RFID Tag Antenna Simulation

I am also working on simulating an RFID tag antenna using HFSS. I am simulating a UPM RAFLATAC Hammer Tag. I have finished the design and assumed a 0.07mm thickness of the antenna. Is this correct? Also, I'm having a hard time with the actual simulation. Can you provide a STEP BY STEP procedure on how to go about it?... I am supposed to examine the de-tuning effects on the antenna when placed near a metal surface.

Uploaded is the HFSS file of the designed I've finished and the UPM RAFLATAC Hammer Tag datasheet... please heeeelp...

hi
your simulation have some problem
1- define your material
2-define and design a lump port
3-define your radiation box and boundary
4-sweep simulation
but i think your design have problem and your substrate too thick

Well, that's actually what the problem is. Im not sure what radiation structure to use and what kind of excitation. I haven't encountered any RFID Tag Antenna simulation anywhere on the internet so I really don't know what to use... I'm sorry. >_<

http://www.sonnetsoftware.com/suppor...ign%200602.pdf

I put the lumped port in the middle of the antenna, the junction in the very center with the two squares. I get the following error:

[info] Port refinement, process hf3d: Too many condcutors touch lumped port '1'. Consider splitting the port into multiple lumped ports (2:00:19 PM Jul 04, 2011)

Isn't the port supposed to touch the antenna?...

hi
i attach a sample of RFID antenna

Wow, thanks so much! I have a question though. The Hammer tag doesn't have a substrate. It's just sort of a sticker. Do i just model the radiating conductor without a substrate?

hi
i dont have any data about which you say but i know with out substrate the antenna size increase and they usually have thin substrate like the antenna that i attach for u

Oh wait, I'm sorry, I looked at the datasheet and it says the tag is covered in PET. There's no PET material in HFSS so i searched the net for PET data and found out that it has 3.7 permeability. Then I "created" a PET material and used it to cover my antenna. It's about 0.05mm thickness on both sides. But when I try to simulate it, S11 is still crappy: A dip that barely goes to -5dB and it goes past 1GHz. It's a tag that's supposed to function at around 900MHz since it's UHF. I don't know if my simulation parameters are correct... Please look at it again. It's better than the first one. =) I'll attach it here:

hi
in the catalog which u attach before this said the the length and width of dielectric and change your substrate size to that. By increase of thickness of substrate your resonance may be reduce to your favorite frequency but i think it have thin substrate and by change u input impedance to the true impedance of the chip which apply for this antenna u able u achieve u favorite result .

Do you know how I can determine the input impedance? Other than asking the UPM company that is... =/

hi
in lump port setting u can change it usually like 30+120j

Oh my goodness it did the trick! Thank you so much! =D

Wait, is it ok to assume a lump port impedance just like that?...

hi
it differ to the chip which u use for RFID i attach a PDF may be help u more

Mr. ferdows, I'd like to ask for help for one more thing. I'm attaching a file that has the UPM dogbone antenna I modeled and a patch antenna designed for 900MHz. They are about 3m apart. I'm supposed to model the RFID System, the tag antenna as the receiver and the the patch antenna as the transmitter. How do I set the parameters? I used waveport for the patch and lumped port for the tag antenna.

I'd like to know the S parameters...

Here is the attachment:

dear daneloctober
i confused when i read your post by confused more when i seen your hfss file
if any one said u to design like this in hfss ?
i sorry i have never seen like this and i think its not true

Oh Im sorry if i confused you. I was trying to ask how I could simulate the RFID Tag as a "receiver" antenna. Do you know how to do it?...

hi
after u design the transmitter and receiver antenna u can find then gain and efficiency and other parameter then u can write a m file base on Farris equation and then find other parameter and i saw another software BY ansoft co which used for radar and system performance