Efficient Methods of Measuring Shielding Effectiveness of Electrically Large Enclosures Using Nested Reverberation Chambers With Only Two Antennas

Measuring the shielding effectiveness (SE) of physically small but electrically large enclosures is an important concern in electronics industry. In recent years, reverberation chambers (RCs) are becoming prevalent in determining the SE of such enclosures. Conventionally, frequency-domain (FD) measurement is adopted. It requires three antennas (one transmitting antenna and one receiving antenna in the large RC and one receiving antenna in the nested small enclosure). Furthermore, to obtain good accuracy, the knowledge of the efficiency of the two receiving antennas is also required. To promote the industrial application of RCs for SE measurement, simplified methods are desired. In this paper, simplified measurement methods are proposed and studied both in the FD and the time domain (TD). Only two antennas are required in the proposed methods. Thus, the measurement setup is greatly simplified. It is found that in the TD, a fast and accurate measurement method can be realized with the simplified measurement setup. Moreover, the measurement simplification can go a step further by replacing the RC with an electrically large metallic enclosure in the TD. The measurement results demonstrate that the TD approach outperforms the FD approach in many ways. The proposed methods have the merits of high efficiency, good accuracy, and simple measurement setups. They are very suitable for SE measurement of electrically large enclosures.

I. Introduction

Electromagnetic shielding has become a significant issue due to the proliferation of electronic devices in the world. Shielding enclosures are used to either protect or control immunity and/or emission of electronic devices for many applications. The shielding effectiveness (SE) is an important figure of merit to characterize the electromagnetic isolation performance of the enclosures.