Information
-
Patent Grant
-
6661381
-
Patent Number
6,661,381
-
Date Filed
Thursday, May 2, 200222 years ago
-
Date Issued
Tuesday, December 9, 200320 years ago
-
Inventors
-
Original Assignees
-
Examiners
Agents
- Birch, Stewart, Kolasch & Birch, LLP
-
CPC
-
US Classifications
Field of Search
US
- 343 700 MS
- 343 795
- 343 846
- 343 848
-
International Classifications
-
Abstract
A circuit-board antenna has a standing wave resonance which is utilized to extend the radiation end of a dipole antenna as its radiation length, e.g. (n+¼) times the wavelength. Half the wavelength in the radiation direction of the dipole antenna is designed to be twisted, the radiation from which cancels with itself, resulting in a radiation gain in the radiation direction. A circuit board is used to make such a dipole antenna. It can conveniently achieve the goal of self cancellation for radiation from the twisty part. The radiation orientation of the antenna can be adjusted to be upward or downward by modifying the extension length between the radiation end and the ground end of the dipole antenna.
Description
BACKGROUND OF THE INVENTION
1. Field of Invention
The invention relates to an antenna and, in particular, to a circuit-board antenna.
2. Related Art
Due to continuous development in communications technology, communication products are very common in daily life. Therefore, the demand for higher mobile communication quality becomes stronger. To obtain high-quality mobile communications, the antenna design in addition to better communication systems is also very important.
The conventional dipole antenna design is usually a ½-wavelength (λ) structure (see FIG.
1
). In
FIG. 2
, however, the open end
11
of the signal part
10
in the dipole antenna is designed to be (1+¼)λ and the open end
21
of the ground end
20
is designed to be ¼λ. The first radiation section
111
and the third radiation section
113
are radiating in the same direction, whereas the second radiation section
112
is radiating in the opposite direction, canceling with the radiation from the first and third radiation sections
111
,
113
. This changes the electromagnetic (EM) field shape of the antenna and therefore cannot increase its gain.
In this situation, increasing the length of the antenna is unable to effectively increase the gain. Therefore, existing dipole antennas are all designed in a symmetric way and the gain cannot be increased. However, for modern wireless communications, it is of great importance to enhance the antenna gain. How to extend the current antenna designs into those with higher gains has become a significant research field.
SUMMARY OF THE INVENTION
In view of the foregoing, it is an objective of the invention to provide a circuit-board antenna device, which has a higher radiation gain and adjusts to give better radiation orientation.
To achieve the above objective, the invention provides a circuit-board antenna, which can radiate and receive EM waves with a particular wavelength and is capable of increasing the radiation gain. The invention includes a circuit board, a signal part with an open end, and an open part with a ground. The circuit board has an upper surface and a lower surface. The signal part is formed on the upper surface of the circuit board. The open end is comprised of a plurality of radiation sections and a plurality of twisty sections. The path length of the open end is (n+¼) times the particular wavelength, where n is a non-negative integer. Each of the twisty section is positioned between two of the radiation sections. The plurality of radiation sections are comprised of some radiation sections with a length of ¼ times the particular wavelength while the rest with a length of ½ times the particular wavelength. The radiation sections are used to radiate and receive EM waves of the particular wavelength. The path length of each of the twisty sections is ½ times the particular wavelength so that the EM waves thus generated cancel with themselves. The open part is formed on the lower surface of the circuit board. The path length of the open part is ¼ times the particular wavelength. Further scope of the applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention, and wherein:
FIG. 1
is a schematic view of a conventional ½λ dipole antenna;
FIG. 2
is another schematic view of a conventional ½λ dipole antenna;
FIG. 3
is a schematic view of the disclosed circuit-board antenna device;
FIG. 4
is a schematic view of a (3+½)λ circuit-board antenna of the invention;
FIG. 5
shows a first embodiment of the invention;
FIG. 6
shows a second embodiment of the invention; and
FIGS. 7A and 7B
show a third embodiment of the invention.
DETAILED DESCRIPTION OF THE INVENTION
In order to increase the antenna gain, the invention makes a second radiation section
112
generate an opposite standing wave with a first radiation section
111
to self-cancel the radiation (see FIG.
2
), so that the radiation end only has radiation in one direction, thus enhancing the antenna gain. A feature of the invention is to print the antenna on a normal circuit board (using conductive metal as its material). A radiation section with self-radiation cancellation can be manufactured in this way.
Please refer to
FIG. 3
for an explicit example of making the invention. As the dipole antenna shown in
FIG. 2
, this antenna includes a signal part
30
and a ground
40
. The second radiation section in
FIG. 2
is designed as a twisty section
312
in FIG.
3
. The first radiation section
311
, the third radiation section
313
, and the open end
41
of the ground
40
in this case are exactly the same of those in FIG.
2
. The shape shown in the drawing can be formed using the circuit board fabricating method, so that the radiation from the twisty section
312
can achieve self-cancellation.
Since the twisty section
312
in
FIG. 3
is made into a twisty shape, the opposite standing wave generated by the second radiation section
112
relative to the first radiation section
111
and the third radiation section
113
in
FIG. 2
cancels exactly. Therefore, the first radiation section
311
, the third radiation section
313
, and the open end
41
of the ground
40
in
FIG. 3
produce radiation in the same direction. Therefore, the antenna forms an array of two elements. This method can increase the antenna gain and the signal transmission distance.
