Meshing goes OK, but Simulation always crashes

Support topics for the Meshing tool provided with newFASANT
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Dennis Burke
Posts: 26
Joined: 18 Oct 2016 22:57
Location: Chicago, USA

Meshing goes OK, but Simulation always crashes

Post by Dennis Burke » 02 Feb 2017 20:05

Hello,
I am new to Fasant, and trying to learn by simple examples. A simple 800 MHz Blade Monopole Antenna is not going well for me. It meshes on MOM just fine ( no errors), but does not simulate, and crashes with Error:

PS: I do not know what i have done wrong.
I dont know what " an invalid state" is?
I dont know what Exit Code 24 is

Best regards, Dennis Burke

______________________________________________
Step: 1 of 1

Preprocessing Geometry ...
Starting level 0 at 0.800000000000000 GHz
Processing Surfaces (%) 0
Writing output files
Written output files
Final Number of elements: 4
Final Number of nodes: 23

---------------------------------------


Step: 1 of 1

MOM SIMULATION frequency = 0.8 GHz
Start program (time) 12:33:56
Start program (date) 02/02/2017

job aborted:
[ranks] message

[0-1] process exited without calling finalize

---- error analysis -----

[0-1] on Tenetics_Laptop
kernel_monurbs.exe ended prematurely and may have crashed. exit code 24

---- error analysis -----
forrtl: severe (24): end-of-file during read, unit 1, file C:\newFASANT\kernel_monurbs\datos\alimen.dat
Simulation aborted due to invalid state.

lozano.plata
Site Admin
Posts: 6
Joined: 29 Sep 2016 14:54

Re: Meshing goes OK, but Simulation always crashes

Post by lozano.plata » 04 Feb 2017 20:57

Hello Dennis,

maybe you don't feed your blade monopole antenna, could you send me your project?

You can find more info on https://www.fasant.com/en/guides/antenn ... feed-point

and

https://www.fasant.com/en/guides/antenn ... mple-blade

But, if you send me your project, I could help you!!!

javi.moreno
Posts: 18
Joined: 30 Sep 2016 08:18

Re: Meshing goes OK, but Simulation always crashes

Post by javi.moreno » 07 Feb 2017 16:27

Dear Dennis,

Thank you for your feedback

The message “Invalid State,… Exit Code 24” is just an internal coding for bugs identification.

Regarding the test case that you were trying to run, I don’t have all the information to replicate exactly your case, but I guess that you have created an empty project with just a Blade primitive antenna (according to the low number of elements obtained in the meshing process). Note that this kind of antenna should be placed on a metallic ground surface (I mean a physicall surface) for achieving a good performance. You can find a similar example in the following link, where a rectangular ground plane is considered for the Blade antenna:

https://www.fasant.com/en/guides/mom/6. ... eed-source

We are going to update the silver version next days with the bug solved. I recommend you to wait to this new version that also will be more robust and able to handle more MoM subdomains and surfaces.

We will notify you as soon as we update the silver version

Best regards,

Javier

Dennis Burke
Posts: 26
Joined: 18 Oct 2016 22:57
Location: Chicago, USA

Re: Meshing goes OK, but Simulation always crashes

Post by Dennis Burke » 07 Feb 2017 17:19

Thank you, Javier.
A quick question.....even if I add a metal in ground plane in the model, will I still fail to execute the simulation because there is a bug in the present Release of the tool?
Meaning, no matter what I simulate, even the example u hot link me to, I will still have failure?
I also note for coaxial feed, the "setup parameters " box does not really tell the user where the connection is made to the geometry surface in the mesh tet. This seems inaccurate. The user does not know where the reference placement is in the model.

Dennis Burke
Posts: 26
Joined: 18 Oct 2016 22:57
Location: Chicago, USA

Re: Meshing OK, but Simulation always crashes

Post by Dennis Burke » 07 Feb 2017 17:23

I have second questions:
if a proper ground plane is added, how much space should there be between the Groundplane and the Blade antenna?

Should there be a gap? Or should the surface of the feed point touch the Groundplane?

javi.moreno
Posts: 18
Joined: 30 Sep 2016 08:18

Re: Meshing goes OK, but Simulation always crashes

Post by javi.moreno » 08 Feb 2017 13:23

A quick question.....even if I add a metal in ground plane in the model, will I still fail to execute the simulation because there is a bug in the present Release of the tool?
Yes, there was a bug with some Coaxial Feed primitives (such as the Blade one) in the present Silver (6.2.7) version, even considering a metal as ground plane. It is already solved in new (6.2.8) version that will be available as soon as we finish the quality tests.

Meaning, no matter what I simulate, even the example u hot link me to, I will still have failure?
The bug may appear in some Coaxial Feed primitive, with and without ground plane.

I also note for coaxial feed, the "setup parameters " box does not really tell the user where the connection is made to the geometry surface in the mesh tet. This seems inaccurate. The user does not know where the reference placement is in the model.
The user can edit both the voltage and impedance given a Feeding point defined by two surfaces. With this information, the feeding is automatically carried out.
When one of the surfaces is shown as “Auto” (as in the Blade Primitive Antenna), the voltage is automatically inserted in the surfaces connected to the antenna that will be typically its ground plane (See attachment “Fig. 1”).
Fig. 1.PNG
Fig. 1: With ground plane
Fig. 1.PNG (42.11 KiB) Viewed 37229 times
If the ground plane has not been considered, the feed point is placed in the closest connection of the feeding surfaces (See attachment “Fig.2”)
Fig. 2.PNG
Fig. 2: Without ground plane
Fig. 2.PNG (35.17 KiB) Viewed 37229 times
if a proper ground plane is added, how much space should there be between the Groundplane and the Blade antenna? Should there be a gap? Or should the surface of the feed point touch the Groundplane?
The ground plane surface and the antenna must be physically connected, that is, without gap between them, as shown in “Fig 1”.


We appreciate your feedback and comments and they will be taken into account for improving the user experience.

Dennis Burke
Posts: 26
Joined: 18 Oct 2016 22:57
Location: Chicago, USA

Re: Simulation details are good Info

Post by Dennis Burke » 09 Feb 2017 02:41

Thank you for clarifying the details needed for a successful Simitation. Without the detail of proper use of Ground plane, it would be useless result!
There is a selection box in simulation that asks "include groundplane". Is this an Infinite groundplane?
I ask because this Plane option does not have any visibility in the GUI.

javi.moreno
Posts: 18
Joined: 30 Sep 2016 08:18

Re: Simulation details are good Info

Post by javi.moreno » 09 Feb 2017 22:20

We will update the user guides and GUI descriptions to clarify those questions.
You are right, the "include ground plane" option enables an infinite ground plane that is usually considered for RCS simulations. For coaxial feed antennas, it doesn't provide the effect of a physicall groud plane where the antenna is placed on, as the one that I mentioned in the previous message. It also will be better explained in the user guides for avoiding confusions.
Best regards,
Javier

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