Dielectric resonator device

Details Dielectric resonator device Dielectric resonator device

1999-04-01

2001-01-23

Pascal, Robert (Department: 2817)

Wave transmission lines and networks

Resonators

Dielectric type

C333S202000, C333S135000

Reexamination Certificate

active

06177854

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a dielectric resonator device used in a microwave band and a millimeter-wave band.
2. Description of the Related Art
Conventionally, there has been a demand for miniaturizing dielectric resonator devices such as filters, oscillators, or the like, which incorporate dielectric resonators. In response to the demand, a plane circuit type dielectric resonator device has been developed. For example, there is a “para-millimeter wave band pass filter equipped with a plane circuit type dielectric resonator”, 1996, Institute of Electronics, Information and Communication Engineers General Meeting C-121, and a “plane circuit type dielectric resonator device” in Japanese Patent Application No. 9-101458.
FIGS. 14 and 15
show an example of a dielectric resonator device employed in the above patent application.
FIG. 14
is an exploded perspective view of the device. In this figure, electrodes having three mutually opposing pairs of rectangular openings are disposed on each of both main surfaces of a dielectric plate
1
. On the upper surface of an I/O substrate
7
are disposed microstrip lines
9
and
10
which are used as probes, and on substantially the entire lower surface of the same is formed a ground electrode. A single dielectric resonator device is formed by sequentially stacking a spacer
11
, the dielectric plate
1
, and a cover
6
on the I/O substrate
7
.
FIGS. 15A
,
15
B, and
15
C respectively show an electromagnetic field distribution view of three resonators formed in the dielectric plate
1
.
FIG. 15A
is a plan view of the dielectric plate
1
;
FIG. 15B
is a sectional view of three electrode openings
4
a,
4
b,
and
4
c;
and
FIG. 15C
is a sectional view in the narrow side direction of the dielectric plate
1
. The rectangular electrode openings
4
a,
4
b,
and
4
c
having a length L and a width W, which are mutually opposed having the dielectric plate
1
therebetween are formed at given gaps g. This arrangement permits formation of a dielectric resonator with a rectangular slot mode on each of the electrode openings
4
a,
4
b,
and
4
c,
leading to formation of a filter having three-step resonators in the overall structure.
The conventional type of dielectric resonator device shown in
FIGS. 14 and 15
is extremely miniaturized overall, since it is a plane circuit type device in which a resonator is formed in a dielectric plate. However, in the conventional type of device incorporating a dielectric resonator with a rectangular slot mode, for example, non-loading Q (hereinafter referred to as Q
0
) is not higher than that in a dielectric resonator with the TE01&dgr; mode, since conductor loss of electrodes formed on both main surfaces of the dielectric plate is large. This causes a problem such as increase in insertion loss when a band pass filter is formed.
In order to increase Q
0
of the resonator, it is effective to make the width of the resonator (the width W of the electrode opening) longer than the length of the same (the length L of the electrode opening). In this case, however, the resonant frequency of a mode (where the directional relationship between the width and length of the electrode opening is reversed), in which the electric field direction is orthogonal to a basic resonant mode, is close to a frequency of a basic mode, resulting in degradation of spurious characteristics.
In addition, in the conventional type of rectangular slot mode resonator, there are great changes in filter characteristics with respect to changes in structural dimensions of the length L and gap g of the resonator. This leads to decrease in production efficiency.
Furthermore, in this conventional type of device, adjustment of the resonant frequency performed by giving perturbation to the magnetic field and the electric field also decreases production efficiency, since control in adjustment is difficult due to great perturbation quantity.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a dielectric resonator device which has characteristics of a plane circuit type dielectric resonator device applicable to miniaturization, and which further can overcome the above-mentioned problems.
To this end, the present invention provides a dielectric resonator device which includes a dielectric plate; an electrode disposed on each main surface of the dielectric plate at least one pair of substantially-polygonal mutually opposing openings formed in the electrodes; a signal input unit for inputting signals from the outside by coupling with a resonator unit formed of the electrode openings; and a signal output unit for outputting signals to the outside by coupling with the resonator unit; in which the length L in the longer side direction of at least one of the openings is longer than a half-wave length of a basic resonant mode determined by a half-wave length in resonant frequency used so as to resonate in a higher mode of the basic resonant mode.
This structure allows the resonator unit to resonate in a higher mode of the basic resonant mode, thereby, resulting in formation of an electrical barrier with no loss between gnarls of electromagnetic distributions. With the electrical barrier with no conductive loss, the entire conductive loss is decreased and Q
0
of the resonator is increased, so that insertion loss is reduced in forming a filter. Since the number of the electrical barriers formed, when a resonant degree is represented by n, is represented by n
1
, the larger the resonant degree, the less the overall conductive loss. However, since this increases the length L of the resonator, the resonant degree n is eventually determined while considering miniaturization of the device.
Furthermore, in the rectangular-slot mode resonator, as the resonant degree becomes larger, lock-in effects of electromagnetic field energy in the inside of the resonator become higher, so that the filter characteristic changes with respect to changes in the resonator length L and the gaps g between the resonators become smaller. As a result, the present invention can enhance production efficiency.
In addition, although the strength distribution of electromagnetic field forms only one wave in the case of a basic mode resonator, distributions of the number corresponding to the resonant degree are presented in the case of a higher mode resonator, so that perturbation effects on electric fields or magnetic fields can be differentiated according to the distribution of electromagnetic field energy. For example, the insertion amount of a metallic screw in an area where electromagnetic field strength is large permits coarse adjustment of resonant frequency, whereas the insertion amount of a metallic screw in an area where electromagnetic field strength is small permits fine adjustment of resonant frequency.


REFERENCES:
patent: 5764116 (1998-06-01), Ishikawa et al.
patent: 6016090 (2000-01-01), Lio et al.

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