general_custard
Newbie level 4
ludwig 3 coordinate
Hi there I've recently been modelling a Vivaldi antenna structure using CST and I'm slightly confused as to how I go about obtaining the co-cross polar isolation for my structure in the E and H planes.
As far as I'm aware, topics similar to this one have already appeared twice before () and using the information provided in the latter topic I used the Ludwig 3 co-ordinate system to obtain the Ludwig 3 vertical and horizontal plots of my farfield results.
Since this coordinate system realigns the farfield such that the z' axis is now aligned with the main lobe of the farfield (which is along the x-axis of my structure) and the y' axis is aligned with the polarisation vector (which is along the y-axis of my structure), this means that the E-plane of my antenna is now in the y'z' plane (in the Ludwig-3 coordinate system). The H-plane was originally in the xz plane, so in the Ludwig-3 coordinate system is now in the x'z' plane.
This means that to obtain the co-cross polar isolation for the E-plane I was just obtaining the difference between the Ludwig-3 vertical (co-polarisation) and Ludwig-3 horizontal (cross-polarisation) farfield results in the y'z' plane. While, to obtain the co-cross polar isolation for the H-plane I was just obtaining the difference between the Ludwig-3 vertical and Ludwig-3 horizontal farfield results in the x'z' plane. Is this a valid method for obtaining the co-cross polar isolation in the E and H planes do you think? Or is there another method I should be using? Thanks for your help with this
Hi there I've recently been modelling a Vivaldi antenna structure using CST and I'm slightly confused as to how I go about obtaining the co-cross polar isolation for my structure in the E and H planes.
As far as I'm aware, topics similar to this one have already appeared twice before () and using the information provided in the latter topic I used the Ludwig 3 co-ordinate system to obtain the Ludwig 3 vertical and horizontal plots of my farfield results.
Since this coordinate system realigns the farfield such that the z' axis is now aligned with the main lobe of the farfield (which is along the x-axis of my structure) and the y' axis is aligned with the polarisation vector (which is along the y-axis of my structure), this means that the E-plane of my antenna is now in the y'z' plane (in the Ludwig-3 coordinate system). The H-plane was originally in the xz plane, so in the Ludwig-3 coordinate system is now in the x'z' plane.
This means that to obtain the co-cross polar isolation for the E-plane I was just obtaining the difference between the Ludwig-3 vertical (co-polarisation) and Ludwig-3 horizontal (cross-polarisation) farfield results in the y'z' plane. While, to obtain the co-cross polar isolation for the H-plane I was just obtaining the difference between the Ludwig-3 vertical and Ludwig-3 horizontal farfield results in the x'z' plane. Is this a valid method for obtaining the co-cross polar isolation in the E and H planes do you think? Or is there another method I should be using? Thanks for your help with this