2D radiation pattern problem

Dear All,

I have good return loss when I draw the airbox lambda/4 away from the antenna BUT the problem is that the 2D radiation pattern isn't correct.
I've noticed that there is a relation between the airbox size and the radiation pattern and the labmda/4 airbox doesn't give good results. Is it supposed to use the same air box for both parameters or use different airboxes and if so what should its dimensions be?

this puzzled me for long.
Thanks in advance.

you should verify your result by the other software in the first step.
I think return loss is not true, you can increase the number of tetrahedrons in the setting of HFSS. if S11 changes then the simulation is not true!

It would clearly help if you stated what software you are using. I woud put that in the title. I think you are speaking of HFSS, in which case someone with knowledge is more likely to look at the post if you put "HFSS" in the title.

Have you actually made all 6 faces a radiation boundary? If one is left PEC, you will get problems. Does the delta S plot seem to be converging nicely. You might want to increase the number of iterations above the default value of 6 and make sure it stays converging. If it starts to diverge, that would indicate a problem.

You should try limiting the size of the tetrahedrals to be be no more than lambda/6 on the boundary.

Remeber if you solve at 600 MHz, but sweep from 300 MHz to 1.2 GHz, the airbox needs to be 250 mm away from the antenna since the longest wavelength used is 1 m @ 300 MHz.

The size of the airbox is more critical for measuring the radiation pattern that it is for measurement of return loss.

If you post your model, someone with access to HFSS might be able to help you.

Dave

thanks for responding.
I don't think return loss is not true. I'm simulating a paper and RL is just like the paper but other parameters are not. it couldn't be a convergence problem as if I increase the no of passes massive increase in the complexity of the problem occurs with very slight difference in return loss.

any suggestions are welcomed.

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Dear Dave, thanks for all of your sincere comments and suggestions.

I'm working on freq range (0.5-3) GHz

Yes u r right I'm using hfss. rad boundary includes 6 faces none is pec.
BUT why tetras shouldn't be more than lambda/6? radiation pattern is more sensitive so how I decide the right dimensions of the airbox, isn't it ALSO lamda/4 ?

Regards

dear catalyst101
could you share your paper that you simulating it. I can simulate it to find your problem.

with my best wishes

Thank you hamidrezakarami.

here is the paper Paper.pdf

REGARDS