Lens antennas are a very attractive solution in space applications because they can provide high directivity beams. A specific type of Lense is called a ‘graded index lense’. This type of antenna is composed of periodic structures that have variable refractive indexes and can convert spherical waves into plane waves. Thus, we can focus the beam and steer it. As the aim is to integrate this antenna into the satellite we also need to make it more compact as well as provide multiple beams to cover multiple countries. In addition to the multiple beams that we need to provide we also need to achieve isoflux radiation pattern in the multibeam antenna. Practically, this type of pattern means that if we want to cover a country that is in the direct path of the satellite we need less gain than a country which is placed some angles from the satellite. Ideally, a 3D graded index Lens would be the best candidate for LEO and GEO satellites because we will be able to steer the beam in both E and H planes and thus cover multiple countries.
Well, I believe that some of these technical expressions might be tough to understand but when you begin to understand the meaning you can begin to be more interested in the space domain and the antennas. Talking to young students that are in high schools and in the universities, I would like to encourage them to become involved in space engineering and electromagnetics and my job will be to simplify the meanings. After that you will really the subject and be more passionate with it.