Communications: radio wave antennas – Antennas – With aircraft
Reexamination Certificate
1999-12-27
2001-01-16
Wong, Don (Department: 2821)
Communications: radio wave antennas
Antennas
With aircraft
C343S705000
Reexamination Certificate
active
06175336
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
(Not Applicable)
STATEMENT RE: FEDERALLY SPONSORED RESEARCH/DEVELOPMENT
(Not Applicable)
BACKGROUND OF THE INVENTION
The present invention generally relates to aircraft antennas and more particularly to an antenna component that is a structural member of the aircraft.
Modern aircraft have a need to provide radio communication over a variety of frequency ranges and communication modes. For example, radio communication may be in the VHF band using amplitude modulation (AM) and/or frequency modulation (FM) or in the UHF band. In order to communicate effectively, the aircraft must include multiple antennas dispersed on the aircraft. Typically, the aircraft will include antennas mounted behind a radio transparent skin of the aircraft, and/or exterior blade antennas mounted to the skin of the aircraft.
For effective communication, the antenna dimensions should be in the same order of magnitude as the wavelength of the signal being propagated. In this respect, the wavelength for operation in the VHF/FM band (i.e., 30-88 MHz) is approximately 3-10 meters. Accordingly, for effective communication within this band range, the antenna must have a size correspondingly large. However, this is not practical because an antenna of this size would be aerodynamically inefficient. Therefore, small blade antennas electrically matched through impedance tuning networks are used. The blade antenna is a small fin protruding from the skin of the aircraft that is used as the radiating element.
Blade antennas are aerodynamically inefficient because they protrude from the skin of the aircraft. Typically, multiple blade antennas are used on the aircraft for the multiple communications bands (i.e., UHF, VHF/FM, VHF/AM). The blade antenna exhibits poor performance characteristics at lower frequencies (i.e., 30-88 MHz). The blade antenna is constructed to withstand the forces subjected to the antenna, however the blade antenna is still susceptible to impact damage (i.e., break off). The blade antenna does not add any structural strength to the aircraft, and interferes with the aerodynamic efficiency of the aircraft.
The present invention addresses the above-mentioned deficiencies in prior aircraft antenna design by providing an antenna that is a structural member of the aircraft. In this respect, the aircraft antenna of the present invention is a structural member of the aircraft tail that electrically couples the skin of the tail to the antenna in order to provide a radiating element. Accordingly, the tail member of the aircraft becomes the antenna radiating element.
BRIEF SUMMARY OF THE INVENTION
A structural endcap antenna for a vertical tail of an aircraft. The endcap antenna comprises an outer skin having an inner surface and an antenna element disposed adjacent to the inner surface of the outer skin. The antenna element is in electrical communication with an RF signal source. Disposed adjacent to the antenna element is an inner support structure bonded thereto. The antenna element and the inner support structure are excited by the RF signal source and provide structural support to the endcap antenna.
In a first embodiment of the present invention the antenna element may be graphite or copper mesh. The antenna element typically wraps around the inner support structure of the endcap antenna. The inner support structure typically comprises a conductive portion and a non-conductive portion. The conductive portion is typically bonded to the antenna element. In the present invention, the conductive portion is aluminum honeycomb and the non-conductive portion is glass honeycomb. Additionally, the outer skin of the antenna endcap is 3-ply fiberglass. The endcap of the present invention further includes an end rib disposed adjacent to a bottom end thereof. The end rib may be configured to be a ground plane for the antenna element and may be fabricated from electrically conductive graphite, or conductively finished fiberglass.
The first embodiment of the present invention may be fabricated from two halves. In this respect, the endcap antenna comprises a first half having a first outer skin, a first antenna element and a first inner support structure. The second half comprises a second outer skin, a second antenna element and a second inner support structure.
In a second embodiment of the present invention, the copper mesh is disposed between two halves of the inner support structure and separated by a center fiberglass section. Accordingly, the second embodiment of the endcap will consist of first and second outer skins bonded to respective halves of the inner support structure. Bonded to respective halves of the inner support structure will be a first and second antenna element which will be bonded together with the center fiberglass section.
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Alt Kevin Herman
Coughlin Daniel Patrick
Durham Michael David
Kudva Jayanth Nandalke
Lacombe Peter
Anderson Terry J.
Hoch, Jr. Karl J.
Nguyen Hoang
Northrop Grumman Corporation
Wong Don
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