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

Abstract

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).

Measurement of the Amplitude and Polarization of the Electric Field by Electromagnetic Infrared Thermography

“…This technique allows visualizing EM maps, on a large 2-D scale (thin films of 1 m 2 have been used). This method can be used for antenna radiation pattern [2], [3] measurement, or field leakage detection and in general, to rapidly obtain EM field characterization. However, using homogeneous and isotropic thin films only allows getting the (square of) amplitude of the field.…”

Using infrared imaging for surface dosimetric measurements during microwaves exposures

“…Another application type was provided in [9], where an antenna operating at 2.45GHz acted as an electromagnetic wave source and an IR camera offered images of the temperature distribution on an absorption screen situated at different distances from the antenna. The authors of [10] used the IR method to obtain a complete characterization of the near field structure (from 0.8 to 2.3GHz) of an antenna, and they proved that the method provided accurate and replicable radiation signatures.…”

High-Resolution Technique for Near-Field Power Density Measurement Accounting for Antenna/Body Coupling at Millimeter Waves

“…In [11], the IR thermography was employed to measure PD and specific absorption rate induced on the surface of a skin-equivalent model by an off-body patch antenna array [12], [13]. A methodology for measurement of the electric field using an absorption screen made of carbonloaded polymers and an IR camera was discussed in [14] for a patch antenna at 2.45 GHz, in [15] for a Ku-band horn antenna at 12-16 GHz, and in [16]- [18] for defects detection at microwaves.…”