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Radiated power of lumped port in electromagnetic frequency module.
Posted May 31, 2017, 12:02 p.m. EDT 8 Replies
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Hi,
I have been working on the electromagnetic frequency module and bioheat transfer module. I made a patch antenna which is placed near to a biological tissue. I then set a lumped port boundary condition for the patch antenna. I wanted to set 1W radiated power for the lumped port, so i chose 10V and 50ohm as the input for lumped port setting section. I am getting the temperature distribution and electric field distribution in result. The results are, i would say okay (not good). I choose volume maximum from the Result-> derived value-> volume maximum, and choose the lumped port, i see that only 0.1 W is absorbed by the tissue ( i am not sure whether it shows the amount which being absorbed by tissue or it shows the power rediated from the patch antenna, in both cases it is very low than 1W). I may be doing something wrong and there are may chances my results could improve, can anyone tell me why is it showing 0.1W lumped port power when i have set 1W in the lumped port boundary condition.
Many thanks for any help.
I have been working on the electromagnetic frequency module and bioheat transfer module. I made a patch antenna which is placed near to a biological tissue. I then set a lumped port boundary condition for the patch antenna. I wanted to set 1W radiated power for the lumped port, so i chose 10V and 50ohm as the input for lumped port setting section. I am getting the temperature distribution and electric field distribution in result. The results are, i would say okay (not good). I choose volume maximum from the Result-> derived value-> volume maximum, and choose the lumped port, i see that only 0.1 W is absorbed by the tissue ( i am not sure whether it shows the amount which being absorbed by tissue or it shows the power rediated from the patch antenna, in both cases it is very low than 1W). I may be doing something wrong and there are may chances my results could improve, can anyone tell me why is it showing 0.1W lumped port power when i have set 1W in the lumped port boundary condition.
Many thanks for any help.
8 Replies Last Post Jun 2, 2017, 12:52 p.m. EDT
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Posted:
8 years ago
> I wanted to set 1W radiated power for the lumped port, so i chose 10V and 50ohm as the input for lumped port setting section
You will only radiate 1 W if the antenna input impedance is 50 ohms. Perhaps it is not.
Also- what boundary condition are you using for the surrounding domain?
D W Greve
DWGreve Consulting
You will only radiate 1 W if the antenna input impedance is 50 ohms. Perhaps it is not.
Also- what boundary condition are you using for the surrounding domain?
D W Greve
DWGreve Consulting
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Posted:
8 years ago
Thankyou for your response,
I used perfect electric conductor boundary condition on 2 patches of the antenna and between them i used a lumped port. so basically on mobile phone i have used only 2 boundary conditions, lumped port and perfect electric conductor.
I used perfect electric conductor boundary condition on 2 patches of the antenna and between them i used a lumped port. so basically on mobile phone i have used only 2 boundary conditions, lumped port and perfect electric conductor.
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Posted:
8 years ago
That's not what I was asking.
To do a calculation you need to surround the antenna and object with a domain (presumably air). There needs to be a boundary condition on the surface of that domain. Usually we use either the scattering boundary condition or a far-field domain to approximate an infinite region. In either case any power radiated but not absorbed by the object is radiated to "infinity."
If you made the surface of the air domain a perfect conductor, then there is no power lost at the boundaries. THEN I would investigate the input impedance of your antenna, which will be affected by the surrounding environment. Evaluate the impedance under Derived values > Global evaluation. You can look at Z11 or S11.
D W Greve
To do a calculation you need to surround the antenna and object with a domain (presumably air). There needs to be a boundary condition on the surface of that domain. Usually we use either the scattering boundary condition or a far-field domain to approximate an infinite region. In either case any power radiated but not absorbed by the object is radiated to "infinity."
If you made the surface of the air domain a perfect conductor, then there is no power lost at the boundaries. THEN I would investigate the input impedance of your antenna, which will be affected by the surrounding environment. Evaluate the impedance under Derived values > Global evaluation. You can look at Z11 or S11.
D W Greve
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Posted:
8 years ago
Hello sir,
sorry for the confusion, yes i did choose air from the material section and set it around the antenna, i have also created a perfectly matched layers around my whole model and set the scattering boundary on the boundaries of perfectly matched layers.
Please tell me what would i be doing wrong?
Thanks.
sorry for the confusion, yes i did choose air from the material section and set it around the antenna, i have also created a perfectly matched layers around my whole model and set the scattering boundary on the boundaries of perfectly matched layers.
Please tell me what would i be doing wrong?
Thanks.
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Posted:
8 years ago
I choose global evaluation, then in the expression setting i select "emw.S11" and evaluate it. I got 0.032260+0.94213i in the table below graphics window. What does this number means?
Thanks.
Thanks.
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Posted:
8 years ago
Updated:
8 years ago
S11 is the ratio between the reflected wave and the incident wave phasors.
Your S11 has a magnitude close to unity and therefore indicates that almost all of the incident energy is reflected. Your antenna is not well matched to 50 ohms.
DW Greve
Your S11 has a magnitude close to unity and therefore indicates that almost all of the incident energy is reflected. Your antenna is not well matched to 50 ohms.
DW Greve
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Posted:
8 years ago
should i increase it to 75 ohms? Can you tell me how can i plot a graph between S11 and frequency? and also what should be a good value for S11? I don't know what else to do with this antenna.
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Posted:
8 years ago
The antenna's impedance is far away from 50 Ohms (also from 75 Ohms) and furthermore since S11 is almost purely imaginary it is also far from resonance.
Your contributions show that you could do with some textbook reading regarding antenna and transmission line basics. Without this knowledge you won't get very far in your project. Do some research on keywords like antenna, impedance, transmission line, s-parameters, etc.
Cheers
Edgar
--
Edgar J. Kaiser
emPhys Physical Technology
www.emphys.com
Your contributions show that you could do with some textbook reading regarding antenna and transmission line basics. Without this knowledge you won't get very far in your project. Do some research on keywords like antenna, impedance, transmission line, s-parameters, etc.
Cheers
Edgar
--
Edgar J. Kaiser
emPhys Physical Technology
www.emphys.com