▁using ▁filters ▁called ▁combin ers . ▁Trans mit ters ▁usually ▁have ▁direction al ▁devices ▁installed ▁along ▁with ▁the ▁filters ▁that ▁block ▁any ▁reflected ▁power ▁in ▁the ▁event ▁the ▁anten na ▁mal functions . ▁The ▁anten na ▁must ▁have ▁a ▁power ▁rating ▁that ▁will ▁handle ▁the ▁sum ▁of ▁energy ▁of ▁all ▁connected ▁transmit ters ▁at ▁the ▁same ▁time . ▁ ▁Trans mit ter ▁combining ▁systems ▁are ▁loss y . ▁As ▁a ▁rule ▁of ▁thumb , ▁each ▁leg ▁of ▁the ▁combin er ▁has ▁a ▁ 5 0 % ▁( 3 ▁de ci bel ) ▁power ▁loss . ▁If ▁two ▁transmit ters ▁are ▁connected ▁to ▁a ▁single ▁anten na ▁through ▁a ▁combin er , ▁half ▁of ▁their ▁power ▁will ▁reach ▁the ▁combin er ▁output . ▁( This ▁assumes ▁everything ▁is ▁working ▁properly .) ▁If ▁four ▁transmit ters ▁are ▁couple d ▁to ▁one ▁anten na , ▁a ▁quarter ▁of ▁each ▁transmit ter ' s ▁power ▁will ▁reach ▁the ▁output ▁of ▁the ▁combining ▁circuit . ▁Part ▁of ▁this ▁loss ▁can ▁be ▁made ▁up ▁with ▁increased ▁anten na ▁gain . ▁Fif ty ▁w att s ▁of ▁transmit ter ▁power ▁to ▁the ▁anten na ▁will ▁make ▁a ▁received ▁signal ▁strength ▁at ▁a ▁distant ▁mobile ▁radio ▁that ▁is ▁almost ▁identical ▁to ▁ 1 0 0 ▁w att s . ▁ ▁In ▁tr unk ed ▁systems ▁with ▁many ▁channels , ▁a ▁site ▁design ▁may ▁include ▁several ▁transmit ▁anten nas ▁to ▁reduce ▁combining ▁network ▁losses . ▁For ▁example , ▁a ▁six - channel ▁tr unk ed ▁system ▁may ▁have ▁two ▁transmit ▁anten nas