Protected GPS Directional Antenna Array

Dr. P. A. Molchanov, Dr. V.M. Contarino, Dr. O.V. Asmolova

Anti-jam GPS Phased Antenna Array

NAVSYS designed CRPA

NOVATEL designed anti-jam GPS antenna arrayStanford’s 7 element controlled reception

pattern antenna array

Jam resistant GPS antenna designed

by Air Force Research Lab.

Feedback signal forming null in phased antenna array pattern, but LNA will be damaged or drive to saturation by powerful

jamming signals before processing LNA LNA LNA LNA

Jammer

Planar omnidirectional antenna array

OmnidirectionalAntenna Pattern

Jammer

Planar Phase Array cannot protect GPS against strong Jamm signals

Anti-Jam antennas manufacturers and researchers

NOVATEL Inc. GAJT (GPS Anti-Jam Technology)

Boeing Inc. AGTFT(Air Forcr’s Anti-Jam GPS Technology Flight Test)

Honywell Inc. GPS anti-jam technology

Raytheon Inc. GPS anti-jam systems

Lockheed Martin Inc. G-STAR

Mayflower Communications Corp. GPS/A Anti-Jam

NAVSYS Inc. CRPA (Controlled Reception Pattern Antenna)

Air Force Research Lab. Jam resistant GPS

Stanford University CRPA

Ohio University, COUNT Anti-Jam Adaptive Antenna Array

Price of anti-jam antenna array 25000 USD

Jammer

Directional antenna array

Directional AntennaPattern

Any time directional antenna array receiving information from a few satellites independent of direction, tilt, jam source.

Second level of protection:

Multichannel processor is estimating direction of arrival (DOA) for each receiving channel and comparing with true satellite position from memory. If position wrong, receiving channel will be turned off by switcher.

First level of protection:

Convex shape. Any time directional antenna array receiving information from a few satellites independent of

direction, tilt, jam source.Switching receiving channel off

(>40 dB) or limiting signal from directional antenna in jammer

direction if jam signal larger than threshold value.

LNA

SW

LNA

SW

LNA

SWLNA

SW

LNA

SW

Multichannel Processor

Summator

Memory

Protected Directional Antenna Array

Gain of Directional antenna larger than omni-directional antenna 5-25 dB

Pattern of Omni-directional antenna

element

Gain of onedirectionalantenna

Gain of omni-directionalantenna element

Jammer

Jammer

Pattern of Omni-directional antennas

array

Patterns of ONdirectionalantennas

Patterns of OFFdirectionalantennas

Gain of onedirectionalantenna G

Gain of omni-directionalantennas array in one

satellite direction <0.5 G

Gain in direction of one satellite decreasing in phase (adaptive) antenna array with increasing number of satellites,

and practically not change for directional antenna array

Number of Satellites

1 2 3 4 5 6 7 8 9 10

Gain,dB

2

4

6

8

10

Phased Array with 10Omni-directional

elements

Array of 10 DirectionalAntennas

Table 1. Beam steering gain on satellites signal

Number of elementsGain (dB) Gain of one element (dB)

7 8.5 1.21

16 12 0.75

109 20.4 0.187

Directional Antenna Array can receive

signals from any direction independent of tilt and have advance

for small UAS, UGS applications

Beamwidthdecreased becausephase shift errors

Beamwidth ofplanar phased array

antenna

Patterns ofdirectionalantennas

DirectionalAntenna Array

Planar Phase arrays have limited beamwidth and can loss signal when

array tilt

8mm

5mm

6mm

Anti-jam GPS Directional Antenna Array Advantages:

• Simplest implementation –many options

• New nano-materials can probably make a much better performance array

• Number of antennas vs performance can be adjusted to provide proper protection.

• Array is easily electronically controlled with gated detector/LNA receivers.

Anti-jam GPS Directional Antenna Array Advantages

• Directional antennas can have higher gain –therefore less sensitive LNAs and less susceptibility to EMI damage.

• Only antennas turned on are susceptible to damage, jamming or spoofing. Jammer would have to be in the path of the tracked satellites for jamming, spoofing or damaging.

• Having more than 3 good satellites tracked would allow detection and defeat of a spoofing signal .

Application of GPS Directional Antenna Array for Robotic Sensors Navigation

Distributed Sensing PlatformEO/Thermal

Imaging System

GPS Directional Antenna Array

Distributed Radar ConceptDistributed Radar Concept

Position of Intruder calculated by measurement time delay and

triangulation

Transmitter + GPS + DAA

Receiver + GPS

Antenna Patterns

Dipole Antenna

Application of Directional Antennas for Aircraft Communications

Monopole Antennas

CommunicationInpossible

Ground Station

AntennaPattern

AntennaPattern

AntennaBlind Zone

AntennaBlind Zone

AntennaPattern

AntennaPattern

AntennaBlind Zone

AntennaBlind Zone

Blimp1.jpg

Disadvantage of Dipole Antenna Application for Sense and Avoid Systems

Directional Anti-jam GPS Antenna Array

Anti-jam Directional Antenna Array for Control and Communications