WDM Low-Cost and Accurate Delay Monitoring for Delay Calibration of Large Antenna Arrays

Within important applicative scenarios (e.g. metrology, basic physics, radioastronomy) the optical fiber is utilized as a transmitting medium and is at the same time required to distribute and/or transmit signals with an almost constant value of the phase shift (or delay) induced in each one of them.In presence of variations of external environmental agents which can change in real time the electromagnetic properties of the fiber optic cable, it is necessary to perform a continuous monitoring of the fiber-induced delay in order to eventually adopt appropriate countermeasures.This paper proposes an innovative, accurate and low-cost technique based on a microwave interferometer-over-fiber which allows to monitor in real time the mentioned delay, without increasing the complexity of the global system, nor reducing the level of its original performance.