A reflector antenna system may include an arc-shaped antenna reflector defining a first antenna beam, and a phased array antenna positioned in the first antenna beam including first and second arrays of antenna elements coupled together in back-to-back relation. The first array may face the antenna reflector, and the second array may face away from it. A controller switchable between a reflecting mode and a direct mode may be connected to the arrays. The controller, when in the reflecting mode, may cause back-to-back pairs of first antenna elements from the arrays to define a feed-through zone for the first antenna beam, and cause second antenna elements in the first array to define a first active zone for the first antenna beam. Furthermore, when in the direct mode, the controller may cause antenna elements in the second array to define a second active zone for a second antenna beam.

Reflector antenna system including a phased array antenna operable in multiple modes and related methods

A two-step method is used to reconfigure beams among different orbital slots for a satellite system. The satellite is biased at one or more orbital slots for a back-up mission, while it looks at the sub-satellite point for the primary mission. Body steering is achieved using pitch and roll biases. The main reflector of the antenna is gimballed in order to steer the beams to different locations for the back-up mission. Beam size is controlled through the use of different sized reflectors and by varying the feed size. Different sized beams are interleaved among multiple reflectors.

Reconfigurable antenna system

Multi-directional antenna apparatuses, including phased array antennas and/or arrays of multiple antennas, and methods for operating them. In particular, described herein are access point (AP) antenna apparatuses for communicating with one or more station devices by assigning a particular directional beam to each access point, and communicating with each station device using the assigned directional beam. Methods and apparatuses configured to optimize the assignment of one or more directional beam and for communicating between different station devices using assigned directional beams are described. Also described are compact lacunated RF lenses that may be used with the multi-directional antenna apparatuses described herein, having a plurality of holes/openings through the lens body so that an electromagnetic signal entering the lens body from any of the input ports into the lens will exit from each of the output ports at a time delay corresponding to a predetermined steering angle.

Array antennas having a plurality of directional beams

We have seen in the above that the SweepSAR technique offers the potential for significant reductions in the transmit peak and average power required for a SAR system This is achieved by making full use of the areal extent of a reflector antenna on receive The SweepSAR rate is not as big a problem as it might appear initially: note that in the 30 years since Seasat launched downlink rates for LEO satellites have increased significantly — from ∼85Mbps up to ∼640 Mbps In addition, analog-todigital converters (ADCs) have increased in bandwidth from ∼ 20 MHz to several GHz

SweepSAR: Beam-forming on receive using a reflector-phased array feed combination for spaceborne SAR

A stepped reflector for being illuminated by at least one multiple-band feed is provided. The reflector includes a central region and a first annular region with an annular width of w. The first annular region is axially stepped a height h above the central region, where h is approximately equal to m x [ϕ ± (ϕ (Θ = 0)- ϕ (Θ=Θ0))]x π/180 xλ/2π x 1/2, where m is a positive odd integer, Φ is a desired amount of phase shift of an outer region of a phase front for reflecting off of the reflector, φ is a feed phase contribution for an angle θ, and Θo is an angle formed between an axis of the at least one feed and a line connecting a phase center of the at least one feed and an inner edge of the at least one annular region. The central region and the annular region of the reflector may be parabolically curved or may alternately be shaped. The reflector may be fed by one or more multiple-band horn antennas.

Stepped-reflector antenna for satellite communication payloads

A reconfigurable multiple beam phased array antenna has radiating elements arranged in a planar array and variable phase shifters. Each one of the phase shifters is connected to a respective one of the radiating elements. The array antenna further includes a beam forming network for forming spot and regional beam signals. The beam forming network forms a regional beam signal from a combination of spot beam signals. The beam forming network has two dimensional stacks of Rotman lenses provided with a first set of ports. Each one of the first set of ports is connected to a respective one of the radiating elements with. The Rotman lenses generate frequency invariant spot beam signals which are communicated between the radiating elements and the Rotman lenses via the first set of ports for transmission and reception of spot beams and regional beams by the radiating elements. The phase shifters are adjusted to steer the spot and regional beams to desired locations.

Reconfigurable multiple beam satellite phased array antenna

An antenna system and method for generating a desired contiguous spot beam pattern, and a signal is disclosed. The contiguous spot beam generating antenna system comprises a reflector system configured in a side-fed Cassegrain (SFOC) configuration, an array of feed horns comprising at least a subset of feed horns for illuminating the reflector system, and a beamforming network, communicatively coupled to the array of feed horns, for controlling an excitation of the subset of the feed horns in the array of feed horns. The method comprises illuminating a side fed offset Cassegrain reflector system with an RF signal emanating from an array of feed horns, and controlling an excitation of the subset of the feed horns. The present invention provides a beamformer network that can produce uniform performance over wide scan angles, is easier to integrate and test, that can change the beam pattern on orbit, and that provides a more complete utilization of space assets without dramatically increasing the cost of manufacturing and operating a satellite. The use of a SFOC configuration or other wide scanning antenna permits the use of a simple beamforming network while maintaining excellent beam beam scanning characteristics.

Multi-beam reflector antenna system with a simple beamforming network

A method and apparatus for producing contiguous spot beam communications coverage on the Earth's surface are disclosed. The apparatus comprises an antenna system including two wide scan antennas and two narrow scan antennas. The two wide scan antennas are disposed substantially opposite each other, and the two narrow scan antennas are disposed substantially opposite each other and substantially normal to the wide scan antennas. The first wide scan antenna, second wide scan antenna, and first narrow scan antenna produce a first beam pattern on a planetary surface and the first wide scan antenna, second wide scan antenna, and second narrow scan antenna produce a second beam pattern on the planetary surface.

Antenna cluster configuration for wide-angle coverage

A hybrid reflector antenna particularly suited for reflecting a frequency band in a satellite includes a central portion fully reflective to the frequency band. A first annular band is disposed directly adjacent to the central portion. The first annular band is partially reflective to the frequency band. The reflector may include several annular bands having various degrees of reflectivity and thus attenuation. The present invention may be implemented using two such reflectors, one for transmitting and one for receiving in a satellite, for either single or multiple beam applications. This invention offers more compact and lower mass/cost antenna configurations compared to conventional antennas from multiple beam satellite payloads.

Multiple beam antenna using reflective and partially reflective surfaces

An antenna configuration suitable for LEO/MEO satellites includes a plurality of lenses whereby each lens has a plurality of feed horns positioned with respect to the lens. The lens has a first surface and a second surface. The plurality of feed horns is disposed upon a curved surface. Each of the plurality of feed horns generates a beam that has a phase distribution. The phase distributions have a predetermined phase relationship with the first surface and preferably the second surface. This allows the lens to transmit and receive a signal with desired phase distribution across a cross-section of the beam. The beams from the plurality of lenses are inter-leaved on the ground to form a contiguous coverage with multiple overlapping spot-beams.

Philip H. Law

Papers

Reconfigurable multiple beam satellite phased array antenna

Multi-beam reflector antenna system with a simple beamforming network

Antenna cluster configuration for wide-angle coverage

Multiple beam antenna using reflective and partially reflective surfaces

Antenna configuration for low and medium earth orbit satellites