Horn antenna, lumped port

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carlos_ddd
Posts: 1
Joined: Thu 13 Dec 2018, 12:48

Horn antenna, lumped port

Post by carlos_ddd » Thu 13 Dec 2018, 18:02

Hi,

I am trying to simulate (an existing) 2,4 GHz horn antenna which has a coax (SMA) feed. Since I am a newbie to electromagnetic simulation I'm in a little struggle. I used the horn antenna tutorial (with rect. waveguide port) and tried to adapt it to my needs. I tried to use a lumped port for excitation. Please do not blame me for my coding style & structure. Furthermore please notice that the geometry is total nonsense at the moment. I am just trying to get the lumped element port to work in a horn antenna.

Maybe somebody can point me in the right direction or tell me if I am heading in the totally wrong direction.

Problems & symptoms:

Code: Select all

VTKPrimitives::AddCube: Warning, can't draw a Point Box... skipping
- obviously no excitation or detection of excitation (energy in FTDT is always 0)

Questions:

- Where does my warning come from (mesh/port problem)?
- How is the lumped port supposed to be used? Currently the port "connects" the metal of the horn to the metal of the feed. How long is the lumped port supposed to be? Should it just connect the two metals (as shown in the patch antenna tutorial) or be as long as the metallic feed of the antenna?
- Of course, I am interested in simulating the SMA-connector a close as possible but that seems to be a quite difficult topic. Is the "style" I use the lumped port correct? Any suggestions for a more appropriate feed structure?
- Is it required to place the lumped port directly on the mesh or is it sufficient to have the mesh penetrating only the connected metal of the feed?

Thanks for your help,

Carlos
Attachments
hornFail.JPG
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Hale_812
Posts: 172
Joined: Fri 13 May 2016, 02:54

Re: Horn antenna, lumped port

Post by Hale_812 » Fri 14 Dec 2018, 09:15

Lumped port is a cuboid-shped resistor, which vertices are strictly coincide with mesh-grid nodes.
generally, is is a single 3D cell box with direction of current and resistance defined.
One side touches ground plane exactly, opposite side touches metal probe, with planes coinciding exactly at the same meshgrid coordinate.
The port should have maximal (0) object priority, just in case. The probe length and diameter is tuned at the place, but in normal situation it should be close to the real sample, you have in lab.
port's handler is returned as the second object in return-array.
So don't forget assigning different variables to each port handler.
[CSX, port1] = AddLumpedPort(...
[CSX, port2] = AddLumpedPort(...
[CSX, port3] = AddLumpedPort(...
Any port and any port number can be excited, and all the ports do receive signal. But only one signal is fed to all excited ports at once.
So generally there is no meaning exciting more than one port.
This also means that probes are added to port by default, but you can still tamper with them in CSX structure.

Recommendation: when creating oblique surfaces, avoid using sin, cos, and especially tan... especially on Intel processors. The errors are large, surface misalignment is possible. Use Pythagoras theorem wherever you can.

You can also create an arbitrary closed surface solid by carefully arranging vertices in space.

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