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== Antennas ==

There are two styles of antennas in use in COSMOS. The first style is directional and used exclusively as part of the large node sectors. The second style is omni-directional and used as part of the medium nodes.

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=== Directional (large node sector) ===
The directional antennas are comprised of a horizontal array of four [attachment:"RFSpace TSA900 directional.pdf" ultra-wideband antenna elements]. Each element is oriented in the vertical plane and spaced 3 inches (7.63mm) from its neighbor. The frequency range covered by the antennas is 900 MHz - 12 GHz. However, due to limitations in the power amplifiers, USRPs, and other RF front end components, the actual frequency ranges are 2.4 - 6 GHz for transmit (non-contiguous, see RF front end for details) and 900 MHz - 6 GHz for receive.

A GPS antenna is located near the transmit/receive antenna and provides the GPS signal to the USRPs in the node.

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=== Omni-directional (medium node) ===
The omni-directional antennas are comprised of four vertically oriented [attachment:"MobileMark RM-WHF omni.pdf​" multi-band antennas] in a 6” (15.24 cm) 2x2 square pattern with a 14.25”x14.25” (36.2x36.2 cm) ground plane. The frequency range covered by the antennas is 1.7 - 6 GHz. However, due to limitations in the power amplifiers, USRPs, and other RF front end components, the actual frequency ranges are 2.4 - 6 GHz for transmit (non-contiguous, see RF front end for details) and 1.7 - 6GHz for receive.

A GPS antenna is located in the middle and provides the GPS signal to the USRPs in the node.

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