Imaging electric and magnetic near field of radiating structures by infrared thermography

The characterization and visualization of the radiated electromagnetic field is a way to diagnose and check microwaves sources, in particular in the space industry. Beyond the traditional 3D scanning of the radiating element, infrared thermography is an alternative way that may give key results in a reduced time, since a few seconds are sufficient to obtain the emitted field map even for a complex multi-cells antenna. This method, called EMIR (ElectroMagnetic InfraRed) has been developed and used for years at ONERA. We have recently extended this technique to the magnetic field, which will lead to a complete characterization of the near field structure. We illustrate this feature in the particular cases of antennas for space application and for a High Impedance Surface (HIS), a metamaterial structure that could be used to reduce the coupling between antennas confined in compact structures (typically size constraints of the spatial components).