CST Port Signal i1, o1,1 and o2,1

Hi,

I am using two vivaldi antennas separated with their far field distance (~80cm) in CST

Since they are UWB antenna, so I am trying to excite Tx antenna with an input UWB signal (i1 as indicated in port signal folder)

But after simulation is completed, I do not see the port signal of Rx Antenna e.g. there is no signal for o2,1 :(

What I am trying to say is I am exciting TX antenna with i1 signal and want to observe the received signal at RX antenna's port ( e.g. o2,1 signal)

Any idea why there is no o2,1 signal ?
Another question what is the difference between o1,1 and o2,1 signal? Does o1,1 refer to any sort of "reflected signal" at antenna1's port?

Thanks