Loss can be gain, given the input signal. Reciprocity always applies.
There is no magic "formula" only the bubble and the polarization/direction it fits.
The only firm rule is a 3db "loss" per 2 way splitter. Unless reflected via swr, where the excess power is burned off as heat, and/or reflected to the transmitter or tuner(which bounces it back to the antenna...), the power is transmitted into the air. The power supplied must be either burned off or transmitted. This is the law of conservation of energy.
I stipulate that there can be no loss of power of a properly tuned(1:1 swr) antenna or multiples of the same no matter the orientation.
The emitted pattern and polarization are the only constraints given to the power output.
Given the distance between antennas this can create nulls a cancellation of a signal in a direction, or an elliptical(or circular) polarization pattern, if mixed polarity(H,V) antennas are used. The same amount of power is radiated not matter the polarity or direction of the output waveform bubble.
The bubble is formally defined as the energy pattern of a sphere about an isotropic radiating point. It can be enlogated by nulls to fit certain directions, once airborne never quashed only fortified on the opposite direction by nulls, cancellation of the waveform in a direction.