Measurement of Radiation Patterns for Ultra-Broadband Folded Long-Hexagon Antenna

In EMI measurements, measuring antennas are needed to be changed according to the frequency bands. Antenna replacement is a factor that increases the time and effort required for measuring and leads to higher measurement costs. Therefore, aiming to perform EMI measurements over the entire frequency band with a single antenna, a folded long-hexagon antenna (FLHA) had been designed and developed in the previous study. The characteristics of the developed antenna, including absolute antenna gain, were measured in the previous study and the usable frequency of the antenna was shown to be from 400 MHz to 40 GHz. However, to determine whether this antenna can be used for EMI measurements, the radiation patterns have also to be evaluated over the entire frequency band. This paper presents a measurement result of the radiation patterns of the developed antenna and discusses its suitability for EMI measurements.