Extending the concept introduced in
FIG. 3
, the open end
31
of the signal part
30
can be elongated to further enhance the antenna radiation gain. In
FIG. 4
, the (1+½)λ-long antenna in
FIG. 3
is extended into a (3+½)λ-long antenna including the signal part
50
and its open end
51
, and the ground
60
and its open end
61
. In the drawing, the increased 2λ-long antenna is also twisted into a fourth twisty section
514
and a sixth twisty section
516
. The other two sections, i.e. the fifth radiation section
515
and the seventh radiation section
517
form a radiation section radiating in the same direction as the first radiation section
511
and the third radiation section
513
. This can extend the radiation section, producing an array with more elements. Similarly, the embodiment in
FIG. 4
is prepared using a circuit board.
From
FIG. 4
, we know that the design of twisty sections can increase the antenna gain without the problem of self-cancellation. Therefore, we can make an antenna with any desired gain. Moreover, such a twisted design can be used in an arrayed antenna.
For an explicit example of making antennas, please refer to
FIG. 5
where various parts of an antenna are formed on a circuit board.
FIG. 6
shows an effective circuit of FIG.
4
. The very same method can be employed to extend the signal part or the open end of the ground to increase the antenna gain.
FIG. 7A
shows an embodiment of extending both ends of a dipole antenna. The open end
71
of the signal part
70
contains first, third, fifth and seventh radiation sections
711
,
713
,
715
,
717
, and second, fourth and sixth radiation sections
712
,
714
,
716
. The open end
81
of the ground
80
contains first, third, fifth and seventh radiation sections
811
,
813
,
815
,
817
, and second, fourth and sixth radiation sections
812
,
814
,
816
. The effective circuit made of a circuit board is shown in FIG.
7
B.
In practice, one can adjust the number of downward (open end of the ground) or upward (open end of the signal part) extensions to adjust the orientation of the antenna field shape. When the number of upward extending radiation sections is greater than that of the downward extensions (n>m), the radiation direction of the antenna is changed downwards. On the other hand, when the number of upward extending radiation sections is smaller than that of the downward extensions (n<m), the radiation direction of the antenna is changed upwards.
Effects of the Invention
The disclosed circuit-board antenna device can achieve the goal of increasing the radiation gain and efficiency.
The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.
Claims
- 1. A circuit-board antenna for radiating and receiving electromagnetic (EM) waves of a wavelength and with an increased radiation gain, the antenna comprising:a circuit board, which has an upper surface and a lower surface; a signal part having an open end formed on the upper surface of the circuit board, the open end having a plurality of radiation sections and a plurality of twisty sections, each of whose path lengths being (n+¼) times the wavelength where n is a positive integer, each of the twisty sections being positioned between two of the radiation sections; wherein the plurality of radiation sections is comprised of radiation sections with a length of ¼ times the wavelength and others with a length of ½ times the wavelength for radiating and receiving the EM waves of the wavelength, and each of the plurality of twisty sections has a path length of ½ times the wavelength to make the EM waves cancel by themselves; and a ground with a second open end formed on the lower surface of the circuit, the path length of the second open end being ¼ times the wavelength.
- 2. The antenna of claim 1, wherein the radiation section has a straight shape.
- 3. The antenna of claim 1, wherein the radiation section has a polygon shape.
- 4. The antenna of claim 1, wherein the open end has a straight shape.
- 5. The antenna of claim 1, wherein the open end has a symmetric π shape, both sides of which consisting successively of radiation and twisty sections of ½ times the wavelength long.
- 6. The antenna of claim 1, wherein the second open end has a straight shape.
- 7. The antenna of claim 2, wherein the second open end has a straight shape.
- 8. A circuit-board antenna for radiating and receiving electromagnetic (EM) waves of a wavelength and with an increased radiation gain, the antenna comprising:a circuit board, which has an upper surface and a lower surface; a signal part having an open end formed on the upper surface of the circuit board, the open end having a plurality of radiation sections and a plurality of twisty sections, each of whose path lengths being (n+¼) times the wavelength where n is a non-negative integer, each of the twisty sections being positioned between two of the radiation sections; wherein the plurality of radiation sections is comprised of radiation sections with a length of ¼ times the wavelength and others with a length of ½ times the wavelength for radiating and receiving the EM waves of the wavelength, and each of the plurality of twisty sections has a path length of ½ times the wavelength to make the EM waves cancel by themselves; and a ground with a second open end formed on the lower surface of the circuit, the open end having a plurality of radiation sections and a plurality of twisty sections, each of whose path lengths being (m+¼) times the wavelength where m is a positive integer, each of the twisty sections being positioned between two of the radiation sections; wherein the plurality of radiation sections is comprised of radiation sections with a length of ¼ times the wavelength and others with a length of ½ times the wavelength for radiating and receiving the EM waves of the wavelength, and each of the plurality of twisty sections has a path length of ½ times the wavelength to make the EM waves cancel by themselves; wherein the radiation direction is downward for n>m and upward for n<m.
- 9. The antenna of claim 8, wherein the radiation section has a straight shape.
- 10. The antenna of claim 8, wherein the radiation section has a polygon shape.
- 11. The antenna of claim 8, wherein the open end has a straight shape.
- 12. The antenna of claim 8, wherein the open end has a symmetric π shape, both sides of which consisting successively of radiation and twisty sections of ½ times the wavelength long.
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