Common aperture reflector antenna with improved feed design
AssigneeRaytheon Company
InventorsKenneth W. Brown, Thomas A. Drake
Life of this patent
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Abstract
A common aperture reflector antenna and feed are provided for use in common aperture sensor systems. The feed includes an array of individual elements. The array elements are configured to increase the overall efficiency of a reflector antenna by flattening the aperture illumination, and also by nullifying the illumination within the centrally-blocked-portion of the reflector antenna surface. More specifically, the array elements are carefully configured with respect to spacing and excitation, for example, such that the array illuminates only the non-blocked portion of the main reflector. In addition, the array pattern is optimized such that the non-blocked portion of the reflector antenna is quasi-uniformly illuminated.
Claims20
A common aperture reflector antenna, comprising:
- a main reflector having a generally parabolic reflective surface and a boresight axis extending from a vertex of the main reflector through a focal point of the main reflector;
- a feed located generally at the focal point for illuminating the main reflector with and/or receiving from the main reflector radio frequency (RF) energy of a predefined RF wavelength to transmit/receive RF energy;
- and
- at least one of a sub-reflector and a sensor located generally at the focal point for reflecting or receiving energy of a predefined wavelength different from the predefined RF wavelength,
- wherein a blockage of the main reflector due to the sub-reflector or the sensor along the boresight axis is equal or greater than a blockage of the main reflector due to the feed, and
- the feed is configured to direct a majority of RF energy from the feed towards regions of the main reflector which are not blocked by the sub-reflector or the sensor.
A method for designing a common aperture reflector antenna which includes a main reflector having a generally parabolic reflective surface and a boresight axis extending from a vertex of the main reflector through a focal point of the main reflector, a feed located generally at the focal point for illuminating the main reflector with and/or receiving from the main reflector radio frequency (RF) energy of a predefined RF wavelength to transmit/receive RF energy, and at least one of a sub-reflector and a sensor located generally at the focal point for reflecting or receiving energy of a predefined wavelength different from the predefined RF wavelength, wherein a blockage of the main reflector due to the sub-reflector or the sensor along the boresight axis is equal or greater than a blockage of the main reflector due to the feed, the method comprising the steps of:
- selecting an initial estimate for a feed array making up the feed on a basis of blockage of the main reflector due to the sub-reflector or the sensor and at least one of a number of array elements, spacing of the array elements, amplitude excitation of the array elements, diameter of the main reflector and focal length of the main reflector;
- evaluating a performance of the feed array based on the initial estimate;
- computing a figure of merit indicative of the RF efficiency of the antenna based on the evaluated performance;
- and
- optimizing the RF efficiency by altering the initial estimate and reevaluating the performance and figure of merit.
Dependencies are inferred from the claim text.