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Determination of Antenna Height for Protection Against Microwave Diffraction Fading
Author(s) -
Dougherty Harold T.,
Wilkerson Robert E.
Publication year - 1967
Publication title -
radio science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.371
H-Index - 84
eISSN - 1944-799X
pISSN - 0048-6604
DOI - 10.1002/rds196722161
Subject(s) - fading , fading distribution , diversity scheme , interference (communication) , antenna (radio) , diffraction , computer science , electronic engineering , attenuation , optics , telecommunications , physics , engineering , channel (broadcasting) , rayleigh fading
The wide variations in refractive index gradients that may be encountered for nominally line‐of‐sight microwave maritime paths can cause severe fading. A common type is known as k ‐type fading which includes phase‐interference fading and also diffraction fading as the refractive index gradient varies over a wide range. Lewin (1962) was the first to provide an engineering design procedure that roughly approximated: (a), the required terminal antenna heights to reduce diffraction fading, and (b), the required diversity separations (frequency or space) to provide a dynamic reduction of phase‐interference fading. The diversity design procedures, (b) above, have since been derived in a more accurate manner although they presuppose that item (a) has been provided for. The present paper meets this requirement. It provides a more accurate design procedure for determining the requirements, (a) above, to reduce diffraction fading. As an aid for the procedure, a new computer‐derived curve is presented for the attenuation by a spherical earth at grazing conditions.