Darrel Emerson's home page
These pages were formerly on a Compuserve web site: ourworld.compuserve.com/homepages/demerson/ .
Identical copies are now mirrored at:
- Profession: Radio Astronomer, working for the National Radio Astronomy Observatory (NRAO)
- Favourite hobby is amateur radio: callsigns AA7FV and G3SYS.
- Lives in Tucson, Arizona, USA.
E-mail aa7fv @amsat.org
Links to other pages:
MGS 437 MHz signal (alternate NRAO site)
Between 1894 and 1901 many of today's now commonplace
microwave components were invented and used. In Calcutta, J.C.
Bose measured the performance of components and materials at
wavelengths as short a 5 millimetres (60 GHz). This early
pioneering work is little known outside of India. Unpublished photographs
of some of his original equipment are included in this
"The Stage is Set" outlines some of the 19th century developments that culminated
in the bridging of the Atlantic with wireless transmission
by Marconi in 1901. Includes images
of D.E. Hughes' transmitter, which was used to demonstrate
radio transmission nearly a decade before
Hertz successfully produced radio waves in 1888.
Images of the Moon and Sun at short (mm-wave) wavelengths. Alternate sites:
Images of the Moon at short radio wavelengths (CIS site)
Images of the Sun at short radio wavelengths (CIS site)
Pages of the National Radio Astronomy Observatory (NRAO)
Useful www links to
current solar flux data,
at a variety of frequencies.
- Movies of the August 1999 solar eclipse, measured at 164 and 236 MHz.
These spectacular movies were measured by the Nancay
radioheliograph, and represent possibly the most fascinating
sequences of radio astronomical data I've ever seen. They show
complete false-colour images of the sun, sampled every 30
seconds, with an angular resolution of about an arc minute.
Besides the occasional flares appearing both within the
solar disc and in the corona, you can follow the moon's disc as
it moves across the sun. It's also a dramatic demonstration of
how the sun's corona causes the diameter of the solar disc
measured at meter wavelengths to be significantly greater than
the optical disk. A spectacular sequence.
Movie of the eclipse at 164 MHz (6 Mb)
Movie of the eclipse at 236 MHz (5 Mb)
Measurements made on various Speake fluxgate magnetometer sensors, and
a comparison with data from the official USGS Tucson Magnetic Observatory.
Thermal measurements, and long-term drift of the FGM-3h magnetometer
Thermal dependence plots of Speake magnetometers
Probably only relevant if you're thinking of monitoring the Earth's
A study of the degree to which linearly polarized VHF and UHF signals can
become elliptically polarized in their passage through the ionosphere.
This is relevant to propagation to and from orbiting satellites, and
to EME operation.
Last changed December 2009