| Author | Do Quang Minh |
| Call Number | AIT RSPR no.TC-97-8 |
| Subject(s) | Electromagnetic interference
|
| Note | A research study submitted in partial fulfillment of the requirements for the degree of Master of Engineering, School of Advanced Technologies |
| Publisher | Asian Institute of Technology |
| Series Statement | Research studies project report ; no. TC-97-8 |
| Abstract | According to the EMC Directive 891336/EEC, all the electronics devices, including
the telecommunication equipments, should .be tested for radiation and immunity before selling
them to the markets. Thus, Electro-Magnetic Compatibility (EMC) is a serious consideration
for every manufacturer. In order to take well controlled EMC measurements, EMC
measurement systems must be well designed and must be reliable and stable.
Reliability of the measurement system can be characterized by the prec1s1on and
repeatability of measurements. Two factors influence the repeatability of the measurement
system. The first is the testing procedure and configuration; and the second is the variation in
each adjustable parameter of the measurement. Repeatability of the measurement depends on
the variation in distance between Equipment Under Test (EUT) and receiving antenna, the
azimuth location of EUT, the antenna height, the antenna polarizations and direction. The
random error in EMI measurement depends on further error introduced by electrical thermal
noise from the coaxial cable and the EMC receiver. The cable thermal noise sets the limits on
the minimum measurable interference, and determines the sensitivity of the measurement
system.
In practical EMI measurement system, the set up for measurement is done one time
per measurement, so that repeatability due to setting up parameters of the system will be seen
as the systematic error. For each single measurement, the thermal noise is added to the
repeatability resulting in the total error. The total error of system can be reduced by averaging
over a number of measurements to reduce the random error. In order to achieve the required
precision for EMI measurements, the precision of angle and distanc'e manipulators, used in the
measurement system, must be specified. In addition to this, the level of thermal noise due to
coaxial cable must be calculated and finally the level of averaging also must be estimated.
Thus, in this research study the most significant sources of errors for repeatability of
EMI measurement system were identified by calculating the relative error caused by small
variation of each parameter (RX antenna height, elevation angle, azimuth angle and distance
between TX and RX antennas) from the point where the maximum received electric field was
observed. In addition, to achieve the required repeatability of the measurement system,
precision values (for setting up of the EMI measurement system) for each parameter were
calculated.
Then, in order to achieve the given system errors (composed of the error for
repeatability and the error due to the thermal noise), the required precision for thermal noise,
the required repeatability and level of averaging has been calculated.
Finally, based on these calculated data the iteration procedure for EMI measurement
system has been proposed. |
| Year | 1997 |
| Corresponding Series Added Entry | Asian Institute of Technology. Research studies project report ; no. TC-97-8 |
| Type | Research Study Project Report (RSPR) |
| School | School of Advanced Technologies (SAT) |
| Department | Department of Information and Communications Technologies (DICT) |
| Academic Program/FoS | Telecommunications (TC) |
| Chairperson(s) | Mohiuddin, Kazi |
| Examination Committee(s) | Sharma, A. B.;Erke, Tapio |
| Scholarship Donor(s) | SIDA-HRD, Sweden |
| Degree | Research Studies Project Report (M. Eng.) - Asian Institute of Technology, 1997 |