Method and apparatus for radio location

An apparatus for determining the direction of arrival of a traveling signal wavefront of measurable wavelength (.lambda.) comprising:

• a noncircular array of discrete sensor elements with a longest linear dimension, or separation, between at least two connected elements, that exceeds 1.22.lambda.;
• means for taking the phasor-difference between the outputs of pairs of spaced elements;
• and
• means for deriving from said phasor-differences the direction of propagation of said signal wavefront relative to a reference associated with said array.

An apparatus for determining the direction of arrival of a signal wavefront, comprising:

• a plurality of sensor elements arranged in a circular Adcock-array way, a diameter (D) of the array circle being greater than 1.22 times the wavelength (.lambda.) of the signal wavefront;
• and
• means for combining outputs of said sensor elements to determine a direction of arrival of the signal wavefront, said plurality of sensor elements further including a number, n, of discrete sensor elements that satisfies the condition
• .vertline.J.sub.n-1 (.beta.)/J.sub.1 (.beta.).vertline.<.epsilon..sub..theta.,sp,max
• where J.sub.n (.beta.) is the Bessel function of a first kind, n-th order and argument .beta.=.pi.D/.lambda., and .epsilon..sub..theta.,sp,max is a maximum design value of an azimuth error magnitude due to deviation of a phasor difference between outputs of diametrically separated pairs of said discrete sensor elements from linear dependence upon the cosine or the sine of an azimuth of arrival angle of said signal wavefront, due to the diameter spacing, D, between diametrically separated discrete sensor elements whose outputs are paired to be subtracted one from the other.