(1) For the chemical element, see
isotope.
(2) The properties of a material that are the same in all directions. For example, an isotropic antenna radiates the same power in all directions. In practice, antennas cannot be 100% isotropic. However, a perfect isotropic antenna, called an "isotropic radiator," can be calculated, and it is used as a basis for measuring the signal strength of real antennas. Contrast with
anisotropic. See
dBi.