Performance Improvement of Conical Horn by using Inserted Metallic Sphere

It has recently been shown that the insertion of a single metallic disc inside the smooth wall conical horn (SWCH) improves its gain by about 3 dB and results in better radiation pattern symmetry. This configuration, however, worsens the return loss. The insertion of three discs, as also shown in the same work, improves the return loss but reduces the gain enhancement level and also results in higher side lobe levels compared to the single disc insertion. It is shown in this paper, using extensive simulation studies on a iif-band conical horn, that the insertion of a single metal sphere inside the SWCH offers all the advantages individually provided by the single-disc and three-discs insertions: improved return loss, gain and radiation pattern.