Design of a pyramidal horn antenna Operating at 325-500GHz

In this paper, a pyramidal horn antenna operating in the $325-500 \mathrm{GHz}$ band is designed. Firstly, the geometric structure of the pyramidal horn antenna is simulated and optimized and the standing wave ratio of the pyramidal horn antenna in the working band is less than 1.1. The gain is greater than 24dBi and the side lobe level is less than $-10 \mathrm{~dB}$. In the process of simulation design, we also found that the aperture size ratio of the pyramidal horn antenna can change the equalization effect, and the equalization effect is better when it is about 1.33. Based on this, a complex permittivity constant test system of the free space method is built.