BRIEF DESCRIPTION OF THE DRAWINGS
The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:
FIG. 1 is a perspective view illustrating a single band U-slot antenna according to the prior art;
FIG. 2 is a perspective view illustrating a multi-band U-slot antenna according to an embodiment of the invention;
FIG. 3 is a front elevation view illustrating arrangement of U-slots which act as a double notch filter according to another embodiment of the invention;
FIG. 4 is a perspective view illustrating a multi-band U-slot antenna according to further another embodiment of the invention;
FIG. 5 is a front elevation view illustrating arrangement of U-slots which act as a double notch filter according to further another embodiment of the invention;
FIG. 6 is a front elevation view illustrating arrangement of U-slots which act as a triple notch filter according to further another embodiment of the invention; and
FIG. 7 is a graph illustrating return loss of a dual notch filter according to the invention; and
FIG. 8 is a graph illustrating return loss of a triple notch filter according to the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. Here, a plurality of U-slots may be configured and arranged variously.
FIG. 2 is a perspective view illustrating a multi-band U-slot planar antenna according to an embodiment of the invention.
Referring to FIG. 2, the antenna of the invention includes a limited ground plane 25 and a radiation device 22 disposed perpendicular to the ground plane 25 and connected to a feeding terminal by a connector 27.
A through hole 26 is perforated in a central portion of the limited ground plane 25 to connect a feeding point 24 of the radiation device 22 to the feeding terminal of the connector 27.
Preferably, the feeding point 24 is centered in a side portion of the planar radiation device 22.
A plurality of U-slots 23 are formed in the radiation device 22. Here, current flows in opposite directions inside and outside of the U-slots 23. If a total length of the U-slots corresponds to a half wavelength of a notch central frequency, the frequency has a return loss of almost 0 dB. Thus, the notch central frequency is determined by adjusting the length of the U-slots.
The U-slots 23 formed in a planar surface of the radiation device 22 are preferably arranged to be vertically symmetrical with each other about a central axis, which is an extended line 24a of the feeding point 24. This ensures the U-slots 23 to act as a notch filter with superior characteristics. Surely, the U-slots, with either a symmetrical or asymmetrical configuration, can function as a notch filter. However, the symmetrical configuration allows the notch filter to achieve better blocking characteristics. Moreover, a notch frequency band is decided by the width of the U-slots.
In FIG. 2, the length and width of U-slots are not limited but variously modified according to a desired notch central frequency and a notch frequency band.
In FIG. 2, a central U-slot 23a is formed in a central area of a planar surface of the radiation device along the central axis which is the extended line 24a of the feeding point. The central U-slot 23a has a central point located on the extended line 24a of the feeding point. Also, the central U-slot 23a is formed in a forward direction to have an opening located opposite to the feeding point 24. Moreover, a pair of auxiliary U-slots 23b are formed in a forward direction to be symmetrical with each other. The auxiliary U-slots 23b are disposed to oppose each other about the U-slot 23a.
The central U-slot 23a has a symmetrical configuration about the extended line 24a of the feeding point. The auxiliary U-slots 23b are symmetrical with each other about the extended line 24a of the feeding point.
Such a configuration leads to change in a length of a current path where current flows, thereby altering a wavelength that generates resonance. In FIG. 2, a current path of the auxiliary U-slots 23a differs in length from a current path of both the auxiliary U-slots 23a and 23b and the central U-slot 23a. This arrangement allows the U-slots 23 to function as a double notch filter, thereby operating in a triple band frequency.
The connector 27 is configured as a coaxial cable with an internal terminal acting as a feeding terminal to feed a signal to the radiation device, and connected to the feeding point 24 of the radiation device. An external terminal is connected to the ground plane 25.
FIGS. 3
a to 3c illustrate an embodiment of the invention in which a central slot is formed in a central area of a radiation device and a pair of auxiliary U-slots are disposed at both sides about the central U-slot, as shown in FIG. 2.
Referring to FIG. 3a, a central U-slot 33a is formed in an inverse direction in a central area of the radiation device 32 and a pair of auxiliary U-slots 33b are formed in a forward direction to oppose each other about the central U-slot 33a.
