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RF Mode?

 
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CU
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Joined: 18 Jul 2006
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Location: USA

PostPosted: Wed Feb 07, 2007 10:25 am    Post subject: RF Mode? Reply with quote

Anthony thanks for another useful tutorial. I just have a question about using momentum: when should I use RF mode? I wish to design a patch antenna using momentum, is this possible, that is can momentum show the far-field?
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Anthony
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Joined: 02 Jan 2006
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Location: New York, NY

PostPosted: Wed Feb 07, 2007 9:03 pm    Post subject: Reply with quote

Hi CU,

RF mode should only be used when you are working with microwave structures that do not radiate...so PCB boards, basic guided-wave microwave components be used with RF mode. However, if your structure radiates such as a patch antenna you cannot use RF mode. I also suggest you do not use RF mode when simulating periodic structures that operate in the fast-wave region. I saw a chart once that showed when you can use RF mode...if I find it I will post it up.

Thank you,

Anthony
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tOngEh
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Joined: 05 Oct 2009
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PostPosted: Thu Oct 15, 2009 7:13 am    Post subject: Reply with quote

Hi Anthony, it really helps alot in posting up that tutorial. However, i do have a question. The tutorial shows a patch that is fedby a port on the same side of the plane. How about feeding aport ie. 50coax connector on the underside of the patch. I tried doing that but the S11 and impedance plot seems low.
Heres the dimension 4.8cmx4.8cm with a feedpoint of 50ohm at 2.33cm diagonally from any edge. It should be working at 1.5GHz with Er = 4.24, thickness of substrate is 1/16"
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Anthony
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PostPosted: Thu Oct 15, 2009 7:49 am    Post subject: Reply with quote

Hi Tongeh,

Yes, you can feed the patch from the bottom (coaxial feed). However, you have to optimize the position of the feed in order to get a good match. You can find some formulas for starting feed position in Balanis's antenna theory or doing a search on IEEE. I suggest you start with that value and optimize. Maybe I will create a coaxial feed position calculator for the feed.

Thank you,

Anthony
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tOngEh
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PostPosted: Thu Oct 15, 2009 7:53 am    Post subject: Reply with quote

Hi ANthony,

The value of 2.33cm diagonally is the actual position for a 50ohm match. Im just stuck at the port properties. The single port define in your tutorial is located at the edge. Whereas for my case, the port should be under the patch on the oppsite side. In a nutshell, my question is only about the port settings for port under the patch rather than on the edge. Thanks!
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Doberman
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PostPosted: Sat Oct 11, 2014 7:43 am    Post subject: Reply with quote

I also suggest you do not use RF mode when simulating periodic structures that operate in the fast-wave region. I saw a chart once that showed when you can use RF mode...if I find it I will post it up.
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