Patch antenna impedance too small

[Antenna (^.^)]

Hi everyone,

I followed a tutorial of how to simulate a patch antenna on youtube.

When I tried to copy the procedure for a 2.4GHz patch antenna design I noticed the
impedance vs frequency graph looks a lot different from the tutorial one.
Also it is a lot smaller.

Could anyone please advise me how to fix?

This is what I was expecting:


This is what I am getting:

 

[gpalomino]

Hi,

I suposse that you are using a wave port, put under the wave port a small cylinder with material PEC.

 

[Antenna (^.^)]

Hi,

Thanks for your reply!
I did use waveport, with a smaller pec cylinder but no difference...
The impedance of the waveport is 50ohms.

This is the results:


I am still not sure what to fix to get proper impedance result...

 

[volker@muehlhaus]

Your absorbing boundaries are much too close to the antenna.

 

[Antenna (^.^)]

Your absorbing boundaries are much too close to the antenna.

What do mean by absorbing boundaries?
Could you please explain further?

 

[volker@muehlhaus]

What do mean by absorbing boundaries?

Your simulation volume has side walls. To allow radiation, these are simulated as absorbers (PML = perfectly matched layer). The distance to the antenna matters. Your tutorial should have details on that.

 

[Antenna (^.^)]

Your simulation volume has side walls. To allow radiation, these are simulated as absorbers (PML = perfectly matched layer). The distance to the antenna matters. Your tutorial should have details on that.

No, unfortunately it didn't.. So what you are saying is that the radiation box is too close to the antenna? Is there any guidelines to how far from the sides it should be?

 

[gpalomino]

Hi,

Good mm.. maybe you can prove with lumped port for feed the patch, draw a rectangle between the microstrip line and ground and assign lumped port. For the radiation box is better use region (Draw-> Region) select absolute distance (31.25mm for 2.4GHz) then assign boundary radiation.