24 GHz feed

Up
 

For home satellite TV reception small offset dish antenna's are very often in use. The diameter of the antenna's are also very good for usage as antenna for 24 GHz. The offset reflectors are mostly releative cheap and are still good enough for amateur use on 24 GHz. Here you see a feed horn design which was made by PA3BPC which is ideal with an offset dish with an f/d of arround 0.6. The opening angle at -10 dB points is between 83°and 90°.

Feed.jpg (37976 bytes)

When using the feed its Phocal point is 2 mm from the front of the feed. In combination with an adaptor from rectangular to round waveguide this can be a very good feeder.

When using an offset dish care must be taken to aim the dish at the horizon. Comparing to a normal dish it seemes like the offset dish is looking into the ground.

In front of the feeder a piece of teflon must be made to prevent rain falling into the feed. The feed is aiming upwards and rain can easily fall into the feeder. Also attention must be taken on birds who are curious on what is under the teflon shield. It happened that birds picked into the shield and making a hole in it. After some time the station was not working anymore because the rain fallen into the waveguide.