US 4,513,290 AGranted

Non-resonant coaxial monopole antenna

AssigneeSperry Corporation

InventorsDonald K. Lefevre, Patrick W. Dennis, Dennis F. Seegmiller

Life of this patent

Estimating the term…

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Abstract

A relatively short broad band monopole coaxial antenna is provided with a center conductor and an outer radiator. The antenna is mounted above a ground plane and comprises a bare outer radiator portion adjacent the ground plane and a portion remote from the ground plane which is covered with a variable thickness microwave absorbent material. The signal to be transmitted is applied to the base of the monopole antenna adjacent the ground plane. Non-radiated signals propagate up the antenna. The high frequency components are absorbed by the microwave absorbing material. A tip matching network and a base matching network are coupled between the outer conductor and the ground plane for attenuating and matching the low frequency components of the non-radiated signals. The resulting monopole coaxial antenna has no undesirable reflections and has the appearance of infinite effective length antenna.

Claims17

Dependent claims

A non-resonant broad band monopole antenna comprising:

a ground plane,
a coaxial input line having a center conductor, and an outer shield which is connected to said ground plane below said ground plane,
a fractional wavelength coaxial monopole antenna extending from said ground plane having a center conductor, and an outer radiator which is connected to said center conductor of said coaxial input line,
said monopole antenna having an exposed ground plane portion and a tip portion,
tip matching means coupled between the center conductor and the outer radiator of said coaxial antenna at the tip portion end remote from said ground plane,
base matching means coupled between the center conductor of said coaxial antenna and said ground plane at the ground plane portion end of said coaxial antenna, and
absorbing means covering a portion of said outer radiator of said coaxial monopole antenna remote from said ground plane,
said absorbing means having a thickness which varies along the length of the antenna increasing in thickness toward said tip matching means,
whereby said fractional wave length monopole antenna displays an equivalent infinite wavelength over a broad band of frequencies.

6 more elements

Dependencies are inferred from the claim text.

Facts

Application: 06/488,485Filed 25 Apr 1983
Granted: 23 Apr 1985
Term ends: Not estimatedThe source records don’t support an estimate.

Classification5 codes

H01Q 9/30
Resonant antennas: with feed to end of elongated active element, e.g. unipole
H01Q 9/005
Electrically-short antennas having dimensions not more than twice the operating wavelength and consisting of conductive active radiating elements:…
H01Q 9/02
Electrically-short antennas having dimensions not more than twice the operating wavelength and consisting of conductive active radiating elements:…
H01Q 17/001
Devices for absorbing waves radiated from an antenna; Combinations of such devices with active antenna elements or systems: for modifying the…