORT   S11  439.88   220.00     432.47   173.41     414.72   146.14
DUT8SHORT   S22  0.4380   419.48     6.3440   436.33     13.375   452.64   
DUT8LOAD    S11  69.992   2.9844     70.457   2.7695     70.879   2.6641  
DUT8LOAD    S22  68.367   12.438     68.414   12.410     68.477   12.410  
DUT13OPEN   S11  16.652   96.520     20.215   100.56     24.230   103.57
DUT13OPEN   S22  0.1172   84.051    -0.0313   85.688    -0.1172   87.402        
DUT13SHORT  S11  8.7559  -35.635     8.3301  -35.455     7.7461  -35.113  
DUT13SHORT  S22  4.1367  -31.157     4.2422  -30.955     4.2949  -30.792  
DUT13LOAD   S11  54.838  -1.2695     55.176  -1.2637     55.490  -1.1777
DUT13LOAD   S22  50.053  -2.4160     50.049  -2.4043     50.049  -2.4102
DUT18OPEN   S11  119.97  -196.77     118.16  -188.02     117.47  -182.77  
DUT18OPEN   S22  190.56  -931.34     181.41  -813.56     174.28  -726.94
DUT18SHORT  S11  3.9663   2.0935     3.5715   3.1500     3.2600   4.4053
DUT18SHORT  S22  2.2598   10.657     2.1714   11.083     2.0430   11.516
DUT18LOAD   S11  39.031  -1.1094     39.232  -0.7500     39.443  -0.3438   
DUT18LOAD   S22  67.684   11.613     67.750   11.602     67.793   11.602 
DUT31OPEN   S11  15.188   92.652     18.492   96.754     22.242   99.828
DUT31OPEN   S22 -0.1328   85.773    -0.2930   87.414    -0.4375   89.086  
DUT31SHORT  S11  8.3887  -34.387     7.9609  -34.215     7.3906  -33.887 
DUT31SHORT  S22  4.2754  -32.299     4.3848  -32.061     4.4404  -31.876
DUT31LOAD   S11  50.977  -5.3066     51.248  -5.2402     51.498  -5.1270 
DUT31LOAD   S22  53.918   2.6738     53.939   2.6621     53.959   2.6543
DUT38OPEN   S11  5.5605   46.515     6.2383   49.066     7.3027   51.459
DUT38OPEN   S22  0.4082   60.639     0.2324   61.486     0.0371   62.348
DUT38SHORT  S11  14.441  -58.812     14.303  -58.975     13.885  -59.143
DUT38SHORT  S22  7.6094  -83.711     8.1172  -82.906     8.5469  -82.273
DUT38LOAD   S11  51.770  -20.043     51.822  -20.078     51.877  -20.064 
DUT38LOAD   S22  68.668   16.074     68.770   16.055     68.863   16.066
DUT81OPEN   S11  268.30  -244.61     254.63  -227.10     248.54   214.63
DUT81OPEN   S22  26.563  -242.95     27.906  -231.59     29.016  -222.07
DUT81SHORT  S11  3.9126   8.3657     3.5918   9.7842     3.4150   11.380 
DUT81SHORT  S22  2.4872   2.7128     2.4357   2.9526     2.3353   3.1884   
DUT81LOAD   S11  69.156   2.9609     69.609   2.7656     70.027   2.6797 
DUT81LOAD   S22  36.756  -0.4063     36.725  -0.2871     36.693  -0.1758
DUT83OPEN   S11  8.9727   68.633     10.625   71.809     12.758   74.434 
DUT83OPEN   S22  1.0039   46.852     0.8340   47.598     0.6406   48.373
DUT83SHORT  S11  22.730  -82.531     23.012  -82.641     22.918  -82.988
DUT83SHORT  S22  5.8008  -58.779     6.0977  -58.438     6.3418  -58.203
DUT83LOAD   S11  70.727   6.0781     71.254   5.8359     71.742   5.7188
DUT83LOAD   S22  53.939  -19.146     53.854  -19.145     53.777  -19.162
DUT138OPEN  S11  9.9922  -40.615     9.5371  -40.168     8.8945  -39.590
DUT138OPEN  S22  5.7832  -48.139     5.9473  -47.303     6.0625  -46.521     
DUT138SHORT S11  10.750   74.090     12.926   77.953     15.637   81.238
DUT138SHORT S22  0.1641   84.539     0.0117   86.469    -0.1445   88.465
DUT138LOAD  S11  55.256   15.723     56.115   15.852     56.945   16.010
DUT138LOAD  S22  67.844   16.727     67.949   16.707     68.051   16.723
DUT183OPEN  S11  7.6387  -29.037     7.1514  -28.551     6.5371  -27.883
DUT183OPEN  S22  5.0547  -43.256     5.2246  -42.818     5.3340  -42.453
DUT183SHORT S11  6.0020   48.278     6.8184   51.176     8.0508   53.916
DUT183SHORT S22  1.0508   85.352     0.9414   88.293     0.8320   91.395
DUT183LOAD  S11  37.924  -2.4434     38.076  -2.0762     38.246  -1.6523
DUT183LOAD  S22  53.721  -18.354     53.641  -18.369     53.580  -18.383
DUT318OPEN  S11  9.5313  -38.738     9.0762  -38.320     8.4551  -37.803
DUT318OPEN  S22  5.5859  -47.160     5.7500  -46.357     5.8555  -45.637
DUT318SHORT S11  9.6914   69.133     11.492   72.762     13.918   76.066
DUT318SHORT S22  0.3672   81.941     0.2070   83.852     0.0625   85.816
DUT318LOAD  S11  52.301   10.443     53.039   10.613     53.729   10.797
DUT318LOAD  S22  65.770   8.7148     65.766   8.7266     65.770   8.7578
DUT381OPEN  S11  12.564  -51.678     12.256  -51.563     11.707  -51.379
DUT381OPEN  S22  4.0908  -25.968     4.1553  -25.573     4.1631  -25.226
DUT381SHORT S11  17.406   92.809     21.422   98.156     26.074   102.54
DUT381SHORT S22  1.1719   43.873     1.0039   44.807     0.8125   45.779
DUT381LOAD  S11  52.020  -19.395     52.076  -19.430     52.139  -19.418
DUT381LOAD  S22  35.447  -1.7324     35.410  -1.6016     35.354  -1.4785
DUT813OPEN  S11  12.930  -51.824     12.553  -51.420     11.920  -50.938
DUT813OPEN  S22  4.5332  -32.676     4.6289  -32.167     4.6689  -31.730  
DUT813SHORT S11  17.664   97.094     21.535   101.67     25.879   105.16
DUT813SHORT S22  0.9531   58.936     0.7754   60.291     0.5859   61.695
DUT813LOAD  S11  66.984   0.6797     67.348   0.5586     67.691   0.5273 
DUT813LOAD  S22  47.324   14.275     47.535   14.381     47.738   14.486 
DUT831OPEN  S11  13.375   53.988     13.004  -53.555     12.371  -53.070
DUT831OPEN  S22  4.7266  -34.002     4.8184  -33.422     4.8594  -32.902
DUT831SHORT S11  18.859   101.29     23.059   105.96     27.688   109.39
DUT831SHORT S22  0.6660   62.896     0.5000   64.277     0.3008   65.715
DUT831LOAD  S11  70.715   6.9102     71.309   6.6641     71.777   6.5508
DUT831LOAD  S22  49.371   20.160     49.615   20.275     49.854   20.416

