Compact dual band circular PIFA

Details Compact dual band circular PIFA Compact dual band circular PIFA

2003-01-14

2004-03-23

Ho, Tan (Department: 2821)

Communications: radio wave antennas

Antennas

With radio cabinet

C343S7000MS, C343S767000

Reexamination Certificate

active

06710748

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to Planar Inverted F-Antenna (PIFA), and more particularly, PIFA antenna with non-conventional shapes and an integrated feed line on a ground plane:
BACKGROUND OF THE INVENTION
In wireless radio frequency (“RF”) data communications there is currently a shift in the requirement from the existing single band operation to dual industrial scientific medical (“ISM”) band operation covering, for example, frequency ranges of 2.4-2.5 to 5.15-5.35 GHz. Generally, dual ISM band operation can be accomplished using either external or internal antennas. External antennas are large and susceptible to mechanical damage. Conversely, internal antennas are unseen by the user, smaller, and less susceptible to mechanical damage. However, internal antenna are constrained in effectiveness because of the size and volume restrictions associated with wireless devices
In most of the devices, only specified regions with defined volume can accommodate the placement of internal antennas. These regions are usually not of perfect rectangular/square shape or of large size. At times, the available space for internal antennas nearly assumes a circular cylindrical shape of very small area and volume. For optimal performance of the internal antenna, it is desirable that the shape of the radiating structure of the antenna use as much of the allowed area as possible. Dual band ISM internal antenna, however, are generally rectangular in shape, which will be explained in connection with
FIG. 9
, below. Thus, it would be desirous to develop a non-conventionally shaped PIFA antenna to use more of the available space for internal antenna.
There seems to be no work reported on circular shaped either single or dual band PIFAs in open literature Wen-Hsiu Hsu and Kin-Lu Wong, “A Wideband Circular Patch Antenna”, MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Vol. 25, No. 5, Jun. 5, 2000 pp. 328 (hereinafter referred to as Hsu et al) reports a dual band microstrip antenna with a circular radiating element using an air-substrate. The dual frequency operation of the microstrip antenna of Hsu et al is realized through two separate linear slots. The two slots are placed symmetrically with respect to the central axis of the radiating element. The axis of the microstrip feed line is also parallel to the axes of the slots.
A dual frequency circular microstrip antenna with a pair of arc-shaped slots has been studied in Kin-Lu Wong and Gui-Bin Hsieh, “Dual-Frequency Circular Microstrip Antenna with a Pair of Arc-Shaped Slots”, MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Vol. 19, No. 6, Dec. 20 1998, pp. 410-412 (hereinafter referred to as Wong et al). The two arc-shaped slots are located on either side of one of the central axes. In the work of Wong et al, the two arc-shaped slots are also symmetrically placed with respect to the referred central axis of the antenna.
In both of the above research papers, the size of the radiating element corresponds to half wavelength at the center frequency of the lower resonant band.
Circular patch antennas also provide some insight into the present invention. The case studies of circular patches with a single arc or U-shaped slot are described in the work of K. M. Luk, Y. W. Lee, K. F Tong, and K. F. Lee, “Experimental studies of circular patches with slots”, IEEE Proc.—Microw. Antennas Propagation, Vol. 144, No. 6, December 1997, pp. 421-424 (hereinafter referred to as Luk et al). With a single arc shaped slot, the choice of center or offset feed determines the dual or single frequency operation. The choice of a U-shaped slot, as in the paper of Luk et al, results only in a single band operation with a wider impedance bandwidth.
Recently there has been a drastic increase in the demand for use of internal antennas in wireless applications. In a variety of options for internal antennas, PIFAs seems to have a greater potential. Apart from extensive utility of PIFA in commercial cellular communications, PIFA continues to find its usefulness in many other systems applications such as WLAN, the Internet, or the like The printed circuit board of the communication device serves as the ground plane of the internal antenna. The PIFA is characterized by many distinguishing properties such as relative lightweight, ease of adaptation and integration into the device chassis, moderate range of bandwidth, versatile for optimization, and multiple potential approaches for size reduction. Its sensitivity to both the vertical and horizontal polarization is of immense practical importance in wireless devices because of multi path propagation conditions. All these features render the PIFA to be as good a choice as any internal antenna for wireless device applications. When it comes to diversity schemes, PIFAs have a unique advantage because it can be fashioned into varieties of either Polarization or pattern Diversity schemes.
A conventional single band PIFA assembly is illustrated in
FIGS. 9A and 9B
. The PIFA
110
shown in FIG.
9
A and
FIG. 9B
consists of a radiating element
101
, a ground plane
102
, a connector feed pin
104
a
, and a conductive post or pin
107
. A power feed hole
103
is located in radiation element corresponding to connector feed pin
104
a
. Connector feed pin
104
a
serves as a feed path for RF power to the radiating element
101
. Connector feed pin
104
a
is inserted through the feed hole
103
from the bottom surface of the ground plane
102
. The connector feed pin
104
a
is electrically insulated from the ground plane
102
where the pin passes through the hole in the ground plane
102
. The connector feed pin
104
a
is electrically connected to the radiating element
101
at point
105
a
with, for example; solder. The body of the feed connector
104
b
is electrically connected to the ground plane at point
105
b
with, for example, solder The connector feed pin
104
a
is electrically insulated from the body of the feed connector
104
b
. A through hole
106
is located in radiation element
101
corresponding to conductive post or pin
107
. Conductive post
107
is inserted through the hole
106
. The conductive post
107
serves as a short circuit between the radiating element
101
and ground plane
102
. The conductive post
107
is electrically connected to the radiating element
101
at point
108
a
with, for example, solder. The conductive post
107
is also electrically connected to the ground plane
102
at point,
108
b
with, for example, solder. The resonant frequency of the PIFA
110
is determined by the length (L) and width (W) of the radiating element
101
and is slightly affected by the locations of the feed pin
104
a
and the shorting pin
107
. The impedance match of the PIFA
110
is achieved by adjusting the diameter of the connector feed pin
104
a
, by adjusting the diameter of the conductive shorting post
107
, and by adjusting the separation distance between the connector feed pin
104
a
and the conductive shorting post
107
. The fundamental limitation of the configuration of the PIFA
110
described in FIG.
9
A and
FIG. 9B
is the requirement of relatively large dimensions of length (L) and width (W) of the radiating element
101
to achieve desired resonant frequency band. This configuration is limited to only single operating frequency band applications. If PIFA was a dual band PIFA, a slot (not shown) would reside in radiating element
101
to quasi partition the radiating element
101
.
As represented by
FIGS. 9A and 9B
, the majority of PIFA designs focus on PIFA designs having a rectangular or square shape. Thus, it would be desirous to develop a compact dual ISM band internal PIFA having a non-conventional shapes.
SUMMARY OF THE INVENTION
This invention presents new schemes of designing circular shaped PIFAs with a small ground plane. Deviating distinctly from the routine and conventional feed structure usually employed in PIFA design, this invention also demonstrates that the RF feed line system can be integrated to the PIFAs.
To attain the advantages and in accordance with the pur

Affiliated with

Also associated with

Rating

Compact dual band circular PIFA 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 dual band circular PIFA, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Compact dual band circular PIFA will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3253149