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saras
Joined: 26 Oct 2004
Posts: 29
Helped: 1
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 21 Dec 2004 15:18 waveguide slot antenna |
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Hi everyone!
I've serious problems with the simulation of a waveguide slot antenna.
It has a single slot on the Broadwall of the waveguide and the frequency is 10GHz. it has one port, located at λ/2 of the slot, and is terminated by a short circuit at 3*λ/4 from the slot.
I'm trying to find the resonant length of the slot for a fixed offset, by parametric sweeps of the length, to get a 0 degree for the angle of the admittance mattrix.
normally, as written in the ansoft hfss 9.1 help documents, a boundary of λ/4 from the slot should do. But the angle of admittance, which I'm very sensitive on, varies a lot with changes of the boundary.
I've used some seed meshing on the slot and the boundary, but it doesn't help much.
How could i get a reliable answer???
Plzzz...help me!!
thanks in advance
sara
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rugbyfun
Joined: 21 Oct 2004
Posts: 22
Helped: 1
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22 Dec 2004 14:14 hfss examples for waveguide slot antenna |
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Hi,
what about to use PML instead of radation BC.
Pml are less sensitive to the angle of incidence and allow you to calculate
antenna parametr
Hope this help
Rugby
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loucy
Joined: 26 Aug 2001
Posts: 432
Helped: 10
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22 Dec 2004 16:04 slot resonance length hfss |
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| I suspect the problem is not on radiation boundary. Something wrong in other part of your setup.
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22 Dec 2004 16:04 Ads |
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XuQing
Joined: 19 Feb 2004
Posts: 50
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24 Dec 2004 6:00 waveguide slot hfss |
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| The boundary cover of λ/4 from the slot seems too small, you must set one-λ at least. No problem in HFSS to get all parameters of you desired.
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saras
Joined: 26 Oct 2004
Posts: 29
Helped: 1
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25 Dec 2004 6:38 slot offset waveguide antenna |
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Hi
with a λ bounadry, it'll take years to solve the problem and it'll take too much memory, and the meshs won't get as dense as it must.
In a Ansoft 2003 Global seminars, there was a section about generating a slot design curve for a broadwall displaced slot design. The curve showed the resonant length of wave guide slot vs. offset distance. The boundary was stated as λ/4. It had done sweeps for a fixed air box and waveguide structure, with just the change of slot's offset and length. with a little change in the air box, everything will change.
I asked the writter of the seminar, and he answered this, with no more explanation or reply to my mail:
" You are right that you set 1/4 lambda of radiation box. But you did not
tell me other settings when solve: Delta S, number of passes, etc.
I have some comments for your case(wave guide slot antenna):
1. make seed mesh on radiation boundary and the slot. For the radiation
boundary, the default mesh is 1/3 lambda in HFSS v9. Please make 1/6 or 1/8
lambda seeding mesh( for your case, 10GHz, 4mm or 5mm is OK). For the slot,
you'd better make about 1/10 of the slot length seeding.
2. build a "virtual object" around the slot to make the mesh better( not so
long and thin mesh)
What about pmls? Are responses with PMLs really accurate? and how should i choose it's settings?
Thanks a lot
sara
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XuQing
Joined: 19 Feb 2004
Posts: 50
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28 Dec 2004 3:54 slot ant |
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Hi
To a single slot, it'll not take too much time & memory if set a λ bounadry. PML is good for pattern computation. If you only want S-parameters, ABC is accurate enough. Build a "virtual object" around the slot is a tradeoff way.
thanks!
XuQing
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