▁First , ▁the ▁receive ▁leg ▁greatly ▁at ten u ates ▁the ▁transmit ter ' s ▁car rier ▁at ▁the ▁receiver ▁input ▁( typ ically ▁by ▁ 9 0 - 1 0 0   d B ), ▁prevent ing ▁the ▁car rier ▁from ▁over loading ▁( block ing ) ▁the ▁receiver ▁front ▁end . ▁ ▁Second , ▁the ▁transmit ▁leg ▁at ten u ates ▁the ▁transmit ter ▁broad band ▁noise ▁on ▁the ▁receiver ▁frequency , ▁also ▁typically ▁by ▁ 9 0 - 1 0 0   d B . ▁ ▁By ▁virtue ▁of ▁the ▁transmit ter ▁and ▁receiver ▁being ▁on ▁different ▁frequencies , ▁they ▁can ▁operate ▁at ▁the ▁same ▁time ▁on ▁a ▁single ▁anten na . ▁ ▁Com bin ing ▁system ▁ ▁There ▁is ▁often ▁not ▁enough ▁tower ▁space ▁to ▁accommod ate ▁a ▁separate ▁anten na ▁for ▁each ▁repe ater ▁at ▁crow ded ▁equipment ▁sites . ▁In ▁same - band ▁repe aters ▁at ▁engine ered , ▁shared ▁equipment ▁sites , ▁repe aters ▁can ▁be ▁connected ▁to ▁shared ▁anten na ▁systems . ▁These ▁are ▁common ▁in ▁tr unk ed ▁systems , ▁where ▁up ▁to ▁ 2 9 ▁repe aters ▁for ▁a ▁single ▁tr unk ed ▁system ▁may ▁be ▁located ▁at ▁the ▁same ▁site . ▁( Some ▁architect ures ▁such ▁as ▁i D EN ▁sites ▁may ▁have ▁more ▁than ▁ 2 9 ▁repe aters .) ▁ ▁In ▁a ▁shared ▁system , ▁a ▁receive ▁anten na ▁is ▁usually ▁located ▁at ▁the ▁top ▁of ▁the ▁anten na ▁tower . ▁Put ting ▁the ▁receive ▁anten na ▁at ▁the ▁top