Communications: radio wave antennas – Antennas – Microstrip
Reexamination Certificate
2003-03-06
2004-08-17
Nguyen, Hoang V. (Department: 2821)
Communications: radio wave antennas
Antennas
Microstrip
C343S767000
Reexamination Certificate
active
06778141
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to patch antennas and more particularly to an improved patch antenna with increased bandwidth.
BACKGROUND OF THE INVENTION
As understood that an antenna is used in transmitting electromagnetic waves (i.e., signals) generated by an electronic device to the air or receiving signals by the electronic device. Hence, antennas have been widely provided in various electronic devices as ubiquitous elements. As such, a quality of transmitted or received signal strongly depends on performance of an antenna provided in the electronic device or whether an antenna characteristic is matched with the electronic device. Further, a high performance radio frequency (RF) circuit and digital circuit of an electronic device can be carried out only by incorporating a high quality antenna. In this regard, all electronic product designers and manufacturers pay a great attention to quality of antenna in the manufacturing process or even performance test of antenna in the finished electronic product.
Conventionally, antennas are classified based on their structures and characteristics as detailed below.
(1) Patch antenna: Referring to
FIG. 1
, a patch antenna
10
comprises a substrate
11
made of ceramic material. In detail, the substrate
11
is formed by heating a ceramic material, molding the melted ceramic material to produce a ceramic plate, and finally sintering the ceramic plate. A patch
12
and a ground plane
13
both of rectangle or square are printed on top and bottom surfaces of the substrate
11
by photolithography and etching respectively. Further, a feed pin
14
is pierced through the patch
12
and the ground plane
13
to connect to a signal wave feed line (e.g., coaxial cable)
15
. As a result, a resonant cavity is formed between the patch
12
and the ground plane
13
. A high frequency electromagnetic field is generated in the resonant cavity. The electromagnetic field is then radiated from a gap between the patch
12
and the ground plane
13
. The patch antenna
10
is advantageous due to compactness, enhanced structural strength, high dielectric coefficient and low temperature coefficient of ceramic, good heat-resistant characteristic, low power loss, and applicable to various environments. A typical implementation of the patch antenna
10
is a ceramic patch antenna provided in a GSM (Global System for Mobile) based cellular phone. However, the patch antenna
10
also has a number of disadvantages. For example, a manufacturing process of the patch antenna
10
is complicated, resulting in a high manufacturing cost. Further, the signal wave feed line
15
such as coaxial cable has several drawbacks, e.g., time consuming in installation, the requisite provision of the additional feed pin
14
, a welding of the feed pin
14
to the patch
12
and the substrate
11
, and poor antenna quality caused by failed welding.
(2) Patch antenna having a patch line as feed line: Referring to
FIG. 2
, a patch antenna
20
comprises a substrate
21
formed on a circuit board. A patch
22
and a ground plane
23
both of rectangle or square are printed on top and bottom surfaces of the substrate
21
by photolithography and etching respectively. A patch line
24
is extended from a center of a side of the patch
22
to an edge of the substrate
21
so as to serve as a signal wave feed line. A gap
221
is formed at either side of the patch line
24
to separate the patch line
24
from the patch
22
. As seen that a substantially W-shaped (i.e., circuitous) current path W indicated by dash line is formed along edges of the patch
22
and patch line
24
adjacent the gaps
221
. Such arrangement can increase the current path W, resulting in a size reduction of the patch antenna
20
. However, a very large inductance is generated by the circuitous current path W caused by forming the gaps
221
and the current path W passing two projections
222
each adjacent the gap
221
. The strong inductance will adversely affect gain and bandwidth of the patch antenna
20
, resulting in a prohibition of bandwidth increase.
(3) Patch antenna having a coplanar wave-guide as feed line: Referring to
FIG. 3
, a patch antenna
30
comprises a substrate
31
formed on a circuit board. A patch
32
and a ground plane
33
both of rectangle or square are printed on top and bottom surfaces of the substrate
31
by photolithography and etching respectively. A space
331
is formed in the ground plane
33
. A patch line
34
is printed in the space
331
. A signal wave feed line is coupled to the patch
32
from one end of the patch line
34
by means of a coplanar wave-guide. However, such antenna is undesirable due to complicated structure, design difficulty, tedious manufacturing process, and high cost.
Moreover, typically for increasing a bandwidth of patch antenna construction of the antenna is changed by patch antenna designers and manufacturers. As such, at least two resonant patterns are produced, resulting in an increased bandwidth in adjacent frequency bands. However, such is difficult to design. Further, thus produced antenna may be bulky due to practical considerations, thereby contradicting the trend of compactness. Hence, a need for improvement exists.
SUMMARY OF THE INVENTION
A primary object of the present invention is to provide a patch antenna with increased bandwidth. By utilizing this, the above drawbacks as experienced by patch antenna designers and manufacturers in attempting to increase the bandwidth of patch antenna can be overcome.
One object of the present invention is to provide a patch antenna including a patch and a ground plane printed on top and bottom surfaces of a dielectric substrate respectively by a technique the same as manufacturing a printed circuit board. The patch has a size smaller than that of the dielectric substrate. The antenna further comprises a patch line extended from a center of a side of the patch to an edge of the dielectric substrate for serving as a signal wave feed line of the patch antenna, and a gap provided at one side of the patch line to separate the patch line from the patch for forming a circuitous current path from one edge of the patch line along the sides adjacent the gap to one side of the patch. By the provision of the gap, the patch antenna can significantly reduce inductance generated by signal wave, increase an effective bandwidth, and significantly reduce design and manufacturing costs by means of a simple structure being easy to manufacture.
In one aspect of the present invention, the size and the shape of the gap between the one side of the patch line and the patch can be modified so as to obtain an improved signal matching.
The above and other objects, features and advantages of the present invention will become apparent from the following detailed description taken with the accompanying drawings.
REFERENCES:
patent: 4780724 (1988-10-01), Sharma et al.
patent: 5594455 (1997-01-01), Hori et al.
patent: 5872542 (1999-02-01), Simons et al.
patent: 5898405 (1999-04-01), Iwasaki
patent: 6218990 (2001-04-01), Grangeat et al.
Bacon & Thomas PLLC
D-Link Corporation
Nguyen Hoang V.
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