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Microwave Defect Detector Ya. M. Kempa, Ya. M. Rybak

Abstract - The paper presents the results of design maaufacture and research into the microwave detector for detecting the tube corrosion under an optically opague coating and protective coating separation. The detector operates in the 5” wave band.

Keywords - microwave defect detector, SHF sensor, multi-layer fiberglass plastic.

1. INTRODUCTION The current and periodic quality control of multilayer composite

structures and paint coatings is of primary importanse in manufacturing and using of multilayer composite structures and paint coatings.

Using theoretical and experimental experience from earlier investigations, the autothors developed a nondestructive quality control technique for adhesion and paint coatings applying probing of tested materials by a microwave elecromagnetic field 113. The criterion of the difference of defective and nondefective materials is the difference of a reflective wave amplitude and microwave signal delay due to loss in adhesion on certain areas of paint coatings and difference in effective dielectric coefficients between adhered and nonadhered areas of the composite material.

II. DESIGN SUMMARY The quality control technique for the composite material adhesion

and paint coating adhesion is based on comparison of the reflective wave amplitude. and phase in defective and known nondefective materials.

Functional diagram of the meter is shown in Fig. 1. The microwave signal fkeguency and phase are variable

parameters.

w1 w2

YaM. Kempa - Lviv Radio Engineering Research Institute, Naukova Str.,7, Lviv, 79060, UKRAINE YaN. Rybak - Lviv Polytechnic National University,S. Bandery Str.,l2, Lviv,79046, UURAINE E-mail: eIvit@oolvnet.lviv.u~

It should be noted that c.e microwave signal phase adjustment to the characteristic linear section with each freguency step is carried out in the reference channel to increase the probability of proper defect detection when calibrating the device.

The experience showed that in material probing in a 5-mm wave band quasi-resonance phe:nomena are detected in many points of the band that are used to increase the efficiency of the defective material sorting out.

111. THE RESULTS OF RESEARCH The measurements are made in 200 measurement

points in a range of 53-61 GHz. Initially, the detector was calibrated in a

predetermined defectless section. The measurements showed that a minimum diameter of the detected detect is 5-8 mm with an antenna hom diameter of 60 mm. Fig. 2 shows the microwave detector sensor (without a cover).

Fig. 2 - Microwave detector sensor

IV. CONCLUSIONS The developed 5-mm wave band meter may be

applied for the process and periodic control of composite material separation and paint coating adhesion quality.

REFERENCES [ I ] N.A. Naumets, Ya.M. Kempa, Ya.N. Rybak, G.V.

Tsukomyk,” SHF defect detector ”, 2 ’ International Conference “AVIA-2000”, pp.23 1- 233,2-6 Oct. 2000, KMUGA, Kiev, Ukraine

TCSET’2002, February 18-23,2002, Lviv - Slavsko, Ukraine