Post on 15-Jan-2016
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