Question about axial ratio in IE3D

Hi,
Dr Jian (or any one else) please I have some questions to ask you:
1_ Can you plase define for me the axial ratio that is calculated in the pattern view ( what is its expression ?)

2_ For the field I see that we can only get the gain and the directivity (in dBi), so is there a mean to get the module of E (in dB).

3_ I have a little matter, in english you define E left and the E right , but in french we define:
the contrapolar (cross) Ecross= EθsinΦ+EΦcosΦ
The coplanar (principal) Eco=EθcosΦ-EΦsinΦ

so what is the left and the right in all this , I know that these questions are basics so excuse me for disturbing.

thanks in advance
best regards

Re: Axial ratio in IE3D

Hi, Alberich:

1. Axial Ratio is following the standard definiton:

AR = Max / Min
Max or Min = Max or Min of ( abs( |Eleft|-Eright| ), abs( |Eleft| + |Eright| )
AR_dB = 20.0 * log10( AR )

2. The pattern quantity is normalized and it is distance independent. If you want to find E and H with a specified distance, you can select Edit->Pattern Manipulation and Wave Propagation. You are allowed to find the E and H values with given locations.

3. Eleft = ( Etheta + j Ephi ) / Sqrt(2)
Eright = (Etheta - j Ephi ) / Sqrt(2)

For the co and contrapolar formulas,

Ecross= EθsinΦ+EΦcosΦ
The coplanar (principal) Eco=EθcosΦ-EΦsinΦ

are Eθ and EΦ complex values? Are they used for characterizing a circularly polarized antenna? I can see the following:

When phi = 0, Eco = Etheta (or Eθ) and Ecross = Ephi (or EΦ) and they correspond to the linearly polarized waves in the English system.

When phi = PI/2, Eco = - Ephi and Ecross = Etheta. They are also linearly polarized waves. Are they supposed to be used for circularly polarized waves?

Re: Axial ratio in IE3D

Hi Dr Jian , excuse me for the late.
Yes we define this field and we compare them if they are close (in values) we tell that the antenna has a High cross polarisation.

But tell me there is still an ambiguity in my head:
for the field (E) if it is normalized, is it normalized to the isotropic antenne, and as long as it is normalized wht did I get some velues which are >0 ( for a normalize field themax is 1 so log(1) =0), I told that I am the first using IE3D in my school ad professor ask me a lot of question and I have to answer them to validate my work and convict them.

Thanks in advance and excuse me.
Best regards

Re: Axial ratio in IE3D

Hi, Aberich:

The field for the pattern is normalized as:

E_true_field = E_pattern * C / r

Because E_true_field is inversely proportional to r, E_pattern is a constant of r. C is a constant of ( r, theta, phi) and it is related to whether E_pattern is for directivity or for gain.

Regards,

Re: Axial ratio in IE3D

Hi Dr JIAN,
I know that I am asking lot of questions but I have to know some things.
Look : remember what I define as being co and cross polar field I find that in english they are also called the horizontal and vertical they are defined in this topic :


SO how can I gt them in IE3D or do I must process them by displaying the E theta and E phi and after create a program that calculate them and plot them (example by matlab)
For thr normalized field I found my mistake if I would get it I call th custum or linear field it give me it in dB or in nodimension respectively so the max is 0 or 1 respectively
thanks a lot
respects and best regards

Re: Axial ratio in IE3D

Hi, Alberich:

You can find the Eco or Ecross with phi = 0, 90, 180 and 270 with appropriate Etheta and Ephi. For other phi angle, you may not be able to get them automatically from IE3D/PATTERNVIEW.

You can do it on MATLAB. We will also try to implement it in future version. Regards.