Nanoantenna calculation using CST

  • #1
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Main Question or Discussion Point

I want to do nanoantenna calculation using CST.
However, there are many project template
One for optical filter and resonator
The other for Antenna-dielectric resonator
I do not know which one should I choose?
Could anyone advice me? Thanks.
 

Answers and Replies

  • #2
berkeman
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I want to do nanoantenna calculation using CST.
However, there are many project template
One for optical filter and resonator
The other for Antenna-dielectric resonator
I do not know which one should I choose?
Could anyone advice me? Thanks.
Can you say more about your antenna structure? If it is made with a metallic pattern on a dielectric substrate, then the Antenna-Dielectric Resonator model would seem to be a good starting point...

Computer Simulation Technology software: https://www.cst.com/solutions/markets/antennas#size=5

https://www.cst.com/solutions/markets/~/link.aspx?_id=A457C5F3486C46269D8CD706EDF060CF&_z=z

cst-studio-suite_2018_website.png
 

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  • #3
122
3
Can you say more about your antenna structure? If it is made with a metallic pattern on a dielectric substrate, then the Antenna-Dielectric Resonator model would seem to be a good starting point...

Computer Simulation Technology software: https://www.cst.com/solutions/markets/antennas#size=5

https://www.cst.com/solutions/markets/~/link.aspx?_id=A457C5F3486C46269D8CD706EDF060CF&_z=z

View attachment 230081

No, I want to consider a fully dielectric material in vacuum.
For instance http://www.mdpi.com/2079-4991/6/6/99
Is there any difference from considering a metallic pattern on a dielectric substrate?

I have seen the CST website and the links you provided. But they are very confusing for me as a beginner.
 
Last edited:
  • #4
Baluncore
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The problem with the term nanoantenna is that it could be just about anything.
Before modelling or discussing any antenna it is important to identify the application.

1. What is the centre frequency or the geometric mean wavelength?
2. What is the bandwidth, or the Q?

3. What approximate dimensions will the antenna have?

4. Is it intended to; Receive energy, or to transmit energy?
5. Will it couple between space and a transmission line?
... or will it act as a passive scatterer in an EM field?
 
  • #5
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3
The problem with the term nanoantenna is that it could be just about anything.
Before modelling or discussing any antenna it is important to identify the application.

1. What is the centre frequency or the geometric mean wavelength?
2. What is the bandwidth, or the Q?

3. What approximate dimensions will the antenna have?

4. Is it intended to; Receive energy, or to transmit energy?
5. Will it couple between space and a transmission line?
... or will it act as a passive scatterer in an EM field?
I do not have much idea about these.
Let me try:

1. frequency is about 800nm
2 Q ....no idea...
3. dimension of the antenna about 10nm
4. intend to receive
5. ...presumably it will be coupled to space?....maybe a passive scatterer.....
 
  • #6
Baluncore
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The first problem is that the dimension of your antenna, at 10nm, is much smaller than your wavelength of 800nm. Your antenna will have a simple dipole pattern, but a very low aperture area for energy capture. Such small antennas do have the advantage of having a very wide bandwidth, but it is never really economic to use an antenna less than a tenth of a wavelength across.

On the good side there is a warm glow. The wavelength of 800nm implies an IR photon with an energy of 1239.84 / 800 = 1.55 eV, just the sort of thing you need to charge a chemical cell to power an organic reaction.

4. intend to receive
5. ...presumably it will be coupled to space?....maybe a passive scatterer.....
Well, to receive energy, the antenna must take photons from the passing flux and feed that energy into a transmission line for delivery to the client. The alternative is to put a rectifying detector at, or in the antenna, which might generate a 1.55 volt potential difference, but a very small current as electrons are pumped one by one along the charge conveyors.

Unfortunately, the undervalued common junkbox detectors available, P680 and P700, peak at a slightly higher energies than your longer wave 800nm.
See; https://en.wikipedia.org/wiki/Photosystem_I#Antenna_complex
and; https://en.wikipedia.org/wiki/Photosystem_II#Structure
Still, you may be able to hand craft a lower voltage detector, or maybe warm it up in the ocean to get the thermal broadening necessary for improved efficiency.
Also consider; https://en.wikipedia.org/wiki/Optical_rectenna

I assume you realise that a multi-layer PV cell would be more efficient at energy production, but very poor at CO2 sequestration.
 
  • #7
Baluncore
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A modelling program can only model things you can conceive and design.
Modelling microwave antennas is totally different to designing optical paths at the molecular level.
The tools that run on your computer should not decide the direction of your research.

1. Will the antenna be made of conductive metal on a dielectric support, or be synthesised using organic chemistry?
2. How, and in what form will the received energy exit the antenna structure?
 
  • #8
Baluncore
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1. Will the antenna be made of conductive metal on a dielectric support, or be synthesised using organic chemistry?
1. dielectric
Organic chemistry is a dielectric. Will the antenna elements be electrically conductive metallic?

2. How, and in what form will the received energy exit the antenna structure?
2. dissipated as heat
The 800nm radiation is heat. Why do you need an antenna when a black brick would work?
A parabolic mirror, (which is a good conductor), could focus the IR onto a black cooking pot.
 
  • #9
Baluncore
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So, what is the difference between the antenna you want to model and a black brick?
 
  • #10
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So, what is the difference between the antenna you want to model and a black brick?
black brick is only one example of the antenna.
furthermore, I am asking CST instead of black bricks.
 
  • #11
Baluncore
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No, I want to consider a fully dielectric material in vacuum.
For instance http://www.mdpi.com/2079-4991/6/6/99
Is there any difference from considering a metallic pattern on a dielectric substrate?
Yes. The paper you referenced is a study of silver nanoparticles coating on a surface being imaged. Those electrically conductive Ag rods form short metallic dipoles that scatter incident energy. They are not really antennas since they do not have feed-lines. A coating of metallic dipoles should not be treated as a dielectric layer at wavelengths close to dipole resonance.

The analysis of random fields of scatterers is best done by the statistical analysis of incident and radiated energy polarisation. Simulators do not work well with huge numbers of randomly orientated elements, that is best done statistically. The presence of randomly oriented dipoles lying on a surface generates a frequency dependence to the scattering from that surface.

A black brick absorbs photons, which heat the brick until it reaches an equilibrium between incident and radiated thermal energy. If a black brick is progressively coated with dipole scatterers it becomes more reflective and better insulated from it's environment. It will take on a colour determined by the dipole length. Coating an object with a film having a quarter wave thickness will reduce the reflection from, and increase the transmission through the surface.

If you want to experiment with CST then start by modelling well behaved objects. Then check your results before embarking on modelling the unknown.
 

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