The central U-slot 33a has a central point located on an extended line 34a of the feeding point of the radiation device, and has a symmetrical configuration about the extended line 34a.
The central U-slot 33a is formed in an inverse direction so as to have an opening located adjacent to the feeding point.
The auxiliary U-slots 33b are formed in a forward direction at both sides about the central U-slot 33a. Preferably, the auxiliary U-slots 33b are symmetrical with each other about a central axis, i.e., the extended line 34a of the feeding point.
As described above, the U-slots have two pairs of symmetrical slot configurations about the extended line 34a of the feeding point of the radiation device, thereby enabling an antenna with two notch filters, i.e., a triple band antenna.
Referring to FIG. 3b, the central U-slot 33a is formed in a forward direction in such a fashion that a central point of the U-slot is located on the extended line 34a of the feeding point. The central U-slot 33a is formed in a forward direction so as to have an opening located opposite to the feeding point. The auxiliary U-slots 33b are formed in an inverse direction at both sides about the central U-slot 33a, respectively, to produce an antenna with two notch filters.
In FIG. 3c, the central U-slot 33a is formed in an inverse direction in such a fashion that a central point of the U-slot is located on the extended line 34a of the feeding point of the radiation device. Also, the auxiliary U-slots 33b are formed in an inverse direction at both sides about the central U-slot 33a, respectively, to obtain an antenna with double notch filters.
FIGS. 7
a to 7d are graphs illustrating return losses of the antennas having the U-slots shown in FIG. 2 and FIGS. 3a to 3c.
Referring to the graphs, frequency and return loss vary depending on arrangement of the U-slots, but the type of a notch filter is determined by the number of the slots which are symmetrical about the extended line of the feeding point.
Therefore, at a return loss of 10 dB, notch characteristics are plotted at frequencies of 3 GHz and 5 GHz, thereby producing three frequency bandwidths.
FIG. 4 is a perspective view illustrating a planar antenna with a microstrip feeding structure according to another embodiment of the invention.
Referring to FIG. 4, the antenna of the invention includes a ground plate 45, a dielectric substrate 41 formed on the ground plate 45, a radiation device 42 disposed on the dielectric substrate 41, a feeding terminal for feeding a signal to the radiation device and a connector 47 having a ground terminal connected to the ground plate 45.
Here, the ground plate is a metal layer for grounding.
The dielectric substrate 41 is interposed between the ground plate 45 and the radiation device 42 to provide uniform medium between the ground plate 45 and the radiation device 42 so that a signal is stored, and transmitted to an electromagnetic wave field.
Referring to FIG. 4, one central U-slot 43a is formed in a central area of a planar surface of the radiation device 42 along a central axis, i.e., the extended line 44a of the feeding point. The central U-slot 43a has a central point located on the extended line 44a of the feeding point. The central U-slot 43a is formed in a forward direction so as to have an opening located opposite to the feeding point 44. Moreover, an auxiliary U-slot 43b is formed in a forward direction to surround the central U-slot 43a. The auxiliary U-slot 43b is formed lower than the central U-slot 43a and has a central point located identical to that of the central U-slot 43a. Here, the auxiliary U-slot 43b has a symmetrical configuration about the extended line 44a of the feeding point.
The central U-slot 43a and the auxiliary U-slot 43b have a vertically symmetrical configuration about the central line, i.e., the extended line 44a of the feeding point. Also, as described above, the central U-slot 43a has a central point identical to that of the auxiliary U-slot 43b.
In this arrangement, the U-slots have two pairs of symmetrical configurations about the central axis to act as a double notch filter, thereby operating in a triple frequency.
FIGS. 5
a to 5c illustrate an embodiment of the invention in which a central U-slot is formed in a central area of a radiation device, as shown in FIG. 4 and an auxiliary U-slot is disposed to surround the central U-slot from above.
Referring to FIG. 5a, a central U-slot 53a is formed in an inverse direction in a central area of the radiation device 52. Also, an auxiliary U-slot 53b is disposed in an inverse direction to surround the central U-slot 53a from above.
