A 180° hybrid coupler (100) includes a first transmission line transformer (101) and a second transmission line transformer (102). Each of the first and second transmission line transformers is comprised of a coplanar stripline structure disposed in a spiral configuration. Each of the coplanar stripline structures has a first characteristic impedance and is configured to function as a balun. A common input feed (202) is coupled to each of the first and second transmission line transformers. A third transmission line transformer (103) and a fourth transmission line transformer (104) are also provided. Each of the third and fourth transmission line transformers is also configured to function as a balun and is coupled to the first and second transmission line transformers.