Table 1. Single port raw data from the HP8753E network analyzer.

Raw data for two port measurements.

Table 2 gives results with links to screen dumps.


                      1293MHz             1296MHz             1299MHz   
Device   Parm.     Ampl     Phase      Ampl     Phase      Ampl     Phase 
                   (U)      (Deg)      (U)      (Deg)      (U)      (Deg) 
none      S11    0.04126   -18.57    0.04448   -17.01    0.04740   -15.03
none      S12    0.89676    -2.73    0.89260    -1.17    0.88801    -0.47
none      S21    0.89551    -1.21    0.89134     0.35    0.88720     1.99
none      S22    0.06634   -53.98    0.06730   -63.37    0.06760   -72.80
DUT1      S11    0.03250   -75.86    0.03179   -71.23    0.03079   -65.72
DUT1      S12    0.90215  -104.55    0.90495  -103.23    0.90750  -101.91
DUT1      S21    0.89646  -103.02    0.89797  -101.63    0.90198  -100.27
DUT1      S22    0.07514    76.87    0.08074    69.32    0.08545    61.82
DUT3      S11    0.06879   -69.84    0.06939   -68.30    0.06938   -66.59
DUT3      S12    0.89280   -48.58    0.89234   -47.01    0.89189   -45.43  
DUT3      S21    0.89056   -47.21    0.88955   -45.62    0.88982   -44.02 
DUT3      S22    0.07484  -144.97    0.07552  -153.43    0.07533  -162.03   
DUT8      S11    0.15108     1.77    0.15352     1.33    0.15581     1.23
DUT8      S12    0.89531   -87.79    0.89591   -86.54    0.89588   -85.28      
DUT8      S21    0.88299   -86.34    0.88118   -84.90    0.88075   -84.45
DUT8      S22    0.18927    47.64    0.20076    47.34    0.21216    46.39
DUT13     S11    0.04304    11.96    0.04742    11.40    0.05122    11.64
DUT13     S12    0.89828  -151.08    0.90022  -149.68    0.90160  -151.08
DUT13     S21    0.89584  -149.54    0.89734  -148.14    0.90029  -146.66
DUT13     S22    0.06994   -21.96    0.07639   -29.61    0.08211   -37.42
DUT18     S11    0.10312  -177.16    0.09974  -179.04    0.09642   178.49 
DUT18     S12    0.89105   171.29    0.89355   172.74    0.89591   174.19
DUT18     S21    0.89071   173.38    0.89416   174.76    0.89858   176.11   
DUT18     S22    0.17234     7.16    0.16120     6.04    0.14955     5.85
DUT31     S11    0.03119   -77.77    0.03101   -71.15    0.03073   -64.33
DUT31     S12    0.89914  -150.86    0.90153  -149.45    0.90348  -148.02 
DUT31     S21    0.89478  -149.12    0.89749  -147.66    0.90156  -146.22  
DUT31     S22    0.10520    12.40    0.10516     5.87    0.10381    -0.68
DUT38     S11    0.17781   -77.77    0.17752   -77.43    0.17680   -77.06  
DUT38     S12    0.88013  -133.72    0.88056  -132.28    0.88071  -130.83
DUT38     S21    0.86593  -131.39    0.86743  -129.75    0.87112  -128.12 
DUT38     S22    0.26897    32.78    0.27142    30.28    0.27194    27.76
DUT81     S11    0.18346     8.46    0.18668     7.61    0.18946     6.95
DUT81     S12    0.87640   170.77    0.87658   172.32    0.87552   173.91    
DUT81     S21    0.87365   171.44    0.87036   173.02    0.86966   174.65
DUT81     S22    0.15631  -155.65    0.16695  -156.45    0.17799  -157.97 
DUT83     S11    0.16940    19.49    0.17284    18.60    0.17629    18.03 
DUT83     S12    0.87979  -134.74    0.87801  -133.39    0.87555  -132.00  
DUT83     S21    0.87938  -133.35    0.87623  -131.92    0.87424  -130.42
DUT83     S22    0.18632   -49.20    0.19711   -49.49    0.20788   -50.42
DUT138    S11    0.13962    56.24    0.14204    53.70    0.14479    51.56   
