em4095

Hi,

I'm building RFID Reader with EM4095 and I want to implement loop PCB antenna. I was wondering if you can give me some guidelines for calculating the copper thickness, track width and width constraint and also number of loops and antenna dimensions.

Can you point me to some literature and calculation tool for building loop PCB antenna.

Thanks in advance.

Best regards,
Dusan Mihajlovic

i also tried to find some guide for these kind of antenna but in vain.
i suppose the parameters are not that rigid if the loop antenna is only used on near-field occasion because in such case a tiny electromagnetic field could be received by the reader.

Hi,

I suppose that these parameters aren't actually so rigid but i have to calculate antenna L and Q factor in order to calculate values of capacitors needed in the antenna circuit.

Best regards.

mdusan, what is the freq of the RFID?

have u found any solution yet?
i'm also trying to design a loop antenna, but it is for remote car key at 433.92mhz.

Hi,

the antenna frequency is 125KHz. Regarding the solution I didn't succeeded to calculate L and Q factor.

Best regards.

mdusan, are u using any simulation software for the antenna?
(e.g : ADS/Momentum, HFSS, CST, etc)

what is ur current solution as of now? i mean, what have u done so far?
could u tell me more about ur application? (e.g: antenna size, dimension, range, etc)

actually i'm also having about the same problem like u. Still figuring out how to 'load' the antenna. So far what i did is i import the layout structure of the PCB and simulate the S11 of the antenna. Then, I just depend on the simulation software to optimize the value of the R,C, L so that I get the best S11 at my freq, 433.92MHz.

After that, I just test out the antenna with a simple range test. And measure the gain of the antenna.

But currently i'm still not able to simulate the full radiation pattern of the antenna together with lumped components ..

* I use ADS/Momentum, HFSS and a bit of CST..

there was app note from microchip regarding 13.56 MHz loop antenna for rfid (some empiric calculations to get it done) . As it was suggested - the EM simulation soft can do that . Let say sonnet. I don't know feasibility of this solution as you need many turns due to higher inductance for 125 KHz .

Not sure if this will help, but there is an application note on using sonnet for RFID applications here (there are two entries for RFID under "applications").

Hi,

thanks for the information.

I didn't used any simulation software. I will download some of the suggested and give it a try. I made a prototype with 16 turn PCB antenna, 20mil track width and 20mil spacing. Dimensions of the outer antenna turn are about the same as standard ISO Card. I'm waiting for the prototype and then I will do some testings and measurement.

Best regards.