HELP required in EBG substrates..

hello friends

guys this is my first post and i am new on this forum. i am working on dual band patch antennas with EBG substrates. i have designed an antenna for dual band which is perfectly resonating at 2.45 and 5GHZ ..i have designed EBG structure also for this band. but when i use that EBG with my antenna and simulate it with HFSS, instead of improving results, it totally changes the radiation pattern..Return loss increases and antenna is no more a dual band..can you please guide me how to fine tune it to get the reduced return loss and improved gain ?

Welcome zain04,

It's a bit hard to tell from your picture, but it almost looks like the antenna solid ground is still there when the EBG is combined with the antenna - is this the case?

thanks for the reply.. HFSS models or Antenna, EBG and Antenna attached with EBG ara attached here for your reference. thanks for your reply. please check and tell me where i am doing wrong,,thanks

yes Antenna solid ground is still there..

Hi zain04,

The files you attached don't appear to have the same antenna as shown in your pictures.

dear i am trying this EBG with both of these antennas and with both of them i am facing the same issue..after integrating antenna with EBG, my dual band antenna only resonates at higher frequency..i.e 5.5GHZ..please help me..you can check this attached model ..i guess something is wrong with EBG structure. also i dont know how to test EBG in HFSS..for now you just check this attached model files and guide me please..



the antenna which i have attached here after some fine tuning and adjustment gives me the resonance at 5.5GHZ but no resonance at 2.45GHZ..the same is with the antenna in the snapshots..please check and tell me that what is wrong with my EBG structure as i don't know how to test and check the phase response of EBG in HFSS. You can also suggest some othe EBG structure designed for 2.45 and 5.5GHZ wireless communication band.Thanks.

please guide me how to simulate reflection phase of EBG ?

Hi zain04,

There are two common methods. The first one is to use Floquet ports, which is slightly more complicated, but allows you do check off-normal incidence response. There is an example in the HFSS help. The second is a simple "waveguide" test for normal incidence response:

Surround once unit-cell with a solid air object, and elongate both directions normal to the surface of the EBG unit-cell (let's call this Z) by at least a quarter wavelength. Apply perfect E surfaces on the faces of the X axis and perfect Hs on the faces of the Y axis. Now, apply wave ports the the faces on the Z axis. You won't have to set an integration line, but do de-embed the ports to the EBG surface. This will simulate a normally incident plane wave on an infinite array of unit-cells. The Phase of S11 is then the reflection phase you are looking for.

Good Luck

ok i got it..so it means it was only problem with my EBG in the attached files? rest everything should look like the same which i have done? Thanks alot for your help..this work is really giving me tension because nobody around me is able to do this..

can you please provide me some solved examples of EBG or dual band antennas designed at 2.45 and 5.5GHZ band? it would be a great help for me..

Hi zain04,

I can't comment on your EBGs as I haven't done the appropriate tests on them (hopefully you have!). I don't have any examples for you, sorry.

i have done the reflection phase optimisation of unit cell as on the steps you told me..now tell me that the antenna while integration will be integrated with its solid ground or not? i mean ebg then antenna with solid ground on it?

Hi zain04,

What are you trying to accomplish? Usually the EBG replacing the solid antenna ground plane in such a fashion is used for antenna miniaturization. If you're leaving the solid ground in I fail to see why you wanted to perform the normal incidence test...

actually i am trying to reproduce the results published by this paper. but i am unable to produce them. antenna without EBG is working fine but with EBG i am not able to get the required results which are published in this paper.and i am unable to troubleshoot my mistakes..:(