Parabolic reflector with wideband splashplate feed
Image of the Parabolic reflector with wideband splashplate feed.

The parabolic reflector with wideband splash-plate feed is a modified version of the splash-plate-fed reflector already in Antenna Magus.

The splash-plate feed uses backfire radiation to illuminate the dish, and the feeder waveguide as a support structure. This is a compact reflector topology with the feed positioned close to the main reflector requiring no additional support struts. Another advantage is that the feed antenna can be fed from behind the main reflector, reducing unwanted aperture blockage.

The splash-plate-fed reflector, with detail of the air-to-dielectric transition modification (left) and original (right).

By modifying the air-to-dielectric transition at the end of the waveguide feed section, as depicted on the right, improved wideband performance can be achieved. A comparison of the reflection response between these two topologies highlights the advantage of using a smooth tapered air-to-dielectric transition. Not only is it easier to manufacture, but the operating bandwidth is increased from 8% to 22%. The radiation pattern is unaffected by the modification to the transition.

Typical reflection coefficient vs frequency.
Typical normalised radiation pattern at the centre frequency.