Sinuous Antenna 3 dBi Typ. Gain, 2-18 GHz Frequency Range RM-SIA218-3

A sinuous antenna is a frequency‑independent broadband antenna consisting of multiple curved metal arms, typically four, arranged in a centrally symmetric pattern. The edges of each arm are defined by a sinusoid, and adjacent arms are excited alternately.

Its operation is based on a self‑complementary geometry and the concept of an active region: as frequency changes, the active region moves along the arms, resulting in extremely wide bandwidth (up to 10:1 or more). The antenna can simultaneously support two orthogonal linear polarizations, or—with a proper feed network—left‑hand and right‑hand circular polarizations.

Key advantages include ultra‑wideband performance, dual‑polarization capability, low profile, and stable radiation patterns. The main drawback is the need for a complex feed network, typically involving broadband hybrids or phase shifters. Sinuous antennas are widely used in electronic warfare, spectrum monitoring, direction‑finding systems, and broadband communications, especially where simultaneous reception of multiple polarizations and wide frequency coverage is required.