No.4（2001）10.A non-directional EMI probe with three antenna elements

Masuo YAMADA and Manabu OHMORI

The extraneous emission from electric product is one of the most difficult problems. Generally, the noise measurement is very complicated, and a simple method is needed. From this background, the EMI(ElectroMagnetic Interference) probe has appeared for more easy examination of extraneous emissions. The EMI probe can examine where the emissions come from. Considering the noise measurement method, the way of bringing an EMI probe close to the noise source is very important, since the EMI probe has directivity. The EMI probe directivity may cause measurement errors. To solve this problem, we developed a non-directional small-sized antenna. This new antenna has three loop-antennas assembled at right angles to each other, and this anntenna has a bulun to control the VSWR(Voltage Standing Wave Ratio) in the wide frequency range. This antenna can be used to find extraneous emissions from electric products. Also this antenna is more useful than the traditional EMI probe.

Keywords
Small-sized antenna, EMC, EMI, Extraneous emission, EMI probe

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