Measurement technique for electromagnetic field intensity distribution using infrared 2-D lock-in amplifier

We have been developing an electromagnetic field intensity measurement system using an absorption screen made of dielectric material. In this developed system, a very small change of temperature on an absorption screen illuminated by the electromagnetic wave is measured using an infrared camera with 2-D lock-in processing technique. An antenna is ordinary used for measurement of electromagnetic field. However, an antenna always disturbs the electromagnetic field as the measurement subject. Since the electromagnetic field as the measurement subject is less disturbed by the screen even if the screen is placed near the wave source, this system is suitable for the measurement of it near the wave source that is difficult to measure by using a common antenna for telecommunications. To show the effectiveness of this system, we tried to measure the electric field of around 2.45 GHz emitted from a dipole and a patch antenna. The theoretically numerical calculations for the electromagnetic field distribution around the antenna were also carried out. The calculated electric field distributions are in good agreement with the measured one.