A STUDY OF SUPERGAIN ARRAYS.
Abstract
A supergain array is one designed for maximum directivity index (MDI). For a linear array of N point elements spaced equally at integral halfwavelengths, with uniform in-phase excitation, the MDI equals 10 log N. For element spacings less than one-half wavelength, MDI requires outof-phase excitation and a relatively large range of amplitudes which must be controlled with extreme accuracy. The aplitude shading required for MDI in wide-band reception may be determined by considering the space noise correlation function. The presence of self-noise in the individual elements of an array or their preamplifiers may seriously reduce the effective gain of the array designed for MDI. This degradation of performance is particularly enhanced if the amplitude shading of any of the elements is considerably larger than the overall value required for uniform shading. The synthesis problem for realizing supergain is discussed. Finally, the noise figure of a piezoelectric hydrophone-cableamplifier circuit and the source impedance required to minimize it, is calculated. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 07, 1965
- Accession Number
- AD0455624
Entities
People
- Alan Winder