JPH0340533B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to a band wave device, such as a coupled tuning type, which is used in wireless communication equipment and whose purpose is to select and extract desired waves and remove unnecessary waves. (hereinafter referred to as BPF)
It concerns the improvement of the characteristics of. Note that the present invention
It can be applied to BPFs that use small capacitance capacitors to couple between tuning elements in the VHF and HF bands.

(Prior art) In the first-stage BPF of a superheterodyne VHF to UHF band receiver, a multi-stage tuning circuit or dielectric resonant element is used to provide the required selection characteristics as a means of removing spurious waves caused by image reception. Conventionally, a method of selectively removing spurious waves using a polarized filter has been used.

However, a BPF using a multi-stage tuned circuit has disadvantages such as a large occupied volume, high insertion loss, and inevitably high cost.On the other hand, a polarized filter also has many parts such as coils and capacitors, and has a large occupied volume. However, it has disadvantages such as a complicated structure and high cost.

In recent years, there has been a strong demand for wireless communication equipment to be smaller, lighter, and lower in price, and the same goes for filters that are smaller, lighter, and lower in cost. Therefore, its relative importance is large.

Figure 5 shows various configurations of conventional BPFs and examples of their characteristics. Since this circuit and its characteristics are well known, details will be omitted.

(Specific Object of the Invention) In order to eliminate the above-mentioned drawbacks to the conventional BPF,
In the present invention, as a result of various studies and experiments, we have found that by providing a simple capacitive coupling plate at the input and output terminals of the filter, we can achieve characteristics equivalent to those of the polarized filter shown in the bottom row of Figure 5 (for example, Figure 2). ) was miniaturized
The feature is that it can be obtained with BPF.

(Structure of the Invention) In order to generate an attenuation pole in the attenuation range of a frequency lower than the pass frequency band of the at least three odd-stage tuned circuit-coupled bandpass transducer, the minute capacitive coupling plate of the bandpass transducer of the present invention has the following features: a thin insulator provided with a hole smaller in area than the surface of the container of the bandpass wave device on which the input terminal and the output terminal are provided, through which the input terminal and the output terminal pass, respectively; and on one surface of the insulator. Two ring-shaped conductor parts are formed concentrically with each of the holes and are attached with a desired insulating part, and a conductor part is attached to connect the two ring-shaped conductor parts. when the insulator is inserted into the input terminal and the output terminal, the electrostatic capacitance generated between the input terminal and the output terminal and each of the two ring-shaped conductor parts It is characterized by an attempt to generate an attenuation pole.

The present invention will be explained in detail below with reference to the drawings.

FIG. 1 and FIG. 2 are diagrams showing an example of the configuration of a BPF according to the present invention and an example of frequency-output characteristics thereof. Furthermore, FIGS. 3 and 4 are according to the present invention.
FIG. 3 is a diagram specifically showing a structural example of a BPF. These will be explained in detail below.

First, in an odd-numbered tuned circuit-coupled BPF, in addition to the reactance coupling element between adjacent tuned circuits,
By coupling the input and output of the BPF with a minute capacitance C ₀ as shown in FIG. 1, an attenuation pole similar to that of a polarized filter can be provided in a frequency range lower than the pass frequency. The attenuation pole frequency is determined by the size of the capacitance that couples the input and output.
For example, the general formula for the above is derived from the following document and is well known.