The central U-slot 53a has a central point located on an extended line 54 of the feeding point of the radiation device, and is vertically symmetrical about the extended line 54a.
The auxiliary U-slot 53b also has a central point located on the extended line 54a of the feeding point of the radiation device, and is vertically symmetrical about the extended line 54a.
As described above, the U-slots have two pairs of symmetrical slot configurations about the central axis, i.e., the extended line 54a of the feeding point of the radiation device, thereby producing an antenna with double notch filters, i.e., an antenna with triple bandwidths.
Referring to FIG. 5b, the central U-slot 53a is formed in a forward direction in such a fashion that a central point of the U-slot is located on the extended line 54a of the feeding point of the radiation device 52. Also, the auxiliary U-slot 53b is disposed in an inverse direction to surround the central U-slot 53a from above, thereby producing an antenna with double notch filters.
Referring to FIG. 5c, the central U-slot 53a is formed in an inverse direction in such a fashion that a central point of the U-slot is placed on the extended line 54a of the feeding point of the radiation device. Also, the auxiliary U-slot 53b is disposed in an inverse direction to surround the central U-slot 53a. The auxiliary U-slot 53b is formed shorter than the central U-slot 53a and has a central point identical to that of the central U-slot 53a
FIGS. 7
e and 7f are graphs illustrating return losses of the antennas shown in FIGS. 5a to 5c.
Referring to the graphs, frequency and return loss vary depending on arrangement of the U-slots, but the type of a notch filter is determined by the number of the U-slots which are symmetrical about the central axis, i.e., the extended line of the radiation device.
Therefore, at a return loss of 10 dB, notch characteristics are plotted at frequencies of 3 GHz and 5 GHz, thereby producing three frequency bandwidths.
FIGS. 6
a to 6h are front elevation views illustrating various arrangements of U-slots to act as a triple notch filter according to further another embodiment of the invention.
Referring to FIG. 6a, a central U-slot 63a is formed in a forward direction in a central area of a radiation device 62. First auxiliary U-slots 63b are formed in a forward direction at both sides about the central U-slot 63a. Second auxiliary U-slots 63c are formed in a forward direction, and located next to each of the first auxiliary U-slots 63b.
The central U-slot 63a has a central point located on an extended line 64a of a feeding point of a radiation device, and is vertically symmetrical about the extended line 64a.
A pair of first auxiliary U-slots 63b are formed in a forward direction to oppose each other about the central U-slot 63a, respectively, preferably to be symmetrical about the extended line 64a of the feeding point of the radiation device.
A pair of second auxiliary U-slots 63c are formed in a forward direction next to each of the first auxiliary U-slots 63b, preferably to be symmetrical about the extended line 64a of the feeding point of the radiation device.
As described above, the U-slots have three pairs of symmetrical slot configurations about the extended line 64a of the feeding point of the radiation device, thereby ensuring an antenna with three notch filters, i.e., a quadruple band antenna.
Referring to FIG. 6b, the central U-slot 63a is formed in an inverse direction in such a fashion that a central point of the U-slot is located on the extended line 64a of the feeding point of the radiation device. A pair of the first auxiliary U-slots 63b are formed in an inverse direction to oppose each other about the central U-slot 63a. Also, a pair of the second auxiliary U-slots 63c are formed in an inverse direction next to each of the first auxiliary U-slots 63b, thereby achieving an antenna with triple notch filters.
Referring to FIG. 6c, the central U-slot 63a is formed in a forward direction in such a fashion that a central point of the U-slot is located on the extended line 64a of the feeding point of the radiation device. A pair of the first auxiliary U-slots 63b are formed in a forward direction to oppose each other about the central U-slot 63a. The second auxiliary U-slot 63c is disposed to surround the central U-slot 63a and the first auxiliary U-slots 63b from above.
Here, the central U-slot 63a and the second auxiliary U-slot 63c have a vertical symmetrical configuration about the extended line 64a of the feeding point. The first auxiliary U-slots 63b are symmetrical with each other about the central axis, i.e., the extended line 64a, achieving an antenna with triple notch filters.
