JPS60145706A - Higher harmonic suppressor filter - Google Patents

Abstract

PURPOSE:To make a device small-sized by arranging distributed constant circuits on the first and the second substrates arranged at right angles. CONSTITUTION:The first dielectric substrate 2 and the second dielectric substrate 3 are arranged on both inside faces of a conductor 1 bent at right angles. Distributed constant circuits 6-10 having characteristic impedances higher than input/output imepdances are arranged in series-parallel on the substrate 2, and distributed constant circuits 11 and 12 having characteristic impedance lower than input/output impedances are arranged on the substrate 3. One side of the circuit 9 and that of the circuit 11 are connected on the boundary between substrates 2 and 3 orthogonal to each other, and one side of the circuit 10 and that of the circuit 12 are connected there also. Circuit 6-10 are inductors equivalently, and circuits 11 and 12 are capacitors equivalently. Thus, this LF is made small-sized.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a high frequency removal filter for television broadcasters, FM broadcasters, etc.

<Prior Art> Conventionally, this type of high-power high-frequency rejection filter used a coaxial tube, and the thickness of the internal conductor was changed to configure the inductance and capacitance isometrically to obtain the necessary filter characteristics.

However, such conventional high-frequency removal filters have a large number of parts, and are three-dimensional and complex in shape, making manufacturing time-consuming and expensive. The size of the circuit also had the disadvantage of being inevitably large if a coaxial tube was used as a distributed constant circuit.

<Object of the Invention> An object of the present invention is to solve the above-mentioned drawbacks by flattening the filter cluster, and to provide a stable high frequency rejection filter with good characteristics.

<Structure of the Invention> In the present invention, a first dielectric substrate and a second dielectric substrate are closely attached to two inner surfaces of a conductor formed at right angles, and input/output of a filter is arranged on the first dielectric substrate. Distributed constant circuits with high impedance) are arranged in series and parallel, and distributed constant circuits with low input/output impedance of the filter are arranged on the second dielectric substrate, and distributed constant circuits with high impedance (low impedance) are arranged in parallel on the first dielectric substrate. The present invention provides a high frequency rejection filter having a configuration in which one piece is arranged in contact with a distributed constant circuit.

<Example> Hereinafter, an example of the present invention will be described based on FIGS. 1 to 3. In FIG. 1, a first dielectric substrate 2 and a second dielectric substrate 3 are placed on both inner surfaces of a conductor 1 arranged at right angles.
are placed closely together. Distributed constant circuits 6, 7, 8, 9, and 10 having a characteristic impedance higher than the input/output impedance (for example, 50π) are arranged in series and parallel on the first dielectric substrate 2. Distributed constant circuits 11 and 12 having a characteristic impedance lower than the input/output impedance (for example, 5'Oπ) are arranged above. The distributed constant circuits 9 and 11 and 10 and 12 are connected at the orthogonal boundary between the first dielectric substrate 2 and the second dielectric substrate 3, respectively. When configuring a high frequency rejection filter with such a structure, distributed constant circuits 6, 7,
8, 9, and 10 are equivalently inductors, and the impedance 7 is higher than the input/output impedance (for example, 50K).
The effect of the inductor is increased by using a lower inductor. 1. Distributed constant circuit 1 on second dielectric substrate 3
1.12 is equivalently a capacitor, and by making the impedance lower than the input/output impedance of 50π, the function as a capacitor increases. Therefore, the configuration of the filter becomes easy. Furthermore, since the first dielectric substrate 2 and the second dielectric substrate 3 are arranged at right angles, a narrow space can be used effectively. It is possible to create a configuration that does not have .

Furthermore, FIG. 2 is an equivalent circuit of the embodiment shown in FIG.
The same parts as those described with reference to the figures are indicated by the same symbols. FIG. 3 is a diagram showing the characteristics of the embodiment of FIG. 1. As shown in FIGS. 2 and 3, the strip lines constituting the distributed constant circuits 11 and 12 provided on the second dielectric substrate 3 equivalently function as capacitors inserted in parallel. The equivalent volumes M and c are shown by the following equation (1).

Here, f: Ja + wave number (Hz) Characteristic innovation of the strip line t Strip line length O Characteristic impedance of the strip line z is the following formula (%) ) W Strip line width t: Thickness of the dielectric substrate Eeff
: Effective permittivity E [ : Relative permittivity of dielectric substrate Gold Predetermined capacitance C required as one element of the high frequency rejection filter
is determined by the stripline impedance 2 and the stripline length t. If t is a constant length, 2 becomes xi, b, formula (2+, (21' and (3)
As shown in , the difference between the zlil mistrip line and the thickness t of the dielectric substrate is determined. For this reason, when obtaining a predetermined impedance, the thickness of the first dielectric substrate 2 is set as tl,
If the thickness of the second dielectric substrate 3 is 12, tl>t2
In this case, the strip line l of the second dielectric substrate 3 can be made narrower than K, and the area occupied by the distributed constant circuit can be made smaller. Also, if the thickness t of the dielectric substrate &2,3 is constant, the impedance 2 of the strip line is determined by the strip line's l]W and relative dielectric constant E', and the formula f21, (2+ and (3), F)Er It can be seen that if W is increased, W becomes smaller.

Therefore, let the relative dielectric constant of the first dielectric substrate 2 be Er, and the second
The dielectric constant of the dielectric substrate 3 is set as Er2, and Er1(Er
2, the IJ tube line width of the second dielectric substrate 3 can be narrowed, and the area occupied by the distributed constant circuit can be reduced. Furthermore, by making the second dielectric substrate 3 thinner than the first dielectric substrate 2 and having a large dielectric constant, the area occupied by the distributed constant circuit becomes much smaller. it is obvious.

<Effects of the Invention> As explained above, according to the present invention, since the above structure is adopted, the first and second dielectric substrates are arranged at right angles, and a distributed constant circuit is used to create a planar structure. As a result, it is possible to reduce the size, and also to be stable and inexpensive.

[Brief explanation of drawings]

Fig. 1 is a perspective view of a high frequency removal filter according to an embodiment of the present invention, Fig. 2 is an equivalent circuit diagram of Fig. 1, and Fig. 3 is a characteristic showing the relationship between frequency and passage loss in this embodiment. It is a diagram. 1... Conductor 2... First dielectric substrate 3... Second dielectric substrate 6.7, 8, 9, 10, 11.12... Distributed constant circuit applicant NEC Corporation

Claims (2)

[Claims] (1) A first dielectric substrate and a second dielectric substrate are closely attached to the two inner surfaces of the conductor formed at right angles, and a distributed constant circuit whose input and output impedance is higher than the input/output impedance of the filter is placed on the first dielectric substrate. are arranged in series and parallel, and on the second dielectric substrate is a distributed constant circuit with a lower input/output invider of the filter, which is lower than 7s, and is connected to the parallel distributed constant circuit on the first dielectric substrate. A high frequency removal filter arranged adjacent to each other. (2) The thickness of the second dielectric substrate is also thinner than the thickness of the first dielectric substrate.
The high frequency rejection filter described in section. 3) The high frequency rejection filter according to claim 1, wherein the second dielectric substrate has a larger dielectric constant than the first dielectric substrate.