Modelling manufacturing tolerances in 1–18 GHz double-ridged horn antennas

The effect of small gaps in the feeding section of a 1–18 GHz broadband double-ridged horn antenna is investigated. It is shown how poor design, assembly or manufacturing tolerances can lead to a dramatic loss in the performance of this type of horn antenna. The gaps are implemented in a highly accurate broadband simulation model of the antenna that includes the coaxial feeding section as well as the N-type connector. The model is implemented in the electromagnetic simulation software package FEKO, which uses the method of moments technique to calculate the electromagnetic fields. Excellent agreement between measured and simulated data is obtained. This study shows the extreme sensitivity of the traditional 1–18 GHz horn's feeding structure.