1、r - i, i, , coil radius): The product N I A is also called a Magnetic dipole moment M of the coil. Tranmonder radiated field The level of a radiated field from the transponder received by the interrogator is dependent on the following transponder parameters: physical size material properties distanc
2、es from the transmitter and the receiver antennas orientation in the field frequency The magnetic radiated field at distance d from the transponder can be calculated as: where Ve* is the effective volume of the transponder. V, can vary significantly between different technologies and is not identica
3、l to the real volume. For most applications the transponder is required to be as small as possible. This makes the radiated field very low and, due to the limited effective volume of a transponder, the field attenuation even in the dominant direction will be at least 100 dB at 1 m distance. In many
4、applications it is not possible to control the physical orientation of the transponder to be optimal. Therefore the orientation loss, the order of which is 6 - 8 dB, has to be taken into account in the system calculation. The ambient noise level The ambient noise is dependent on the location of the
5、equipment. Most equipment is used in commercial and industrial environments, where the ambient noise, especially below 135 kHz, is very high. The main noise sources are the harmonics of different electric equipment, for example switch mode power supplies, PCs and TV sets, fluorescent lights, electri
6、c distribution in general, etc. The noise level in an industrial environment, measured in a 1 kHz bandwith, varies STD-CEPT ERC REPORT 44-ENGL 3997 m i326434 0015627 357 9 ERC REPORT 44 Page 6 in the range 5 - 30 dBWm at 50 WZ. A typical level is 13 dBWm. The noise level falls at 3.5 the higher fiel
7、d strength level would be allowed in the bands: 9-70kH 119 - 135 Hz. To be able to cany out this proposal, the measuring receiver bandwidth for inductive equipment in I-ETS 300 330 is proposed to be changed from the current value of 9 kHz at 30 - 135 IrHz to 200 Hz in the whole band 9 - 135 k;Hz A d
8、ivision into subbands would not change the status of the primary radio services: inductive applications operate on a non-protected and non-interference basis. To avoid interference all suitable site-engineering means should be used by all parties involved. Note: In Germany the higher limit would only be. allowed in the bands: 57 - 67 WZ 119 - 127 kHz
