are u talking about simulation.or when u are testing your stripline on the analyzer.most probably u are talking about analyzer because there aint no ripples on simulations.if it is the network analyzer then first thing is change the IF bandwidth.which depends on the frequency of operation.
thanks for your answer to my post . well i understand these settings in simulation software helps to remove ripples if your structure is highly resonant.
but what i am talking about is the ripples in the S11 of matched transmission line.
actually i forgot where i read but theseripples have to something to do with the length of the transmission line .i mean if transmission line is multiple of wavelength longs you will get these nodes and antinodes in your s11 however i want to know the exact explanantion of this behaviour
you can test this behaviour urself.
just model any matched microstrip line and keep its length ( electrical) long and than observe s11 ,
you will understand what i am talking
A transmission line that is perfectly matched to the source and load will give no S11 ripple. For example a 50 ohm source connected to a 50 ohm transmission line, terminated by a 50 ohm load gives no S11 ripple vs frequency - in theory.
In practice, there is always some mismatch giving S11 ripple. Can you upload a plot of your simulations/measurements?