dual frequency and frequency ratio

i would like to ask what is frequency ratio?its application?the range of frequency ratio ?

and
what is application of dual frequency antenna?
tq ...help me

Come on man! why are u trying to get other people to do your HW for u?

Try to use your logic. For example every cell phone antenna these days is at least dual band. (for 3G, GSM, etc..)

thanks a lot..actually im just 13 years old..i just hear my aunt talk about that..so, i want to know what's that...tq...

As I know, the application for dual antenna is in one cellular phone which can used for CDMA and GSM