US Navy Turns to Optical Beamforming for Real-Time Communication, Connectivity

Isotropic Systems, a developer of broadband terminal technologies, has today announced an antenna evaluation and development contract with the Defense Innovation Unit (DIU). The aim is to test the ability of its multi-beam antennas based on the company’s innovative optical beamforming technology.

 

Optical beamforming antennas are to be evaluated against the uncompromising requirements of naval service. Image (modified) used courtesy of Isotropic Systems

 

The DIU is evaluating Isotropic Systems’ beamforming antenna technologies and circuits with an eye to support multiple links with smooth handover between multi-orbit satellites operating over the S-, C-, Ka-, Ku-, X-, and Q-bands.

The company’s terminal features optical lens modules designed to fit within the limited space available aboard navy ships. Evaluators will test the new systems’ capacity to operate reliability in the harshest naval environments, including salt-water, EMI, and intense winds.

“Isotropic Systems has cracked the code for a new age of seamless and secure connectivity and communications in some of the most challenging conditions facing government agencies and military operations around the globe,” said John Finney, CEO and founder of Isotropic Systems.

He goes on to say, “We will enable the Navy, and other government forces and agencies, to arbitrage all the capacity it needs from across low-Earth, geosynchronous- equatorial and medium-earth orbit constellations over a single multi-beam platform.”

 

The Shortcomings of Parabolic Antennas and Phased Arrays

As Finney explained at the Interlligent 2019 RF Design Seminar, it was not too far in the past when satellite communications meant geosynchronous satellites, orbiting at 22,000 miles above the earth, and, from the standpoint of an earth observer, unmoving. Parabolic reflectors, the large mechanical devices with little need for adjustment, served usefully.

But then came the advent of inexpensive launch systems and a plethora of low-earth-orbit (LEO) satellites. These devices are attractive from a warfighting angle because they are replaceable. The problem is that from the parabolic antenna’s standpoint, whether on land, in the air, or on a Navy ship, they are only visible for minutes.

Another important technology, phased array antennas, can have thousands of elements and can catch a flotilla of satellites as they speed by in space; one of the thousands of elements is sure to catch one or more of them at any moment. 

 

Phased array. Screenshot used courtesy of Isotropic Systems at the Interlligent UK's 2019 RF Design Seminar (14:50)

 

The main problems, however, are twofold: they are expensive and they consume power in the order of kilowatts.

 

Isotropic Systems’ Optical Beamforming Antenna

Isotropic Systems' overall optical beamforming system is illustrated below with one lens removed to illustrate the transmission points.

 

Optical beamforming. Image used courtesy of Isotropic Systems

 

Then, as illustrated below on the left (red), the appropriate transmission point under each lens is turned on to send the beam in the direction of the target. The same might be done from other lenses. 

 

Element beam steering compared to array beam steering. Screenshot used courtesy of Isotropic Systems at the Interlligent UK's 2019 RF Design Seminar (18:42)

 

The result is a small number of beams targeted at the appropriate point in space. The computational process is, at that point, somewhat similar to that of a classical phased-array system, but with a far smaller number of transmission points. Among the resultant benefits are huge savings in power.

As illustrated, there are also green and blue transmissions, which mean more than one satellite can be accessed at the same time.

 

The Navy Blazes a Trail for LEO Satellites

The navy, like everyone else, will be moving away from stationary geosynchronous satellite communications and toward swarms of LEO satellites, each visible only for minutes and rapidly changing positions even during that time. Clearly, cumbersome parabolic antennas, which have to be steered mechanically, won’t cut it.

Phased-array systems are a good intermediary for ships, but even there the high power requirements and the need for cooling are undesirable. And, of course, those requirements mean even more difficulties for planes and missiles, where every watt counts.

Because of the practicality of cheap, replaceable LEO satellites, the world’s capacity for satellite bandwidth will begin to expand mightily in the near-term future. Additionally, it is postulated that the signal pathway from a point on Earth to an LEO satellite and back will turn out to be faster than fiber cable.

The navy may be the organization that pioneers this technology, and it's possible that this method could be a new avenue for internet service to be delivered to homes, businesses, and ultimately cellphones.