JPS5814601A - Band pass filter - Google Patents

Abstract

PURPOSE:To improve the cutoff performance at the high frequency side, by providing >=2 1/4-wavelength resonators and >=2 parallel resonators, insulating and drawing out an end of each of the parallel resonators to connect them to each other and opening the other end respectively. CONSTITUTION:A shielding case 8 contains 4 rooms 11 and 12, and the rooms 11 at both ends of the case 8 include the 1/4-wavelength resonators 13 and 13' with an end opened and the other end connected to the case 8, and the input windings 14 and 15 with an end connected to the case 8 and the other end insulated from the case 8 and then drawn outside. A coupling window 16 is provided to a partition wall 9 between the rooms 11 and 12, and the coils 17 and 17' are disposed in the room 12. In addition, the capacitors 18 and 18' are connected to both ends of the coils 17 and 17' to form the parallel resonators 19 and 19'. As no window is provided to a partition wall 10 of the room 12, the resonators 19 and 19' are separated from each other in terms of the electric field. Then an end of each of the resonators 19 and 19' is connected to each other to have an electromagnetic connection. The other end of each of the resonators 19 and 19' is opened, and a trap circuit is formed for connection of capacity by means of the capacity between the resonators 19/19' and the case 8.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a band titanium oxide semiconductor device consisting of two or more wavelength resonators and two or more parallel resonators each composed of a coil and a capacitor.
) This relates to F-wave devices.

A conventional band F wave filter of this type will be explained using a helical filter as an example, with reference to the schematic configuration diagram of FIG.

In Figure 1, a shield case 1 made of aluminum etc.
A plurality of (four in the figure) chambers 3 are formed by a plurality of (three in the figure) partition walls 2, and a joining window 4 is provided in each partition wall 2. Each chamber 3 of such a shield case 1 is constructed by winding several tens of good conductors such as copper wire around a plastic bobbin or the like, leaving one end open and connecting the other end to the shield case 1. A wavelength resonator 6 is arranged in each of the chambers 3 at both ends, and an input winding 6 and an output winding 7, which are formed by winding several turns of copper wire or the like, are arranged. One end of the shield case 7 is drawn out to the outside of the shield case 1 .

However, the frequency transmission characteristics of this helical filter are as shown by the dotted line in Figure 4, and the cutoff characteristics are gentle on both the wide frequency side and the high cylindrical wave side of the passband, and the cutoff characteristics are particularly sharp near the outside of the passband. The present invention eliminates these conventional drawbacks,
Embodiments of the present invention will be explained below with reference to the drawings of FIGS. 2 to 4 showing embodiments of the present invention.

FIG. 2 shows a helical filter according to an embodiment of the present invention. In FIG. 2, 8 is a shield case made of aluminum or the like, and this shield case 8 has two
partition walls 9 and one partition wall 10 are provided, and one partition wall 9, 1o
and the shield case 8 form four chambers 11 and 12.

The chambers 11 at both ends of the chambers 11 and 12 are constructed by winding copper wire or the like around several tens of turns around plastic bobbins, etc., with one end open and the other end connected to the shield case 8. % wavelength resonator 13.13' and several turns of copper wire, etc., and one end is wrapped in a shield case 8.
Input windings 14 and 16 are arranged, the other end being insulated from the shield case 8 and drawn out to the outside.

The partition wall 9 between the chambers 11 at both ends and the central chamber 12 includes
A coupling window 16 is formed, and in this central chamber 12, copper wire or the like is wound around a plastic bobbin or the like with several turns to about ten turns (considerably less than the winding of the K wavelength resonator 13° 13'). Coils 17, 17' configured by
is located.

Further, capacitors 18 and 18' are connected to both ends of the coils 17 and 17', and parallel resonators 19 and 19' are connected to each other.
It consists of .

Here, the partition wall 1o of the central chamber 12 is usually not provided with a window, so the two parallel resonators 19 and 19' are electrically separated, but one end of the parallel resonators 19 and 19' are electromagnetically coupled by a connecting wire 20 that connects them to each other. In addition, the other ends of the parallel resonators 19, 19' are open, and a trap circuit of mutual coupling is formed by the amount of waste between the parallel resonators 19, 19' and the shield case 8, and the pass band is An attenuation pole occurs in the cutoff region on the higher frequency side.

That is, the frequency transmission characteristics of the filter according to the present invention, as shown by the solid line in FIG. 4, are significantly improved in the cutoff characteristics on the high frequency side compared to the characteristics of the conventional helical filter shown by the dotted line in the figure.

- Fig. 3 shows another embodiment of the present invention.
.

In the embodiment shown in FIG. 2, the auxiliary winding 21.
21' is provided to inductively couple with the parallel resonators 19 and 19', and the parallel resonator 1 is insulated from the shield case 8.
9, 19' and one end of the auxiliary winding 21, 21' are connected,
The other ends of the auxiliary windings 21 and 21' are connected as shown in FIG. 3, so that the electromagnetic coupling can be changed appropriately and the bandwidth can be set at any point.

As described above, the bandpass filter according to the present invention has excellent blocking characteristics on the high frequency side of the passband, so when used as a video intermediate frequency filter of a television receiver, it is easy to design an audio carrier frequency trap for an adjacent channel. Moreover, it has a large amount of attenuation in the stopband, has a simple configuration, and can be used as a small video intermediate frequency filter, which is of great practical value.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of a conventional band F wave device, FIG. 2 is a schematic configuration diagram of a band offshore wave device according to an embodiment of the present invention, and FIG. 3 is a schematic configuration diagram of a band ν wave device according to another embodiment of the present invention. FIG. 4 is a diagram showing the frequency transmission characteristics of the band offshore wave device of the present invention and the conventional band F wave device. 8...Shield case, 9,10...,...
Partition, 11, 12, --- Chamber, 13, 13'--
3A wavelength resonator, 17, 17'・river coil, 18
, 18'...Capacitor, 19, 19'...
...Parallel resonator, 2゜...Connection wire, 21,
21'...Auxiliary winding.

Claims (2)

[Claims] (1) It has two or more % wavelength resonators and two or more parallel resonators composed of a coil and a capacitor, and one end of the parallel resonators is insulated by a shield case and brought out and connected to each other. However, the other end is open. (2) An auxiliary winding that is inductively coupled to the parallel resonator is provided, one end of the auxiliary winding is insulated from the shield case and connected to the parallel resonator, and the other end is connected to the auxiliary windings. A band F wave device according to claim 1.