15:08 - It may be for nostalgic reasons to build a large horn antenna. However, they are not used anymore today because yagis or dish antennas are much more effective for the material required and they are readily available. A WIFI-yagi comes at about 20 US$ and will beat the horn hands down.
A wifi yagi has nowhere near the gain of a large horn like what was pictured, and only works properly at wifi frequencies. A horn is broadband and works on a large range of frequencies. A 2.4GHz yagi isn't going to have a good pattern at 1.42 GHz because yagis are not wide bandwidth antennas. A parabolic dish might be a better antenna if you can buy it with a feed for your frequency, but it is a lot harder to build than the simple horn shown.
@@stargazer7644 Sorry, my mistake, "A WIFI-yagi comes at about 20 US$ and will beat the horn hands down" is surely not correct. *But,* the typical DIY horns shown for 21cm reception have an aperture of only about 50 * 50 cm and could be easily equalled by a reasonalbly compact DIY yagi if you adapt a 23 cm design. As to a dish, they can be found from surplus in one way or another and the feed is not much different from the feed you need for a pyramidal horn.
Here is an excellent resource of beginner level radio astronomy videos The videos are from members of SARA : Society of Amateur Radio Astronomy www.youtube.com/@radio-astronomy/playlists Hydrogen Line Radio Telescopes ru-vid.com/group/PLCEbOD5_znsmOAz8fcIIF9JC-qogFntQN Regards, Alex KK4VB
