Development of Folded Rhombic Antenna without Balun for Microwave Frequency Range

As a broadband antenna, we are now researching and developing a new-type antenna not only for using electromagnetic interference (EMI) measurements but also radiofrequency (RF) immunity tests including a radiator for transient immunity tests. In our previous studies, the complex antenna factors (CAF) and actual gains of the prototype antennas were measured by the 3-antenna method. However, there were periodic fluctuations of these characteristics due to the mismatch between the balun and the antenna feed point. In this paper, these characteristics of an improved folded-rhombic antenna without balun are reported.