Brian May's New Horizons video (below) was released at about the same time that the New Horizons spacecraft passed 2014 MU69 Ultima Thule and includes a lot of technically meaningful graphics.
One item is the illustrating of downlink and uplink of data, shown as a narrow blue beam and wide green beam, respectively.
This answer to Function and nature of the RHC/LCH pair of cables to New Horizons's dish antenna secondary mirror? shows that the backside of the secondary mirror of the high gain antenna also has a small primary dish forming the medium gain antenna.
- Is it accurate that even out at Pluto and MU69 that New Horizons is using mostly its medium gain antenna for transmission, rather than its high gain antenna?
- If so, why? Returning the Pluto/Charon data took months, and it will be quite a while for MU69 data as well. Why not shorten it up and use the high gain antenna?
Downlink animation GIF (via New Horizons' medium gain antenna) from video
Uplink animation GIF (via New Horizons' high gain antenna) from video
Source: Spaceflight 101's New Horizons Spacecraft Overview borrowed from Function and nature of the RHC/LCH pair of cables to New Horizons's dish antenna secondary mirror? Images of dishes available in this answer.