Communications: radio wave antennas – Antennas – With radio cabinet
Reexamination Certificate
1999-05-20
2001-03-27
Le, Hoanganh (Department: 2821)
Communications: radio wave antennas
Antennas
With radio cabinet
C343S833000, C455S090300
Reexamination Certificate
active
06208300
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an antenna assembly for a hand-held radio device, and more particularly to a parasitic director element used in conjunction with a fed whip or shortened whip-type omnidirectional antenna.
BACKGROUND OF THE INVENTION
A need remains for antenna assemblies having characteristics of improved signal strength (gain) and front-to-back ratio, and reduced susceptibility to multipath interference. There have been a number of efforts in the past to provide an antenna for a portable radio communication device for at least the purposes of signal reception and transmission. These efforts usually have involved substantial intrusions into the limited space available to the transceiver electronics or substantial additions to the housing or substantial complexity, any or all of which factors render manufacturability difficult and costly.
SUMMARY OF THE INVENTION
This disclosure relates generally to an antenna assembly for a hand-held radio-frequency transceiver, examples of which include a cellular telephone and PCS device for the 800-900 MHz or 1850-1990 MHz frequency ranges, respectively. A multiple-element antenna assembly is utilized to provide improved performance characteristics, e.g., front-to-back ratio and gain. The antenna assembly may consist of an existing fed whip or shortened whip-type omnidirectional antenna of a typical transceiver and a user-attachable antenna enhancement device. In one embodiment, the antenna enhancement device is an “after-market” director element device which may be secured to an active antenna element (e.g., monopole or whip antenna element) of a typical cellular telephone or PCS device. In another embodiment, the antenna enhancement device may be incorporated into the handset and be transitioned into an operating position during transceiver use. The antenna enhancement device may include a single parasitic director element. During transceiver use, the parasitic director element is maintained a predetermined distance away from the active antenna element by a support member which may be formed of a dielectric material. The dielectric support member may include a securement device to attach the antenna enhancement device relative to the active antenna element. The securement device may include a plurality of differently sized securement rings adapted for use on a variety of transceivers. Several purposes and objects of the disclosed apparatuses are described herein. One object of the present disclosure is to provide an antenna assembly with improved directionality and reduced absorption of radio frequency radiation to a user of a cellular telephone or a PCS device.
The present invention includes an antenna assembly designed for use with PCS devices operating in the 1850-1990 MHz frequency range. The antenna assemblies as hereinafter described can also be used for wireless communication devices, such as a cellular telephones, wireless LANs, etc. Both portable and stationary antenna assemblies may utilize aspects of the present invention. The disclosed design technique provides an antenna assembly with improved performance characteristics and physical characteristics, i.e., ruggedness, simplicity, and low cost.
The antenna assembly according to the present invention provides a performance-enhancing director element spaced a predetermined distance away from an active antenna element by a support member. In one embodiment, the antenna enhancement device may be disposed upon a distal end of a dielectric support member. In another embodiment, the director element may be fixed in length and may be substantially elongated in form. In yet another embodiment, the antenna director element may be movably attached at the back side of the radio device from the support member. In an alternative embodiment, a pivotal antenna director element may be partially received or concealed within a portion of the back side of the radio device.
Additional improvements and benefits of the antenna assembly of the present invention include:
Increased signal strength, resulting in extended signal range and fewer dropped calls for a given power consumption rate;
Increased battery life for a given output signal level (for battery powered units);
Reduced radio frequency radiation incident to the user's body;
Increased in the front-to-back ratio; and
Reduced susceptibility to multipath interference.
The present invention has several objects. One object is to redistribute the radiation in the vicinity of the transceiver away from the user. Consistent with this object, the present invention alters the near-field radiation pattern surrounding the radio communication device. One benefit of an antenna assembly of the present invention is an attenuation in the radiation directed toward the user (and a concomitant reduction in the amount of radiated energy which is absorbed by a user) with an augmentation in the radiation directed away from the user thereby increasing the effective power of the radio transmission.
Another object of the present invention provides a radiation directing device suitable for use on or in conjunction with a variety of transceivers. The antenna enhancement device is positioned in proximity to the active antenna element on the opposite side of the antenna to the user. The materials out of which the antenna enhancement device is made may include dielectric materials, magnetically permeable materials, conductive materials, insulating materials, semiconducting materials, or combinations of these materials. The director element of the antenna enhancement device may include a conductor (which may be a wire form) and a dielectric support arm for supporting and maintaining the conductor element in proper relation to the active antenna element. In particular, polymer materials of construction of the antenna enhancement device may have, in order of preference, a dielectric constant of up to 10, or in the range of 2-3.
The antenna enhancement device according to the present invention is designed to be placed in proximity to the active antenna element, or in contact with the active element, or even form an extension of the active element. However, it can be appreciated that the director device does not act as a radiation shield so as to come between the active antenna element and the user.
In one embodiment, the present invention may take the form of an improved antenna assembly for a portable radio communication device which includes an elongate active antenna element adapted to be coupled in electrical communication to the radio device for generating a radiation field pattern. An example of such an active antenna element is a monopole or whip antenna element of a typical cellular phone or PCS device. The antenna assembly further includes a radiation director element which is disposed relative the active antenna member by a support member. During radio transmission, at least a portion of the antenna assembly's radiation field pattern is redirected away from the user by the parasitic director element. The parasitic director element may be an elongate conductive member positioned by the user in a preferred orientation generally parallel to the active antenna element.
The radio communication device radiates within a range of wavelengths corresponding to an operational bandwidth. The parasitic director element has a length of less than approximately one-half of a wavelength within the range of operational wavelengths. The parasitic director element may advantageously have a length of approximately 0.36 of a wavelength (0.36&lgr;) for a preselected wavelength within the range of operational wavelengths. In the present invention, the parasitic director element may be a short length of conductive material generally parallel to the active antenna member on a side away from the user.
The operation and usefulness of the device of the present invention for redistributing radiation depends on many of the design parameters chosen. The present invention includes a range of shapes, thicknesses, orientations and compositions of possib
Klos John F.
Larkin Hoffman Daly & Lindgren Ltd
Le Hoang-anh
RangeStar Wireless, Inc.
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