JPS6055702A - High frequency filter - Google Patents

Abstract

PURPOSE:To facilitate adjustments of coupling quantities and resonance frequencies among strip conductors by providing grooves on a dielectric plate and forming strip conductors in grooves. CONSTITUTION:Strip conductors 1-5 are formed in grooves 13-17 provided in parallel at prescribed intervals on a dielectric plate 10. One ends of conductors 1 and 5 are connected external leading-out terminals 11 and 12, and the other ends are short-circuited with an earth conductor 6. Strip conductors 2-4 have one ends opened and have the other ends short-circuited with the conductor 6 and are formed as 1/4-wavelength resonators. They are so arranged that open ends are in the same direction. Since conductors 1-5 are formed on an exposed surface of the dielectric plate 10 in a high frequency filter having this structure, coupling quantities and resonance frequencies among conductors 1-5 are adjusted easily.

Description

[Detailed description of the invention] [Technical field of invention] This invention applies to relatively high frequency bands, especially VIP bands.

This invention relates to high frequency filters that are often used in the UHF band and microwave band.

[Prior Art] First, a conventional high frequency filter shown in FIG. 1 will be explained. In Figure 1, Figure 0 is a plan view with some parts missing, and Figure (b) is a sectional view taken along line A-A* (1&) to (5a)
, (1b) to (5b) are strip conductors, (Sa
), (6b) are ground conductors, +7), +8) are coaxial terminals, (9) are center conductors of coaxial terminals, (10a)
, (10b) is a dielectric plate.

Strip conductors (1a) to (5a), ground conductor (6a)
) is formed of a conductive film in close contact with the dielectric plate (10a),
Strip conductors (1b) to (sb), ground conductor (6b)
) is formed of a conductive film in close contact with the dielectric plate (10b). Moreover, these strip conductors (1a) to (5a)
, (1b) to (5b).

Ground conductor (6a), ((51)), dielectric plate (1
0a), (lob) is.

They are superimposed so as to have a symmetrical structure with respect to the B-B plane in FIG. 1(b).

The shape of the connection part of the coaxial terminal (8) is as shown in detail in Figure 2, and the coaxial terminal (8) is connected to the center conductor (9).
) are connected to match the positions of the strip conductors (5a) and (5b). Further, the method of connecting the coaxial terminal (7) is also the same.

In this high frequency filter, the strip conductor (2a)
e (2b) v (3a) I (5b) e and (
4a) and (4b) resonate at the same frequency fO, then at two frequencies fO, the strip conductor (1a),
(1b), (5a), (sb) are co-located strip conductors (2 &) I (+ on 2) ~ (4a)
I (4b) and the incident wave on the coaxial terminal (7) is guided to the terminal (8). However, at frequencies other than 9 frequency fO.

Strip conductor (Ia), (Ib) ~ (5a) L
The coupling of (5b) is very weak and most of the power of the wave incident on terminal (7) is reflected. In this way, the high frequency filter shown in FIG. 1 functions as a bandpass filter.

By the way, conventional high frequency filters are made of strip conductors (1
Since the structure is such that a), (lb) to (5a), (5b) are sandwiched between the dielectric plates (10a) and (10b), the strip conductor (la) I (1b)
) ~(5a) ? There was a drawback that it was difficult to adjust the amount of coupling between C5b) and the resonance frequency.

[Summary of the Invention] In order to eliminate these drawbacks, the present invention provides a dielectric plate with a groove, and forms a strip conductor in the groove.
The drawings will be explained in detail below.

[Embodiment of the Invention] FIG. 3 is a diagram showing a high frequency filter according to an embodiment of the invention, in which (ri~(5) is a strip conductor, (6) is a ground conductor, 01 is a dielectric plate, On, 01 is an external lead terminal.

0 to c11) are grooves provided in the dielectric plate.

The strip conductors (1) to (5) are formed in grooves α (Iη) arranged in parallel at predetermined intervals in the dielectric plate a.The strip conductors (11 and (5) are One end is connected to the external lead terminal αυ, a, and the other end is connected to the ground conductor (6
) is shorted. In addition, strip conductors (2) to (4
) has one end open.Conductors (2) to (4) are arranged so that their open ends are oriented in the same direction.

Normally, a single-wavelength resonator installed in a homogeneous medium and with its open ends oriented in the same direction will have no coupling, but in the case of a microstrip wire connection as in the high frequency filter of this invention, a non-uniform medium The IJ tube conductors (2) to (4) are coupled to each other.

