Communications: radio wave antennas – Antennas – Active sleeve surrounds feed line
Patent
1998-03-27
2000-03-07
Wong, Don
Communications: radio wave antennas
Antennas
Active sleeve surrounds feed line
343791, 343792, H01Q 904
Patent
active
060346485
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
This invention relates to antennae which are capable of being used for signal transmission and/or reception purposes at radio and microwave frequencies.
Antennae capable of operating in the radio and/or microwave frequency range are commonly attached to, or incorporated within, electrical equipment for use in the home, commercial or laboratory environments, such as televisions, radios, cellular telephones, and wireless local area networks (WLANS). One known type of antenna is the conventional "loop-type" antenna which essentially consists of a tuned loop of wire designed to receive or radiate signals at frequencies falling within a relatively narrow usable frequency bandwidth which may, typically, be approximately 50-60 MHz wide. Such antennae have the disadvantage of having directional radiation properties the effect of which is that the antenna needs careful orientational adjustment in order to operate effectively. Moreover, the antenna is incapable of receiving or radiating signals at frequencies falling outside its relatively narrow operational bandwidth.
Another known type of antenna is the "quarter wave" antenna which generally consists of an elongate antenna element whose length is chosen to be equal to one quarter of the wavelength at the desired optimum operating frequency of the antenna and which operates against an electrical ground which is usually provided by the earthed outer conducting element of a coaxial cable, the antenna element being connected to the central signal carrying element of the cable. Although such antennae have omni-directional radiation characteristics, they also have the disadvantage of operating effectively only over a fixed, relatively narrow frequency bandwidth. The antenna element of such quarter-wave antennae may often be telescopic such that the length of the element may be varied by a user. Such antennae still require careful adjustment by the user in order to operate at different frequencies which can be time consuming and frustrating for the user. Such variable length antennae are, moreover, unsuitable for use in, for example, local area networks and cellular radio communications applications where constant antenna adjustment is not a viable option for maintaining effective operation.
SUMMARY OF THE INVENTION
It is an object of the present invention to overcome one or more of the foregoing disadvantages and to provide an antenna having a relatively broad usable bandwidth and substantially omni-directional radiation characteristics.
According to the present invention, an antenna comprises a first elongate antenna element of fixed predetermined length, a proximal end of which is electrically connected, in use, to a signal carrying conducting element of an apparatus with which the antenna is used, and a second antenna element of fixed predetermined length, a proximal end of which is electrically connected to the proximal end of the first antenna element, the length of the second antenna element being substantially less than the length of the first antenna element and the second antenna element being formed and arranged so as to extend substantially around a proximal end portion of said first antenna element so as to substantially screen said proximal end portion, with the proximal end portion of the first antenna being supported by a body of dielectric material disposed between said first and second antenna elements, said proximal end portion of the first antenna element being electrically insulated from said second antenna element by said body of dielectric material.
One advantage of the antenna of the present invention is that it has two optimum operating frequencies (i.e. resonant frequencies), each with an associated usable bandwidth. This is due to the fact that in combination said first and second antenna elements operate together like a single quarter wave antenna having a total length equal to the distance from a distal end of the first element to the signal carrying conducting element of the apparatus with which the antenna is
REFERENCES:
patent: 3945013 (1976-03-01), Brunner et al.
patent: 4400702 (1983-08-01), Tanaka
patent: 4658260 (1987-04-01), Myer
patent: 5317327 (1994-05-01), Piole
patent: 5473336 (1995-12-01), Harman et al.
patent: 5565880 (1996-10-01), Wang et al.
patent: 5604506 (1997-02-01), Rodal
patent: 5668564 (1997-09-01), Seward et al.
Galtronics (UK) Limited
Nguyen Hoang
Wong Don
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