Radio Sky summary, page 4/4: 432 MHz observations with an 8-element Yagi

Although relatively large antennas, with a 10-degree or smaller beamwidth, are needed to distinguish radio point sources from the background, the extended radiation can be detected easily even with relatively tiny antennas.

The following image shows the visible sky as seen from AA7FV at 434 MHz in July at about midnight. The left image was measured with an 8-element Yagi, about 5 feet long, with a beamwidth of 30 degrees. The right image is a simulated observation using the professional 408 MHz data at the head of this article, smoothed to a 30-degree beamwidth. The images are presented as you would see the sky lying on your back, with your feet to the south, at latitude 32 degrees; north is to the top and east to the left. The point directly overhead, the zenith, is in the centre of the plot, with the horizon all around the perimeter. In the 434 MHz observation strong ground radiation is picked up at low elevations, visible as the bright red rim around the perimeter of the image. The 408 MHz simulation did not include ground radiation. In both maps the Galactic Centre is visible in the south, with the galactic plane stretching across to the north-east (upper left.)

False-colour plot of AA7FV 434 MHz sky map, using 8-element Yagi just 5 ft. long

Please refer to the original article in the June & July 1996 issues of QST for more details.

Radio Sky, p.1: All-sky 408-MHz false-color image
Radio Sky, p.2: 432 MHz brightness contours with 10-degree & 40-degree beams
Radio Sky, p.3: Max & Min sky temperatures. Solar emission.

Darrel Emerson top page