Tham khảo tài liệu 'radio frequency identification fundamentals and applications, bringing research to practice part 2', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Field Conditions of Interrogation Zone in Anticollision Radio Frequency Identification Systems with Inductive Coupling 13 Fig. 9. Orientation of tag which is deviated by a and p angles from components of magnetic induction vector a deviation in 3D coordinate x-y-z b deviation by a angle in z-x plane c deviation by p angle in a-y plane Next in second part by using of the superposition theorem after deviating tag by p angle the perpendicular magnetic induction component is given as follows Bap - Byp Bxzap 26 where the values of vector components are given by Byp - By sin p 27 Bxzap - Bxa cos p 28 It comes from the equations 23 - 28 that the perpendicular magnetic induction component for passive tag which is deviated by a and p angles is given by Bap - Bz cos a cos p Bx sin a cos p By sin p 29 Knowing the magnetic induction separately for individual components in directions x y and z Bx By Bz the obtained equation 29 permits calculation of the perpendicular magnetic induction component. The aforementioned necessity of changing tag orientation should be carried out for assurance of correct tag work in the individual space point P x y z . In this way there is possible to calculate the system interrogation zone which is forced by specification of identified object what results from the necessity of individual tag location on marked object. Changes of the interrogation zone for single tag with minimal value of magnetic induction have been presented as examples in Fig. 10-c d calculated results and Fig. 10-b measured results . The black colour represents no communication area between tag and RWD. The area results from no fulfil condition of minimal magnetic induction Brnm for the tag and its location in relation to perpendicular magnetic induction component. Above mentioned parallel location of tag and RWD antenna loops causes appearance of symmetrical interrogation zone and lack of communication area in relation to symmetry axis 14 Radio Frequency Identification .