DUT138    S12    0.89077   124.13    0.88940   125.39    0.88753   126.56
DUT138    S21    0.88534   125.37    0.88106   126.53    0.87770   127.79
DUT138    S22    0.15274    45.68    0.15920    49.26    0.16867    51.92
DUT183    S11    0.13903  -158.30    0.13675  -159.73    0.13434  -161.55   
DUT183    S12    0.87110   124.91    0.87160   126.30    0.87218   127.64
DUT183    S21    0.87926   126.76    0.88098   128.02    0.88369   129.23
DUT183    S22    0.17494   -88.21    0.16435   -89.60    0.15306   -90.08
DUT318    S11    0.08784    62.85    0.09025    59.46    0.09305    56.55
DUT318    S12    0.89399   124.68    0.89290   125.96    0.89161   127.17
DUT318    S21    0.89101   126.00    0.88779   127.21    0.88578   128.45
DUT318    S22    0.09567    34.99    0.09998    41.76    0.10819    47.08
DUT381    S11    0.20951   -73.40    0.21020   -73.48    0.21035   -73.51
DUT381    S12    0.85672   125.31    0.85611   126.85    0.85613   128.39
DUT381    S21    0.85099   126.48    0.85026   128.10    0.85175   129.73
DUT381    S22    0.23091  -171.71    0.23387  -174.82    0.23525  -177.97  
DUT813    S11    0.15462    -5.98    0.15655    -6.42    0.15822    -6.55 
DUT813    S12    0.88475   124.81    0.88341   126.10    0.88199   127.42 
DUT813    S21    0.87295   125.72    0.86890   127.13    0.86641   128.63
DUT813    S22    0.15402   115.70    0.16527   114.40    0.17630   112.35
DUT831    S11    0.18211     8.34    0.18402     7.52    0.18634     6.99
DUT831    S12    0.88305   124.28    0.88128   125.55    0.87932   126.82
DUT831    S21    0.86951   125.13    0.86451   126.55    0.86074   128.00
DUT831    S22    0.18934    98.28    0.20089    98.05    0.21292    97.10

Table 2. Two port raw data from the HP8753E network analyzer.

Theory.

Table 1 contains 192 measured values for each frequency and table 2 contains 128. That is 320 data points. We can set up a model for all the measurements with one S-parameter matrix for each of the three DUTs. That is 18 unknowns. (S12 = S21) The calibration kit contains 6 parts and can be described by two variables each. That is 12 more unknowns. As a theoretical model we can assume a perfectly matched port on each side followed by a matching network that produces the impedances that actually occur at the SMA connectors. That gives 12 more unknowns. Finally, there is a DC offset caused by leak-through in the directional couplers which adds 4 more unknowns. In total 46 unknowns which are required to set up a model to reproduce the experimental results. The "unknowns" are actually known, but not with high enough precision. By setting up all the equations and using a least squares fit it should be possible to find the optimum values for all the unknowns. The S-parameters for the three DUTs is of particular interest since they would give the dissipative losses.

This all looked like a good idea when I started it, but as it turns out I am not smart enough to set up all the equations right. Particularly, the measurements labeled none constitute a complete set of the measurements required for a "full calibration" of the instrument. All the HP 85033C calibration kit parts, port impedances and forward as well as reverse transmission are included.

This page and the data was prepared before I realized processing was not so simple (at least not for me.) Iy you have a suggestion how to proceed, pleas send a note.