JPH02159102A - Microwave filter device - Google Patents

Abstract

PURPOSE:To reduce the mismatching loss or the transmission loss by separating plural filters from each other via the narrow wall surface parts of a shielding casing and connecting these separate filters via a microstrip line. CONSTITUTION:A microwave signal of 10GHz is supplied form an input connector 1 and led to a filter substrate 2 made of a dielectric board to undergo the band limitation via the first filter 6. Then the microwave signal is supplied to a microstrip line part 5 formed at a part to be connected to the second filter 6. The distance between wall surfaces of a shielding room 4c set at the connecting part is smaller than the distance between wall surfaces of a shielding casing of a shielding room 4a. The cut-off frequency is increased so that the interference is reduced between both filters 6 connected to each other. Thus it is possible to secure an effect equivalent to that obtained in such a case where both filters 6 are filtered independently of each other. As a result, the mismatching loss or the transmission loss can be reduced in a connection state.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a microwave filter device used in microwave communication equipment and the like.

2. Description of the Related Art A conventional microwave filter device has a configuration as shown in FIG. This will be explained below based on the drawings.

FIG. 2a is a view of the microwave filter device as seen from the top with the cover removed. The same figure is a cutaway view seen from the side. 10a and 10b are filter substrates, 16 is a filter 9 formed in a pattern, is a shield housing, 11 is a connection connector, 12 is an input connector, 13 is an output connector, and 14 is a cover.

The operation of the conventional microwave filter device configured as described above will be described below.

The microwave signal inputted from the input connector 12 passes through the filter board 10& and is band-limited, passes through the connecting connector 11, passes through the filter board 10b, is further band-limited, and is output through the output connector 13.

Here, the reason why at least two or more filters 16 are required is that when the filter device is configured with a microstrip line or the like, in order to make the band-limiting characteristic steep, it is necessary to configure the filters in multiple stages. With dielectrically charged leather plates that are easily available, it is difficult to obtain steep band-limiting characteristics without using 3 to 6 stages of filters.
It is necessary to connect two or more completely shielded filters 16 in series using a connector 11 or the like.

Problems to be Solved by the Invention However, in such a conventional method, it is necessary to connect the completely shielded filter 1F5 with the connecting connector 11, etc., and it is necessary to convert the strip line to the connecting connector 11 and to connect the completely shielded filter 1F5 with the connecting connector 11. There was a problem in that mismatching loss and transmission loss were added, deteriorating performance.

The present invention aims to solve these problems,
It is an object of the present invention to provide a high-performance microwave filter device with little mismatching loss and transmission loss.

Means for Solving the Problems and In order to achieve the above object, the present invention connects two or more sets of filters formed by microstrip lines on two dielectric substrates with a microstrip line track, and The microwave filter device is constructed by making the distance between the shield casing walls in the microstrip line section smaller than the distance between the shield casing walls in the filter sections on both sides thereof.

According to the present invention, with the above-described configuration, a plurality of filters are separated by the narrow wall portion of the shield case and connected by a duck microstrip line line, so compared to a method of connecting using a connector or the like, mismatching is possible. A microwave filter device with less gloss and transmission loss can be obtained.

Embodiments Hereinafter, an embodiment of the present invention will be described based on the accompanying drawings. FIG. 1 shows a microwave filter device according to an embodiment of the present invention. It is a cutaway view seen from the side.

In FIG. 1, 1 is an input connector, and 2 is a filter board that integrally forms left and right filters and their connection parts. 3 is a shield housing that houses the filter board 2, 4& and 4b are shield chambers for the two filter 6 parts,
Reference numeral 40 denotes a shield chamber that connects the two filters 6.

5 is a microstrip line that connects the two filters 6. Note that the filter 6 is formed by a pattern. Next, 7 is an output connector, and 8 is a cover of the shield housing 3.

Next, the operation of the microwave filter device configured as above will be explained. Now, as an example, a band-limiting filter (hereinafter referred to as a band-pass filter/BPF) that passes a microwave signal having a ratio of about 1°O in a certain band will be explained. Generally, filters using dielectric substrates are constructed using wavelength-coupled microstrip lines, which are stable and have excellent mass production reproducibility. The present embodiment will be explained using this example.

As shown in FIG. 1, a 10G)4z microwave signal is input from an input connector 1, guided to a filter substrate 2 made of a dielectric substrate, and band-limited by a first filter 6. The shape of the shield chamber 4a made of the shield casing 3 here is a waveguide structure that has a higher cutoff frequency for a microwave signal of 10 GHz. Next, the microwave signal is supplied to a microstripline line 6 provided at a portion connected to the second filter 6. The distance between the walls of the shield chamber 4c in this connecting portion is made smaller than the distance between the walls of the shield case in the shield chamber 4a. As a result, the cutoff frequency is changed to a higher side, thereby reducing interference between the two connected filters 6, and creating a state equivalent to shielding the two filters 6 separately. Further, this shield chamber 4C divides the two filters 6 by its length and the distance between the walls as described above, and its walls have a mirror finish. Thereafter, the signal is guided to the second filter 6, further band-limited, and output to the output connector 7.

With the above configuration, the two filters 6 can be easily connected without using a connecting means such as a connector, and mismatching loss and transmission loss in connection can be reduced, resulting in a high-performance microwave filter. The device will be obtained.

Effects of the Invention As described above, according to the present invention, two or more sets of filters formed by microstrip lines are connected via a microstrip line on a dielectric substrate, and Since the distance between the walls of the microstrip line section of the rolled case housing the dielectric substrate is made smaller than the distance between the walls of the filter sections on both sides, it is possible to easily connect imaginary numbers without using any connection means such as connectors. Filters can be connected, reducing mismatching loss and transmission loss during connection, and improving performance. In addition, it eliminates the need for connectors and the like required for connection, reducing costs, and also contributes to reducing the number of man-hours by eliminating the need for work time required for connection. Furthermore, although the above embodiments have been described using a bandpass filter as an example, the present invention is not limited to this, and a lowpass filter, a bypass filter, or a band-pass filter can have similar effects.

Furthermore, although filters of the same type are connected in the above embodiments, the invention is not limited to this, and it goes without saying that similar effects can be obtained even if filters of different types are combined.

[Brief explanation of the drawing]

Figures 1a and 1b show a microwave filter device according to an embodiment of the present invention, and Figure 1a is a top view with the cover removed;
Figure 2a is a cutaway view seen from the side, Figure 2a, I) shows a conventional microwave filter device, and Figure 2a is a view of the microwave filter device with the cover removed from the top. is a cutaway view seen from the side. 1...Input connector, 2...Filter board, 3...Seal)" housing, 42L, 4b
・・・・・・Shield chamber, 4C・・・Connection section shield chamber, 5・・・Microstrisoprine line, 6・・・Filter, 7・・・・・・・Output connector, 8...Name of cover agent Patent attorney Shigetaka Awano and 1 other person 0wa◇)

Claims (1)

[Claims] It includes a shielded housing, a filter board provided inside the shielded housing, and an input connector and an output connector connected to this filter board, and the filter board is formed with a microstrip line on a single dielectric board. two or more sets of filters connected via a microstrip line, and the distance between the shield housing wall surface at the microstrip line portion is smaller than the distance between the shield housing wall surfaces at the filter portions on both sides thereof. microwave filter device.