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2. Semi-Rigid Cables with SMA Plugs a) .141" As shown above, there is a significant difference using straight or angle connectors. To highlight this, the following measurements were made (again using a network analyser and so terminated at 50 ohm):
Note: More cables of this kind have been measured, with about the same results as indicated. The reflection coefficient (S11) behaviour of these cables is also interesting: It is clear that the large transmission losses (S21) of the 3 cm right angle connector cable are not caused by absorption but rather by reflection at the connectors.
Conclusion: Using semi-rigid cables with straight cable plugs at frequencies up to 24 GHz causes some signal loss, but this was expected. Semi-rigid cables with right angle cable connectors have unpredictable impedances at higher frequencies and are, therefore, not recommended to be used above 5 GHz. These unpredictable impedances can lead to difficulties i.e. in tuning and non-reproducible results when exchanging cables.
b) .086"
Note: More cables of this kind have been measured, with about the same results as indicated. Conclusion: There is no big difference in the measurements compared to the thicker semi-rigid. The slightly higher losses were again expected. So the same conclusions apply as with 0.141" semi-rigid cables.
Some additional measurements on semi-rigid cables with straight connectors.
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