Data sheets do not mention any attenuation, does that mean it is ZERO / negligible ? Less than 0.005 dB ?
Ain't much (negligible), which is why it's probably never spec'd, but the question and any answer is meaningless until we've got a frequency nailed down. The cable will represent the largest portion of any attenuation, and will swamp anything the connectors would contribute. The typical coax for SMA (RG-174, RG-188, RG-196 or RG-316) runs on the order of 60~80db/100' loss. Even the semi-rigid cables have a lot of loss in the microwave freqs. Decent SMA connectors are good to around 12.4GHz with flex cable, and 18GHz with semi-rigid cable. Some very special (and a bit expensive) ones are available for use up to the 26.5~27GHz !
