Antenna Range Illuminator Based on a Septum Polarizer and a Dual-Mode Horn [Measurements Corner]

In this article, an original design of a range illuminator based on a stepped-septum polarizer and a dual-mode horn is discussed. However, the designed polarizer can also be used with other waveguide antennas, such as pyramidal horns and corrugated horns. A simple procedure for determining the initial septum geometry for the subsequent optimization is described, and based on this, a two-step septum polarizer is developed. A carefully designed dual-mode horn antenna with a rectangular aperture is then utilized to increase the illuminator's gain and suppress sidelobe levels. Results of full-wave electromagnetic simulations are presented and compared to experimentally measured data with good agreement.