spid3rx
Member level 2
Hi all,
its about the TL for the Bluetooth antenna.
I am using a multilayer PCB and the feed line has matching circuit in between.
the first part of the trace is thin in terms of width based on the gnd layer 2 calculation, and the second part of the trace is wider based on the gnd layer 4 ( layer2 and 3 are keep outs).
when I measure the S21 for the thin trace, it is pretty low (around 0.6dB) but S11 is slightly less than 50ohms, around 35ohms+reactance.
the S21 for the wider trace, the S21 is also low ( around 0.1dB), but the S11 is around 47ohm.
does this consider a mismatch? and the S21 does not add up (e.g. 0.6 + 0.1dB) in this case if i measure from thin to wide trace due the S11 mismatch ?
and the add up calculation will make sense if both are 50ohms?
thanks
its about the TL for the Bluetooth antenna.
I am using a multilayer PCB and the feed line has matching circuit in between.
the first part of the trace is thin in terms of width based on the gnd layer 2 calculation, and the second part of the trace is wider based on the gnd layer 4 ( layer2 and 3 are keep outs).
when I measure the S21 for the thin trace, it is pretty low (around 0.6dB) but S11 is slightly less than 50ohms, around 35ohms+reactance.
the S21 for the wider trace, the S21 is also low ( around 0.1dB), but the S11 is around 47ohm.
does this consider a mismatch? and the S21 does not add up (e.g. 0.6 + 0.1dB) in this case if i measure from thin to wide trace due the S11 mismatch ?
and the add up calculation will make sense if both are 50ohms?
thanks
