Microwave photonics has been introduced as a tool of achieving ultra broad communication systems. RADAR, navigation, and radio astronomy systems can also utilize microwave photonics to achieve broader bandwidths. Hybrid couplers play a major role in microwave equipments. Traditional wideband hybrid couplers are already available in the microwave domain but there are still limitations on bandwidth and phase ripple as well as input/output impedance. The aim of this work is to develop a wideband quadrature hybrid coupler utilizing microwave photonics technology and to demonstrate the application of such a coupler. Major contributions made by this work include the implementation of a photonic Hilbert transformer, used to achieve in-phase and quadrature-phase generation over a wideband frequency range with low phase ripple. This Hilbert transformer is used as a hybrid coupler to implement a microwave photonic instantaneous frequency measurement system and a photonic feed for a reconfigurable sinuous antenna. This book is recommended for students and researchers working in the area of optical communication and microwave photonics.