An experimental study of phase variations in line-of-sight microwave transmissions

Abstract

These include the development and maintenance of the national standards of measurement and the provision of means and methods for making measurements consistent with these standards; the determination of physical constants and properties of materials; the development of methods and instruments for testing materials, devices, and structures; advisory services to government agencies on scientific and technical problems; invention and development of devices to serve special needs of the Government; and the development of standard practices, codes, and specifications. The work includes basic and applied rsearch, development, engineering, instrumentation, testing, evaluation, calibration services, and various consultation and information services. Research projects are also performed for other government agencies when the work relates to and supplements the basic program of the Bureau or when the Bureau's unique competence is required. The scope of activities is suggested by the listing of divisions and sections on the inside of the back cover.

Phase and amplitude diversity in over-water transmissions at two microwave frequencies

“…Such variations are caused by fluctuations in the three-dimensional structure of the atmospheric refractive index along the radio path. Phase-of-arrival variations have been investigated in an extensive experimental program carried on by the National Bureau of Standards using predominantly over-land paths Norton, et al , 1956; Thompson and Janes, 1959;Thompson, Janes, and Kirkpatrick, I960] • Although these experiments were not designed to study amplitude variations, the signals were observed to undergo occasional deep and prolonged fading on paths of the order of 15 km in length. Two questions which these previous experiments have left unanswered are: (1) how will the signal phase and amplitude behave on an over -water path, and (2) to what extent will the phase and amplitude variations be correlated in two signals separated in frequency.…”

Optical scintillation:

“…Besides, they cause irregular fluctuations in the apparent position of a radio source viewed through the ionosphere. As long as the mean phase changes imposed on the incident radio wave are less than one radian, the scale of the pattern on the ground is the same as that in the ionosphere [Booker, 1958;Aarons, 1962 [Norton, et al , 1961[Norton, et al , , 1963 In the optical case, Ellison and Seddon [1952] We only refer to the development of models of the atmosphere by Gerrard [ 196l], to work by Strand [ 1953] and Hamilton [1956] Index of refraction profiles obtained on different days, using a microwave refractometer carried aloft in an airplane.…”

Fading characteristics and bandwidth capability for within-the-horizon propagation at 1040 and 9300 MCs

“…24(a). Next the correlation coeffi¬ cients of the two components are related in such a way that the trend in [Norton, et al, 1961] . It is indicated there that this correlation is quite high for spacings of the order of magnitude used here.…”