Dc blocking capacitor between balun and transmission line

Hi All,

Assume that balun output and transmission line are matched (both 50 ohm), is there a mismatching issue if I insert a dc blocking capacitor between balun and transmission line?

Thanks,
Kevin

There will be some mismatch, but you can minimize it by choosing the SRF of the capacitor to be in your frequency band.

In a nutshell, no. May I ask why you want to put a DC blocking cap between the two? Baluns are most commonly implemented as common mode chokes.

A 100pF capacitor is recommended in balun's data sheet between the balun's output and the transmission line. This is a Sub-1 GHz antenna (868MHz).

a 1pF capacitor will shift the impedance at 1GHz far away from 50Ohm, however the proposed 100pF will do no harm.