JPH082001B2 - Band pass filter - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bandpass wave device used in a high frequency band.

2. Description of the Related Art Bandpass wave filters in the high frequency band are indispensable devices for high frequency circuits, and have been put to practical use in a large number of devices such as wireless communication devices and measuring devices. This wave device is required to be small, low loss, low cost, and have sharp attenuation characteristics. To meet the requirements of small size, low loss, and low cost, the structure of the resonator that constitutes the wave device is also required. I can't neglect it. Conventionally, for example, a split ring resonator disclosed in Japanese Patent Publication No. 54-42574 is known as a resonator under the above conditions in the UHF band or higher. FIGS. 2 (A) and 2 (B) show a two-stage structure in which both end faces of a cylindrical ring-shaped dielectric are metallized and one end face is used as a ground conductor and the other end face is used as a resonant line conductor with both ends open. It shows the wave instrument of.

 FIG. 2 (C) shows the frequency response.

Hereinafter, a bandpass wave device using a conventional cylindrical ring resonator will be described with reference to FIG.

In FIGS. 2A and 2B, 101 is a cylindrical and ring-shaped dielectric, 102 is a ground conductor metallized on the lower surface of the dielectric 101, and 103 is a resonance metallized on the upper surface of the dielectric 101. Reference numeral 104 is a line conductor, 104 is an input / output terminal drawn from above the resonant line conductor 103, 105 is an input / output coupling capacitor, 106 is a capacitor for resonant frequency tuning, and 108 is a housing. The cylindrical ring resonators arranged as shown in the figure obtain the inter-stage coupling degree k necessary for obtaining a desired bandpass characteristic by spatial coupling. In addition, if we explain about a wave device that uses a cylindrical ring resonator, this resonator is a cylindrical ring dielectric.
Utilizing the top and bottom of 101, it is close to the TEM mode, the required dielectric 101 is the smallest, and it is a structure that can control the loss by changing only the thickness, and by mounting the capacitor 106, It is much smaller than ordinary ring resonators, economical, and low loss. That is, when constructing a wave device, it is expected that the wave device will be downsized, the insertion loss will be reduced, and the cost will be reduced.

The operation of the above configuration will be described below. A high-frequency signal input to one of the terminals 104 is output by a bandpass wave filter composed of a ring resonator, an input / output capacitor 105, and an interstage coupling degree k, and its frequency response is shown in FIG. It becomes like the locus 109 of C).

Problems to be Solved by the Invention As described above, the bandpass wave device having the above-described configuration has the features of being small in size, having a small insertion loss, and being low in cost due to the structure of the resonator. However, there is a problem that the amount of attenuation in the stop band in the frequency response cannot be secured sufficiently. In order to obtain sufficient damping characteristics with a small number of stages, the configuration of a polar wave device is optimal, but the TE
When an M transmission line type resonator is used, an auxiliary circuit for polarization is conventionally required, which complicates the structure of the wave device, and causes problems such as large size and complicated adjustment. .

The present invention solves the above-mentioned problems of the prior art, and an object thereof is to obtain a large amount of attenuation in the stop band by polarization without complicating the structure of the wave device.

Means for Solving the Problems In order to solve the above problems, the present invention metallizes conductors on the upper surface of a substantially cylindrical ring-shaped dielectric material so as to have both open ends, and connects the both open ends with a capacitive element. As a resonance line conductor, two or more resonators, which are grounded conductors by metallizing the conductor on the lower surface of the substantially cylindrical ring-shaped dielectric, are arranged adjacent to each other.
Between the resonance line conductors of the adjacent resonators,
The above object is achieved only by connecting a minute capacitance that gives an attenuation pole to the stop band of the pass band width.

The present invention has the above-described configuration, by effectively utilizing the narrow spaces of the ring resonators adjacent to each other, without using an auxiliary circuit that requires a space only by providing a minute capacitance, and in the frequency response of the wave resonator, a stop band is obtained. Not only is it possible to form a damping pole to obtain a sharp damping characteristic, but also the frequency of the damping pole can be controlled by the minute capacitance value.

Example Hereinafter, an example of the present invention will be described with reference to the drawings.

1 (A) and 1 (B) are a top view and a side view showing a bandpass wave device according to an embodiment of the present invention. In FIGS. 1A and 1B, 101 is a cylindrical ring-shaped dielectric, 102 is a ground conductor metallized on the lower surface of the dielectric 101, and 103 is a resonance metallized on the upper surface of the conductor 101. A line conductor, 104 is an input / output terminal drawn from the resonance line conductor 103, 105 is a capacitance for input / output coupling provided between the resonance line conductor 103 and the input / output terminal 104, and 106 is the resonance line conductor 103.
A resonance frequency tuning capacitance mounted in the notch portion, 107 is a minute capacitance for polarization provided between the resonance line conductors 103 of the resonators A and B, and 108 is a casing. Further, FIG. 1 (C) shows a frequency response characteristic. In FIG. 1 (C), 109 is the frequency response of the conventional configuration, and 110 is the frequency response characteristic of this embodiment.

The operation of the above configuration will be described below. In this embodiment, by providing a minute capacitance 107 between the resonators A and B adjacent to each other, an attenuation pole is provided in the frequency response indicated by the locus 110 in FIG. 1C, that is, in the stop band of the pass bandwidth. You can Further, when the capacitance value of the minute capacitance 107 is changed, the frequency of the attenuation pole in the stop band can be controlled as shown by the locus 111 in FIG. 1 (C).

As described above, according to the present embodiment, by connecting the minute capacitances by effectively utilizing the narrow spaces of the ring-shaped resonators adjacent to each other, the attenuation pole is formed in the stop band in the frequency response characteristic, and the steep attenuation characteristic is obtained. At the same time, it becomes possible to easily control the frequency of the attenuation pole by the value of the minute capacitance.

Although the ring resonator has a cylindrical shape in the present embodiment, the present invention is not limited to this, and it goes without saying that a ring resonator having a strip line with both ends open or a microstrip line may be used.

EFFECTS OF THE INVENTION As described above, according to the present invention, it is possible to form a damping pole in the stop band and obtain a steep damping characteristic only by using the ring-shaped resonator and connecting the mutually adjacent resonant lines with a minute capacitance. In addition to being possible, the frequency of the attenuation pole can be controlled by a minute capacitance value, which has great industrial utility value.

[Brief description of drawings]

1 (A) and 1 (B) are a plan view and a side view of a bandpass wave device according to an embodiment of the present invention, and FIG. 1 (C) is a characteristic diagram showing a frequency response of the bandpass wave device. Figure 2 (A),
FIG. 2B is a plan view and a side view of a conventional bandpass wave resonator using a cylindrical ring resonator, and FIG. 2C is a characteristic diagram showing a frequency response of the bandpass wave resonator. 101 ... Dielectric, 102 ... Ground conductor, 103 ... Resonance line conductor, 104 ... Input / output terminal, 105 ... Input / output coupling capacitance, 10
6 ... Resonant frequency tuning capacitor, 107 ... Micro capacitor, 108 ...
… Case.

Claims (1)

[Claims] 1. A ring-shaped dielectric having a substantially cylindrical shape, wherein conductors are metallized on the upper surface of a substantially cylindrical ring-shaped dielectric so as to have both open ends, and the open ends are connected by a capacitive element to form a resonance line conductor. Two or more resonators, which are metallized conductors on the lower surface of the body and are used as ground conductors, are arranged adjacent to each other, and a small attenuation pole is provided between the resonance line conductors of the adjacent resonators in the stop band of the pass band width. Bandpass wave device with connected capacity.