Absorption is negligible for radio propagation in air at frequencies less than about 10 GHz, but becomes important at multi-GHz frequencies where rotational molecular states can be excited.
42.
The translator's coverage area mimics its parent station, as both achieve relatively the same distance, except during the evening hours when skywave radio propagation is present for KUGR.
43.
The data obtained in the worldwide net of such instruments were important for the developing theory of short wave radio propagation to which Berkner himself gave important contributions.
44.
The zone of RF interference moves hourly and daily based on weather and overnight temperature inversions, which affect radio propagation, especially over the longer distance from the main station.
45.
The actual distance a station's signal travels depends highly on weather, where factors like temperature inversions and heavy precipitation have a strong and highly variable influence on radio propagation.
46.
Understanding the effects of varying conditions on radio propagation has many practical applications, from choosing frequencies for international shortwave mobile telephone systems, to radio navigation, to operation of radar systems.
47.
In 1946, CU Boulder became a joint sponsor with Harvard of the observatory, while the Central Radio Propagation Laboratory ( CRPL ) of the NSB funded HAO s operational costs.
48.
With range limited to around 1000 kilometers in normal radio propagation conditions, a location on high ground close to a major metropolitan area is an often unbeatable advantage in VHF contests.
49.
In addition there are several less common radio propagation mechanisms, such as tropospheric scattering ( troposcatter ) and near vertical incidence skywave ( NVIS ) which are used in specialized communication systems.
50.
Since SMS messages only require an instant to send, a brief peak in radio propagation ( such as due to changing cloud cover ) is often enough to get a message sent.
