Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 1 Design, Manufacture, Transport and Integration on-site in Chile of ALMA Antennas EMC ANALYSIS PM#05, June 2006 PM#05, June 2006

Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 2 CONDUCTED AND RADIATED EMC ANALYSIS The scope of these analyses is to evaluate conducted and radiated margins in ALMA design. According to ALMA Technical Specification and ALMA System EMC Requirements the IEC EMC standards (the entire series) and the EN (CISPR 11 and 22) standards are applicable to all equipment and sub-systems. In the following slides it is demonstrated, by means of two similar analyses, as consistency to these standards is enough to guarantee a sufficient margin between emission and susceptibility (for conducted and radiated events). The approach consists in considering a certain number of emitting units and checking if the total background noise can disturb another unit in its operative function. The configurations assumed in the analyses are always a worst case respect to ALMA one.

Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 3 CONDUCTED MARGIN Emission Limit The applicable standards are : CISPR 22 – “Information Technology equipment – Radio Disturbance Characteristics” CISPR 11 – “Industrial, Scientific and Medical (ISM) Radio-Frequency Equipment – Radio Disturbance Characteristics ” IEC – “Emission Standard for Industrial Environments” Normally a quasi-peak detector detects lower values than a peak-detector. In our analysis the quasi-peak levels are considered as peak levels. A “quasi-peak” detector presents an output value very similar to a peak detector if are present only disturbances with rapid time fluctuation and for a short periods (i.e. random noise).

Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 4 Immunity Limit The analyzed standards are: IEC – “Immunity to Conducted Disturbances Induced by Radio-Frequency Fields” standard can be applied. Standard limits are reported hereafter : In the analysis a pessimistic electric field of 3V (130dBuV) un-modulated is considered as immunity limit. Conducted EMC Model The EMC model considers 30 emitting units (emitting simultaneously in the same power line) and the produced total noise is the sum of each single contribution (without considering difference of phase – Worst Case Situation). The aim is to verify if the margin is enough to guarantee the system compatibility. A minimum margin of 12dB (factor 4) is usually required at system level. Environmental Phenomenon Test Specification Radio Frequency Continuous Conducted Frequency Range0.15  80MHz Applicable Signal (un-modulated)3Volt 80% amplitude modulated signal with 1kHz sine wave.

Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 5 RESULTS The green curve (with black square) is the conducted emission limit while the blue curve is the conducted immunity limit. Both are imposed by examined standard. In purple (with black star) is reported the estimated conducted noise of N=30 radiating units on the same cable. The margin is greater of 30dB and it is enough to guarantee the compatibility at system level for conducted disturbances.

Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 6 RADIATED MARGIN Radiated Emission The used standards are : CISPR 22 – “Information Technology equipment – Radio Disturbance Characteristics” CISPR 11 – “Industrial, Scientific and Medical (ISM) Radio-Frequency Equipment – Radio Disturbance Characteristics” According to both standards the radiated emission, measured at a distance of 10 meter, shall be:. Radiated Susceptibility As susceptibility limits are used the following standard: IEC – “Radiated, Radio-Frequency, Electromagnetic Field Immunity Test” Frequency Range [MHz] Quasi Peak Limits [dB(μV/m)] Environmental Phenomenon Test Specification Radio-frequency Electromagnetic field Frequency Range 80  1000MHz Applicable Signal (un-modulated) 10V/m 80% amplitude modulated signal with 1kHz sine wave.

Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 7 Radiated EMC Model An equipment / sub-system is compliant with the standard when it radiates an electric field lower than Standard limits at a distance of 10meter. If the radiating unit is placed at a lower distance, an increased electric field is present. In this analysis care is given to evaluate this E-field increment. Talking about a radiated field it is important to consider far and near field contribution. The distance at which both contribution are equal is /6. Normally when the distance from radiating point is greater than 3, only far field contribution is considered. In our analysis the following criteria was considered: If a radiating unit is placed at a distance greater than 3, only its far field contribution is considered; If a radiating unit is placed at a distance between 3 to /2 the near field contribution is considered. The Standard considers as maximum frequency f=1GHz, which, in free space, has the wavelength of =30cm. This means that 3 =90cm is the limit beyond which the contribution is only far field. In our analysis are considered 25 radiating units at a distance of 90cm and 10 radiating units placed at a distance of 15 cm from victim equipment. It is important to highlight that this situation is worst case respect to ALMA project because: The total electric field don’t consider difference of phase The number of total radiating units (N=25+10=35) are higher than the real situation.

Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 8 RESULTS In figure is reported: The CISPR 22 radiated emission limit (green curve + squares). The purple curve +black stars is the total radiating contribution (N=25 units with L=90 cm and M=10 units with L=15 cm). The blue curve is the susceptibility curve reported by IEC standard. In figure is reported the margin that is obtained with this analysis. It is greater than 12dB and this if enough to validate that no EMC problems are foreseen at system level if each equipment follows the standard limits.

Reproduction interdite © ALMA EUROPEAN CONSORTIUM Reproduction forbidden Design, Manufacture, Transport and Integration in Chile of ALMA Antennas Page 9 CONCLUSION These brief analyses show that in ALMA project there is sufficient margin between emission and susceptibility limits both for radiated and conducted phenomena. These analyses are general and not focused on a specific equipment and are considering a worst case situation. Nevertheless it is important to highlight that possible non conformances with respect to the applicable Standards are to be highlighted as soon as possible. At this stage of the project is still relatively simple foreseeing some EMC recovery devices (i.e. filtering, shielding, etc.) to guarantee the system level compatibility