Referring to FIG. 6d, the central U-slot 63a is formed in an inverse direction in such a fashion that a central point of the U-slot is located on the extended line 64a of the feeding point of the radiation device. A pair of first auxiliary U-slots 63b are formed in an inverse direction at both sides about the central U-slot 63a, respectively. Also, the second auxiliary U-slot 63c is disposed in an inverse direction to surround the central U-slot 63a and the first auxiliary U-slots 63b, ensuring an antenna with triple notch filters.
Referring to FIG. 6e, the central U-slot 63a is formed in a forward direction in such a fashion that a central point of the U-slot is located on the extended line 64a of the feeding point of the radiation device. The first auxiliary U-slot 63b is disposed in a forward direction to surround the central U-slot 63a. The first auxiliary U-slot 63b is formed lower than the central U-slot 63a, and has a central point located identical to that of the central U-slot 63a. Moreover, the second auxiliary U-slot 63c is disposed in an inverse direction to surround the central U-slot 63b and the first auxiliary U-slot 63b from above.
Here, the U-slots each have a symmetrical configuration about the central axis, i.e., the extended line 64a of the feeding point, thus achieving an antenna with triple notch filters.
Referring to FIG. 6f, the central U-slot 63a is formed in an inverse direction in such a fashion that a central point of the U-slot is located on the extended line 64a of the feeding point of the radiation device. The first auxiliary U-slot 63b is disposed in an inverse direction to surround the central U-slot 63a. The first auxiliary U-slot 63b is formed shorter than the central U-slot 63a, and has a central point located identical to that of the central U-slot 63a. Furthermore, the second auxiliary U-slot 63c is disposed in an inverse direction to surround the central U-slot 63a and the first auxiliary U-slot 63b from above. This enables an antenna with triple notch filters.
Referring to FIG. 6g, the central U-slot 63a is formed in a forward direction in such a fashion that a central point of the U-slot is located on the extension line 64a of the feeding point of the radiation device. The first auxiliary U-slot 63b is disposed in a forward direction to surround the central U-slot 63a. The first auxiliary U-slot 63b is formed lower than the central U-slot 63a and has a central point located identical to that of the central U-slot 63a. Also, the second auxiliary U-slot 63c is disposed in a forward direction to surround the central U-slot 63a and the first auxiliary U-slot 63b. The second auxiliary U-slot 63c is formed lower than the first auxiliary U-slot 63b and has a central point located identical to that of the first auxiliary U-slot 63b. This ensures an antenna with triple notch filters.
Referring to FIG. 6h, the central U-slot 63a is formed in an inverse direction in such a fashion that a central point of the U-slot is located on the extended line 64a of the feeding point of the radiation device. The first auxiliary U-slot 63b is disposed in an inverse direction to surround the central U-slot 63a. The first auxiliary U-slot 63b is formed shorter than the central U-slot 63a and has a central point located identical to that of the central U-slot 63a. Also, the second auxiliary U-slot 63c is disposed in an inverse direction to surround the first auxiliary U-slot 63b. The second auxiliary U-slot 63c is formed shorter than the first auxiliary U-slot 63b and has a central point located identical to that of the second auxiliary U-slot 63c, thereby realizing an antenna with triple notch filters.
FIG. 8 is a graph illustrating return loss of a radiation device including a coaxial cable as shown in FIG. 2 and U-slots as shown in FIG. 6g.
That is, at a return loss of 10 dB, four notch frequency bands are plotted at 2.0 GHz to 2.8 GHz, 3.1 GHz to 3.3 GHz, 4.0 GHz to 4.5 GHz, and 4.9 GHz to 5.7 GHz.
Here, the type, number and arrangement of U-slots can be variously modified in accordance with a necessary frequency band.
As set forth above, according to exemplary embodiments of the invention, a multi-band U-slot antenna can act as multiple notch filters depending on configuration and arrangement of U-slots formed in a planar radiation device. This allows transmission and reception of a multi-band frequency through a single antenna.
While the present invention has been shown and described in connection with the preferred embodiments, it will be apparent to those skilled in the art that modifications and variations can be made without departing from the spirit and scope of the invention as defined by the appended claims.
Patent Application
20070247386
