Slide 1

Report
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
Stanford’s 7 element controlled reception
pattern antenna array
Jam resistant GPS
antenna designed
by Air Force
Research Lab.
NOVATEL designed antijam GPS antenna array
Planar Phase Array cannot protect GPS against strong Jamm signals
Jammer
Jammer
Omnidirectional
Antenna Pattern
LNA
LNA
LNA
LNA
Planar omnidirectional antenna array
Feedback signal forming null in phased antenna array pattern,
but LNA will be damaged or drive to saturation by powerful
jamming signals before processing
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
Pattern
Directional antenna array
Any time directional antenna array receiving information from a few satellites
independent of direction, tilt, jam source.
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.
SW
LNA
SW
SW
SW
LNA
LNA
LNA
LNA
Memory
SW
Multichannel Processor
Summator
Protected Directional Antenna Array
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.
Gain of Directional antenna larger than omni-directional antenna
5-25 dB
Gain of one
directional
antenna
Gain of omni-directional
antenna element
Pattern of Omnidirectional antenna
element
Patterns of ON
directional
antennas
Jammer
Patterns of OFF
directional
antennas
Jammer
Pattern of Omnidirectional antennas
array
Gain of one
directional
antenna G
Gain of omni-directional
antennas 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
10
8
Gain,
dB
Array of 10 Directional
Antennas
6
4
Phased Array with 10
Omni-directional
elements
2
1
2
3
4
5
6
7
8
9
10
Number of Satellites
Table 1. Beam steering gain on satellites signal
Gain (dB)
Gain of one element (dB)
7
8.5
1.21
16
12
0.75
109
20.4
0.187
Number of elements
Planar Phase arrays have limited
beamwidth and can loss signal when
array tilt
Beamwidth of
planar phased array
antenna
Beamwidth
decreased because
phase shift errors
Patterns of
directional
antennas
Directional Antenna Array can receive
signals from any direction
independent of tilt and have advance
for small UAS, UGS applications
Directional
Antenna Array
8mm
6mm
5mm
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
GPS Directional
Antenna Array
EO/Thermal
Imaging System
Distributed Sensing Platform
Distributed Radar Concept
Patterns
Distributed RadarAntenna
Concept
Position of Intruder calculated
by measurement time delay
and triangulation
Transmitter + GPS + DAA
Receiver + GPS
Application of Directional Antennas for Aircraft
Communications
Dipole Antenna
Monopole Antennas
Disadvantage of Dipole Antenna Application for Sense and Avoid
Systems
Antenna
Blind Zone
Antenna
Pattern
Antenna
Pattern
Antenna
Blind Zone
Communication
Inpossible
Antenna
Blind Zone
Blimp1.jpg
Antenna
Pattern
Antenna
Pattern
Antenna
Blind Zone
Ground Station
Directional Anti-jam GPS Antenna Array
Anti-jam Directional Antenna Array for Control and Communications

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