antennens

Antennas, or antennae, are transducers that convert electrical signals into electromagnetic waves for transmission and, conversely, convert incoming waves back into electrical signals for reception. The form "antennens" is not standard in English; common plurals are antennas or antennae. They are used in radio, television, radar, mobile networks, Wi‑Fi, satellite communication, and many sensing systems.

Operation depends on wavelength, so size and shape are chosen to resonate near the target frequency. Impedance is typically matched to the feed line to maximize power transfer and minimize reflections. Antennas can be broadly categorized by their structure: wire antennas (such as dipoles and monopoles), aperture antennas (including parabolic reflectors and horn antennas), and microstrip or patch antennas for compact, surface-mounted applications. Antenna arrays combine multiple elements to steer beams and increase gain without moving the physical structure.

Key characteristics include the radiation pattern (omnidir ectional or directional), polarization (linear, circular, or elliptical), gain, bandwidth, efficiency, and input impedance. Practical design also considers environmental factors, nearby objects, and regulatory constraints on emissions and antenna height. Impedance matching networks, feed lines, and mounting arrangements affect performance and SWR (standing wave ratio).

History and impact: early experiments by Hertz demonstrated radiating and receiving antennas, and subsequent work by Marconi, Tesla, and others shaped modern antenna theory and a range of designs such as Yagi, loop, and patch antennas. Today, antennas are central to wireless communication and sensing, with designs adapted to frequency, medium, and regulatory considerations.