Reception of Nonhomogeneous Signal Fields in the Presence of Homogeneous Noise Fields

The reception of a nonhomogeneous signal field embedded in a homogeneous noise field, using a simple two-element subtractive array, is studied. For element spacing which is small compared to both the distance to the source and to the center-frequency-wavelength, the signal-to-noise improvement over a single element is shown to be independent of element spacing d, relatively independent of bandwidth and the noise spatial distribution, and to depend only on the distance to the signal source in wavelengths and on the signal ground-wave attenuation rate.