Estimating Electromagnetic Emissions from a Site Installation with Multiple Racks of Server Equipment

More than hundreds, sometimes even thousands, of servers operate simultaneously inside a data center. Their radiation can be a problem and cause electromagnetic interference (EMI) issues. However, it is not feasible to perform full-wave 3D simulation of these racks because of the large electrical size of the model. In this paper, an algorithm is proposed to predict the emission from rack arrays. The equivalent dipole source is extracted from EMI measurement data of a single rack and reconstructed as a radiation source in a multiple rack model. The racks in an array can be divided into a few categories and the racks in each category have similar radiation patterns. Thus only one modeling of a representative rack is needed for each category. In order to take rack to rack scattering into consideration, a simplified model for each category is developed and method of moments is used to describe the radiation of representative racks. After the radiation calculations from a representative rack in all the categories are completed, the total radiation from the data center is predicted based on these representative-rack calculations. This method is much faster than the brute-force simulation of the entire data center, and is highly scalable to handle arbitrary number of racks in the data center.

I. Introduction

Electromagnetic noise is an unintentional signal generated by hardware. It can interfere with other wireless communication signals, and affect the communication bandwidth due to the decreased signal to noise ratio (SNR). This electromagnetic interference (EMI) issue can be effectively controlled during the hardware design stage. However, when multiple identical hardware are located close to each other, how different radiated emissions from each hardware interact has not been investigated. The total emission from multiple hardware can increase or decrease depending on the phase. In modern data centers, hundreds to thousands of server racks are working simultaneously, and each of them emits electromagnetic noise. Thus, analyzing the interaction among multiple server racks and estimating their total electromagnetic emissions are critical for mitigating the EMI concern in the data center environment.