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Dielectri Resonator Antenna Simulation

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kelvchan

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I am trying to simulate DRA in free space with CST and if possible, does anyone have some matlab codes to obtain the multiple modes in a DRA in free space? I was trying to use the eigenmode solver in CST to obtain the modes but the modes obtained were inaccurate according to the solver. I used an airbox to create air interface beyond the DRA and with perfect magnetic conductor at the boundaries. How big should the box be to get a decent accuracy?[/b]
 

burton

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I have some advice as follows:
(1) You can only get the resonant frequency and field distribution using eigenmode solver. The face of the airbox is at least 0.25*wavelength far away from the boundary of DR. The boundary of the airbox can be set to PEC or PMC. You must view the field distribution to decide the resonant modes of DR.
(2) In order to get the performance of the DRA, you must simulate the whole structure composed of the feed structure and DRA.
 

kelvchan

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Hi Burton, thanks for the useful advice. Actually, I intend to omit the feed structure because I do not want external modes from the feeding structure, for example, if I have an aperture coupled DRA, the aperture is a resonant structure and will contribute to the modes of the DRA which I am more interested to find out for a separate study, which is why I chose to use the eigenmode solver to obtain the mutiple modes and field distribution of the DRA in free space without any feeding structures.

I came across a paper by D. Kajfez, "Modal field patterns in Dielectric Rod Waveguides". This paper tells me that to obtain the eigenmodes, one has to solve the transcendal equation by a numerical procedure which would be too time-comsuming.

What I require is to obtain the various modes of the cylindrical DRA, like the various HEM, TM and TE modes, together with their field distributions. In addition, I am also interested to use the same study on rectangular DRA.
 

flyhigh

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Hi,

not the expert of DRA but I did sam work on DRs in the past. I think that what you try to simulate is known in the analytical form. Packages such as Mathematica or MATlab can do this pots in seconds, you don't have to do any complicated numerics.

flyhigh
 

kelvchan

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Hi flyhigh, do you have any sources for the matlab codes for solving the eigenmodes and plotting the fields of rectangular and cylindrical DRAs in freespace without any sources or excitations?
 

flyhigh

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Hi,

in book Dielectric Resonators by D. Kajfez you can find expressions for cylindrical DR fiels components based on dielectric waveguide model. There is also a model of DR on a microstrip. The extensions to ractangle should be straightforward and even easier because only sin/cos are involved as oposed to Bessel functions involved with cylindrical geometry.

flyhigh
 

kelvchan

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Hi Flyhigh

thanks for the tip, may I know if you have any source for a soft copy of this book you mentioned as I am unable to get it. I would grateful if you can give me any links for it.
 

pappumaity

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kelvchan said:
Hi Flyhigh

thanks for the tip, may I know if you have any source for a soft copy of this book you mentioned as I am unable to get it. I would grateful if you can give me any links for it.

post ur email ID--i will give u this LINK definitely
 

Vasily

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HEM and TE/TM modes
Is HEM the mode of “combat unit” in the sense that excitation by one of its components (for example, the axial component of electric field automatically indicates the appearance of all remaining magnetic and electrical components of field. Or, IT mode this is not more than the designation of combination THOSE and TM modes with the identical indices, and excitation by one of the components of electric field (for example, radial component) on no account leads to the automatic excitation of the axial component of electric field. In other words - is IT mode simply the designation of line combination THOSE and TM modes, or this is independent mode. prompt, if you please.
 

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