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Lumped Port Microstrip antenna set up

Posted 11 mars 2013, 16:05 UTC−4 RF & Microwave Engineering Version 4.3, Version 4.3b 5 Replies

Lee Edwards
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Hi folks,

i am completely new to COMSOL and i am struggling with a few basic things for my uni project. I followed the tutorial for the inset microstrip antenna provided. I must have done this ten times now and it works fine. I tried to transfer the same procedures over to my design, a circular polarised microstrip antenna but i am having a few problems. My end goal is to find the S parameters and impedance so i can design a quarter wave transformer to go on the end to match the antenna. The design is really simple, i have attached it at the bottom if anyone wants to take a look.

Anyways the mesh seems to be an issue

I have one mesh covering the inner sphere (i think this is a gaussian surface or something to calculate electric fields but it doesn't say. The tutorial used a free tetrahedral mesh and creates a further 2 sizes. One for the microstrip line edges, or at least that's what the turorial seemed to do so i selected my edges too and one cover the ground, substrate and patch... i dont know if this is right because i aint got a clue where the ground is on the turoial one given as the patch is inside the substrate.....

anyways, i get a few errors,

Edge is much shorter than the specified minimum element size.
Face is (or has a narrow region that is) much smaller than the specified minimum element size.

Question 1
previously i never had to specify a minimum element, i thought it would just do this for me.... how do i choose an appropriate minimum element???


Question 2
on the tutorial for the lumped port domains, he chooses the microstrip line edge which is to be excited, i have done this but when i compute the study i receive the following message

error in automatic sequence lumped port .....

any ideas??

and thanks for your help.

Lee.
5 Replies Last Post 31 juil. 2014, 19:31 UTC−4
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Hello Lee Edwards

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Nebil Kristou
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Posted: 1 decade ago 1 juin 2013, 20:25 UTC−4
Hi Lee,

I'm also beginner in Comsol, i'm designing a rectangular patch antenna, and i'm also using the the inset microstrip antenna model provided, sorry I dont have answers to your questions yet, but i need some help :
Theoretically, the microtrip antenna have 3 major parts : the ground, the substrate and finally the metallic patch, but in this model i found only the subsrate !! Why ? I don't understand :(
Hi Lee, I'm also beginner in Comsol, i'm designing a rectangular patch antenna, and i'm also using the the inset microstrip antenna model provided, sorry I dont have answers to your questions yet, but i need some help : Theoretically, the microtrip antenna have 3 major parts : the ground, the substrate and finally the metallic patch, but in this model i found only the subsrate !! Why ? I don't understand :(
Lee Edwards
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Posted: 1 decade ago 1 juin 2013, 20:31 UTC−4
Hey,

The ground plane and patch are modelled as planar surfaces i.e with no thickness so only the face of the patch is selected.
Hey, The ground plane and patch are modelled as planar surfaces i.e with no thickness so only the face of the patch is selected.
Nebil Kristou
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Posted: 1 decade ago 1 juin 2013, 20:48 UTC−4
if you see in the materials section, you will only find air and subsrate, normally we found copper also, no ?
because i want to study the effect on the microstrip antenna if I vary the conductivity of the patch, have you please any idea how can i do this ?
if you see in the materials section, you will only find air and subsrate, normally we found copper also, no ? because i want to study the effect on the microstrip antenna if I vary the conductivity of the patch, have you please any idea how can i do this ?
Lee Edwards
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Posted: 1 decade ago 1 juin 2013, 22:23 UTC−4
I had the same question when i started. I think by default it was set to copper so u only have to set the air and substrate. Idont have comsol installed on my home computer to check. If u want to change the material just go to materil section click add material choose your material and assign it to the patch shape and ground plane. There is a program called antenna magnus which u shud check out. It will build the antenna you want and transfer it to cst studio i am notbsure about comsol but may b worth a try.
I had the same question when i started. I think by default it was set to copper so u only have to set the air and substrate. Idont have comsol installed on my home computer to check. If u want to change the material just go to materil section click add material choose your material and assign it to the patch shape and ground plane. There is a program called antenna magnus which u shud check out. It will build the antenna you want and transfer it to cst studio i am notbsure about comsol but may b worth a try.
Farrukh Mateen
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Posted: 10 years ago 31 juil. 2014, 19:31 UTC−4
Hi Lee

With regards to your reply (I know its old) but how can we change the material of the patch to be different to that of the substrate. Presently all the model examples presented by COMSOL simulate the patch and the substrate with the same material. I want to simulate the patch made of copper on a silicon substrate.

PLease help

Thanks
Hi Lee With regards to your reply (I know its old) but how can we change the material of the patch to be different to that of the substrate. Presently all the model examples presented by COMSOL simulate the patch and the substrate with the same material. I want to simulate the patch made of copper on a silicon substrate. PLease help Thanks

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