Learning Forum

[pnair]

Hello,

I am working on the farfield simulations using a dipole source on a SiC thin film. I have a question related to the polar plots generated for different dipole orientation using the Scat_ff analysis group. This is the polar plot generated for a dipole source with phi=0 and theta = 0 and the orientation of the dipole is along Z-axis

But from the theory/text books, this is what i understood about the radiation pattern of the dipole along the z-axis

So, From the textbooks, if we consider a x-z plane, maximum radiation intensity  for theta=90 and this matches with how we are see from a spherical coordinate system with theta is the between Z-axis and x-y plane.. But in the polar plots generated, for theta = 90 (i have assumed the angles in polar plot as theta)radiation intensity is maximum.

I am concerned about the x-y axis of the polar plot and what is angle represented in polar plt?

,

So, if its theta, I am assuming it should start from 0 degree in the top along z-axis and 90 degree perpendicular to the z-axis. Please help regrading this.

Thanks,

Prabha

 

[Guilin Sun]

Polar plot does not have x-y. The simulation results shows two planes: one is the xy and the other is xz (yz omiited). The actual 3D radiation pattern is donut shape. Thus depending on the cut you will see different polar radiaiton pattern.

along the polarization direction the farfield is zero. In the perpendiuclar plane it is circle.

The angle showing in the above plots is phi, from 0 to 360 deg.

 

 

 

[pnair]

Thank you for the reply. Could you explain a little bit? For X-Z plane, I am thinking the above plot is obtained by creating phi=0 (constant) and theta from 0 nto 90. thats what the textbooks explain. And we will get 

So, how this angle can be phi? Because for X-Z plane, phi is constant, right?

[pnair]

Can you please explain how the xz plane in the above-mentioned polar plot is created ? Based on my understanding, it is created by keeping phi=0 and phi = 180 constant in a 3D polar radiation plot and theta varying from 0 to 180 degrees. But, I would like to know if this angle is phi, how it can be used to plot both XZ planes and XY planes?

[Guilin Sun]

No, here we have different meaning of phi. While usually theta and phi are for spherical coordinate, here I mean "phi" is the angle from 0 to 360 deg. Once the farfield is calculated with farfieldexact, it uses "ploar" to plot. Please check the analysis group script: