Summary Radar Antennas
- A radar antenna is a microwave system, that radiates or receives energy in the form
of electromagnetic waves.
- Reciprocyty of radar antennas means that the various properties of the antenna apply
equally to transmitting and receiving.
- Parabolic reflectors („dishes”) and phased arrays are the two basic
constructions of radar antennas.
- Antennas fall into two general classes, omni-directional and directional.
- Omnidirectional antennas radiate rf energy in all directions simultaneously.
- Directional antennas radiate rf energy in patterns of lobes or beams that extend
outward from the antenna in one direction for a given antenna position.
- Radiation patterns can be plotted on a rectangular- or polar-coordinate graph.
These patterns are a measurement of the energy leaving an antenna.
- An isotropic radiator radiates energy equally in all directions.
- An anisotropic radiator radiates energy directionally.
- The main lobe is the boresight direction of the radiation pattern.
- Side lobes
and the back lobe are unwanted areas of the radiation pattern.