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Near field coupling

I want to simulate a coupling between antennas using a point source and an ideal receiving antenna, between 2 different antennas.

As the distance between the antennas is short, they are in the Near Field region.

I already requested a NF of the antennas alone.

Here is where I have some doubts, When I am making the point source and ideal antenna, I don't know in FEKO what is the difference between import NF data from file and import NF data from structure.

For the point source I can choose to import from file or from structure, I choose to import from file, since this is how I can move the point source (transmitting antenna is a few centimetres away from the receiving antenna that is at the origin)

Is there any example to simulate couplings with antennas in the NF region?

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Altair Forum User

How was the near-field data that you are using generated (sorry it is not automatically embedded into the .cfx, you are welcome to attach the files)? The one method will use all the points in the file as the aperture source, while the Cartesian boundary will only use the points on the face(s) for the aperture source.

Once you have run the simulation, you will have the source and receiver power which you can use to calculate the coupling.

JIF

Hello Iricardo,

The original FEKO EFE/HFE files only contained information regarding the position and the filed values, but contained no information regarding the coordinate system, frequency or even the number of points. For these files (that have no additional information), it is not possible for FEKO (or any other product / component) to deduce the information and the user is required to provide the number of points in each dimension (this is what is required when selecting the option to specify 'data from structure'). We have since extended the EFE/HFE file formats to include all this information, but we have not yet extended CADFEKO and the FEKO solver to use this information, thus, it is required to still supply the number of points and coordinate system. You should use the 'data from structure' option.

For some 3rd party formats, we have already implemented the feature to read the number of points and coordinate system information from the files and thus the user does not need to enter these values. For these formats that are supported, the 'data from file' option is appropriate. Although there is also a FEKO boundary option, this should not be used by you since it was added for reading measurement files that have fields points only on the boundary.

We plan on extending and improving the functionality for equivalent sources so that users don't need to specify the number of points (etc.) for the next release (2018).

I think the important part is that you should use the 'data from structure' option and then everything should work and you should also not have problems with opening the CFX files as logged in another question.

Kind regards

JIF

Altair Forum User

OK, let's say that I have two antennas, antenna A at (0,0,0) and antenna B at (b,b,b)

The antennas are close to each other, so they are in the Near Field region.

I want to use a point source and an ideal receiving antenna.

First of all, I have to compute the near field radiation of each antenna, A and B

In this first step, when I request a near field of the antenna A alone, do I need to request a near field region that comprises the entire volume of antenna B? or only request a region around (b,b,b)?

the same for antenna B?

Based on the previous requests, in the point source and ideal rx antenna model, I have to set the near field structure in the same way that was requested, right?

Also, it would help to get an example,

thanks!

JIF

Examples B-02 and B-03 in the example guide should be enough to show you how these work. I would suggest that you work through these examples first.

Basically, you just need to create the near field aperture around each antenna. Thus, one request around antenna A (where only antenna A is in the model) and one around antenna B (where only antenna B is in the model), both located at the origin (just as an example). Then, the third model uses the near field requests that were made in the other two models and applies them as sources or receiving antennas in your larger model - if it is coupling from the one to the other, the one will be a source and the other a receiving antenna. These equivalent models obviously won't be placed at the origin, you can place them where you need them - one at the origin and one at (b,b,b). There should be nothing inside the near field aperture of either of the antennas and the apertures should also not intersect (they should probably not be too close to each other).

Regards

JIF