Case Study

Using Military Antenna Technology to Relay Ocean Data

Published: November 2, 2009

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California-based Liquid Robotics Inc. has developed a wave-powered autonomous surface vehicle called Wave Glider. The vehicle provides a persistent presence on the ocean surface to perform a wide variety of sensor functions and communicate the collected information back to the operator via satellite.

However, the amount of information that could be communicated by the unique Wave Glider platform was constrained by the limits of traditional antenna solutions, including available data bandwidth and/or high power consumption. In need of a more reliable and faster way to receive high-bandwidth information such as streaming audio and video from the Wave Glider, the company turned to the Georgia Tech Research Institute (GTRI).

GTRI researchers had developed a reconfigurable aperture antenna technology several years earlier for a military software-defined radio that could be repurposed to quickly send and receive the required information. For Liquid Robotics, this information included environmental and global positioning data, video, audio from a hydrophone, and instructions telling the vehicle where to go.

"We're very pleased with the results of the Wave Glider platform to date and we're excited about the additional capabilities that GTRI's technologies will bring to the platform," said Tim Richardson, chief operating officer at Liquid Robotics.

The original antenna technology was developed by GTRI's Signature Technology Laboratory, now the Advanced Concepts Laboratory, including principal research engineer Paul Friederich .

"The antenna technology being developed at GTRI allows for fast data transfer because it can be steered electronically with very low power so that it stays pointed toward the satellite as the boat is moving around and bobbing back and forth on the waves," said GTRI principal research engineer Don Davis.

The antenna's performance can be optimized because it is reconfigurable, which means the electrical structure of the antenna can be easily changed. The antenna consists of a thin dielectric substrate that supports an array of square, metallic patches that can be switched on or off as needed to provide the proper configuration. The researchers simulate the antenna patterns to determine which switches should be open and which should be closed to maximize the antenna performance.

"This antenna technology allows limited space on a vessel to be used most effectively because it can conform to the surface of an object. Additionally, it gives the user the ability to repurpose an antenna for other frequencies, bandwidths or directivity requirements," added Davis.