Communications: radio wave antennas – Antennas – With aircraft
Reexamination Certificate
1999-05-10
2001-03-27
Wong, Don (Department: 2821)
Communications: radio wave antennas
Antennas
With aircraft
C343S708000
Reexamination Certificate
active
06208304
ABSTRACT:
FIELD OF INVENTION
This invention relates to phased array antennas and specifically to aircraft mounted antenna arrays.
DESCRIPTION OF THE RELATED PRIOR ART:
Antenna arrays mounted on aircraft are a fact of life in today's world. Commercial aircraft are equipped with phased antenna arrays that track orbiting satellites to enable communications. Such communications can be between two aircraft or between an aircraft and ground based stations. The tracking is accomplished by phased array antennas that effectively track the satellite until it is either below the aircraft's horizon or the signal received by the aircraft is too weak to be of any use. The satellite's movement can be in any direction relative to the direction of the aircraft. For effective tracking of such satellites, the phased array antenna must be properly located on the aircraft to maximize the antenna's exposure to the satellite. This means having an antenna system that can track a satellite over the entire upper hemisphere of the aircraft.
A number of approaches have been taken to properly locate and track the orbiting satellite. One possible approach is the use of a rotating radome mounted atop an aircraft. This approach, used by military battle management aircraft, is impractical for commercial aircraft. Not only is it expensive but also quite cumbersome.
Another approach, taken by Ganz et al. and disclosed in U.S. Pat. No. 4,336,543, is to mount the antenna array on the extensions to the aircraft fuselage. Ganz et al. discloses mounting the antenna arrays inside the wings. Also disclosed in the same patent is the idea of mounting antenna arrays on the sides of the fuselage and on the flat portions of the stabilizer. (See
FIG. 1
) While this concept of installing antenna arrays on or within the airfoil surfaces of the aircraft, such as on the leading edges of the wing and on the horizontal stabilizer trailing edge, is useful, it has a number of drawbacks. As Ganz et al. envision it, the forward looking antenna elements are mounted on the forward section of the wing. This prevents the scanning beam from scanning behind the aircraft. The antenna elements mounted on the horizontal stabilizer trailing edge may solve the backward scanning difficulty yet this configuration can only work with an aircraft having a large stabilizer and not with all aircraft types.
Another related approach is that taken by Canonico in U.S. Pat. No. 4,749,997. In this document, Canonico discloses mounting the antenna arrays within the wing and having a hinged radome to permit easy access for servicing. Unfortunately, this configuration also suffers from the same drawbacks as the Ganz et al. device.
A better approach is taken by Maynard in U.S. Pat. No. 3,737,906. In that document, Maynard discloses mounting a fixed linear array of dipole elements on the upper parts of the aircraft. The scanning advantages of this configuration are readily apparent by examining the possible scanning patterns of such a device. (See
FIG. 2
) Unfortunately, such a device also has a number of drawbacks. Specifically, these drawbacks relate to a complete loss of gain as the scanning beam moves towards zenith. At zenith, when the satellite is directly over the aircraft, the dipole element has a gain null and the array cannot be used for communications in this direction.
Another approach is the use of conformal rectangular phased arrays. However, such arrays suffer from large scan losses in all planes with the loss being roughly proportional to the cosine of the scan angle. At the horizon, the received signal power is typically far below the detection threshold.
From the above, it can be seen that there is a need for an aircraft mounted antenna system that provides not only a scanning area over the entire upper hemisphere but also a near constant gain over that same scanning area.
SUMMARY OF THE INVENTION
The present invention seeks to overcome the deficiencies identified in the prior art by providing an antenna system which can scan and provide a constant gain over the entire upper hemisphere.
The present invention seeks to provide an antenna system comprising a plurality of linear blade phased array assemblies mounted on an upper half of an aircraft fuselage wherein the longitudinal axis of the fuselage is parallel to the longitudinal axis of each blade array and each array plane containing the longitudinal axis of the fuselage and the longitudinal axis of a blade array is at an angle with a plane vertically bisecting the upper half of the fuselage.
Preferably, there is an equal number of blade arrays on either side of the bisecting plane.
Also preferably, the system includes a blade array located substantially between the upper right quarter of the fuselage and the upper left quarter of the fuselage.
Conveniently, a symmetry angle between an array plane in the upper right quarter of the fuselage and the bisecting plane is substantially equal to an angle defined by an array plane in the upper left quarter of the fuselage and the bisecting plane. Even more conveniently, the symmetry angle is 45 degrees. Also conveniently, the number of blade arrays is two. Preferably, the system further includes a plurality of circularly polarized antenna elements arranged in rows on each blade array. Also preferably, on each blade array the number of elements in each row is at least ten times the number of rows on that blade array.
More preferably, each blade array has 192 antenna elements arranged in three rows of 64 elements per row.
In another embodiment of the invention, there is provided an antenna array system for communicating between an aircraft and an orbiting satellite comprising a plurality of antenna blade arrays longitudinally mounted on an upper portion of an airframe such that there is symmetry between the upper right side of the airframe and the upper left side of the airframe.
In yet another embodiment, there is provided a method of locating blade antenna arrays on an upper portion of an aircraft fuselage, the method comprising:
i) providing a plurality of linear blade phased antenna arrays;
ii) mounting an equal number of blade arrays on each side of the fuselage.
Conveniently, step ii) includes the step of symmetrically mounting the blade arrays on each side of a plane that vertically bisects the fuselage.
More conveniently, the method includes the step of locating a blade array on the fuselage such that the blade array is located on a plane that vertically bisects the upper portion of the fuselage.
In yet another embodiment of the invention, there is provided a method of improving the communication between an aircraft and an overhead satellite comprising: providing a plurality of linear blade phased antenna arrays, and symmetrically mounting an equal number of blade arrays on each side of the aircraft fuselage.
The advantages of the present invention are numerous. Mounting the blade arrays on the upper portion of the fuselage gives a scanning area that covers the whole upper hemisphere. Also, having an equal number of blade arrays on each side of the fuselage provides equal coverage and scanning area for each side of the aircraft. Because the blade arrays are arranged at an angle to the top of the aircraft, the problem of gain decrease due to large scanning angles is eliminated. Also, the balanced character of the blade arrays has the further benefit o balancing the airflow over the top of the aircraft, as opposed to a single blade array configuration.
REFERENCES:
patent: 3737906 (1973-06-01), Maynard
patent: 3836971 (1974-09-01), Bickel et al.
patent: 4336543 (1982-06-01), Ganz et al.
patent: 4405986 (1983-09-01), Gray
patent: 4749997 (1988-06-01), Canonico
patent: 5382959 (1995-01-01), Pett et al.
patent: 5889491 (1999-03-01), Minter
patent: 5927648 (1999-07-01), Woodland
patent: 5945943 (1999-08-01), Kalafus et al.
Chen Shih-Chao
EMS Technologies Canada Ltd.
Pascal & Associates
Wong Don
LandOfFree
Aircraft mounted dual blade antenna array does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Aircraft mounted dual blade antenna array, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Aircraft mounted dual blade antenna array will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2457461