Compact broadband antenna

Details Compact broadband antenna Compact broadband antenna

2001-11-26

2003-11-18

Phan, Tho (Department: 2821)

Communications: radio wave antennas

Antennas

Microstrip

C343S702000, C343S846000

Reexamination Certificate

active

06650294

ABSTRACT:

FIELD OF THE INVENTION
The present invention pertains to antennas. In particular, the invention relates to compact antennas with increased bandwidth.
BACKGROUND OF THE INVENTION
Antennas are an important component of all wireless communication systems and are particularly important for mobile wireless communication terminals (e.g., wireless telephones, personal communication devices, personal digital assistants (PDA), portable global position system (GPS) devices, web pads, laptop personal computers (PC), tablet PC, etc.). Over time, these mobile wireless communication devices have become smaller in size and lighter in weight. This is particularly true for wireless telephones.
Further, more and more functionality is being incorporated into wireless telephones and personal communication devices. In fact, various devices are starting to be combined into a single all-in-one personal computing and communication device that may need wireless communications with broader frequency bandwidth, for example, having multiple frequencies. Such devices could be supported by multiple antennas incorporated in the single multi-function device. However, multiple antennas generally would require multiple transceivers or a more complex transceiver with some type of power driver network for splitting the drive signal among the plurality of antennas and a method of switching between the plurality of antennas. This would add size and weight to the mobile device.
The increased device functionality and reduction in device size and weight of wireless mobile communication devices continues to push the emergence of antenna designs that are more compact and lightweight, and have broader bandwidth communication capability. Now and in the future, more compact lightweight antenna designs with broader bandwidth are needed for mobile wireless devices, particularly antennas that operate in the 300 MHz-3000 MHz frequency range. However, a single antenna having smaller size and broader bandwidth may be difficult to achieve because bandwidth is generally proportional to the volume of an antenna. Therefore, a compact or miniaturized antenna that would be small in area and lightweight will typically result in narrow bandwidth.
A number of compact and multi-frequency-band antennas have been proposed. For example, micro-strip or patch antennas, such as the planar inverted-F antenna (PIFA) has been used for mobile telephones. (See, for example, K. Quassin, “Inverted-F antenna for portable handsets”, IEEE Colloqium on Microwave Filters and Antennas for Personal Communication Systems, pp. 3/1-3/6, February 1994, London, UK.) As suggested by its name, a patch antenna includes a patch or conductive plate. The length of the patch is set relative to the wavelength &lgr;
0
of a desired transmission and/or reception frequency. A quarter wave patch antenna will have the length of the patch set at ¼ &lgr;
0
.
FIGS. 1A and 1B
provide an exemplary prior art PIFA
100
. Referring to
FIG. 1A
, the PIFA includes a ground plane
105
, a planar patch
110
, a grounding pin
120
, and a feeding pin
115
. A signal source and/or receiver
125
is connected to the feeding pin
115
for radio wave reception and/or transmission to and/or from the PIFA. The feeding pin
115
is connected to the planar patch
110
and signal source and/or receiver
125
. The planar patch
110
is connected to the ground plane
105
by ground pin
120
.
FIG. 1B
is a cross section view of the PIFA taken across line IB of FIG.
1
A. The planar patch
110
of PIFA
100
provides the resonating antenna surface for wireless communications over the air waves. Although small in size, the PIFA has a relatively narrow bandwidth. The bandwidth is limited mainly by the height of the patch
110
relative to the ground plane
105
.
Micro-strip antennas are low profile, small in size and light in weight. However, as mobile wireless communication devices become smaller and smaller, both conventional microstrip patch and PIFA antennas may be too large to fit the small mobile device chassis or the space available for an antenna(s) in a multi-function wireless device. This is particularly problematic when new generation mobile wireless communication devices need multiple frequencies (and possibly multiple antennas) for cellular, wireless local area network, GPS and diversity (e.g., Global System for Mobile communications (GSM) and Personal Communication System (PCS)).
Recently, Lai, Kin, Yue, Albert et al. proposed in Patent Cooperation Treaty (PCT) publication No. WO 96/27219 a meandering inverted-F antenna. With this antenna the size can be reduced to about 40% of conventional PIFA antenna.
Some devices, such as the all-in-one device (e.g., an integrated PDA and telephone) or a mobile telephone with diversity may be served by a multi-band antenna. Typically in the past, multi-band antennas have been directed to supporting two operating frequencies. One such antenna is the dual-frequency band PIFA proposed by David Ngheim in PCT publication WO 98/44588. This antenna has two separate adjacent patches that resonate at different frequencies that are interconnected by a common electrical single feed connection. Another such antenna was proposed by Davie Ngheim in U.S. Pat. No. 6,008,762. This antenna uses a folded quarter wave patch antenna to achieve dual frequency band operation. A still further dual-frequency antenna has been proposed by Rowell and Murch in the paper titled “A Compact PIFA Suitable for Dual-Frequency 900/1800-MHz Operation,” IEEE Transactions on Antennas and Propagation, Vol. 46, No. 4, April 1998. This antenna includes a capacitive feed and a capacitive load.
Unfortunately, none of the previously proposed antennas provide a satisfactory solution for the small size, light weight, broad bandwidth coverage needed by the upcoming new generations of wireless mobile communication devices operating in the 300 MHz-3000 MHz frequency range with minimal antenna return power loss. In particular, one recently developed application calls for a multi-function four band (quad-band) mobile terminal covering GSM800 (824-894 MHz), GSM900 (880-960 MHz), GSM1800 (1710-1880 MHz) and GSM1900 (1850-1990 MHz). None of the above mentioned antennas can meet this requirement. The presently known antennas do not have enough bandwidth to be used directly in this four band application without incurring significant loading loss at one or more of the desired operating frequency bands.
SUMMARY OF THE INVENTION
It should be emphasized that the term “comprises/comprising” when used in this specification is taken to specify the presence of stated features, integers, steps or components but does not preclude the presence of addition of one or more other features, integers, steps, components or groups thereof.
Generally, the present invention includes compact antennas utilizing capacitive coupling between multiple conductive plates that achieves broad bandwidth. The capacitive coupling between the conductive plates may create a variable capacitance, inductance, and/or impedance as a function of frequency that increases the bandwidth. The number and design of conductive plates may be set to achieve the desired bandwidth and/or the number of distinct transmission frequencies for a particular application. The antenna may include capacitive coupling for the antenna feed and capacitive coupling of a parasitic conductive plate.
To achieve compact size and broad bandwidth, the antenna may include, for example, three or more layers of conductive plates or traces. One layer may be a feeding patch, one layer may be a main patch, and one layer may be a secondary patch. The secondary patch may be a parasitic patch. The main patch and/or the secondary patch may include one or more distinct areas which will be resonant at predetermined desired frequencies that has wider bandwidth due to the capacitive coupling between the various conductive plates. All of the conductive plates may be micro-strips and approximately parallel to one another and may have connection pins approximately parallel with one

Affiliated with

Also associated with

Rating

Compact broadband antenna does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Compact broadband antenna, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Compact broadband antenna will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3171217