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<H1>7 MHz Moonbounce </H1>
<P><FONT face=Verdana>Last year BAE Systems completed work on the world’s
largest and most capable ionospheric research facility at Gakona, Alaska. It has
now been used to achieve Moonbounce for the first time on 7 MHz.</FONT></P>
<P><FONT face=Verdana><STRONG>Scientists Detect Lowest Frequency Radar Echo From
The Moon<BR></STRONG><BR>A team of scientists from the Naval Research
Laboratory, the Air Force Research Laboratory's (AFRL's) Research Vehicles
Directorate, Kirtland Air Force Base, N.M., and the University of New Mexico
(UNM) has detected the lowest frequency<BR>radar echo from the moon ever seen
with earth-based receivers.</FONT></P>
<P><FONT face=Verdana>In the lunar echo experiment (more properly called a lunar
bistatic radar experiment), the Air Force/Navy High Frequency Active Auroral
Research Program (<STRONG>HAARP: </STRONG><A
href="http://www.haarp.alaska.edu/haarp/ion4.html">http://www.haarp.alaska.edu/haarp/ion4.html</A> )
high power transmitter, located near Gakona, Alaska, launched high power radio
waves toward the moon. The reflected signal, weakened because of the long
distance to the moon and back, was detected by receiving antennas in New
Mexico.</FONT></P>
<P><FONT face=Verdana>NRL consultant scientist Dr. Paul Rodriguez, of NRL's
Information Technology Division, who conceived and proposed the experiment
explains, "Analysis of the echo gives information on the properties of the lunar
sub-surface topography, because the low frequency radar waves propagate to
varying depths below the visible surface of the moon. It is somewhat like sonar,
except that we are using electromagnetic waves rather than sound
waves.</FONT></P>
<P><FONT face=Verdana>The experiment also allows us to study the interaction of
the echo signal with the earth's ionosphere along its return path, because the
ionosphere is only partially transparent at low frequencies."</FONT></P>
<P><FONT face=Verdana>During the experiment, which was carried out on Oct. 28
and 29, 2007, the radar signals from HAARP were at 7.4075 MHz and 9.4075 MHz.
Both the transmitted signal and the echo from the moon were detected by NRL
Remote Sensing Division scientist, Dr. Kenneth Stewart, and NRL engineer Brian
Hicks with antennas built for the Long Wavelength Array (LWA). LWA is a radio
interferometer being built in the desert west of Socorro, N.M., by UNM, NRL, the
Applied Research Laboratories at the University of Texas at Austin, Virginia
Tech, and Los Alamos National Laboratory, for studies of space physics and
astrophysics.</FONT></P>
<P><FONT face=Verdana>The LWA is intended to work below the 88 MHz edge of the
FM band, but to get down to the HAARP signal frequencies, the antennas were
equipped with digital receivers and specially designed matching networks
developed by Stewart, Hicks, and engineer Nagini Paravastu at NRL.</FONT></P>
<P><FONT face=Verdana>"Detecting the very weak radio signals after their round
trip to the moon and back was challenging and required careful modification of
the LWA antennas to improve their performance at these frequencies," says
Stewart. NRL LWA Project Scientist Dr. Namir Kassim notes, "One of the
successful goals of this experiment was to demonstrate that the LWA can work
with instruments like HAARP at lower frequencies than its nominal
design."</FONT></P>
<P><FONT face=Verdana>The HAARP radar antenna array was "phased" to point about
45 degrees away from the zenith, in order to track and directly illuminate the
moon. Its full total power capability, about 3.6 MW, was used to transmit pulses
two seconds in<BR>length every five seconds over a period of two hours each day,
one hour at each frequency.</FONT></P>
<P><FONT face=Verdana>Using such a pulse pattern makes the echo, which arrives
back from the moon 2.4 seconds later, immediately recognizable, allowing the
scientists to distinguish the moon's echo signal from the HAARP signal. The
HAARP signal reached the receiving antennas in New Mexico by reflecting off the
underside of the ionosphere, the region of the Earth's atmosphere from 50 to 400
km in altitude that is partially ionized by solar radiation.</FONT></P>
<P><FONT face=Verdana>The lunar echo measurements at 7,407.5 MHZ are believed to
be the lowest frequency (longest wavelength) at which bistatic radar
measurements have been conducted. "Even though lunar echoes have been detected
before at higher<BR>frequencies, it was really exciting to see them arrive in
real time out under the full moon in the New Mexico desert," says NRL's
Hicks.</FONT></P>
<P><FONT face=Verdana>From <BR></FONT><A
href="http://www.moondaily.com/reports/Scientists_Detect_Lowest_Frequency_Radar_Echo_From_The_Moon_999.html"
target=_blank><FONT
face=Verdana>http://www.moondaily.com/reports/Scientists_Detect_Lowest_Frequency_Radar_Echo_From_The_Moon_999.html</FONT></A></P>
<P><FONT face=Verdana>Moon Daily <BR></FONT><A href="http://www.moondaily.com/"
target=_blank><FONT face=Verdana>http://www.moondaily.com/</FONT></A><FONT
face=Verdana> </FONT></P>
<P><FONT face=Verdana>US Naval Research Laboratory <BR></FONT><A
href="http://www.nrl.navy.mil/" target=_blank><FONT
face=Verdana>http://www.nrl.navy.mil/</FONT></A><FONT face=Verdana> </FONT></P>
<P><FONT face=Verdana>NRL Press Release <BR></FONT><A
href="http://www.nrl.navy.mil/pressRelease.php?Y=2008&R=4-08r"
target=_blank><FONT
face=Verdana>http://www.nrl.navy.mil/pressRelease.php?Y=2008&R=4-08r</FONT></A><FONT
face=Verdana> </FONT></P>
<P><FONT face=Verdana>World's Premiere Facility For Ionosperic Research
Completed <BR></FONT><A
href="http://southgatearc.org/news/july2007/ionospheric_research_facility.htm"
target=_blank><FONT
face=Verdana>http://southgatearc.org/news/july2007/ionospheric_research_facility.htm</FONT></A></P>
<P><FONT face=Arial size=2>Fonte: <FONT face="Times New Roman" size=3>The
Southgate Amateur Radio Club</FONT></FONT></P></DIV></BODY></HTML>