JPS60185402A - Polar hair pin line filter - Google Patents

Abstract

PURPOSE:To attain miniaturization and to improve the selectivity by adopting the constitution that hair pin resonators are coupled adjacently together at each inner side face of a hair pin curve and they are coupled loosely with next resonators at an outer side face of a hair pin curve. CONSTITUTION:The energy introduced to an external connecting line 1 is led to a resonator 6 with a degree of coupling (a). The resonator is coupled with an adjacent resonator 7 with a degree of coupling (b) at each inner side face of each hair pin curve. Further, the resonator 7 is coupled to the resonator 8 similarly. The energy is led to an external coupling line 2 with the degree of coupling (a) finally. The resonator 6 is coupled with the adjacent resonator 8 with a degree of coupling (c) (c<b) at an outer side face of each hair pin curve. Then a polar BPF with an excellent selectivity is obtained by selecting the relation of the degrees of coupling (b), (c) to a prescribed value.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a band-pass filter composed of a strip line or the like in an ultra-high frequency band such as a microwave band or a millimeter wave band.
In particular, it relates to polarized hairpin line filters.

[Prior art]

Conventionally, in the ultra-high frequency band, a band pass filter (hereinafter abbreviated as BPF) composed of a strip line has been used. Among them, parallel line filters that couple the resonators of half-wavelength lines at their sides are often used because they provide sufficient coupling between the resonators. However, since the length of the resonator of the half-wavelength line is relatively long, this filter tends to have a large volume, making it unsuitable for small devices, and structurally unsuitable for polar types. However, it had the disadvantage that only mild selectivity could be obtained.

Among these, a BPF that has been improved with consideration to miniaturization is the hairpin line filter, which is the same as the one commonly used in the past.

For example, FIG. 1 shows an example of the configuration of a conventionally used hairpin line filter of this kind. This example is for a three-stage BPF, but of course there are also cases with more stages.

In FIG. 1, 1 and 2 are external connection lines, and 3
, 4.5, a half-wavelength line forming a hairpin-shaped curve is
Each is a hairpin-shaped resonator. The hairpin-shaped resonators adjacent to each other are coupled at the outer surface of the hairpin-shaped curve at a coupling portion that is approximately half the length of the cow wavelength line.

In this way, by making the resonator of the half-wavelength line into a hairpin shape, a /T-shaped BPF was achieved, but in terms of characteristics, only gradual selectivity was still obtained, and there was a lot of proximity noise. The major drawback remained that the system was unsuitable.

[Object and structure of the invention]

The present invention has been made in view of the above circumstances, and its purpose is to provide a polarized hairpin line filter that uses a hairpin resonator that is excellent in terms of miniaturization and also has excellent selectivity. be.

In order to achieve such an object, the present invention arranges adjacent hairpin-shaped resonators such that they are coupled to each other at the inner surfaces of each hairpin-shaped curved shape, and further connects one adjacent hairpin-shaped resonator to another adjacent hairpin-shaped resonator. The shaped resonators are arranged so that the outer surfaces of each hairpin-shaped curved line are loosely coupled to each other. Hereinafter, the present invention will be explained in detail using Examples.

〔Example〕

FIG. 2 is a diagram showing an embodiment of the present invention.

In the figure, 1 and 2 are external connection lines, 6° 7.
Each of the eight half-wavelength lines forming a hairpin-shaped curve is a hairpin-shaped resonator. The energy introduced into the external connection line 1 is guided to the resonator 6 with a coupling degree & of only the frequency band that resonates in the resonator 6°7.8. The resonator 6 is coupled to the adjacent resonator T with a coupling degree between the inner surfaces of each hairpin curve, and the resonator 7 has a similar structure and is coupled to the resonator 8 with a coupling degree. ing. In this way, the energy is finally led to the external coupling line 2 with a degree of coupling a.

Here, the resonator 6 is further coupled to the adjacent resonator 8 with a degree of coupling C between the outer surfaces of each hairpin curve. The magnitude of this degree of coupling C is determined in advance by the resonator 6. The position of γ, 8 is selected. Now, move the energy from resonator 6 to 7 and from γ to 8 in the direction of the energy that is coupled with the degree of coupling.
The direction of the energy directly coupled to the resonator 8 with the coupling degree C is in the opposite direction, that is, in the opposite phase.

Therefore, by selecting a predetermined value for the relationship between the degree of coupling and C, a polarized BPF with sharp selectivity can be obtained.

Although the above-mentioned embodiment is an example in which the hairpin resonator has three stages, it goes without saying that the effects of the present invention do not depend on the number of stages of the resonator. FIG. 3 is a diagram showing another embodiment of the invention. This embodiment is an example of a 5-stage BPF, and in the figure, 1 and 2 are external connection circuits, 9, 10, 11.12.1
3 are hairpin-shaped resonators. The mutually adjacent resonators 9, 10.1G, 11.11, i2, 12, and 13 are connected to each other on the inner side of the hairpin curve, and furthermore, the resonators 9 and 13, which are adjacent resonators, are connected to each other on the inner side of the hairpin curve. 11.11
and 13 are loosely connected to each other on the outer surface of the hairpin-shaped curve. The direction of bonding between the inner surfaces and the direction of bonding between the outer surfaces are opposite to each other, thus forming a polarized BPF.

Although the above description has been made assuming a strip line as the structure, it goes without saying that the effects of the present invention can be obtained in the same manner as long as the circuit is a so-called planar circuit, such as a Zasubendesoto line.

Furthermore, although the explanation has been given by taking the case of use in the ultra-high frequency band as an example, it is clear that the same effect can be obtained even if the present invention is used in optical integrated circuits in other frequency bands, for example, in the light wave band.

〔Effect of the invention〕

As described above, according to the polar hairpin line filter of the present invention, each hairpin resonator is coupled to the adjacent resonator at the inner surface of the hairpin curve, and furthermore, the adjacent resonator is coupled to the adjacent resonator at the inner surface of the hairpin curve. and are loosely connected to each other on the outer surface of the hairpin-shaped curve, which has the effect of being small in size and easily achieving sharp selectivity in terms of characteristics.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of the configuration of a conventional hairpin line filter, FIG. 2 is a diagram showing one embodiment of the present invention, and FIG. 3 is a diagram showing another embodiment of the present invention. 1.2...External connection line, 6, 7, 8, 9゜10,
11.12,13...-Fist hairpin-shaped resonators. Patent applicant: NEC Corporation Representative: Masaki Yamakawa (and 2 others) 7- Figure 1 Figure 2

Claims (1)

[Claims] In an extremely high frequency band polarized hairpin line filter composed of at least three or more hairpin-shaped resonators, each hairpin-shaped resonator is located on the inner surface of the hairpin-shaped curve with respect to the adjacent hairpin-shaped resonator. A polarized hairpin line filter characterized in that the adjacent hairpin resonator is coupled loosely to an adjacent hairpin resonator on the outer surface of the hairpin curve.