Ok, this what I have understood, please tell me if I am wrong.
if you see transmission line terminology,
If your end is open then electic field that is voltage is maximum& for short voltage is zero, right?
so if you are using Open circuit then Electric field will dominate right?
Then it can be termed as magnetic wall.
I know I may be wrong but this was how I wam trying to convince myself.
Please let me know if there is other explanation..
Added after 11 minutes:
If there is a side couple filter & you want to couple two microstrip line by magetic field that is by inserting electric wall, what will you do?