Dipole and Reflector
A single driven element plus one parasitic element, a parasitic element being one that is not attached to the lead in wire. The driven element could be a single dipole, a folded dipole, a conical or one of a few other variations.
The addition of the parasite called a reflector, makes the antenna higher in gain and more directional. The reflector sits broadside behind the dipole as they look at the transmitter.
The pattern is narrowed and rear entrance pickup is reduced drastically. For all practical purposes you can consider the reflector like a mirror. It bounces back signal to the dipole and bounces off any signal trying to come in the rear entrance. The best reception is obtained by carefully aiming the antenna’s front door, the dipole, at the transmitters.