Ham Radio For Dummies by H. Ward Silver

Author:H. Ward Silver
Language: eng
Format: epub
ISBN: 9781119454861
Publisher: Wiley
Published: 2018-04-03T00:00:00+00:00

NIGHTTIME DXING

The nighttime bands of 10, 7, 5, 3.5, and 1.8 MHz are known as the low bands. These bands are throttled for long-distance communication during the daytime hours by absorption in the lower layers of the ionosphere. At sunset, these bands start to come alive.

First, 10, 7, and 5 MHz may open in late afternoon and stay open somewhat after sunrise. The 3.5 and 1.8 MHz bands, however, make fairly rapid transitions around dawn and dusk. Signals between stations operating on 3.5 and 1.8 MHz often exhibit a short (15- to 30-minute) peak in signal strength when the easternmost stations are close to sunrise, a peak known as dawn enhancement. This time is good for stations with modest equipment to be on the air and to take advantage of the stronger signals on these more difficult DX bands.

The 160 meter (1.8 MHz) band is known as the top band because for a long time it had the longest wavelength of any currently authorized amateur band. This long wavelength requires larger antennas. Add more atmospheric noise than at higher frequencies, and you have a challenging situation, which is why some of the most experienced DXers love top-band DXing. Imagine trying to receive a 1-kilowatt broadcast station halfway around the world. That’s what top-band DXers are after, and many of them have managed it. The new 630 meter and 2,200 meter bands will present their own challenges. Maybe they’ll become the “tip-top bands”?

Download

Copyright Disclaimer:
This site does not store any files on its server. We only index and link to content provided by other sites. Please contact the content providers to delete copyright contents if any and email us, we'll remove relevant links or contents immediately.