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12th January 2011, 23:19 #1
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HFSS help in S11, S12 and how Can I get the actual distance coverabe of my antenna
Hello
I'm currently working on designing a rectangular microstrip antenna and I can find the S11 but not sure how to get S12 parameter?
Also, how can i get the actual distance coverage of my antenna? I can see there is a directivity and power of radiation but not sure how to convert those to actual distance?
Also, the angle coverage??
Please let me know if you have any idea what i'm talking about??
Thanks
Sam

12th January 2011, 23:23 #2
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Re: HFSS help in S11, S12 and how Can I get the actual distance coverabe of my antenn
Antenna is a single port device. So you will have only S11.

12th January 2011, 23:23

12th January 2011, 23:30 #3
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Re: HFSS help in S11, S12 and how Can I get the actual distance coverabe of my antenn
as sv has noted, unless you have a two port antenna, you will only have s11. you can use friis equation to get a line of site distance for two antennas if you know the input power at the tx side using
Pr/Pt = GtGr(lambda/(4pi*r) where r is radiation distance Pr & Pt are power at receive and transmit ends and Gt and Gr are gains.
good luck

12th January 2011, 23:39 #4
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Re: HFSS help in S11, S12 and how Can I get the actual distance coverabe of my antenn

12th January 2011, 23:39

13th January 2011, 16:48 #5
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Re: HFSS help in S11, S12 and how Can I get the actual distance coverabe of my antenn
Hello ghb,
Thanks for the info but where did you get this formula and how can I get those parameters? Do you think I can get them from HFSS directly? The think is that I'm building a rectangular array antenna and I'm trying to add array patches to increase the distance coverage and adjusting the angle by adding arrays!
Can you please explain a little bit more??
Thanks,
sam

13th January 2011, 18:17 #6
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Re: HFSS help in S11, S12 and how Can I get the actual distance coverabe of my antenn
Hi ihamieh,
You cannot get the information about the actual distance covered by antenna using HFSS results. Using the Friis's equation mentioned by ghb, you can calculate that. But for that you need to know the gain of the Tx antenna, power transmitted and power received and the remaining parameters.
And what 'ghb' meant by a 2port antenna is that, for doing the Friis measurement you need to have two antennas (one Transmitting and other receiving).
sv

13th January 2011, 18:29 #7
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Re: HFSS help in S11, S12 and how Can I get the actual distance coverabe of my antenn
just to confirm. to use friis equation a couple of things must be known.
Tx power  should be easily achievable
Gt,Gr  sounds as if you're working on one of these, you would have to know the antenna on the other end or assume its a duplicate of what you're currently evaluating.
Rx power  if the goal is to find some distance where the system would still work you should be able to think along these lines  lets assume you know the receiver sensitivity or the min power that the receiver needs. lets assume thats 100dBm. well now you should be able to use Friis to calculate what distance can i place these two antennas knowing this is the received power  100dBm
google friis equation or wiki  you'll find lots.
good luck, hope this is clear
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13th January 2011, 19:47 #8
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Re: HFSS help in S11, S12 and how Can I get the actual distance coverabe of my antenn
Thank you sv this is very helpful. I really appreciate your help..
 Post added at 19:47  Previous post was at 19:46 
Thank you ghb this is the best explanation that I ever had from this site!! I'll look into and I'll let you know...
I appreciate your help.

13th January 2011, 19:47

13th January 2011, 23:34 #9
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Re: HFSS help in S11, S12 and how Can I get the actual distance coverabe of my antenn
sounds good, feel free to ask if you get stuck and dont forget to click the 'helpful' in our helpful posts :)
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