Communications: radio wave antennas – Antennas – Microstrip
Reexamination Certificate
2001-03-23
2002-12-10
Wong, Don (Department: 2821)
Communications: radio wave antennas
Antennas
Microstrip
C343S702000
Reexamination Certificate
active
06492946
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a surface-mounted type antenna incorporated in a communication device such as a portable telephone, and to a method for adjusting and setting the dual-resonance frequency thereof. The present invention further relates to a communication device including the surface-mounted type antenna.
2. Description of the Related Art
FIG. 17
shows an example of a surface-mounted type antenna. The surface-mounted type antenna
1
shown in
FIG. 17
is formed by juxtaposing a power supplied first radiation electrode
3
and a second radiation electrode
4
to which power is not directly supplied on a dielectric substrate
2
having a rectangular parallelepiped shape, with a space (slit) S therebetween. One end side of the first radiation electrode
3
is connected to a power supply portion (power supply terminal)
5
, and the other end side thereof constitutes an open end
3
a
. One end side of the second radiation electrode
4
is connected to a short-circuit portion (ground short-circuit terminal)
6
, and the other end side thereof constitutes an open end
4
a.
By connecting the power supply portion
5
to a signal supply source
7
and directly supplying a signal from the signal supply source
7
to the first radiation electrode
3
via the power supply portion
5
, and by supplying the signal which has been supplied to the first radiation electrode
3
to the second radiation electrode
4
by an electromagnetic coupling, the first radiation electrode
3
and the second radiation electrode
4
each resonate, thereby performing an antenna operation (operation of signal transmission/reception).
In a surface-mounted type antenna
1
as shown in
FIG. 17
, by bringing the resonance frequencies of the first radiation electrode
3
and the second radiation electrode
4
close to each other and by causing the resonance waves of the first radiation electrode
3
and the second radiation electrode
4
to create a dual resonance, a widening of the frequency band of signal transmission/reception can be achieved.
A surface-mounted type antenna
1
as described above is required to be miniaturized. In order to achieve the miniaturization thereof, the spacing between the first radiation electrode
3
and the second radiation electrode
4
is narrowed as an inevitable consequence. As a result, the electromagnetic coupling between the first radiation electrode
3
and the second radiation electrode
4
strengthens. This makes it difficult to stably achieve a desired dual-resonance state which allows a required antenna characteristic condition such as the widening of the frequency band to obtained. In order to solve this problem and to stably achieve a desired dual-resonance state, it is necessary to control the electromagnetic coupling between the first radiation electrode
3
and the second radiation electrode
4
.
In the surface-mounted type antenna
1
shown in
FIG. 17
, by adjusting the width of the uniform-width space S between the first radiation electrode
3
and the second radiation electrode
4
, the electromagnetic coupling between the first radiation electrode
3
and the second radiation electrode
4
is controlled. However, the control of the electromagnetic coupling using the uniform-width space S is very difficult to execute, and provides a limited degree of flexibility in the design.
The present invention has been made to solve the above-described problem, and aims to provide a surface-mounted type antenna which allows the miniaturization thereof and which is capable of easily meeting a required antenna characteristic condition, and to provide a method for adjusting and setting the dual resonance thereof, as well as a communication device including the surface-mounted type antenna.
SUMMARY OF THE INVENTION
In order to achieve the above-described object, the present invention, in a first aspect, provides a method for adjusting and setting the dual-resonance frequency of a surface-mounted type antenna which includes a dielectric substrate, a first radiation electrode to which power is supplied being formed on the top surface opposed to the mounting bottom-surface of the dielectric substrate, and a second radiation electrode which is juxtaposed with the first radiation electrode on the dielectric substrate with a space therebetween. This method comprises arranging the first radiation electrode and the second radiation electrode so that the strong electric-field regions of the first radiation electrode and the second radiation electrode wherein the electric fields of these radiation electrodes are each the strongest, are adjacent to each other, and so that the-strong electric-field regions of these radiation electrodes thereby come into an electric-field coupling, simultaneously arranging the first radiation electrode and the second radiation electrode so that the high current regions of the first radiation electrode and the second radiation electrode wherein the currents of these radiation electrodes are each highest, are adjacent to each other, and so that the high current regions of these radiation electrodes thereby come into a magnetic-field coupling, variably adjusting each of the quantity of the electric-field coupling between the strong electric-field regions of the first radiation electrode and the second radiation electrode, and the quantity of the magnetic-field coupling between the high current regions of the first radiation electrode and the second radiation electrode, and setting the reflection loss of the dual resonance of the first radiation electrode and the second radiation electrode to a low value not higher than a predetermined value within the range of the set frequency, by adjusting both the quantities of the electric-field coupling and the magnetic-field coupling.
In the method for adjusting and setting the dual-resonance frequency of a surface-mounted type antenna in accordance with the first aspect of the present invention, preferably, the quantity of the electric-field coupling between the strong electric-field regions of the first radiation electrode and the second radiation electrode is variably adjusted, by making variable the spacing between the strong electric-field regions of the first radiation electrode and the second radiation electrode.
Also, in this method in accordance with the first aspect, it is preferable that the first radiation electrode be provided with a capacitance between the open end thereof which is the strong electric-field region thereof on one end side thereof and ground, that a power supply terminal or a ground short-circuit terminal be connected to the high current region thereof on the other end side thereof, while the second radiation electrode be provided with a capacitance between the open end thereof which is the strong electric-field region thereof on one end side thereof and ground, that a ground short-circuit terminal be connected to the high current region thereof on the other end side thereof, and the quantity of the electric-field coupling between the strong electric-field regions of the first radiation electrode and the second radiation electrode be relatively variably adjusted, by variably adjusting the capacitance between the open end of the first radiation electrode and ground, and the capacitance between the open end of the second radiation electrode and ground.
Furthermore, in the method in accordance with the first aspect, it is preferable that the dielectric substrate be formed as a rectangular parallelepiped, and that the capacitive coupling portion between the open end of the strong electric-field region of the first radiation electrode and ground thereof and the capacitive coupling portion between the open end of the strong electric-field region of the second radiation electrode and ground thereof be each formed on mutually different surfaces of the dielectric substrate.
Moreover, in the method in accordance with the first aspect, preferably, the quantity of the magnetic-field coupling between the high current regions of the fir
Ishihara Takashi
Kawahata Kazunari
Nagumo Shoji
Onaka Kengo
Tsubaki Nobuhito
Clinger James
Murata Manufacturing Co. Ltd.
Ostrolenk Faber Gerb & Soffen, LLP
Wong Don
LandOfFree
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