/ænˈtɛnə/
noun … “Device that converts electrical signals to radio waves and back.”
Antenna is a transducer used in radio and wireless communication systems to convert electrical signals into electromagnetic waves for transmission, or to receive electromagnetic waves and convert them back into electrical signals. It serves as the critical interface between a Radio transmitter or receiver and free space, enabling communication without physical conductors.
Key characteristics of Antenna include:
- Resonant frequency: the frequency or range of frequencies at which the antenna efficiently radiates or receives energy.
- Radiation pattern: the spatial distribution of radiated power, often visualized as directional or omnidirectional lobes.
- Gain: a measure of how effectively the antenna directs energy compared to a reference isotropic radiator.
- Impedance matching: ensures maximum power transfer between the antenna and the transmitter or receiver circuitry.
- Polarization: orientation of the electric field vector, affecting compatibility with other antennas and signal propagation.
Workflow example: In a cellular base station, a transmitter outputs an electrical signal encoding voice or data. The antenna converts this signal into radio waves that propagate through the environment. A mobile device with a compatible antenna captures a portion of this energy, converts it back into an electrical signal, and decodes the information. System designers carefully select antenna type, orientation, and placement to maximize coverage, reduce interference, and optimize link reliability.
-- Example: simple dipole antenna parameters
frequency = 2.4e9 -- 2.4 GHz
wavelength = 3e8 / frequency
length = wavelength / 2 -- half-wave dipole
gain = 2.15 -- dBi for standard dipole
print("Antenna length: " + str(length) + " meters, Gain: " + str(gain))Conceptually, an antenna is like the mouth and ears of a communication system: it speaks by radiating energy into space and listens by capturing faint signals, translating between the language of electrons and the language of waves.
See Radio, Modulation, Signal-to-Noise Ratio, Wavelength, Gain.