High Speed System for Measuring Electromagnetic Field Distribution

Masanori TAKAHASHI
Eiji SUZUKI
Satoru ARAKAWA
Hiroyasu OTA
Ken Ichi ARAI
Risaburo SATO

Publication
IEICE TRANSACTIONS on Communications   Vol.E89-B    No.10    pp.2905-2912
Publication Date: 2006/10/01
Online ISSN: 1745-1345
DOI: 10.1093/ietcom/e89-b.10.2905
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Electromagnetic Compatibility(EMC)
Keyword: 
electro-optic crystal,  electromagnetic near-field,  galvano scanner,  

Full Text: PDF(1.5MB)>>
Buy this Article


Summary: 
An optically scanning electromagnetic field probe system consisting of an electro-optic or magneto-optic crystal and a galvano scanner is proposed for high-speed electromagnetic field distribution measurements. We used this technique to measure electromagnetic field distributions near printed circuit boards or ICs to address electromagnetic compatibility problems or in designing electronic devices. With our scanning system, we can measure the electric field intensities of about 40,000 points with an area of 4040 mm in about 3 minutes (4 ms per point) up to 2.7 GHz. We measured the electric near-field distribution above a five-split transmission line using a cadmium telluride (CdTe) electro-optic crystal. The measurement results showed that the spatial resolution of the system was less than 400 µm in the case of a common current with a crystal thickness of 1 mm. The electric near-field distribution above a microstrip line filter was measured using LiNbO3 electro-optic crystal. Changes in the distribution according to the frequency were observed. The experimental results obtained using this system were compared with simulation results obtained using a finite-difference time-domain method. The overall results indicated that the measurement system is capable of accurately measuring electric near-fields. We also discuss the invasiveness of the measurement system, due to the electro-optic crystals, in terms of both the experimental and simulated results.