Communications: radio wave antennas – Antennas – With radio cabinet
Reexamination Certificate
2000-04-04
2001-07-31
Phan, Tho (Department: 2821)
Communications: radio wave antennas
Antennas
With radio cabinet
C343S7000MS
Reexamination Certificate
active
06268831
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 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 centimeters in length. As a result, there is increasing interest in small antennas that can be utilized as internally-mounted antennas for 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 are designed to fit within the confines of radiotelephones, particularly radiotelephones undergoing miniaturization. As is well known to those having skill in the art, inverted-F antennas typically include a linear (i.e., straight) conductive element that is maintained in spaced apart relationship with a ground plane. Examples of inverted-F antennas are described in U.S. Pat. Nos. 5,684,492 and 5,434,579 which are incorporated herein by reference in their entirety.
Conventional inverted-F antennas typically resonate within a narrow frequency band. In addition, conventional inverted-F antennas may be large in size compared with available space within many contemporary radiotelephones. Lumped elements can be used to match a smaller antenna to an RF circuit. Unfortunately, lumped elements may introduce additional losses in the overall transmitted/received signal, may take up circuit board space, and may add to manufacturing costs.
High dielectric substrates are commonly used to decrease the physical size of an antenna. Unfortunately, the incorporation of higher dielectrics can reduce antenna bandwidth and may introduce additional signal losses. 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 can provide various configurations of compact inverted-F antennas for use within communications devices, such as radiotelephones. According to one embodiment, an inverted-F antenna that resonates within first and second frequency bands includes first, second and third planar conductive elements. The first planar conductive element has an elongated, rectangular configuration that extends along a first direction. The first planar conductive element has opposite first and second sides and an elongated edge.
The second planar conductive element is electrically connected to the elongated edge of the first planar conductive element. The second planar conductive element has an elongated, rectangular configuration that extends along a second direction that is substantially parallel with the first direction. The second planar conductive element is maintained in adjacent, co-planar, spaced-apart relationship with the first planar conductive element.
The third planar conductive element is electrically connected to the elongated edge of the first planar conductive element and has an elongated, rectangular configuration that extends along the second direction. The third planar conductive element is maintained in adjacent, co-planar, spaced-apart relationship with the first and second planar conductive elements. The first planar conductive element has a width that is less than a width of the second planar conductive element and less than a width of the third planar conductive element.
A signal feed electrically extends outwardly from the first conductive element and electrically connects the first conductive element to a transceiver within the communications device. A ground contact is electrically connected to the first conductive element adjacent the signal feed and grounds the antenna to a ground plane within the communications device.
According to another embodiment of the present invention, an inverted-F antenna that resonates within first and second frequency bands includes first and second planar conductive elements maintained in adjacent, co-planar, spaced-apart relationship with each other. The first planar conductive element has an elongated, rectangular configuration that extends along a first direction. The first planar conductive element includes opposite first and second sides, and an elongated edge.
The second planar conductive element is electrically connected to the elongated edge of the first planar conductive element. The second planar conductive element has an elongated, rectangular configuration that extends along a second direction substantially parallel with the first direction. The second planar conductive element is maintained in adjacent, co-planar, spaced-apart relationship with the first planar conductive element. The length of the first planar conductive element is greater than the length of the second planar conductive element. The width of the first planar conductive element is less than the width of the second planar conductive element.
A signal feed electrically extends outwardly from the first conductive element and electrically connects the first conductive element to a transceiver within the communications device. A ground contact is electrically connected to the first conductive element adjacent the signal feed and grounds the antenna to a ground plane within the 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, which may save internal radiotelephone space and which may lead to manufacturing cost savings.
REFERENCES:
patent: 5365246 (1994-11-01), Rasinger et al.
patent: 5764190 (1998-06-01), Murch et al.
patent: 5926139 (1999-07-01), Korisch
patent: 5986606 (1999-11-01), Kossiavas et al.
patent: 6100850 (2000-08-01), Utsumi
patent: 6166694 (2000-12-01), Ying
patent: 6184836 (2001-02-01), Ali
patent: 0630069 (1994-12-01), None
patent: 0892459 (1999-01-01), None
patent: WO90/13152 (1990-11-01), None
Ericsson Inc.
Myers Bigel & Sibley & Sajovec
Phan Tho
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