What's at 1420 MHz????
Pieter Ibelings
results. One of the frequencies where tests were conducted is 1420 MHz.
Why 1420 MHz? Also has anyone heard of a NASA beacon that was left at the
moon around 2.4 GHz?
73's
Pieter Ibelings
AC4OP
Charles W. Doolittle-Scovish
--
Charles W. Doolittle-Scovish
doo...@rpi.edu n1...@acm.rpi.edu
N1SPX
Frequencies at http://acm.rpi.edu/~n1spx
Steve Muther
The Apollo 16 mission (I think) left behind an array of scientific
instruments on the moon which transmitted telemetry somewhere near
2.8GHz. I think it was shut off a long time ago due to lack of funding
to analyze the data.
Steve M.
Pieter Ibelings
>
>1420 MHZ = first harmonic of water. Microwaves operate near there.
>--
Last time I checked microwave ovens were on 2450MHz. I tried putting my
optoelectronics freq counter in hold mode and put it in the microwave for
5 minutes.....
Darrel Emerson
that detected from atomic hydrogen in the interstellar medium, at
1420.405 MHz. Because of Doppler shift from the motions of interstellar
hydrogen the emission can be detected over a range of frequencies.
The band 1400 MHz to 1427 MHz is a protected radio astronomy band.
If you have a sufficiently sensitive receiver and antenna, it's
possible for an amateur to receive emission from the hydrogen line in
our Galaxy. It would appear as a slightly higher background noise,
spread over a few 100 kHz near the rest frequency of 1420.4 MHz.
Hope this helps,
regards,
Darrel Emerson, AA7FV.
Darrel, AA7FV.
Steve Muther
>1420 MHZ = first harmonic of water. Microwaves operate near there.
>--
>doo...@rpi.edu n1...@acm.rpi.edu
>N1SPX
>Frequencies at http://acm.rpi.edu/~n1spx
>
ham band).
Steve Muther WF6R
Mike Keitz
More like all over the band. The signal is about 25 MHz wide. If it's any
consolation, it's only on half of the time. The power supply in the oven
is a half-wave voltage doubler, so the magnetron doesn't operate during one
half-cycle of the power line. This varying, unfiltered power causes the
mangetron frequency to FM all over the place though. In very limited
research (sample size of 2), the ERP from a typical closed, apparently
properly maintained oven was about 1 Watt peak. Doesn't look like the
commercial communication interests are going to want to take over *that*
band anytime soon!
As I understand it, the frequency chosen doesn't have to have anything to
do with resonance of water molecules. It's the current induced by the
waves due to resistance and/or dielectric loss in the food or drink that
cause the heating effect. For example, the metallized lining in a
microwave popcorn bag will absorb the microwave energy and heat up the fat
inside the bag, which transfers heat to the corn to pop it. No water is
involved other than that in the corn kernels, and that is heated
indirectly.
-Mike KD4QDM
J. L. Blanton
(Pieter Ibelings) wrote:
> I got my copy of Feed Point yesterday and there is a list of noise figure
> results. One of the frequencies where tests were conducted is 1420 MHz.
> Why 1420 MHz?
1420 MHz is an emission line of neutral hydrogen. It is used by radio
astronomers to map hydrogen density in the Milky Way galaxy and beyond. A
small frequency band surrounding 1420 MHz is a protected radio astronomy
frequency and no other manmade emissions are permitted there.
Lee, WA8YBT/6
Temecula, CA
Tom Clarke
frequency of the hydrogen atom. Radio astronmers use it to
map the distribution of hydrogen in space. Digging deeper the
OH radical has a radio line at 1680 MHz(?) so that the region
between 1420 and 1680 has come to be called the water hole
(H to OH) by those who SETI (Search for Extraterrestrial
Intelligence). Presumably any life forms will know water
and think this frequency range as nice a pun as we do.
Sort of an intergalacitic calling channel. Also
I think the galactic radio noise has a minimum in this
general frequency range.
Tom Clarke
--
People of the same trade seldom meet together, even for merriment
and diversion, but the conversation ends in a conspiracy against
the public, or in some contrivance to raise prices - Adam Smith, WofN
Kein{nen Paul
Pieter Ibelings (wa...@mindspring.com) wrote:
> I got my copy of Feed Point yesterday and there is a list of noise figure
> results. One of the frequencies where tests were conducted is 1420 MHz.
> Why 1420 MHz?
It is the 21 cm spectral line from interstellar hydrogen. It is produced
from spin reversals of the only electron in a hydrogen atom.
What was the noise figure quoted and from which direction was that
measurement obtained ? There are large variations in the 21 cm emission,
while most radiation comes from the Milky Way.
Another well known spectral line is the hydroxyl (OH-) spectral
line at 18 cm (1667 MHz).
> Organization: -.-. --.- -.. -..-
The ultimate CQ DX was attempted by the SETI (Search for ExtraTerrestrial
Intelligence) people who transmitted simple "pictures" at 21 cm towards
some nearby stars, hoping for a reply from some intelligent creatures
that were hoped to live near these stars :-).
IMHO, the high noise 21 cm spectral line is the worst place for such
experiments.
> Also has anyone heard of a NASA beacon that was left at the
> moon around 2.4 GHz?
Is this the transmitter that was in in the ALSEP scientific station
that was left on the moon by the Apollo astronauts ? The SNAP nuclear
batteries that powered these stations have depleted long ago, so I doubt
that there are any more operationals beacons.
Paul OH3LWR
Zack Lau
>
> 1420 MHZ = first harmonic of water. Microwaves operate near there.
around 900 MHz, and then were moved to 2.45 GHz. The frequency
of a microwave oven has *nothing* to do with any water resonance
frequency. It has a lot more to do with the politics of spectrum
allocation, and secondarily, the physics needed to make a safe and
useful cooking tool.
Fortunately for those searching for extra-terrestial intelligence
(SETI), microwave ovens don't operate near the water hole (1420
to 1660 MHz).
Zack Lau KH6CP/1 zl...@arrl.org