Summary
International Symposium on Antennas and Propagation
2010
Session Number:2WD1
Session:
Number:2WD1-2
MAGNETIC PROBE WITH EXTENDED GROUND PLANE FOR EMC MEASUREMENT
Shun-Yun Lin, Chin-Yen Li, Shang-Kuei Yen, Pao-Hsia Cheng,
pp.-
Publication Date:2010/11/23
Online ISSN:2188-5079
Summary:
Nowadays, increasing functionalities of high speed digital circuitry and rapid development of wireless devices in a limited space introduce numerous design and fabrication issues. These neighboring circuitry modules sometimes cause electromagnetic interference in self equipment or excessive electromagnetic radiation to generate electromagnetic interference (EMI) problems [1]. The knowledge of the electromagnetic environment of circuitry is therefore essential and the use of near-field techniques in EMC applications increases rapidly.With a map of electromagnetic field intensity on the circuitry [2-3], one can find the whole field intensity distribution and find out the corresponding noise source. To predict far-field emission level or to position the source of electromagnetic noise, magnetic near-field measurement by a loop probe is a promising method . According to measuring requirements, considerations of broad operating bandwidth, high spatial resolution, and large isolation between sensed electrical field and magnetic field for the magnetic probe are respect. In ref. [4], a set of quasi-periodic notches was embedded into the connecting portion of a loop. The embedded notches, acted as a microstrip filter, effectively suppress the inherent resonances of the circular loop to up the usable frequency to 9 GHz. A stripline magnetic near-field probe for high frequency band up to 10 GHz achieved an improved spatial resolution [5]. The smaller sensor causes higher operation frequency and degraded sensing zone. However, three layer structure with 1 mm2 dimension is seemly an uneasy fabrication. A shielded magnetic loop using CMOS?silicon-on-insulator (SOI) micro-fabricated technology obtains a further-miniature and high spatial-resolution function [6]. However, the sensing sensitivity is degraded because of the tiny IC scale. In addition, a rectangular magnetic field probe with air-bridge, which effectively suppresses resonance between probe and ground plane [7], was proposed to gauge much higher frequency region than conventional magnetic probe. In this paper, we propose a magnetic field probe with a circular loop. In addition, an extended ground plane is used to effectively suppress self-resonance of the magnetic loop. It ups the usable frequency to larger than 9 GHz. Moreover, the extended ground plane acts as a reflector of E-field. The feature introduces a 20 dB isolation between sensed electrical and magnetic field.