JPS59128803A - High frequency filter - Google Patents

Abstract

PURPOSE:To miniaturize a high frequency filter by providing a dielectric material between the inner and outer conductors to form a re-entrant resonator and putting the inner conductor through the wall surface of the outer conductor movably to the axial direction to change the distance between the inner conductor and another wall surface of the outer conductor. CONSTITUTION:The outer conductors 1 and 2 have square or circular cross sections, and a dielectric material 5 is provided between an inner conductor 3 and outer conductors 1 and 2. Thus a re-entrant resonator 6 is formed. The conductor 3 has a capacity plate having an area larger than the cross section of the conductor 3 at its end of one side together with a screw part formed at the other end. Furthermore the conductor 3 is put through the wall surface of the conductor 2 movably to the axial direction. The distance between the capacity plate of the conductor 3 and the wall surface of the conductor 1 to control the resonance frequency. Such resonators 6 are connected to each other via connecting holes 8 to form a high frequency filter. Then signals are extracted to the input and output terminals P1 and P2 respectively. In such a way, the size of a high frequency filter can be reduced.

Description

[Detailed Description of the Invention] This invention applies to relatively high frequency bands of 2%, VHF band and UHF band.
This paper relates to improvements to high-frequency filters that are often used in the microwave and microwave bands.

Without further ado, the conventional high frequency filter shown in FIG. 1 will be explained.

In Fig. 1, (11, (21 is the outer conductor, (3) is the inner conductor.

(4) is a frequency adjustment screw, (5) is a dielectric, (6) is a semi-coaxial resonator, (7) is an input/output loop, (8) is a coupling hole,
(9) is a nut for fixing the frequency adjustment screw (4), and Pl and P2 are input/output terminals. FIG. 5A is a plan view with the outer conductor (1) cut away, and FIG. 1B is a longitudinal cross-sectional view.

Here, one end of the inner conductor (3) is short-circuited with the outer conductor (2).

The other end is an open end. The inner conductor (3) has at one end a capacitive plate having an area larger than the cross-sectional area of the inner conductor (3). The length of the inner conductor (3) is determined by the capacitance of the capacitor formed by the capacitance plate of the inner conductor (3) and the frequency adjustment screw (4). In addition, a semi-coaxial resonator (6) is formed by the dielectric (5).
Since the wavelength of the inner conductor (3) is shortened, the length of the inner conductor (3) is shortened, and the high frequency filter can be made smaller.

Assuming that all the semi-coaxial resonators (6) resonate at the same frequency f0, the waves incident on the input/output terminal P1 at two frequencies f0 will sequentially resonate in the semi-coaxial resonator (6), and will be transmitted to the terminal P2. be expelled. Frequency f. Since the semi-coaxial resonator (6) does not resonate with other waves, the coupling to the terminal P2 is very small, and most of the power is reflected. In this way, the high frequency filter shown in FIG. 1 has a function as a bandpass filter.

However, in a conventional high frequency filter with frequency adjustment screws (4), one frequency adjustment screw (4) is connected to a semi-coaxial resonator (6).
The disadvantage is that the corrugations that protrude from the inside become larger.

In order to eliminate this drawback, the present invention aims at miniaturization by omitting the two frequency adjustment screws (4) by inserting the inner conductor (3) into the wall surface of the outer conductor (2) so as to be movable in the axial direction. The drawings will be described in detail below.

FIG. 2 shows an embodiment of the present invention (1) to (3).

(5) - (91, pl, ``2 is the same as in Fig. 1. In the wave device according to the present invention, the inner conductor (3) has a threaded portion at one end and is movable in the axial direction. The capacitor is inserted into the conductor (3).At this time, the capacitor is formed by the inner conductor (3) capacitance plate and the outer conductor (1), and its capacitance is equal to the inner conductor (3).
It can be adjusted by moving. Therefore, the high frequency filter of the present invention does not require the conventional frequency adjustment screw, and has the advantage that the filter size is reduced.

FIG. 3 shows another embodiment of the present invention.
(11~(31, (41~+91). Pl and P2 are the same as in FIG. 2.

In the high frequency filter of the present invention, weight reduction is achieved by making the cross section of the outer conductor (2) of the semi-coaxial resonator (6) square and thinning the wall thickness. In addition, the binding hole (8)
By making the shape continuous over the entire length of the semi-coaxial resonator (6), processing of the coupling hole (8) is facilitated.

Note that although the case where the number of resonators is three stages has been described above, the number of resonator stages is not limited to three stages. Furthermore, although the case has been described in which the resonators are coupled using a coupling hole, the present invention is not limited to this and may be applied to a case where the resonators are coupled using a loop.

As described above, the high frequency filter according to the present invention has the advantage that the inner conductor (3) performs frequency adjustment, so a frequency adjustment screw is not required, and the filter can be made smaller.

[Brief explanation of the drawing]

Figure 1 is a schematic configuration diagram showing a conventional high frequency filter.
Figure (a) is a plan view with some parts missing, Figure (b) is a vertical sectional view, Figure 2 is a schematic configuration diagram showing one embodiment of the present invention, and Figure 3 is another example of the present invention. FIG. 1 is a schematic configuration diagram showing an embodiment, in which FIG. 3(a) is a partially omitted plan view, and FIG. 1(b) is a longitudinal cross-sectional view. In the figure, (1), (2+ is the outer conductor, (3) is the inner conductor,
(4) is a frequency adjustment screw, (5) is a dielectric, (6) is a semi-coaxial resonator, (7) is an input/output loop, (8) is a coupling hole,
(9) is a nut for fixing the frequency adjustment screw (4), P7. P2 is an input/output terminal. In FIG. 4, the same or corresponding parts are designated by the same reference numerals. Agent Makoto Kuzuno - Dormitory 1 Shame (ku) (1)) 2 Shame Mu Otsu wo MineJ ρ (ku) (,b)

Claims (1)

[Claims] In a high frequency filter in which multiple resonators are coupled together,
The resonator is a semi-coaxial resonator in which the cross section of the outer conductor is square or circular and a dielectric material is installed between the inner conductor and the outer conductor, and the inner conductor has an area larger than the cross section of the inner conductor at one end. The inner conductor is inserted into one wall of the outer conductor so as to be movable in the axial direction. A high frequency filter characterized in that the resonant frequency of the resonator can be adjusted by changing the distance between the resonator and the wall surface.