Reflector antennas are devices that reflects electromagnetic waves. They focus a beam signal into one point (called focal point) or directs a radiating signal into a beam. They are used when high gain (more than 30dBi is common) is required, typically for earth to space communication or microwave point-to-point links.

For theory see:

Orphanids, S: Electromagnetic Waves and Antennas, 2004-10, chapter 14:
Kraus, J.D., Marhefka, R.J.: Antennas for all applications, Mc Graw Hill 2003, chapter: Slot, Patch and Horn antennas (9)

Simulations - Cassegrain reflector:

 Jabs Cassegrain reflector antenna, surface current distribution.
 Eabs_z_cut  Cassegrain reflector antenna, electric field (absolute value) at the cut.
parabola_ozarovac_ok_EyXZ Cassegrain reflector antenna, electric field animation at the cut.
 parabola_ozarovac_FF 3D radiation pattern of the Cassegrain antenna.

Simulations - Offset reflector:

 offset_Efield Offset reflector antenna, distribution of the electric field at the surface.
 offset_Jabs  Offset reflector antenna, distribution of the surface electric current.
 offset_farfield  Offset reflector antenna, radiation pattern.
 offset_parabol_Currents_time  Offset reflector antenna, animation of the electric current.
 offset_parabol_Efield_time  Offset reflector antenna, animation of the electric field. Note the main physical effect of the reflector: transformation of the spherical waves emanating from the horn to "plane" waves.