In the filter of this invention, the strip conductors (2) to (
If 4) resonates at the same frequency fO, then at 9 frequency fO, the IJ tube conductors (1) and (5) are strongly coupled via the resonant strip conductors (2) to (4), The incident wave to the external extraction terminal fi+) is the external extraction terminal a.
guided to the neighborhood. However, at frequencies other than fo, the coupling between the strip conductors (1) to (5) is very weak, and most of the power of the wave incident on the external extraction terminal 60 is reflected. In this way, the high frequency filter shown in FIG. 3 has a function as a bandpass filter.

In the high frequency filter of this invention, the strip conductors (1) to (
5) is formed on the exposed surface of the dielectric plate tm.

It is easy to adjust the amount of coupling and resonance frequency between the 17-strip conductor (υ~(5).
) to (5) can be changed by changing the size of the groove a-00 or by filling a part of the groove with a dielectric material. Further, the resonant frequency can be easily adjusted by changing the lengths of the strip conductors (2) to (4) or by bonding a dielectric material to the open ends.

The strip conductors (1) to (5) in FIG.
Since it is formed within αη, the electric field leaking into the space outside the dielectric plate 01 is very small, and it can be more shaped than a normal microstrip line circuit formed on a flat dielectric plate.

Further, the strip conductors (1) to (5) have a shape in which the center portions are close to the ground conductor (6), as shown in FIG. 4, which is a sectional view taken along the line a-a in FIG. Therefore, the current distribution on the surface facing the ground conductor (6) does not concentrate at the end like in the case of a planar microstrip wire fault, and the current distribution becomes more uniform, reducing wire fault loss. .

Therefore, a filter with low loss can be obtained.

FIG. 5 is a diagram showing another embodiment of the present invention,
+21 ~ (41, (61, (tl ~ (tl, <+
4~G! , 61.121 are the same as in FIG.

It is continued. The amount of coupling between the external lead terminal aυ, 03 and the strip conductors (2), (4) is the same as that of the strip conductor (21).
, +4 can be adjusted by changing the distance l between the short-circuited ends and the positions where the external lead terminals (2) and (4) are connected.

The operation of this filter is similar to the filter of FIG.

Also, like the filter in Figure 3, the IJ tube conductor (2)
The amount of coupling between (4) and the resonance frequency can be easily adjusted.

Moreover, it is smaller and has lower loss than the case of microstrip wiring.

FIG. 6 shows still another embodiment of the present invention, (
21~(4), is), H~[3tα4~i+
d I , HI 'jl are the same as in Figure 3, (to),
(c) is a capacitor.

External lead terminals at+ and a'a are capacitors (2)
, (c) are connected to the strip conductor (2+, (4)), and the amount of coupling can be adjusted by changing the capacitance of the capacitor.The operation of the filter is shown in Figure 3.

It is similar to the filter shown in FIG. 5, and has the same features as the filter shown in FIGS. 3 and 5.

Note that 2 or more has been described for cases where the number of strip conductors is 3 or 5, but it may also be applied to cases where the number of strip conductors is 4 or 6 or more.

[Effects of the Invention] As described above, in the high frequency filter according to the present invention, the amount of coupling between the strip conductors and the resonance frequency can be adjusted by providing grooves in the dielectric plate and forming the strip conductors in the grooves. This has the advantage that it is easy to obtain a filter that is small and has low loss.

[Brief explanation of drawings]

Figure 1 is a schematic diagram of a conventional high-frequency filter, with (a) being a plan view with some parts missing, and (b) being the same as (a).
2 is a sectional view of the stop conductor (5a
), (sb) and an enlarged view of the connection part with the coaxial terminal (8). FIG. 3 is a schematic configuration diagram of the high frequency filter of the present invention. FIG. 4 is a sectional view taken along line a-a in FIG. 3, FIG. 5 is a schematic diagram of another embodiment of the present invention, and FIG. It is also a schematic configuration diagram. In the figure, (1) to (5) are strip conductors, and (6) is a ground conductor. (7), +8) are coaxial terminals, (9) is the center conductor of the coaxial terminal, 011° (L is the external lead terminal, eel ~ clD is the groove, and 123. (to) is the 9 conductor. The same or corresponding parts are indicated by the same reference numerals. Agent Masuo Oiwa Figure 1 (C) Figure 2 Figure 3ya Figure 4 @ Figure 5 Figure 6

Claims (1)

[Claims] In a high-frequency filter with a conductor film formed on a dielectric plate and an IJ tube conductor and a ground conductor, a plurality of grooves are provided in parallel on the dielectric plate, and one end is short-circuited and the other end is open in the groove. A high frequency filter characterized in that the strip conductors are formed and arranged so that the open ends of the strip conductors are oriented in the same direction.