Communications: radio wave antennas – Antennas – Microstrip
Reexamination Certificate
2002-05-28
2003-12-02
Wong, Don (Department: 2821)
Communications: radio wave antennas
Antennas
Microstrip
C343S702000, C343S770000
Reexamination Certificate
active
06657593
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to surface mount type antennas in which a radiation electrode is provided on a substrate, and radio transmitters and receivers including such surface mount type antennas.
2. Description of the Related Art
FIG. 8A
shows an example of a typical antenna. An antenna
30
is disclosed in European Patent Laid-Open No. EP0938158A2, and includes a conductor line
31
. One end of the conductor line
31
defines a fed-end section connected to the signal source (transmission and receiving circuit)
32
of a radio transmitter and receiver, such as a portable telephone, and the other end defines an open end. The conductor line
31
is bent in a loop manner, and the open end &bgr; of the conductor line
31
is disposed in the vicinity of the fed-end-section side &agr; with a gap therebetween.
The antenna
30
has a return-loss characteristic similar to that shown in FIG.
8
B. More specifically, in the antenna
30
, the conductor line
31
resonates at resonant frequencies F
1
and F
2
to execute an antenna operation according to a signal sent from the signal source
32
. Among a plurality of resonant frequencies of the conductor line
31
, a resonant operation at the lowest resonant frequency is called a basic mode, and a resonant operation at a higher resonant frequency than that of the basic mode is called a high-order mode.
In the antenna
30
, the high-order-mode resonant frequency F
2
is variably controlled, with the basic-mode resonant frequency F
1
being rarely changed when the capacity between the fed-end-section side &agr; and the open end &bgr; of the conductor line
31
is variably controlled to variably change the amount of electromagnetic coupling between the fed-end-section side &agr; and the open end &bgr;. Therefore, in the antenna
30
, the basic-mode resonant frequency F
1
and the high-order-mode resonant frequency F
2
are easily adjusted to desired frequencies.
Recently, very compact antennas have been demanded for portable telephones and global positioning systems (GPSs). Because the antenna
30
includes the conductor line
31
, and the conductor line
31
must have a length corresponding to the specified basic-mode resonant frequency, however, it is difficult to reduce the size of such antennas and it is very difficult to successfully satisfy the recent demand for reducing the size of such antennas.
In addition, since the antenna
30
includes only the conductor line
31
, it is difficult to prevent the size of the antenna
30
from increasing while its frequency band is expanded.
SUMMARY OF THE INVENTION
In order to overcome the above-described problems, preferred embodiments of the present invention provide a surface mount type antenna having a reduced size and a wide frequency band, and a radio transmitter and receiver including such a novel antenna.
One preferred embodiment of the present invention provides a surface mount type antenna including a fed radiation electrode to which a signal is sent from a signal source that is provided on a substrate, wherein one or a plurality of fed radiation electrodes each having a loop shape in which a first end defining a fed-end-section which receives a signal from the signal source is disposed opposite the other end which defines an open end, with a gap disposed therebetween is provided, and in addition, a non-fed radiation electrode which is electromagnetically coupled with at least an adjacent fed radiation electrode to generate a double-resonant state is provided on the substrate.
The surface mount type antenna is preferably configured such that the non-fed radiation electrode includes one ground end connected to the ground and another open end, and one or a plurality of non-fed radiation electrodes each having a loop shape in which the open end is disposed opposite a ground-end side with a gap disposed therebetween is formed.
The surface mount type antenna is preferably configured such that the fed radiation electrode and the non-fed radiation electrode perform a basic-mode resonant operation and a high-order-mode resonant operation having a higher resonant frequency than in the basic mode, and the distance between the open end of the loop-shaped fed radiation electrode or the loop-shaped non-fed radiation electrode and a portion opposite the open end through a gap is changed to adjust the capacitance of a capacitor generated between the open end and the portion opposite the open end to that corresponding to a specified high-order-mode resonant frequency.
The surface mount type antenna is preferably configured such that the loop-shaped fed radiation electrode or the loop-shaped non-fed radiation electrode has a loop shape by providing a slit for a plane-shaped pattern, and the slit is folded one or more times, or has a bent shape.
The surface mount type antenna is preferably configured such that the substrate is a dielectric substrate, and the dielectric substrate defines a coupling-amount adjusting element for adjusting the amount of coupling between the fed radiation electrode and the non-fed radiation electrode by the dielectric constant of the substrate.
The surface mount type antenna is preferably configured such that the fed radiation electrode and the non-fed radiation electrode perform a basic-mode resonant operation and a high-order-mode resonant operation having a higher resonant frequency than in the basic mode. The substrate is a dielectric substrate, and the dielectric substrate functions as open-end-capacitor adjusting element for adjusting the capacitance of a capacitor provided between the open end of the loop-shaped fed radiation electrode or the loop-shaped non-fed radiation electrode and a portion opposite the open end by the dielectric constant of the substrate to adjust the high-order-mode resonant frequency.
Additionally, the surface mount type antenna is preferably configured such that one or both of a capacity-loaded electrode disposed through a gap adjacently to the fed radiation electrode and having a capacitor between itself and the fed radiation electrode and a capacity-loaded electrode disposed through a gap adjacently to the non-fed radiation electrode and having a capacitor between itself and the non-fed radiation electrode are provided, and the capacity-loaded electrode(s) is electrically connected to the ground.
Another preferred embodiment of the present invention provides a radio transmitter and receiver including one of the surface mount type antennas according to preferred embodiments described above.
In various preferred embodiments of the present invention, since a surface mount type antenna includes a fed radiation electrode provided on a substrate, the antenna is much more compact than the line-shaped antenna shown in the conventional example. On the substrate, a non-fed radiation electrode is disposed in the vicinity of the fed radiation electrode and is electromagnetically coupled with the fed radiation electrode to generate a double-resonant state. Double resonance caused by the fed radiation electrode and the non-fed radiation electrode can easily extend the frequency band. Therefore, an antenna and a radio transmitter and receiver having a greatly reduced size and a wide frequency band are obtained.
According to preferred embodiments of the present invention, since, on a substrate, a loop-shaped fed radiation electrode is provided and a non-fed radiation electrode is also provided to generate a double-resonant state together with the fed radiation electrode, the antenna is made much more compact than the line-shaped antenna, shown in a conventional example, and the frequency band thereof is easily expanded. Therefore, the surface mount type antenna and the radio transmitter and receiver having a greatly reduced size and an extended frequency band are provided.
When a non-fed radiation electrode has a loop shape, the capacitance of a capacitor defined between an open end and a ground end side of the non-fed radiation electrode is adjusted to easily adjust the high-order-mode resonant fre
Ishihara Takashi
Nagumo Shoji
Onaka Kengo
Sato Jin
Chen Shih Chao
Keating & Bennett LLP
Murata Manufacturing Co. Ltd.
Wong Don
LandOfFree
Surface mount type antenna and radio transmitter and... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Surface mount type antenna and radio transmitter and..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Surface mount type antenna and radio transmitter and... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3159878