GPS Antenna
From:http://gracie.grdl.noaa.gov/GRD/GPS/Projects/ANTCAL/Models/Images/SENS67157549.s.jpg
SEN 67157549
SENSOR SYSTEMS L1
GPS Antenna with Choke Ring
From:http://gracie.grdl.noaa.gov/GRD/GPS/Projects/ANTCAL/Models/Images/SENS671575+cr.s.jpg
SEN 67157549+cr
SENSOR SYSTEMS L1 WITH CHOKE RING
GPS Antenna
LEI AT302
From:http://gracie.grdl.noaa.gov/GRD/GPS/Projects/ANTCAL/Models/LEI_AT302.shtml
Antenna Arrays
Two Elements -- Pattern adds
constructively or destructively
From: http://server5550.itd.nrl.navy.mil/projects/HAARP/images/ant/pat1.gif
Antenna Arrays
More Elements:
Higher Directivity
Sidelobes
From: http://server5550.itd.nrl.navy.mil/projects/HAARP/images/ant/pat2.gif
Scanning Antenna Array
Changing the phases on the element
feeds can make a scanning array.
From:http://server5550.itd.nrl.navy.mil/projects/HAARP/images/ant/pat3.gif
HAARP Observatory
From:http://server5550.itd.nrl.navy.mil/projects/HAARP/images/ohd.jpg
HAARP (High frequency Active Auroral Research Program) is to be a major Arctic facility
for upper atmospheric and solar-terrestrial research. HAARP is being built on a DoD-owned
site near Gakona, Alaska.
HAARP Antenna Array
From:http://server5550.itd.nrl.navy.mil/projects/HAARP/images/twr/pan2.jpg
The HF antenna system to be used for Active Ionospheric Research at the HAARP site will assist other facility instruments in the
study the overhead ionosphere. As a result, it too has been designed to optimize or restrict the transmission pattern to lie within a
narrow overhead region. To achieve this desirable antenna pattern, the HAARP system uses an "array" of individual antenna
elements. The HAARP antenna array is similar or identical to many other types of directive antenna types in use for both military and
civilian applications including air traffic control radar systems, long range surveillance systems, steerable
communication systems and navigation systems.