Comms remain stable even after going over horizon

[m_spaceman]

Is this a normal or a possible bug? Even after I go well past the horizon of Kerbin and even Duna, the communication link remains completely normal. Is this mimicking ionosphere bounce or something...?

[Vanamonde]

Signal blockage is a difficulty setting in the game options. I don't remember whether it defaults to on or off, but you could check your settings and see which you have selected. 

[Robin Patenall]

It's normal.

Somewhere in the settings, there are commnet occlusion modifier settings that sets the size of the commnet occluder based on the planet/moon size. By default the settings allow the commnet links to pass through the edge of the planets/moons slightly as you've noticed. You can change the settings (one for bodies with atmosphere, one for bodies without)  to 1.00/100% if you want to stop this happening.

[jimmymcgoochie]

There are separate signal occlusion settings in the difficulty options, atmospheric and vacuum bodies. Atmospheres can bounce signals slightly so the atmospheric one defaults to being set slightly lower. A value below 1 can lead to signals travelling through the visible terrain.