Communications: radio wave antennas – Antennas – Wave guide type
Reexamination Certificate
1999-12-13
2001-03-13
Wong, Don (Department: 2821)
Communications: radio wave antennas
Antennas
Wave guide type
C343S776000, C343S786000, C343S853000
Reexamination Certificate
active
06201508
ABSTRACT:
BACKGROUND
The present invention relates generally to satellites, and more particularly, to a low cost, injection molded phased array antenna system that may advantageously be used on satellites.
In addition to lower costs and shorter delivery schedules, the current trend in synchronous orbit satellites and satellite antennas is to provide more power and more payload capability, including more independent antenna beams. Satellite antennas while meeting other requirements must be low cost, quickly produced and mount to available spacecraft mounting locations. Also, the spacecraft with antennas and solar arrays must fit within the shroud of the launch vehicle. Spacecraft mounting space and shroud volume are limited, and larger launch vehicles with larger shrouds are costly.
Transmit and receive functions are often separated into two antennas, each covering a narrow bandwidth, resulting in a reduction in transmit feed system losses and an improvement in antenna beam shape optimization efficiency. Improved transmit antenna performance reduces the high costs associated with supplying more solar array DC power, traveling wave tube amplifier (TWTA) RF power, and thermal control.
A deployed shaped-reflector antenna is frequently used to satisfy transmit requirements and an earth facing, deck-mounted reflector antenna is used to satisfy receive functions. An earth deck structure is necessary to hold the receive antenna reflector, subreflector and RF feed. At Ku-band, the projected aperture of the earth deck antenna diameter is typically 1.2 meters. The reflector, subreflector and structure are made of graphite composite materials.
It would therefore be advantageous to have an improved phased array antenna system which may be used on satellites that improves upon conventional antennas.
SUMMARY OF THE INVENTION
The present invention provides for an injection molded phased array antenna system that may advantageously be used on satellites. The phased array antenna system comprises a plurality of metal plated, injection molded plastic waveguide components. A reduced-to-practice embodiment of the phased array antenna system includes five injection molded plastic components, some of which require no secondary machining, while some require minimal secondary machining.
More particularly, the phased array antenna system comprises a plurality of metal plated, injected-molded radiation elements that include a plurality of metal plated, injected-molded horn radiating elements. A plurality of metal plated, injected-molded orthomode junctions are respectively coupled to the horn radiating elements. A crossed septum is preferably disposed in the radiating aperture of each horn radiating elements that equalizes E and H-plane radiation and increases radiating element gain. A noncontacting through port septum and a side port septum are disposed in each of the orthomode junctions. 90 degree E- and H-plane waveguides are coupled to appropriate side ports of the orthomode junctions. Vertical and horizontal metal plated, injected-molded phase shifters are coupled to each of the plurality of orthomode junctions.
A metal plated, injected-molded power combiner-divider network comprising a plurality of cascaded vertical polarization and horizontal polarization power combiner-divider elements is coupled to outputs of the phase shifters and to outputs of the 90 degree E- and H-plane waveguides. Each power combiner-divider network is split along the broadwall of the waveguide and is riveted together. This method of constructing the power combiner-divider networks makes them relatively insensitive to perturbations. The broadwall split block technique used to produce the power combiner-divider networks allow accurate injection molding without electrical performance degradation.
A plurality of subassemblies are produced that comprise a pair of horns and orthomode junctions, a pair of two-way power combiners and four phase shifters interconnected using spring clips are coupled to a plurality of eight-way power combiner-divider networks and are secured together using an intermediate structural panel. The assembled plurality of subassemblies are coupled to sets of four-way power combiner-divider networks for each polarization and secured together using a main structural panel. Each set of four-way power combiner-divider networks respectively produces vertical and horizontal polarized outputs of the antenna system.
Near net dimensional, injection molding is used to reduce the required machining of the various components to a minimum. The phased array antenna system uses waveguide slip joints, snap together features, and clips for ease of assembly. The phased array antenna system has lighter weight, is produced at lower cost, with quicker fabrication and assembly, than conventional comparably performing antennas.
The use of the injected-molded components produces a densely packed package that is a physically small array. The use of the injected-molded components reduces or shortens lengths of waveguide runs and therefore reduces the insertion loss of the phased array antenna system. The slip joints allow components to slide or snap together. This eliminates fasteners and is less sensitive to alignment, and allows the use of clips for ease of assembly.
REFERENCES:
patent: 4527165 (1985-07-01), De Ronde
patent: 5517203 (1996-05-01), Fiedziuszko
patent: 5623269 (1997-04-01), Hirshfield et al.
patent: 5886671 (1999-03-01), Riemer et al.
patent: 5977910 (1999-11-01), Matthews
patent: 5995062 (1999-11-01), Denney et al.
Bruno Richmond D.
Metzen Phillip L.
Smith Terry M.
Float Kenneth W.
Nguyen Hoang
Space Systems Loral, Inc.
Wong Don
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