An array antenna includes a ferrite substrate having a two-dimensional planar array of antenna elements disposed over a first surface thereof and means for applying an external magnetic field having a magnitude and direction which can be varied at least in a plane in which the antenna elements lie. The amplitude and direction of the external magnetic biasing field is varied to control the relative phases between each of the plurality of antenna elements and to steer the direction of a main antenna beam in two dimensions.

Antenna array having two dimensional beam steering

Phased array antennas can steer transmitted and received signals without mechanically rotating the antenna. Each radiating element of a phased array is normally connected to a phase shifter, which determines the phase of the signal at each element to form a beam at the desired angle. The most commonly used phase shifters are ferrite and diode phase shifters. Phase shifters using ferroelectric materials have been proposed previously. A typical phased array may have several thousand elements and is very expensive. Therefore, reducing the cost and complexity of the phase shifters and the phase shifter controls is an important consideration in the design of phased arrays. The phased array described uniquely incorporates bulk phase shifting, the array does not contain individual phase shifting, using a ferroelectric material along with simpler phase shift control. Bulk phase shifting using diodes has been proposed and developed in the Radant lens. The lens described uses a voltage controlled ferroelectric, which introduces an analog phase shift rather than a digital phase shift as in the Radant lens. The ferroelectric lens has further advantages of smaller lens thickness, higher power handling, simpler beam steering controls, and it uses less power to control the phase shift compared to the Radant lens. Thus, it can potentially lead to low cost phased arrays.

Voltage controlled ferroelectric lens phased arrays

A device (10) for changing the divergence of a beam of microwave radiation comprises a ferrite body (12) having an aperture through which the beam passes. Magnetic means in the form of a plurality of wires (20) passing both through the body (12) and across the aperture or in the form of a coil on either side of the aperture causes a differential phase delay as the beam passes through the aperture which broadens or narrows the beam.

Magnetic beam deflection devices

A millimeter wave imaging system includes a plurality of millimeter wave radiometer elements disposed in a sparse antenna array integrated into a lower surface of an airborne vehicle The antenna elements preferably form a cross or T-shaped sparse array Images are formed using interferometric techniques Each radiometer element includes a receive antenna coupled to an electronic mirror which provides beam steering To compensate for deflection of the airborne vehicle, a mechanical deflection measurement system is provided Additional radiometer elements having transmitter antenna elements may be integrated into the sparse array to provide active illumination to enhance image formation and to operate as target designators

Large aperture vibration compensated millimeter wave sensor

A lens is provided. The lens includes a first two-dimensional (2-D) grid of capacitive patches and a first sheet layer. The first sheet layer includes a dielectric sheet and a second 2-D grid of capacitive patches. The dielectric sheet has a front surface and a back surface. The first 2-D grid of capacitive patches is mounted directly on the back surface of the dielectric sheet, and the second 2-D grid of capacitive patches is mounted directly on the front surface of the dielectric sheet. The first 2-D grid of capacitive patches is aligned with the second 2-D grid of capacitive patches to form a time delay circuit at each grid position of the aligned 2-D grids.

True-time delay, low pass lens

A radiating element (10) having a continuous aperture substantially greater than one half the center frequency wavelength for use in an electronically scanned phased array antenna operating in the range of 94 GHz. The new radiating element comprises a ferrite block (12) having a radiating aperture which measures 5 lambda by 5 lambda in contrast to the conventional discrete radiating element which measures one-half lambda by one-half lambda. A tapered magnetization (see lines 22) is applied to the continuous aperture ferrite block (12). The degree of phase shift can be varied by adjusting the slope of the tapered magnetization. This permits scanning of the continuous aperture pattern. When a plurality of such continuous aperture subarrays is used to form an antenna array (80 or 100), provision is made to adjust the phase at the center of each continuous aperture subarray with respect to the phase of the adjacent subarrays, thereby allowing scanning of the entire pattern of the phased array antenna (100).

Joseph M. Hellums

Papers

Continuous ferrite aperture for electronic scanning antennas