Communications: radio wave antennas – Antennas – With radio cabinet
Reexamination Certificate
2000-02-08
2001-02-06
Le, Hoanganh (Department: 2821)
Communications: radio wave antennas
Antennas
With radio cabinet
C343S895000, C343S7000MS, C343S866000
Reexamination Certificate
active
06184836
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to antennas, and more particularly to antennas used with wireless communications devices.
BACKGROUND OF THE INVENTION
Radiotelephones generally refer to communications terminals which provide a wireless communications link to one or more other communications terminals. Radiotelephones may be used in a variety of different applications, including cellular telephone, land-mobile (e.g., police and fire departments), and satellite communications systems. Radiotelephones typically include an antenna for transmitting and/or receiving wireless communications signals. Historically, monopole and dipole antennas have been widely employed in various radiotelephone applications, due to their simplicity, wideband response, broad radiation pattern, and low cost.
However, radiotelephones and other wireless communications devices are undergoing miniaturization. Indeed, many contemporary radiotelephones are less than 11-12 centimeters in length. As a result, there is increasing interest in antennas smaller than conventional monopole and dipole antennas that can be utilized internally within radiotelephones.
In addition, it is becoming desirable for radiotelephones to be able to operate within multiple frequency bands in order to utilize more than one communications system. For example, GSM (Global System for Mobile communication) is a digital mobile telephone system that typically operates at a low frequency band, such as between 880 MHz and 960 MHz. DCS (Digital Communications System) is a digital mobile telephone system that typically operates at high frequency bands, such as between 1710 MHz and 1880 MHz. The frequency bands allocated in North America are 824-894 MHz for Advanced Mobile Phone Service (AMPS) and 1850-1990 MHz for Personal Communication Services (PCS). Since there are two different frequency bands, radiotelephone service subscribers who travel over service areas employing different frequency bands may need two separate antennas unless a dual-frequency antenna is used.
Inverted-F antennas may be designed to fit within the confines of radiotelephones, particularly radiotelephones undergoing miniaturization. Unfortunately, conventional inverted-F antennas are typically narrow band and occupy more volume as compared with other types of antennas, such as helices, monopoles and dipoles. As such, a need exists for small, internal radiotelephone antennas that can operate within multiple frequency bands, including low frequency bands.
SUMMARY OF THE INVENTION
In view of the above discussion, the present invention provides small antennas for internal mounting within wireless communicators, such as radiotelephones, that can operate within multiple frequency bands, including low frequency bands. A pair of adjacent, spaced-apart, substantially parallel conductive strips are electrically connected to ground. A planar radiating element overlies the pair of conductive strips and is spaced-apart from the conductive strips in substantially parallel relationship. A dielectric material, such as a foamed material, may or may not be disposed between the conductive strips and the radiating element. The conductive strips are configured to parasitically couple with the radiating element.
The planar radiating element includes a first meandering segment and a second meandering segment that is a mirror image of the first meandering segment. The first meandering segment includes a set of periodically spaced-apart planar undulations, such as U-shaped portions, and the second meandering segment includes a corresponding set of periodically spaced-apart planar undulations. The first and second meandering segments are connected together in opposing relationship therewith to form a continuous, conductive loop. An RF signal feed is configured to electrically connect the planar radiating element with RF circuitry within a wireless communications device.
Antennas according to the present invention may be particularly well suited for use within a variety of communications systems utilizing different frequency bands. Furthermore, because of their small size, antennas according to the present invention may be easily incorporated within small communications devices. In addition, antenna structures according to the present invention may not require additional impedance matching networks.
REFERENCES:
patent: 5966097 (1999-10-01), Fukasawa et al.
patent: 6100848 (1999-10-01), Hayes
Ali et al., “A Wide-Band Dual Meander-Sleeve Antenna,” Journal of Electromagnetic Waves and Applications, vol. 10, pp. 1223-1236 (1996).
Ali et al., “Dual-Frequency Strip-Sleeve Monopole for Laptop Computers,” IEEE Transactions on Antennas and Propagation, vol. 47, No. 2, pp. 317-323 (Feb. 1999).
Rowell et al., “A Capacitively Loaded PIFA for Compact Mobile Telephone Handsets,” IEEE Transactions on Antennas and Propagation, vol. 45, No. 5, pp. 837-842 (May 1997).
Wong et al., “Height-Reduced Meander Zigzag Monopoles with Broad-Band Characteristics,” IEEE Transactions on Antennas and Propagation, vol. AP-34, No. 5, pp. 716-717 (May 1986).
Ericsson Inc.
Le Hoang-anh
Myers Bigel & Sibley & Sajovec
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