Measurements in an Anechoic Chamber for DRA Antennas, EMI and EMC

Internet on things and 5G are the current trends in data and voice communication domain. Wireless communications require faster bit rates transfer. The antenna is considered as an integral part of all wireless communication has to keep pace with current communication requirements. Qualification of the antenna needs accurate measurements for its validation. Anechoic chambers help to provide accurate measurements for the radiation patterns of the antenna system. These radiations are a function of frequency, angle, and polarization. An anechoic chamber is a shielded room, which is reflections less or echoes free indoor environment. These chambers are classified as EMI/EMC/ESD (electromagnetic interference / electromagnetic compatibility / electrostatic discharge) measurements and antenna radiation measurements. EMI/EMC/ESD measurements belong to low-frequency tests and antenna measurements are high-frequency tests. The figure of merit of an anechoic chamber is defined in terms of reflectivity and quiet zone inside the chamber. Researchers have felt the need for the large volume of a quiet zone and low reflectivity in dB inside the anechoic chamber. The proposed work has emphasized on optimization of these two parameters i.e. reflectivity and quiet zone. A new class of structure by making use of multi-dielectric cone by housing frustums of reducing size one on each other. These hollow frustums are placed on pyramid absorber. The ray falling on any part cloaks to top of the absorber. Thus reflections are minimized. The proposed design has been verified by HFSS simulation. Results of improved reflectivity and quiet zone volume are presented. These new class of absorbers may become the backbone to anechoic chambers for reduced reflections.