You've probably noticed that, actually, the combiner is nothing more than a divider, but used in the reverse way....
And that's exactly what it is: a RF Power Combiner simply combines (sum) different signals in a single output. In the above case, the signals are transmitted over port B and C go out through that output (A).
In the same way as the divider, the name is suggestive: the combiner combines! At first you can find very simple ... and it really is, but it is extremely important for all systems where we need group (and ungroup) signals with same or similar characteristics.
The RF Power Combiner then are used in applications where it is necessary to transmit/send multiple signals over a single medium.
We will use the same example above, to see how this is done. A user (in yellow in the figure) transmits his conversation, which arrives via antenna (1) to the BTS (2). Another user (red) also broadcasts their conversation, only via antenna (3) until the same BTS. On BTS then these signals are present (summed or combined), and the BTS can then continue the processing of each one of the calls.
See that the different signals of each one of the users (yellow and red) were then summed (or combined) in a combiner, and both signal followed by a single cable from antennas to the BTS.
The combiner doesn't make any kind of transformation or change in the signal. Simply combines them into a single output.
And also it is easy to understand that all the features as Loss and Isolation of RF Power Combiner are the same we've previously seen for the divider. As the divider, the combiner is also a passive element.
Now know what is a RF Power Combiner!
What we've seen so far applies to signals that have the same characteristics, no matter the frequency: the splitter and combiner 'don't care' about the frequency.
But what about when we need to convey different and specific frequencies via a single broadband antenna, what do we do?
In this case, we need to 'adjust' the RF filters to ensure that interconnection in a single transmission medium.