Investigation on EM Wave Absorbers by Using Resistive Film with Capacitive Reactance

Hiroshi KURIHARA  Toshifumi SAITO  Koji TAKIZAWA  Osamu HASHIMOTO  

Publication
IEICE TRANSACTIONS on Electronics   Vol.E88-C   No.11   pp.2156-2162
Publication Date: 2005/11/01
Online ISSN: 
DOI: 10.1093/ietele/e88-c.11.2156
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Electronic Materials
Keyword: 
EM wave absorber,  resistive film,  capacitive reactance,  impedance,  DSRC,  wireless LAN,  

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Summary: 
It is known that the thickness of the λ/4 type EM wave absorber having a resistive film with the capacitive reactance is thinner than 1/4 wavelength. This paper investigates EM wave absorbers using the resistive film with capacitive reactance. We introduced the impedance into the resistive film, and then clarified the relationship between the impedance and the matching thickness in the single layer EM wave absorber. Practically, we carried out to grasp the impedance of the resistive films, which were prepared using the conductive flake powder. As the results, we have proven that the matching thickness in the single layer EM wave absorber could be realized 0.17 λ-0.09 λ in the frequency range from 2 GHz to 8 GHz by using these resistive films. We also fabricated the single resistive layer and the double resistive layers EM wave absorber using these resistive films for Dedicated Short Range Communications (DSRC) and wireless Local Area Network (LAN), in which the matching thickness could be reduced to 45% and 30%, respectively, as compared with the each absorber using the non-capacitive reactance.