bandwidth measurement

[deepmala pinto]

Hi,
how to measure bandwidth of antenna from return loss(s11) graph or how to analysis bandwidth whether it is increasing o decreasing from return loss (s11)graph of an antenna

 

[Ow@i$]

although S21 is the graph that will define bandwidth.....
but if you want to extract Bandwidth info from S11 than for general understanding u can say ... "the band on which the magnitude or S11 is below -10db or more (-20db, -30db etc) is your bandwidth... as because where S21 has its positive peak on the same frequency the S11 will have its negative peak...!!!
hope that answers your question