Cubic Defense Systems, Inc.

Bernard Berkowitz

Mark E Bonebright

Michael L Tentler

Paul R Eberhardt

William F McNaul

David J Miller

James Boelens

A planar array of linearly polarized antenna elements, each element tilted so that its polarization orientation is disposed at an angle with respect to the array vertical axis so that array polarization loss is minimized as a function of roll about an array normal. Half of the elements are tilted uniformly at a positive angle with respect to the array vertical axis and the remaining elements are tilted at a negative angle with respect to the array vertical axis. The invention substantially reduces the unwanted variation in received RF energy magnitude as a function of array roll angle caused by polarization loss, for both vertical and horizontal components. The vertically polarized signal component magnitude remains nearly constant with respect to array roll angle values of 50.degree.-60.degree. and more. If the element tilt angle magnitude is between 0.degree.-45.degree., the vertically polarized components from the two element groups are additive whereas the horizontally polarized components from the two groups are subtractive. Monopulse sum and difference outputs isolate the vertical and horizontal energy components. Broadside beam scanning without losing this roll compensation is possible if the two element groups are segregated into horizontal rows spanning the planar array.

Linear array dual polarization for roll compensation

A multimode low-profile avionics antenna is disclosed for use in Automatic Direction Finder (ADF) systems. The low profile antenna generates a steerable cardioid radiation pattern having a minimum bandwidth of 30% and an unusual degree of independence from mutual coupling and coupling to ground-plane currents. The antenna includes two resonant cavity-backed slot antennas. The upper cavity, which backs a directional crossed-slot antenna, is the larger of the two cavities. The shallow lower cavity is actually a short-circuited radial transmission line employing a stepped inner radius and band-switching to extend the operating bandwidth to the required 30%. The crossed-slot antenna elements are configured orthogonally and the slot ends are folded over the side of the cylindrical cavity to minimize the resonant cavity diameter for the requisite slot length. The slot width is stepped open at the crossover point to enhance antenna bandwidth and to provide for greater spacing between the symmetrically-located feedpoints. The shallow circumferential slot antenna is equipped with two band-switched inductances for wider bandwidth. The two stacked cavities have a combined height of less than 0.1.lambda. at the operating frequency and are suitable for use as a flush-mounted aircraft or helicopter ADF antenna.

Low-profile steerable cardioid antenna

A system for correcting phase errors in a space based radar system utilizing probes located in front of an array of lens elements of a phased array antenna. Included is a mechanism for supplying a stored perfect value signal indicative of the distance between the probes and lens elements for a perfect, nondeformed array, and the mechanism for receiving radiated pilot signals to supply an actual value signal indicative of the actual distance between the probes and the lens elements to determine an amount of structural deformation. A mechanism is provided for measuring the difference in phase between the perfect value signal and the actual value signal to supply a deformation phase correction signal to adjust the beam steering command to correct for phase error introduced as a result of the measured structural deformation. Further disclosed is a system and method for effecting phase coherence across the array by utilizing a radiated reference pilot frequency pulse to each lens element. Any difference in phase between the measured reference pilot frequency pulse and a stored value is utilized to command a phase correction at each lens element utilizing a feedback loop for effecting phase coherence for the array, both on transmit as well as receive. Further disclosed is a method and system incorporating a digitally synthesized phase error correcting module with each lens element. In one embodiment, the correcting modules are dispersed among the lens elements utilizing an interpolation method for phase error correction.

Growing community of inventors

San Diego, CA, United States of America

Bernard Berkowitz