Systems using gigahertz electromagnetic radiations are nowadays everywhere providing communication, localization, or detection functionalities. Economic and defense stakes concerning their operation are high even though they are particularly vulnerable to accidental or deliberate electromagnetic perturbation. Existing protection solutions still need to be improved. Their resistance to pulsed power is satisfying and so their time response, but their insertion loss tends to increase the overall noise figure and reduce the sensitivity of the receiver. Moreover, high power quickly breaks operation. The DIOMEDE project aims at addressing scientific and technologic issues in order to provide innovative microwave power limiters based on plasma microdischarges. The project consortium gathers three partners: two belongs to Université Fédérale Toulouse Midi Pyrénées, namely LAPLACE laboratory and ISAE, and the third one is the CEA Gramat. Complementarity of the partners comes from their respective expertise in microwave engineering, plasma microdischarges, and electromagnetic perturbations. The first part of the DIOMEDE project deals with improving scientific knowledge of interaction mechanisms between a microwave and a microplasma discharge. Both experiments (hot S parameters measurements, CCD imagery) and numerical computation with ANR funded MACOPA program will be used. One of the main goals is to identify key parameters to optimize plasma igniting time. Then, several microwave power limiters prototypes in both conduction (wire protection) and radiation (antenna protection) will be developed to assess their behavior and optimize their performance. A parametric study will be conducted considering different topologies (above and below the circuit ground plane), preionization currents, gas composition, and pressure. Regarding pressure, two specific solutions will be considered: one close to atmospheric pressure and the other at lower pressure. Specific work will also be carried out to achieve an original instrumentation dedicated to these characterizations. A vacuum chamber will thus be designed, produced and operated. The joint identification of measurement protocols dedicated to diversity and the microwave plasma approach will be a major concern of the project.It is well known that the effectiveness of the protection is highly dependent on the waveform of the electromagnetic threat. The second part of this project proposes a series of studies to evaluate the performance of these innovative devices in a realistic context. The methodology is well identified and controlled by the CEA Gramat. It can be implemented with a framework for GPS reception system. Finally, keeping the same experimental setup, a receiving system including state-of-the-art diode-based microwave power limiters will be tested. This experiment will effectively compare our innovative system to the dominant technology today. At the end of DIOMEDE project, partners will be in capacity to support industrial transfer in order to make available, either for other defense or critical civilian applications, high performance antennas and circuits hardened against electromagnetic interferences.