Defense

A New Radar with Complex Phase Fronts

These patents describe a new type of radar that generates electromagnetic waves with complex phase fronts. This would make it virtually impossible to identify the point of origination of such an electromagnetic wave. Today there are existing methods for finding the location of a radar transmitter sources. This requires information from 2 or more locations and the rate of relative motion of the source. Today’s radar sources are vulnerable to countermeasures because the source radiation have very simple phase fronts. Today, the countermeasures from an aircraft that is being detected is to send a missile down a course perpendicular to the phase fronts to destroy the radar or sending back electromagnetic waves with a changed phase front to mislead the radar that the waves are reflections from another source. These methods require an evaluation of the phase front received from the source, which is easier to do if the phase fronts are simple in their structure.

Although adjustments of relative phases of a phased array can be done to perform beam steering as well as changes to phase fronts, the simple structure of the phase fronts make them vulnerable to being identified and exposed to countermeasures. In a combat situation, it is critical to identify the location of the source using radar. However, any advanced enemy will potentially create interference to prevent the use of detection equipment against targets. There are other methods including inverse gain repeater, a pull-off repeater, chaff, radar decoys, image frequency jammers, and others. Some advance fighter jets already have such systems on board. Today, even knowledge of modulation of the source in the time or frequency domains (scan rate and pulse duration, pulse interval and/or the frequency modulation patterns) is used for such purpose. But also the angle of arrival or the signal time of arrival and even angular rates are used to triangulate the locations.

Today, there are even advanced techniques in which an interrogating radar signal is cheated by returning a distorted signal having a discontinuity or other changes to the phase front, so that it appears to be coming from a different point in space. Such advances have also been used in laser radars. The detection of the location of a radar source by evaluation of phase front and the capability to change the phase front so that it appears that the target is at a different point, is because current systems use of simple electromagnetic phase fronts. Therefore, a more complex phase front is needed to avoid some of these countermeasures. There are three ways to build systems that prevent such conventional systems to detect the source. Use of complex OAM phase fronts, use of accelerated electric or magnetic dipole currents (not conduction currents) to generate the electromagnetic radiation that produce very complex wave fronts, and a combination of the two techniques which is purposed in our patents.

 

High Capacity FSO and RF with New Spatial Multiplexing

High capacity Free-Space-Optics (FSO) and multiplexing with RF using muxed OAM states on every wavelength are covered in several patents. They also include OAM as a detection signature for applications of detecting friendly targets when they are obstructed by trees and vegetation.

 

Beam Focusing Techniques and Ground Penetrating Radar

Beam focusing techniques with impulse radio for ground penetrating radar for defense, geological and oil and gas discovery applications.

Multi-Dimensional Quantum Key Distribution & Applications in Defense

Multi-dimensional Quantum Key Distribution (QKD) for cybersecurity using OAM states in photonics and RF. The current state of technology uses two-states of polarization for QKD. However, we have introduced new OAM states of photons as the basis for QKD. We have extended Bennett-Brassard (BB84) beyond polarization (2 state system) using LG modes or HG modes (multi-state system) for qubits. We also have extended Ekert 91 (E91) scheme with entangled pairs of photons using LG modes or HG modes (multi-state system) for qubits. We explore new techniques to combat denial of service attacks by routing communication via alternate links in case of disruption. We have included new techniques to combat Trojan horse attacks which does not require physical access to the endpoints as well as new techniques to combat faked-state attacks, phase remapping attacks and time-shift attacks. We introduced cloud-based Quantum Key Distribution for a multiuser network in a HetNet configuration.

 

Electromagnetic Knots and Applications in Defense Industry

Some of the highlights include electromagnetic knots. Natural processes such as reflection, diffraction and scattering degrade the information signals in wireless communications. However, they cannot open an electromagnetic knot and such EM knots are resistant to channel impairments. Natural processes also destroy coherence in quantum computing superposition of states for qubits. However, they can not open an electromagnetic knot and such topological knots are resistant to de-coherence. If electromagnetic waves can be knotted using sophisticated antenna structures (ring, toroidal and 3-dimensional patch antennas), then information could be encoded into the electromagnetic knots using a new modulation using knots as the states (modulated knots). It is possible to create paraxial solutions using EM knots that produce knotted OAM states. These states can be muxed to achieve improvements in wireless, security and QKD and quantum computing.

We introduce a new way of combating the degradations due to fading in wireless communications as well as quantum de-coherence in quantum computing using electromagnetic knots. In general, natural processes can degrade fabrics and signals, but generally they are not able to undue a knotted fabric or a knotted electromagnetic wave. Maxwell equations have an underlying topological structure given by a scalar field which represents a map that determines the electromagnetic field through a certain transformation (from 3-sphere to 2-sphere). Maxwell equations in a vacuum also have topological solutions, characterized by a Hopf index equal to the linking number of any pair of magnetic lines. This allows the classification of the electromagnetic fields into homotopy classes, labeled by the value of the helicity. This helicity is proportional to an integer action constant. Different methods of generation will be required depending upon the form of disturbance required and the frequencies required (ring, toroidal and 3D- patch antennas). We have included cylindrically polarized vector beams to generate an electric ring. We can also use toroidal antennas to create electromagnetic knots. We can wrap a solenoid on the ring element and control the electromagnetic knots based on homotopy classes. We can also have more sophisticated antennas such as knotted toroids. Multiple patch antennas can be configured in circular, elliptical or mixed configuration to generate electromagnetic knots. Each component of patch antennas would have a different phase to produce knotted eigen-channels. Multiple layers of such antennas can be overlaid to naturally mux the independent modes using the EM knots. Design and simulations of the EM knots can be performed using HFSS with microstrip feed structure to prepare for manufacturing. Cleanroom and lithography process are used to build the 3D structure of patch antennas that produce EM knots.  We can generate qubits using the EM knots in photonics using polarization states. We can also generate knotted OAM states in both photonics as well as EM waves.

We can then multiplex the muxed OAM knotted beams with a specific radio frequency or transmit the muxed EM knotted states and multiplex them with different radio channels. We can also de-Multiplex the Muxed knotted OAM beams. We can transmit multiple knotted beams each carrying different message signals and can do a Knot Division Multiplexing (KDM) with one frequency. This KDM can have improvements in Backhaul and Fronthaul scenarios. It can also be configured in MIMO setting for a compactified massive MIMO with patch antennas.

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