In this paper we analyze various structures of branch line coupler with different frequencies of 1GHz to 2.5GHz. Couplers are used for splitting or combining power. It is basically a 3dB power divider or combiner with symmetrical four port network for obtaining 900 phase difference between its output.It has been used in many applications such as in mixers, power amplifiers, modulators, anteena beam forming networks.The major advantages of branch line coupler are low profile, easy to fabricate, light weight.