MWS Simulation question

Hi,
I have designed a structure that consists of 2 antennas.First there is a circular spiral external antenna.Behind this there is a rectengular spiral antenna.I want to find resonant frequency (Fo) of the structure.How should I stimulate? Can you tell me the way step by step in every detail.If needed I can also add the picture of the structure there.Also I can add another circular spiral external antenna behind the rectengular spiral antenna.[/list]

Hello :
As you know , the resonant frequency is the frequensy in which the input impedance be only real . an hence every simulation program which be able to plot smith chart , can help you for determining of Fo . how ever I could not understand if you want to analyse your stracture in a spesific frequency as Fo or not .
good luck .