Search for electromagnetic wave sources using the maximum entropy method

Abstract

Undesirable electromagnetic waves radiated from various electrical and electronic apparatus recently have become social problems. Research to prevent these effects is in progress in various fields. This paper presents a method of determining the location of electromagnetic wave sources two‐dimensionally. The analysis method is based on the deduction of the power spectrum by applying the maximum entropy method to time‐series information, i.e., the location of electromagnetic‐wave sources in two‐dimension, corresponds to the power spectrum. It is confirmed by computer simulation that the location can be determined with very high accuracy. The relationship between the amount of data measured and the accuracy of location determination, and the relationship between the accuracy of a source‐location detection and the offset of the measuring position, were examined. The number of measurements was found to be almost twice the number of electromagnetic sources, and the detection of the location of a source can have a very high resolution if the measuring position is kept at a high accuracy. The results show that this method is very effective in determining the position of sources, for example, radiated from a system consisting of subsystems.

Localization of low-frequency electromagnetic sources

“…Previously, for rather high frequencies (above several hundred megahertz), there has been research on localizing the unwanted electromagnetic wave sources existing rather close to the observation point by the synthetic aperture method [1] and the maximum entropy method [2] with electric field antenna arrays. Also, visualization of the wave sources by means of electromagnetic holography [3] and current estimation by a CISPR measurement system [4] have been attempted, as well as position estimation of high-frequency sources at a finite distance with the MUSIC method [5][6][7][8][9].…”

Electromagnetic-wave visualization for EMI using a new holographic method

“…To detect far wave sources, there are various methods designed to realize high resolution, such as the high spectral resolution algorithms [4] using the maximum-likelihood method (MLM), the maximum entropy method (MEM), multiple signal classification (MUSIC), and improved estimation of signal parameters via rotational invariance techniques (ESPRIT) [5]. The application of the MEM algorithm to near wave sources is also reported [2,6].…”