Directional couplers are an essential component in several microwave applications. Lumped element directional couplers gained a lot of attention due to their compact size. This thesis represents a lumped element model for transdirectional and codirectional couplers. Unlike the classical inductive coupling used for modelling, capacitors are used to represent the coupling mechanism between the two coupled lines. Transdirectional couplers are recommended for many applications such as power dividers and power combiners because of the direct current (DC) isolation between the input and output ports. Generic design equations are demonstrated at any frequency with arbitrary coupling coefficients for the lumped element transdirectional coupler. In addition, design equations for lumped element codirectional couplers at any frequency with 3 dB coupling coefficient are presented. lumped element transdirectional coupler and codirectional coupler are designed and fabricated at 1 GHz to verify the design methodology. Both are fabricated using FR-4 substrate. There is good agreement between the simulated and measured results for both designs.
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