A simple Uhf/Vhf splitter connected in reverse will not work.
A simple splitter connected in reverse allows the UHF and VHF antennas to cross talk producing out of phase signals and bleed off signal strength the two antennas.
_____________
Use a , UVSJ , = UHF/VHF Seperator Joiner.
A UVSJ isolates the UHF and VHF antennas.
Use a UVSJ so that there is/are no antennas cross talk out of phase signals and no signal power bleed off.
At
http://www.soldsignal.com.
Buy and use a , Pico Macom UVSJ or Blonder Tongue ZUVSJ.
Connect the UHF antenna to the UHF connection of the UVSJ.
Connect the VHF antenna to the VHF connection of the UVSJ.