Communications: radio wave antennas – Antennas – Antenna with parasitic reflector
Reexamination Certificate
1998-10-09
2001-03-06
Wimer, Michael C. (Department: 2821)
Communications: radio wave antennas
Antennas
Antenna with parasitic reflector
C343S909000, C343S912000, C343S916000
Reexamination Certificate
active
06198457
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a satellite data link and, more particularly to satellite antennas designed to be lightweight and have low-windload.
2. Description of the Prior Art
It is desirable in many applications involving the transmission and reception of microwave signals to provide a reflector/antenna to alter the travel of the signal to a focal point for reception. Such reflectors/antennas are commonly used on merchant and naval ships for establishing communications links. For example, commercial C-band satellites are currently in place which provide a high data rate connection, anywhere on the world's oceans, from ship to shore and back.
The C-band satellite systems (4 GHz downlink, 6 GHZ uplink) currently are the only satellite systems that provide full worldwide deep ocean coverage. High data rate C-band satellite communications systems typically require large antenna apertures for low cost, long term efficient operation. To date, high data rate communication systems have been limited to the largest ships due to the sail factor or windload presented by the large antenna and the corresponding dedicated space requirements for the antenna (large volume radome and associated platform).
Thus, it would be desirable to provide a low-windload satellite reflector for receiving and transmitting C-band communications signals which may be used on any size vessel. Furthermore, it would be advantageous to make the satellite reflector with a small footprint for mounting to a deck. Still another desirable feature would be to make the antenna deployable so that it may be taken down and easily deployed elsewhere on the vessel should the current mounting space be needed for other reasons.
OBJECTS AND SUMMARY OF THE INVENTION
It is an object of the present invention to provide a satellite reflector/antenna which has a low-windload so that it may be mounted anywhere upon any size vessel.
It is a further object of the present invention to provide a satellite reflector/antenna which is deployable, i.e., the reflector is easily dismantled and reassembled for deployment at another location if desired.
It is still a further object of the present invention to provide a low-windload satellite reflector/antenna and associated communications system capable of communicating with existing commercial C-band satellites.
It is yet another object of the present invention to provide a low-windload satellite reflector/antenna which has highly reflective properties only near the desired frequencies of operation and being substantially transparent outside the desired frequency bands.
In accordance with the present invention, a satellite reflector/antenna includes a reflector mounted to a pedestal wherein the pedestal has a base for mounting to a horizontal surface, such as a deck of a ship. The reflector is mounted to the opposite end of the pedestal by means of a steering platform capable of aiming the reflector at a desired satellite. The reflector may be either parabolic or substantially flat in shape. The reflector further includes an outer frame assembly. The frame assembly may include a plurality of radially extending spaced apart support arms extending to an outer periphery of the reflector as well as annular axial support members attached thereto. In a first embodiment, a grid-like support structure is mounted within the frame assembly. In a second embodiment, the support arms and axial support members define therebetween a subframe in which a grid-like support structure is provided. In either embodiment, the grid-like support structure has apertures therethrough such that grid intersections are spaced up to about &lgr;/2 wavelength apart, where &lgr; is a desired wavelength of energy to be received by the antenna. Reflective radiators are arranged and mounted to the support assembly for reflecting a desired wavelength to a focal point of a reflector. A feed assembly is provided at the focal point of the assembly for receiving/transmitting energy at the desired frequency.
In accordance with the present invention, the support assembly is preferably made from a dielectric material and is parabolic in shape, although the reflector may take many different shapes. The support assembly is also formed in several parts, e.g., four quadrants, which can be mounted together to form the reflector making assembly/disassembly of the relatively large reflector easy so that it may be deployed in a different location should the need arise.
The reflective radiators are preferably in the form of dipoles which are particularly dimensioned to reflect energy of a selected frequency of operation. The dipoles are mounted to the support structure and, more specifically are in the shape of a cross such that the dipoles are mounted to intersections formed in the grid-like support structure. In order to effectively operate with existing C-band satellites, the antenna is frequency selective to the specific frequencies of operation for C-band communications. In a preferred embodiment, a first set of dipoles are mounted to a front surface of the support assembly for reflecting energy at a frequency F
1
and a second set of dipoles are mounted to a back surface of the reflector support assembly for reflecting energy at a frequency F
2
, wherein the frequencies F
1
and F
2
are different. It is envisioned however, that the antenna may be set up to receive as few as one frequency or a number of frequencies, depending upon the requirements of the system. The system further includes electronics for processing received signals and generating signals for transmission by the antenna. The antenna is electrically connected to the electronics, preferably via fiberoptic cables or a waveguide and coaxial cables.
A preferred form of the satellite reflector/antenna and associated communications systems, as well as other embodiments, objects, features and advantages of this invention, will be apparent from the following detailed description of illustrative embodiments thereof, which is to be read in connection with the accompanying drawings.
REFERENCES:
patent: 3893123 (1975-07-01), Bieser
patent: 4348677 (1982-09-01), Salmond
patent: 4647943 (1987-03-01), Metcalfe
patent: 5485167 (1996-01-01), Wong et al.
patent: 5543809 (1996-08-01), Profera
patent: 5554999 (1996-09-01), Gupta et al.
Flaps™ Reflector Antennas, Malibu Research, publisehd at least as early as 1993.
Specification Sheet, “Low-Windload Flaps™ Antennas”, published at least as early as 1993.
Specification Sheet, DMSP/HRPT Tracking Antenna System:, published at least as early as 1995.
Gonzalez Daniel G.
Pollon Gerald E.
Walker Joel F.
Hoffmann & Baron , LLP
Malibu Research Associates, Inc.
Wimer Michael C.
LandOfFree
Low-windload satellite antenna does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Low-windload satellite antenna, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Low-windload satellite antenna will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2516900