JPS6033602Y2 - bandstop filter - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a band rejection characteristic device using a coaxial dielectric resonator.

In recent years, with the development of ceramic materials that have a high dielectric constant, low high-frequency loss, and good temperature characteristics, dielectric resonators using these materials have come into practical use.

Along with this, band-stop filters using dielectric resonators have also been realized.

A band-stop filter is formed by arranging one or more dielectric resonators, for example, at appropriate intervals near the center conductor of a microstrip line.

FIG. 1 is a perspective view of a one-stage band-elimination filter using a microstrip line.

In the figure, 11, 12, and 13 are a center conductor, a dielectric substrate, and a ground conductor, respectively, which constitute a microstrip line.

14 is a disc-shaped dielectric resonator provided on the dielectric substrate 12.

The band rejection characteristic of the filter is based on the center conductor 11 and the dielectric resonator 1.
4.

Ratio of diameter and thickness 1 of disc-shaped dielectric resonator 14]/D
is often chosen to be around 0.4 to avoid unnecessary modes.

The diameter is the dielectric constant E and the operating frequency f of the dielectric resonator 14.
is required once it is determined.

For example, in the case of E~40, f=1c; H2, the diameter is approximately 5orIr! IL1 thickness 1 is approximately 20 layers.

As can be seen from this, since the dielectric resonator 14 becomes large at low frequencies below IGH2, there is a drawback that the band-elimination filter using this also necessarily becomes large.

The purpose of this invention is to eliminate these drawbacks of the conventional ones,
The object of the present invention is to provide a miniaturized band-stop filter suitable for a microstrip structure in a relatively low microwave band.

1 According to the present invention, there is a central conductor in which two linear conductors spaced apart from each other and arranged in a straight line are connected by a U-shaped intermediate conductor, a conductor part inside the cylinder of a hollow cylindrical dielectric body, and a conductor on the outer peripheral surface of the cylinder. A coaxial dielectric resonator is provided with a coating, and the conductor coating near the center of the cylinder axis on the outer peripheral surface of the cylinder is removed in a slit shape over the outer circumference, and the coaxial dielectric resonator is formed on the center conductor. The band-stop filter is characterized in that the cylindrical axis of the coaxial dielectric resonator is arranged near the linear center conductor and substantially parallel to the linear center conductor through a gap or an insulating sheet. It will be done.

Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 2a and 2b show a cross-sectional view and a vertical cross-sectional view of a dielectric resonator used in the present invention.

In the figure, 21 has a length of 172 which is the T'EM mode fundamental wave.
It is a hollow cylindrical dielectric part with a wavelength, and its inner diameter and outer diameter are determined by taking into consideration the loss of this dielectric resonator.

22 is a conductive film covering the inner peripheral surface of the dielectric portion 21, and 23 is a conductive film covering the outer peripheral surface of the dielectric 21.

The conductor coating 23 is provided with a slit-shaped conductor coating removal portion 24 extending around the outer periphery of the cylinder near the center of the cylindrical axis.

The relative permittivity of the dielectric material 21 shown in FIG.
When calculated assuming that GH2 is excited by a TEM mode fundamental wave, the length of this dielectric resonator is approximately 24 mm.

However, because the slit-shaped conductive film removed portion 24 is provided on the outer peripheral surface, the excited mode is considered to be different from the TEM mode fundamental wave, and according to experiments, the length of the dielectric resonator that excites IGH2 is It was about 30 rran.

Further, the outer diameter and inner diameter of the dielectric resonator are determined by considering many design conditions, and in this case, they were approximately 16 mm and 5rIrII&, respectively.

Therefore, this dielectric resonator is smaller in size than the conventional disc-shaped dielectric resonator.

Note that the conductive coating 22 provided on the inner circumferential surface of the dielectric 21 in FIG.
The same effect can be obtained by filling the hollow part with a conductor instead.

FIG. 3 is a perspective view showing an embodiment of the microstrip line type band-stop filter of the present invention using the dielectric resonator shown in FIG. 2.

In the figure, 31, 32 and 33 are the center conductors of the microstrip line, 34 is a dielectric substrate, 35 is a ground conductor, and 36 is the dielectric resonator shown in FIG.

The center conductors 31 and 32 are linear center conductors that are separated from each other but arranged in a straight line.

The center conductor 33 is U-shaped, and its ends are connected to the center conductors 31 and 32, respectively.

The dielectric resonator 36 is located near both ends of the U-shaped central conductor 33 and approximately parallel to the linear central conductor 31 or 32.
Further, the dielectric resonator 36 is arranged so that its longitudinal center is near the symmetry axis of the U-shaped central conductor 33.

A gap may be provided between the dielectric resonator 36 and the microstrip line, or an insulating sheet may be interposed between the dielectric resonator 36 and the microstrip line.

According to experiments, the length of the U-shaped center conductor 33 should be around 18 wavelengths of the center frequency, and the distance between the linear center conductors 31 and 32 should be about 172 times the length of the dielectric resonator 36. Understood.

Furthermore, although a hollow cylindrical dielectric resonator has been described here, the cylindrical shape may be modified into a polygonal shape as necessary.

According to the present invention, a band-stop filter suitable for a microstrip structure and miniaturized in a relatively low microwave band is obtained.

[Brief explanation of drawings]

Fig. 1 is a perspective view of a conventional band-stop filter using a microstrip line, and Fig. 2 a and b are cross-sectional views of an example of a dielectric resonator used in the band-stop filter according to the present invention. The vertical sectional view and FIG. 3 are perspective views of an embodiment of a band-stop filter according to the present invention. In the figure, 11... center conductor of the microstrip line, 12... dielectric substrate 13...
. . . Ground conductor, 14 . . . Disc-shaped dielectric resonator, 21 . . . Hollow cylinder dielectric part, 22, 23.
...Conductor coating, 24...Conductor coating removed portion, 31-33...Center conductor of microstrip line, 34...Dielectric substrate, 35... ...
- Ground conductor, 36... is a coaxial dielectric resonator.

Claims (1)

[Scope of utility model registration request] A center conductor in which two linear conductors spaced apart from each other and arranged in a straight line are connected by a U-shaped intermediate conductor, and a conductor coating is provided on the conductor part and the outer peripheral surface of the cylinder inside the cylinder of the hollow cylindrical dielectric body, The conductor coating near the center of the cylinder axis on the outer peripheral surface of the cylinder is removed in the form of a slit to form a coaxial dielectric resonator,
The coaxial dielectric resonator is arranged with the center conductor through a gap or an insulating sheet such that the cylindrical axis of the coaxial dielectric resonator is near the linear center conductor and is substantially parallel to the center conductor. Characteristic band-stop filter.