Design_of_an_X-band_dual_circularly_polarized_offset_reflect(3)

of feed antenna. The parabolic reflector is described by the diameter D which is objected circular aperture, focal length F, offset height H and the edge angle θ.

Figure2. The schematic drawing of the horn feed

This offset configuration eliminate the block of the horn feed and reduce the side lobe generated by the block and improve the VSWR of the whole antenna. Furthermore, the axial symmetry of the feed makes it suitable for any polarization.

3 Results and discussion

3.1 Horn feed performance

Figure 4 and 5 show the symmetrical normalized radiation pattern at 8GHz without any obvious side lobes which are suitable for the feed of the reflector antennas.

Figure3. The axial ratio of horn feed at 8GHz Figure4. The normalized radiation pattern

of horn feed at 8GHz

3.2 Reflector performance