The disclosure is directed to semiconductor structures and, more particularly, to a three dimensional microstrip branchline coupler and methods of manufacture. The structure includes a plurality of through silicon vias and conductive lines electrically connected to a first end and a second end of respective ones of the plurality of through silicon vias. A first through silicon via of the plurality of through silicon vias forms a first port of a three dimensional (3D) branchline coupler. A second through silicon via of the plurality of through silicon vias forms a second port of the 3D branchline coupler. A third through silicon via of the plurality of through silicon vias forms a third port of the 3D branchline coupler. A fourth through silicon via of the plurality of through silicon vias forms a fourth port of the 3D branchline coupler.