3. Antenna with focusing system

3.1 Definition

The two typical focusing systems are the transmission-focusing lens (figure 43 ) and the reflection-focusing paraboloid (figure 44 ). Focusing means transforming a plane wave into a spherical wave centered on a point: the focal point.

• Paths such as F - M ₀ - A ₀ and F - M _i - A _i are electrically equal in the lens (figure