Adaptation by direct phase-shift adjustment in narrow-band adaptive antenna systems

Voltage-controlled phase shifters are used as the adjustable elements in an adaptive phased-array antenna system for spatial filtering of narrow-band inputs. A gradient-search adaptation algorithm for adjusting phase angle is developed and applied to an adaptive antenna system which can be adapted either to enhance signals or reject interference. The transient behavior of this system during adaptation is analyzed in terms of steepest ascent/descent on a multidimensional trigonometric performance surface approximated in two regions by quadratic surfaces.