Masao Saito: On coupled tuned transmission networks with attenuation poles [IEICE Theory (A) 53-A, 4, P163-168, Akira
45-04] Since this capacitance C ₀ has a significantly small value, in the present invention, a method for realizing this was studied. This will be explained next with reference to FIGS. 3 and 4. In these figures, A is the entire external view, 1 and 11 are the cases that hold the entire BPF, 2 is the dielectric resonant element, 12 is the lumped constant resonant circuit, and 3 and 4 are the cases that hold the entire BPF.
The input terminal and output terminal of the BPF, 5 is a minute capacitive coupling plate that couples the input and output terminals. Figures 3B and 4B show this coupling plate 5 in detail, with BPF input and output terminals 6 and 7.
A hole 8 passing through is a coupling conductor for coupling the input and output terminals with a minute capacitance. Further, FIGS. 3C and 4C show the through-hole portion of the minute capacitive coupling plate 5 in more detail. This coupling plate 5 is the third
In the case of the figure, a printed circuit board is used, and in the case of FIG. 4, a polyimide film is used, and a copper coupling conductor 8 is adhered to the surface thereof. Furthermore, in the case of FIG. 4, the surface of the conductor 8 is covered with a polyimide overcoat 9 for protection, as shown in FIG. B.

(Operation of the invention) It has already been mentioned that characteristics equivalent to those of a polarized filter can be easily obtained by coupling between the input and output of a BPF using odd-stage inductive resonators via a minute capacitance. The following method is explained below.

3 and 4, by inserting the input and output terminals 3 and 4 into the through holes 6 and 7 of the microcapacitance coupling plate 5, a connection is made between these input and output terminals and the coupling conductor 8. It can have a minute capacity.
This capacitance value is determined by the dimensions of the inner diameter d and outer diameter D of the ring portion of the conductor 8 shown in FIGS. 3C and 4C,
It is determined by the thickness of BPF input and output terminals 3 and 4.

Any general high-frequency printed circuit board, polyimide film, ceramic substrate, etc. can be effectively used for the microcapacitive coupling plate 5, but in the example shown in Fig. 3, resist printing is performed on the conductor etching of a 0.6 mm glass epoxy board. In the example shown in FIG. 4, the conductor etching of the polyimide film is overcoated. Although the shape of the coupling conductor 8 is hook-shaped in these figures, it is not limited to this shape, and the pattern may be determined for other reasons.

According to the above means, even if the pass frequency band is changed, the change adjustment can be made while keeping the frequency interval between the attenuation pole frequency and the pass frequency band almost constant without changing the coupling capacitance of the microcapacitive coupling plate. There are features that allow it. This feature is a simple and effective feature, which is significantly different from the polarized filter shown in the above-mentioned document, in which a tuning element is provided for the attenuation pole.

(Effects of the Invention) By implementing the present invention, a small, lightweight, and inexpensive BPF can be obtained by setting an attenuation pole in the image spurious frequency band of the intermediate frequency of a radio receiver, and the image spurious sensitivity of the receiver can be easily reduced. The improvement in properties is a significant practical effect.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an example of the circuit configuration of a coupled-tunable bandpass wave generator according to the present invention, FIG. 2 is a diagram showing an example of the frequency vs. output characteristic of the circuit in FIG. 1, and FIGS. FIG. 5 is a diagram showing an example of the circuit configuration of a conventional coupled-tunable bandpass wave device and its wave characteristics. C ₀ ... Coupling capacitance between input and output, 1, 11...
Filter holding case, 2... Dielectric band resonant element, 1
2... lumped constant resonant circuit, 3, 4... filter input terminal, output terminal, 5... minute capacitive coupling board,
6, 7...hole, 8...coupling conductor, 9...polyimide overcoat.

Claims (1)

[Claims] 1. In order to generate an attenuation pole in an attenuation range of a frequency lower than a pass frequency band of at least three stages of odd-numbered tuned circuit combined bandpass transducers, an input terminal and an output of the container of the bandpass transducer are provided. a thin insulator provided with holes smaller in area than the surface on which the terminals are provided, through which the input terminal and the output terminal pass, and a thin insulator provided with holes concentric with each of the holes on one surface of the insulator; the insulator, comprising: two ring-shaped conductor parts provided with desired insulating parts and deposited thereon; and a coupling conductor integrally formed with a conductor part deposited to connect the two ring-shaped conductor parts; is inserted into the input terminal and the output terminal, the bandpass wave generator is configured to generate the attenuation pole by capacitance generated between the input terminal and the output terminal and each of the two ring-shaped conductor parts. micro capacitive coupling plate.