Communications: radio wave antennas – Antennas – Microstrip
Reexamination Certificate
2000-06-13
2001-11-20
Le, Hoanganh (Department: 2821)
Communications: radio wave antennas
Antennas
Microstrip
C343S702000, C343S895000
Reexamination Certificate
active
06320545
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a surface-mount antenna incorporated in a communication apparatus, such as a portable telephone, and relates a communication apparatus using the surface-mount antenna.
2. Description of the Related Art
FIG. 16
shows one example of a surface-mount antenna incorporated in a communication apparatus, such as a portable telephone. A surface-mount antenna
1
includes a dielectric substrate
2
in which a radiation electrode
3
, a ground electrode
4
, and a feed electrode
5
are formed on the surface thereof. The radiation electrode
3
is formed over side surfaces
2
a,
2
b
and
2
c
of the dielectric substrate
2
. The ground electrode
4
is formed on the entirety of a side surface
2
d
of the dielectric substrate
2
so as to establish electrical connection with the radiation electrode
3
. The feed electrode
5
is formed on the side surface
2
a
so that a predetermined distance is maintained between the feed electrode
5
and the radiation electrode
3
.
The feed electrode
5
is connected to a power supply
6
. When the power is supplied from the power supply
6
to the feed electrode
5
, the radiation electrode
3
is supplied with the power by means of capacitive coupling from the feed electrode
5
. When the supplied power drives the radiation electrode
3
, the surface-mount antenna
1
transmits or receives electromagnetic waves in a single predetermined frequency band.
A 900 MHz band and a 1.9 GHz band are currently used as operating frequencies for portable telephones.
When the communication apparatus is required to use two different operating frequency bands such as these, a single surface-mount antenna must transmit and receive the electromagnetic waves in the two different frequency bands. However, the surface-mount antenna
1
in
FIG. 16
can transmit or receive the electromagnetic waves only in a single frequency band.
SUMMARY OF THE INVENTION
To overcome the above described problems, preferred embodiments of the present invention provide a surface-mount antenna capable of transmitting and receiving electromagnetic waves in more than one frequency band, and a communication apparatus using this surface-mount antenna.
One preferred embodiment of the present invention provides a surface-mount antenna, comprising: a dielectric substrate in a rectangular parallelepiped shape and including a first major surface, a second major surface, a first side surface, a second side surface, a first end surface and a second end surface; a radiation electrode having a meandering pattern disposed on at least two surfaces among the first major surface, the first side surface and the second side surface of the dielectric substrate and comprising at least a first meandering electrode unit and a second meandering electrode unit being connected in series; and the first meandering electrode unit having first meander pitches and the second meandering electrode unit having second meander pitches which are narrower than the first pitches; whereby the radiation electrode is allowed to transmit and receive electromagnetic waves in at least two different frequency bands.
Since the meandering radiation electrode is disposed in which at least two meandering electrode units having different meander pitches are connected in series, the radiation electrode has a plurality of resonant frequencies that correspond to the at least two meandering electrode units. Therefore, the surface-mount antenna can transmit and receive electromagnetic waves in at least two different frequency bands.
The above described surface-mount antenna may further comprise at least one passive radiation electrode disposed on the surface of said dielectric substrate and electromagnetically coupled with the radiation electrode, whereby the at least one passive radiation electrode causes dual resonance to occur in at least one frequency band among said at least two different frequency bands of the surface-mount antenna.
When a desired bandwidth of a frequency band cannot be obtained merely by driving the radiation electrode, the passive radiation electrode causes dual resonance in the frequency band to occur, whereby the bandwidth of the frequency band can be expanded to the desired bandwidth. Therefore, the bandwidth of the surface-mount antenna can be broadened.
In the above described surface-mount antenna, the at least one passive radiation electrode may have a meandering pattern.
In the above described surface-mount antenna, the at least one passive radiation electrode may be disposed on at least two faces among the first major surface, the first side surface and the second side surface of the dielectric substrate.
Since the radiation electrode or the passive radiation electrode is disposed on more than a single surface of the rectangular parallelepiped dielectric substrate, a larger disposed area thereof can be obtained compared to a case in which the radiation electrode or the passive radiation electrode is disposed on a single surface of the dielectric substrate. Regardless of the size of the radiation electrode or the passive radiation electrode, miniaturization of the dielectric substrate can be achieved.
In the above described surface-mount antenna, the at least one passive radiation electrode may be disposed on at least the first major surface of the dielectric substrate, the disposed position thereof being different from the disposed position of the radiation electrode; and the meandering pattern of the at least one passive radiation electrode is substantially perpendicular to that of the radiation electrode.
Since the meandering pattern of the passive radiation electrode and that of the radiation electrode are disposed so as to be substantially perpendicular to each other, an interference problem in that the driving of the radiation electrode adversely affects the driving of the passive radiation electrode can be avoided. In particular, when the unconnected end of the passive radiation electrode and the ground are indirectly coupled due to capacitive coupling, this capacitive coupling can more positively prevent the above-described interference problem. The driving of the radiation electrode and the driving of the passive radiation electrode can be independently performed and lead to dual resonance in a predetermined frequency band. Accordingly, the deterioration of antenna characteristics due to the above-described interference between the radiation electrode and the passive radiation electrode can be prevented.
The above described surface-mount antenna may further comprise a matching circuit in association with the dielectric substrate, and the radiation electrode is coupled with a power supply via the matching circuit.
When the matching circuit is provided in the dielectric substrate, there is no need to form the matching circuit on a circuit substrate that is to be provided with the surface-mount antenna. Accordingly, since the implementation area of the parts of the circuit substrate as well as the number of the parts can be reduced, the cost of the parts and the cost of the implementation can be reduced.
Another preferred embodiment of the present invention provides a surface-mount antenna for transmitting and receiving electromagnetic waves in at least two different frequency bands, the surface-mount antenna comprising means for broadening the bandwidth thereof by causing dual resonance to occur in at least one of the at least two different frequency bands.
Yet another preferred embodiment of the present invention provides a communication apparatus having the above described surface-mount antenna mounted on a circuit substrate.
In the communication apparatus that uses the surface-mount antenna according to the present invention, since a plurality of frequency bands can be covered using a single surface-mount antenna, the communication apparatus can be miniaturized.
REFERENCES:
patent: 5903240 (1999-05-01), Kawahata et al.
patent: 5966097 (1999-10-01), Fukasawa et al.
patent: 6124831 (2000-09-01), Rutkowski et al.
Kawahata Kazunari
Nagumo Shoji
Tsubaki Nobuhito
Le Hoang-anh
Murata Manufacturing Co. Ltd.
Ostrolenk Faber Gerb & Soffen, LLP
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