This scheme can be used to combine two antennas. It has several advantages over a typical non-isolation type air dielectric antenna splitter:
1) If the two load impedances are identical, whatever they are, the input retrun loss (SWR) looks perfect.
2) If one load (antenna) has a bad return loss, the reflected power will go to the 50 Ohm termination, not back to the power amplifier.
3) If the termination resistor is replaced with an antenna (50 Ohm) it will radiate the reflected power. This should be a high reliability antenna, not subject to damage and must maintain a good return loss in order to assure good hybrid performance.
4) The antenna termination instead of the resistor eliminates the need for a high power dummy load.