Integrated antenna aperture

Claim 1

In a microwave landing system providing narrow scanning beam of microwave energy for guiding an aircraft during approach and landing and providing data signals transmitted in a broad pattern so as to be receivable in a greater area than the area covered by said narrow scanning beam, said system including a phased array antenna having a plurality of radiating elements with adjustable phase shifter means for adjusting the relative phases of currents radiated by said elements and signal sequence control means for controlling the sequence of transmission of said narrow beam signals and said broad beam signals, the improvement comprising means for applying non-uniform values of phase shift to said phase shifters of said array to broaden the antenna pattern of said array, said non-uniform values of phase satisfying the relationship d.sup.2 φ(x)/dx.sup.2 =c f.sup.2 (x)/P (θ) wherein c is a constant; f(x) is the aperture illumination function; θ is the space angle; x is the distance along the array; and φ(x) is the non-uniform phase function; and means applying uniform values of phase shift to said phase shifters of said array to cause said array to transmit with a narrow pattern in a direction determined by the value of said uniform phase shifts; said sequencer selecting said means for applying non-uniform values of phase shift or said means for applying uniform values of phase shift according to whether or not transmission in a broad beam antenna pattern is desired.

Claim 4

The method of operating a phased array antenna to provide transmission of signals with broad beam coverage and transmission of signals with narrow beam coverage in ordered sequence, said antenna having a plurality of radiating elements and adjustable phase shifters for controlling the relative phases of currents in said elements, comprising adjusting said phase shifters each to a value of phase shift specified by a set of non-uniform values of phase shift derived from a relationship between the phase shift φ(x) at an element of said array located a distance x along said array is such that the second derivative with respect to x of said relationship, d 2 φ(x)/d x 2 , is proportional to the ratio of the square of the amplitude of excitation, f 2 (x), of said element to the desired broad beam pattern, P(θ); exciting the elements of said array with radio frequency energy to transmit signals with broad beam coverage defined by said broad beam pattern, P(θ); removing said non-uniform values of phase shift from said phase shifters; readjusting said phase shifters to uniform values of phase shift such that the difference between values of phase shift for adjacent elements of said array is constant; and exciting the elements of said array with radio frequency energy to transmit signals with narrow beam coverage.

Claim 5

The method of operating a phased array antenna to provide transmission of signals with broad beam coverage and transmission of signals with narrow beam coverage in ordered sequence, said antenna having a plurality of radiating elements and adjustable phase shifters for controlling the relative phases of currents in said elements, comprising adjusting said phase shifters each to a value of phase shift specified by a set of non-uniform values of phase shift derived from a relationship between the phase shift φ(x) at an element of said array located a distance x along said array is such that the second derivative with respect to x of said relationship, d 2 φ(x)/d x 2 , is proportional to the ratio of the square of the amplitude of excitation, f 2 (x), of said element to the desired broad beam pattern, P(θ); exciting the elements of said array with radio frequency energy to transmit signals with broad beam coverage defined by said broad beam pattern, P(θ); removing said non-uniform values of phase shift from said phase shifters; readjusting said phase shifters to uniform values of phase shift such that the difference between values of phase shift for adjacent elements of said array is constant; and exciting the elements of said array with radio frequency energy to transmit signals with narrow beam coverage.