UWB antenna on PCB _ Mobile Phone

Dear all,
As you know, UWB antennas are with partial ground plane and slotted partial ground plane. but when these antennas are to be mounted on mobile phone or PCB (that are on metal) and have large ground plane, this can affects largely the performance of antenna. So in this case what problems can arrive, and how we can resolve this problem?
Thank u very much.
Best regards.

Bigger ground planes are generally helpful rather than a problem.

Dear Azulykit;
many thanks indeed for your reply.
Please, Can you explain more!
i'll be grateful for your help.

Dear Simotic

One of the main focus part for UWB antenna is reducing ground plane effect.

You are right. different ground plane size affect the UWB performance.

So, it is one of the main research area for UWB application.