SOME THEORETICAL CONSIDERATIONS IN THE DESIGN OF DIRECTIONAL-NULL-TYPE ANTENNAS

摘要

The essential characteristics of directional-null-type antenna patterns as produced by the superposition of two primary antenna patterns phased 180 degrees apart are derived mathematically for the purpose of determining the design parameters and estimating the effect of their variation. Both omni-directional (in one plane) and directional types of primary antenna elements are considered. Equations are derived for the rate of change of field strength with azimuth angle near the central null and for the angular position of the first maximum. The effects of squinting the beams by intro¬ducing an angular displacement between the directions of maximum gain are considered as well as the effects of mutual impedance and inequalities of current amplitude, phase, and primary antenna patterns.