Siddig Gomha received his B.Sc. (honor) in electronics and instrumentation,and M.Sc. in Electronics and Electrical Communications Engineering, Currently he is Ph.D student at PAN African University, Institute for Basic Science Technology and Innovation PAUSTI, Nairobi, Kenya.

For decades, engineers have been searching for ways to reduce the size of electronic circuits while maintaining the efficiency and effectiveness of the circuits. At low frequencies of the microwave band, the size of the conventional transmission line becomes larger, because the wavelength is inversely proportional to the operating frequency; thus, it is needed to reduce the size to agree with the application requirements. In this book miniaturization of the Branch-Line Couplers BLCs are investigated. Beginning with classical methods for minimizing the circuit area of the BLC. Later, a new proposed compact 3dB Branch-Line Coupler (BLC) is designed and implemented, based on coupled line D-CRLH unit cells that have the same properties as Dual Composite Right/Left L Handed (D-CRLH). To attain more compactness and high performance with low insertion loss, High Temperature Superconductor HTS is used rather than a copper microstrip conductor. The CST full wave EM simulator has been used to simulate the proposed BLCs. Moreover, the tunable frequency BLC is designed using a thin film layer of STO Strontium Titanate (SrTiO3) ferroelectric material