Wideband antenna and RF module

Hello!

I want to ask for advice.
Is it important to use, for examle, GSM rf module with related 2 band antenna or I could also use some wideband structure, which covers both of bands?
Maybe somebody know if these unnnecessary bands are filtered in rf modules?

Thanks!

Yes, the unwanted bands (and frequencies) are filters out by front-end filters, so you can use a wideband antenna.