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On the limitations of the concept of space frequency equivalence
Author(s) -
MacPhie R. H.
Publication year - 1979
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 - 10.1029/rs014i006p01185
Subject(s) - wideband , interferometry , equivalence (formal languages) , isotropy , mathematics , physics , frequency band , optics , space (punctuation) , mathematical analysis , bandwidth (computing) , telecommunications , computer science , pure mathematics , operating system
A narrow‐band correlation interferometer using directive (large) antennas is equivalent to a wideband correlation interferometer employing isotropic (small) antennas. This concept of space frequency equivalence, due to Kock and Stone, is reexamined and is shown to hold exactly only for the mean or expected values of the correlation interferometer outputs. If their variances are considered, the equivalence disappears, with the variance of the wideband system always equal to or greater than that of the narrow‐band system.