7000-7300 KHz (7.0-7.3 MHz) or 40 m band
The popular 40 m band has clearly
defined skip zone during the day. D-layer absorption is not as severe as on the lower
bands, so short-distance skip via the E and F layers is possible. During the day, a
typical station can cover a radius of approximately 800 km. Ground-wave propagation is not
important. At night, reliable worldwide communication via F2 is common on the 40 m
band.Atmospheric noise is less troublesome than on 160 and 80 m, and 40 m DX signals are
often of sufficient strength to override even high-level summer static. For these reasons,
40 m is the lowest-frequency amateur band considered reliable for DX communication in all
seasons. Even during the lowest point in the solar cycle, 40 m may be open for worldwide
DX throughout the night.
Source: ARRL Handbook, 1993