Reactive-Field Anechoic Box for ESPAR Antenna Measurement

Qing HAN
Kyouichi IIGUSA
Takashi OHIRA

IEICE TRANSACTIONS on Electronics   Vol.E85-C    No.7    pp.1451-1459
Publication Date: 2002/07/01
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Electromagnetic Theory
reactive-field anechoic box,  backscattering characteristics,  radio wave absorber,  ESPAR antenna,  reactive near field,  

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Reactive near field reflection characteristics of commercial RF absorbers are investigated to determine the minimum size of a reactive-field anechoic box necessary for measuring the reactive near field of an ESPAR antenna. The reflectivity of the absorber placed in close proximity to an antenna is inversely proportional to the distance between the antenna and the absorber. For carbon filled urethane foam tapered absorbers, we find that the backscattered reflection characteristics mainly depend on their tapered height rather than the thickness of absorber base. As a result, we show that carbon filled urethane foam pyramidal and wave surface shaped absorbers can be used to make reactive-field anechoic boxes. A prototype of a reactive-field anechoic box is presented and the distance from the absorber to the antenna is reduced to a wavelength. The prototype is verified by comparing its performance with that obtained from a large anechoic chamber.