“It was in the late 1940s and early 1950s, when the microwave technology was beginning to emerge from the cocoon of war time secrecy that its applications started encompassing the non-military fields as well Since then, the entire field of microwaves has undergone tremendous revolution both in terms of techniques and technologies” _Prof.Bharathi Bhat (International pioneer in Microwave Integrated Circuits_M.I.C.s). The 1950s saw the entry of a new era of microwave semiconductor technology. The availability of small size semiconductor devices made it necessary to look for transmission media compatible with these devices. The answer was given by “Planar transmission line”. Skin depth at higher frequencies also found an indispensable need in the usage of ‘Planar transmission lines’ which formed the backbones of Microwave Integrated Circuits. M.I.C.s played an unparalleled technology when Waveguides found lesser preference. The planar transmission lines include Stripline,  Microstripline, Slot line, Coplanar waveguide (CPW), Coplanar Strip(CPS), Finline and the variants of each transmission line like “inverted’. ‘V-groove’, ‘suspended’ etc. Substrate Integrated Waveguide(S I W) acts as the bridge between waveguide and planar transmission lines. Frequency Selective Surfaces (F S S) too are the present hot field technology. It will be shown that designing of M.I.C. components (Stub branch line couplers Backward wave couplers, Hybrid ring, Equal and Unequal Power dividers and Combiners etc.) up to THz are simply EASY as long as the Microwave Theory is followed with thorough understanding. Transmission lines being distributed network, initially the lumped equivalent of the corresponding stubs are obtained. .Initially ‘S’ matrix is obtained from the effective chain parameters and every stub is expressed in terms of the admittance and then Impedance. While designing the M.I.C. components three dimensions length (l), Width (w) and height (h)   are to be determined. Out of three ‘h’ is taken care of by the substrate manufacturers (default being 1/16 “). Length is mostly in terms of guide wavelength (λ_g) which takes care of any material (since €_eff is used) and frequency .Guide wavelength does miracles in the function of M.I.C.component design. There are infinite lambdas from ‘0’ to “lambda”. Transmission line equation will make one know the application of each length of a transmission line. The width ‘w’ is based on the characteristic impedance or even mode and odd mode impedances. Suitable nomograms are then used. Well defined closed form expressions are there .Matlab or Python programming can be used for self-coding. The layout of the components can be got with 100 % dimensional accuracy. Once the components are designed, systems (E.g. Mixer, Antennae, all types of filters, transponders etc) can be generated. When needed, even mode and odd mode analysis are taken for the analysis. FINALLY LAYOUT DESIGN IS OBTAINED WHICH CAN DIRECTLY BE TRANSFERRED FOR FABRICATION PROCESS.