Also known as: antenna, aerial

An antenna is a conductor that converts electrical signals into radio waves and, on receive, converts passing radio waves back into a tiny current.¹ It sets the ceiling on everything downstream — no receiver can recover a signal the antenna never captured.

An antenna couples radio waves to and from the receiver; its size follows the wavelength it works at.

How it works

An antenna works best when its dimensions are a fraction of the signal’s wavelength (a quarter-wave whip is λ/4). Its key properties are resonance/bandwidth, gain, polarization, and impedance match (SWR).

Relevance to SDR

Choosing an antenna cut for the target band and placing it high with a clear path usually improves reception more than any change at the radio.

Sources

1. Antenna (radio) — Wikipedia, for the definition and key properties of antennas. ↩

See also

• Dipole antenna
• Antenna gain
• Polarization
• Standing wave ratio (SWR)
• Wavelength

Learn it step by step

• Antennas 101