JPS5840902A - Directional filter - Google Patents

Abstract

PURPOSE:To divide the waves of a wide frequency band, by providing inductive irises into both main and secondary waveguides at the places near the coupling holes respectively. CONSTITUTION:Inductive irises 8 and 9 are provided into a main waveguide 1 and a secondary waveguide 2 at the places near the coupling holes 5 and 7. Owing to the presence of the irises 8 and 9, the holes 5 and 7 can be set at the positions distant away from the wall at the smaller diameter side of the waveguide 1. As a result, the diameters of the holes 5 and 7 can be increased without receiving any limit of the pipe wall of the smaller diameter side. Thus the coupling quantity of the circular polarized waves can be increased for the holes 5 and 7 by the function of the irises 8 and 9.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in directional filters used in microwave bands and millimeter wave bands.

Here, for convenience of explanation, we will limit the frequency to three, and these three frequencies will be referred to as 'le'2e'3.

The explanation will be given assuming that there is a mutual relationship of fs < h < fs.

Here, a case will be described in which the f2 wave is separated from the waves consisting of the three frequency bands mentioned above.

First, the conventional directional filter shown in FIG. 1 will be briefly explained.

In Figure 1, (11 is the main waveguide, (2) is the sub waveguide, (31, (4) is the cylindrical cavity resonator, (5) to (7)
is a binding hole.

■, 1 is the main waveguide (11 terminals, I, IV are the sub waveguides (
2) is the terminal.

Here, the coupling holes (51, (71) allow waves incident on one end of the main waveguide (1) and the sub waveguide (2) to enter the cavity resonator (
31 and the cavity resonator (4) are positioned and shaped so that they couple with K circularly polarized waves.

Now, the main wave tube (11 terminals [fl, f2. fs
(Introducing 73 waves into the cavity resonator +a+. If the tube axis length of (4) is selected to be about 10 times the tube wavelength of frequency f2, the wave of f2 coupled with circular polarization by the coupling hole (51) resonates in the cavity resonator (31).Other waves fl, f, resonate in the cavity resonator (3).

The afl0 wave that passes through without being affected by the terminal IK and is extracted from the terminal IK further resonates in the cavity resonator (4) and is coupled to the sub waveguide (2) through the coupling hole (71). At this time, since the wave in the cavity resonator (4) is a circularly polarized wave, the wave of f2 coupled to the sub waveguide (21) has directionality due to reversibility and is taken out to the terminal (2).

As described above, such a directional filter has the function of a so-called demultiplexer that demultiplexes and combines waves of nine different frequencies.

However, in such a directional filter, the coupling hole +51.
+71 must be provided at a position where the magnitude of the tube axis direction component and the transverse direction component of the magnetic field in the main waveguide (1) and the sub waveguide (2) are equal; ) and the narrower tube wall surface of the sub-waveguide (2), the coupling hole +51. +71 cannot be made large. For this reason.

Binding hole +51. The coupling amount of +71 is small and there are 9 waves f
There was a drawback that the frequency band of No. 2 was narrow.

This invention aims to eliminate these drawbacks.

Coupling hole +51 in main waveguide (1) and sub waveguide (2)
．． It has an inductive iris close to +71,
The drawings will be explained in detail below.

FIG. 2 shows an embodiment of this invention, and shows (11 to (7) #
1 to ■ are the same as in Figure 1, 181. t91Vi inducible iris, tlα inducible iris t8+, (
This is an iris for alignment with respect to 91.

Here, the inductive iris +81. +91 is formed by a conductor plate protruding from the narrower tube wall surface of the main waveguide 11+ and the sub waveguide (2), and the coupling hole +51.171 is provided close to the inductive iris (B+, (9)). It is being

In addition, the iris for matching is a cavity resonator (31° (4)
For waves that do not resonate at
) shall be arranged and shaped so as to cancel the reflection.

Next, the function of the inductive iris (8+, (91) will be explained. The inductive iris (81) changes the magnetic field distribution in the cross section of the main waveguide 111 as shown in FIG.

In Fig. 3, the arrows indicate the magnetic field, the figure (,) shows the case where the inductive iris (81) is provided, and the figure (b) shows the case where the inductive iris (81) is provided. As shown in FIG. The coupling hole (5) can be provided at a position away from the narrow tube wall of the main waveguide (1), and the size of the coupling hole (51) can be increased without being constrained by the narrow tube wall. The function of the inductive iris (9) is exactly the same, and the size of the coupling hole (7) can be increased.

Therefore, in the directional filter of the present invention, the coupling hole (51° (7)
The amount of coupling of circularly polarized waves can be increased.

Now, connect '1* '2e f3 to terminal ■ of main wave tube (1).
waves are introduced into the cavity resonator +31. If the tube axis length of (4) is selected to be about 7 of the tube wavelength of frequency f2, then the wave of f2, which is circularly polarized and coupled by the coupling hole (51), resonates at the cavity resonator (31). The other '1sfS waves pass through the inductive iris (81, cavity resonator +31) as they are without being affected, and are taken out at the terminal summer.The +20 wave further resonates in the cavity resonator (4). , is coupled to the sub-waveguide (2) through the coupling hole (7), and taken out to the terminal ring.

Therefore, the directional filter of the present invention has a function as a 9-band splitter, and can further increase the coupling amount of the coupling holes (51 to 71), so it can split f2 in a wide frequency band. be able to.

In addition, although the case where the number of cavity resonators is two was described above, the number of cavity resonators is not limited to two. Furthermore, although the case where the coupling hole is X-shaped has been described, the shape of the coupling hole is not limited to the X-shape.

As described above, in the directional filter according to the present invention, the coupling hole (51° (71°)
By providing the inductive irises (8+, +91) close to the inductive iris (8+, +91), there is an advantage that waves in a wide frequency band can be separated.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a conventional directional filter. FIG. 2 is a schematic configuration diagram showing an embodiment of the present invention. FIG. 3 is a diagram for explaining the operating principle of the directional filter. In the figure, (11 is the main waveguide, (2) the secondary waveguide, 13+
, (4) is a cavity resonator, (51 to +71 are coupling holes,
(8+, (91 is a d-conducting iris. In Figure 9, the same or corresponding parts are indicated by the same reference numerals. Agent Shin Kuzuno - @1 Figure 2 Figure 3 v!! J Continuation of page 1--- ■Applicant Mitsubishi Electric Corporation 2-2-3 Marunouchi, Chiyoda-ku, Tokyo

Claims (1)

[Claims] In a directional filter in which a pair of waveguides are provided with coupling holes in opposing parts, and a cavity resonator is provided between the coupling holes,
A directional filter characterized in that the waveguide is provided with an inductive iris projecting from the narrow wall surface of the waveguide toward the center of the coupling hole.