Antenna Research Institute (ARA) has developed Spiral Antennas that operate up to 40 GHz for signal monitoring applications. These antennas have a wide bandwidth and are circularly polarised, with peak emission patterns perpendicular to the spiral plane. They have high half-power bandwidth making them an excellent choice for airborne Electronic Warfare (EW) applications such as Radar Warning Receivers, Direction Finding, and Interferometry Systems. Furthermore, these antennas are employed in sensing applications where extremely wideband antennas with tiny footprints are appropriate. Other uses of spiral antennas include GPS applications, where it is preferable to have right-handed circularly polarized (RHCP) antennas.
The increasing use of wireless devices in recent times has led to the need for greater bandwidth in wireless communication. Effectively managing and monitoring these signals is significant. Signal monitoring requires wideband antennas or frequency-independent antennas such as spirals. Spiral antennas have high spectral efficiency, low gain, and are circularly polarized. Spiral antennas provide frequency-independent performance over wide operational bandwidths with a compact form-factor and superior performance. They have nearly constant input impedance and are capable of VSWR below 2.0:1. They can be designed for left-hand or right-hand circular polarization and provide almost perfectly circularly polarized radiation over their entire coverage area, with an axial ratio better than 1 dB on-axis. In addition, spiral radiation patterns are nearly constant in frequency. These characteristics are achieved in a cylindrical volume of approximately 1/3 wavelength in diameter by 1/4 wavelength in depth. The gain of spiral antennas can be increased considerably by forming an array. Thus, spiral antenna arrays are used for Ultra-Wideband (UWB) radio applications.
ARA has a family of individual spiral antennas and multi-channel antenna arrays for applications including wideband communications, electromagnetic interference (EMI), radar warning receivers, electronic intelligence (ELINT), and signal intelligence (SIGINT). These antennas meet airborne requirements and are MIL-Std-810G compliant.
Spiral antennas are used as single elements, arrays of elements, feeds for reflectors or other high-gain apertures in communication applications. Single elements are used in low gain systems such as low data rate satellite communications, global positioning systems (GPS), and receive-only mobile systems. Spiral arrays are used for high-gain applications such as high-data-rate satellite and terrestrial communication networks. In EW applications, spiral antennas are used as single elements or in interferometer arrays. Single elements are used in radar warning systems, SIGINT systems, or low-power jamming systems. Interferometer arrays employ a set of a few (typically four) spiral antennas in amplitude or phase-matched sets. They are used to determine the angle-of-arrival (AOA) of received signals.
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