finding the index

[Matt_Parry123]

hi,

we are trying to work out the bandwidth of S11 parameter of a resonator. firstly if you know the curve fitting equation would make this alot easier as we dont :-s
otherwise we have made a discrete plot of the curve and have found the magnitude of the 3dB marker, which has a corresponding index, we need to find this index
to relate it to the frequency (x co-ordinates). i did not write the program so i have no idea  about most of the program, but i have attached it. any help would be very
much appreciated

matt.

[James_McN]

Hi Matt,

If you are able to find the index of the 3dB point in the y-data of your xy graph then the same index in the x data will return the frequency at which this point occurs so just use index array in the x data array and it should return the value you require.

EDIT: Re-reading this post Im not sure if you have found your index yet!  There is a function to search a 1D array in the array pallette.  You can search for your -3dB point using this and it will return its index.  I have attached an example of this at work.

Hope this is what your after.

Message Edited by James McN on 08-05-2008 01:50 PM