- device converting electric signals to electromagnetic (radio) waves and back
- transmitting antenna: accelerates electrons, radiating energy into space
- receiving antenna: electromagnetic waves induce current in conductor
- types: dipole, monopole, parabolic dish, phased array, patch, loop, Yagi-Uda
- parameters: gain, bandwidth, radiation pattern, polarization, impedance
- parabolic dish focuses signals for telescope and satellite communication
- phased array steers beam electronically using semiconductor control
- communication infrastructure: radio, television, cellular, Wi-Fi, deep space
- energy harvesting antennas (rectennas) convert ambient RF to DC power
- meshes of antennas form the physical layer of cyberia network connectivity