The H series antenna couplers are designed are designed to couple multiple receiver systems to a single antenna with minimum insertion loss. These antenna couplers allow signal from a single antenna to be split equally to either redundant systems or provide a dual function role, such as glide slope and VHF range localizer. The H series has a rugged construction built with an aluminum housing which fully encapsulate all circuit elements. This H21 antenna coupler (EDMO# DM H21-1) includes marker beacon support.