Wave transmission lines and networks – Plural channel systems – Having branched circuits
Reexamination Certificate
2000-02-10
2003-03-11
Pascal, Robert (Department: 2817)
Wave transmission lines and networks
Plural channel systems
Having branched circuits
C333S219100, C333S202000
Reexamination Certificate
active
06531934
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to high-frequency electronic parts and particularly to a dielectric resonator to be used in microwave and millimeter wave bands and a dielectric filter, dielectric duplexer, oscillator, and communication device using such.
2. Description of the Related Art
A first example of a conventional dielectric filter is explained with reference to FIG.
26
.
The dielectric filter
110
a
comprises a dielectric substrate
120
a
on the opposing upper and lower surfaces of which electrodes are arranged, a lower case
112
, and an upper case
111
. By removing part of the upper electrode five round electrodeless portions
121
a
through
121
e
are formed. In like manner, electrodeless portions
121
a′
through
121
e′
(not shown) of the same shape are formed at the corresponding locations of the lower electrode. A dielectric resonator
122
a
is composed of a dielectric substance between the electrodeless portions
121
a
and
121
a′
and the upper and lower cases
111
and
112
surrounding the substance. Other pairs of the electrodeless portions also constitute dielectric resonators likewise. The resonance frequency of each of the resonators depends on the shape of the electrodeless portions
121
a
through
121
e,
the thickness of the dielectric substrate
120
a,
etc.
The lower case
112
is made up of a substrate
113
and a metal frame
114
placed on the substrate. Inside the metal frame
114
a support
115
to support the dielectric substrate
120
a
is formed. On substantially the whole upper surface of the substrate
113
an electrode
116
is arranged. Part of the electrode
116
is removed, and in the electrodeless portion microstrip lines
130
and
131
are arranged. These lines function as input-output lines of the filter
110
a.
Further, on nearly the whole surface of the bottom of the substrate
113
an electrode
116
′ (not shown) is arranged.
In this filter, for example, the TE
010
resonance mode of each of the dielectric resonators is used. When a signal is input into the microstrip line
130
, the microstrip line
130
and the dielectric resonator
122
a
are electromagnetically coupled. Further, through the coupling between the neighboring dielectric resonators
122
a
through
122
e
a signal is output from the microstrip line
131
on the output side. As a result, the dielectric filter
110
a
functions as a five-stage bandpass filter. The non-loaded Q of a dielectric resonator using the TE
010
mode is higher than the non-loaded Q of a dielectric resonator having a rectangular slot, which will be described later. For example, at 26 GHz the non-loaded Q of the former is about 1900 and the non-loaded Q of the latter is about 900. Thus, when TE
010
mode is used, non-loaded Q of the dielectric resonators is high, and accordingly there is an advantage of being able to obtain a dielectric filter with a small insertion loss.
Next, a second example of a conventional dielectric filters is explained with reference to FIG.
27
.
In a dielectric filter
110
b,
the shape of the electrodeless portions
1121
f
through
1121
j
of the electrode is rectangular. The shape of the electrodeless portions on the lower surface of the substrate
1120
b
is the same. By making the shape of the electrodeless portions
1121
f
through
1121
j
rectangular, a rectangular slot mode is used as a resonance mode. For example, the TE
102
mode, which is a rectangular slot mode, can be used. When a rectangular slot mode is used, the amount of an electromagnetic field leaking outside the resonator increases, compared with the case where the TE
010
mode is used, and the degree of coupling between the input-output lines and the resonators and between the dielectric resonators
1122
f
through
1122
j
increases.
In the dielectric filter to be used in a communication device, a sufficient damping characteristic is required in the vicinity of a pass band. Generally, dielectric resonators constituting a dielectric filter have many resonance modes, and there are cases where the resonance frequencies of undesired resonance modes exist in the vicinity of the resonance frequencies of resonance modes to be used. In such cases, by changing the diameter of the resonators and the thickness of the dielectric substrate adjustment takes place so that the resonance frequencies of both modes are separated from each other. However, in the above conventional filters the separation of the resonance frequencies of both modes could not be effectively separated.
FIG. 28
shows the relationship between the resonance frequency and the resonator's diameter of the dielectric resonators contained in the dielectric filter
110
a.
The solid line represents the TE
010
mode as a resonance mode to be used, and the broken line the HE
310
mode which is an undesired resonance mode. Further,
FIG. 29
shows the relationship of the resonance frequency to the resonator length (here, resonator length measured along the direction in which the plurality of resonators are arranged) in the dielectric filter
110
b.
The solid line represents the TE
102
mode as a resonance mode to be used, the broken line the TM
111
mode as an undesired resonance mode, and the one-dot chain line the TM
112
mode as another undesired resonance mode.
As understood in
FIGS. 28 and 29
, even if the sizes or shapes, etc., are changed in these dielectric resonators, the resonance frequency of an undesired resonance mode can not be so effectively separated from the resonance frequency of a resonance mode to be used.
SUMMARY OF THE INVENTION
According to the present invention, a dielectric resonator, dielectric filter, dielectric duplexer, oscillator, and communication device which have a good transmission characteristic or reflection characteristic are provided by separating the resonance frequency of an undesired resonance mode sufficiently far from the resonance frequency of a resonance mode to be used.
A dielectric resonator according to one aspect of the present invention comprises a dielectric substrate having two opposing two main surfaces, on which surface electrodes are formed. Electrodeless portions are formed in the surface electrodes, and a conductor is arranged a fixed distance away from the dielectric substrate. At least one electrode projection portion which projects into the electrodeless portion is provided in the boundary portion between the electrodeless portion and the electrode.
Further, a dielectric resonator according to a second aspect of the present invention comprises a dielectric substrate on the two opposing main surfaces on which surface electrodes are formed, electrodeless portions formed in the surface electrodes on the two main surfaces, and a conductor arranged a fixed distance away from the dielectric substrate, wherein at least one electrode recessed portion is formed in the surface electrode in the boundary portion between the electrodeless portion and the electrode.
Further, at least one projection portion and at least one recessed portion may be combined in a single dielectric resonator.
These projection and recessed portions can have an influence on the resonance frequencies of various resonance modes existing in a dielectric resonator and can separate the resonance frequencies of undesired resonance modes away from the resonance frequencies of resonance modes to be used.
Further, in a dielectric resonator of the present invention, the electrode projection portions can be arranged at fixed locations corresponding to undesired resonance modes in the dielectric resonator, respectively.
Further, in a dielectric resonator of the present invention, the recessed portions of electrode can be arranged at fixed locations corresponding to undesired resonance modes in the dielectric resonator, respectively.
These projection and recessed portions can change the resonance frequency of an undesired resonance mode most affecting the resonance mode to be used, that is, the undesired resonance mode having a resonance fre
Hiratsuka Toshiro
Kanagawa Kiyoshi
Mikami Shigeyuki
Sonoda Tomiya
Murata Manufacturing Co. Ltd.
Ostrolenk Faber Gerb & Soffen, LLP
Pascal Robert
Takaoka Dean
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