JPS6019302A - Low-pass filter using dielectric substrate - Google Patents

Abstract

PURPOSE:To offer an LPF used practically at a high frequency band by providing a line electrode functioning as an inductance at a frequency region to one side of a dielectric substrate and also providing incorporatedly a tip open type resonance electrode projected from the line electrode and resonated at a specific frequency. CONSTITUTION:The line electrode 2 is provided on one side of the dielectric substrate 1 and the resonance electrodes 3, 3 and 4, 4 projected from both ends of the electrode at an optional angle with the line electrode are provided incorporatedly. An input lead 5 and an output lead 6 are connected across the electrode 2. The inductance component of the electrode 2 and the leads 5, 6 is utilized. The length of the resonance electrodes 3, 3 is set so that the 1/4lambda resonance is generated in a frequency component three times the basic resonance frequency of a resonator of a band-pass filter (BPF) combined with a low-pass filter (LPF). The length of the resonance electrodes 4, 4 is set so that the 1/4lambda resonance is caused at a frequency component four times said resonance frequency. The inductance value is set to a prescribed value by the width and length of the electrode 2, the characteristic impedance is set to a prescribed value by the width of the resonance electrodes 3, 3, 4 and 4 so as to attain a required attenuation band and also the impedance matching is attained at a pass band of the BPF combined with the LPF.

Description

[Detailed description of the invention] The present invention relates to a low-pass filter.

In a bandpass filter using a 1/4λ resonator, such as a dielectric coaxial resonator, odd-order higher-order modes occur,
Furthermore, when the frequency becomes high and exceeds the cutoff frequency of the resonator, other higher-order modes are generated, so that spurious responses of the third and fourth harmonics cannot be suppressed.

To solve this problem, a low bass fill was inserted after the band pass fill J letter.

An example of this low-pass filter circuit is shown in FIG. A pair of capacitor electrode films each have a comb-like shape in order to increase the required number of years.

The coils L, +, l-2, and 13 are linear electrode films with a necessary inductance of 1+7'.When a line is formed on the dielectric substrate in this way, this line has a special impedance of 1#1 impedance 7a. ] Then, when the line is considered as an inductance, the impedance is ωL
= Z asin (only the value determined by 7 will be taken, and the required impedance will not be obtained.Moreover,
The effective dielectric constant εeH of the dielectric substrate is ¥1. As the IN1 wave number increases, the effective dielectric constant εe[[ increases. At the same time, the aforementioned characteristic impedance also decreases. Then, the filter having the structure shown in FIG. 2 will no longer function as a low-pass filter. Also, while the capacitor electrode controls the inductance, since the capacitor electrode is large, self-oscillation occurs in the low frequency range and the capacitor does not work in the higher frequency range.

Therefore, an object of the present invention is to provide a practical low-pass filter in a high frequency range.

The gist of this invention is to provide a line electrode on one surface of a dielectric substrate that acts as an inductance in the operating frequency range, and to integrate a resonant electrode with a number of tips protruding from the line electrode and resonating at a specific frequency. The inductance value was set to a predetermined value using the width and length of the line electrode, and the characteristic impedance was set to a predetermined value (fff) using the width of the resonant electrode to obtain the required attenuation bandwidth and impedance matching in the passband. This is a low-pass filter using a dielectric substrate, which is characterized by the following.

Embodiments of the present invention will be described below with reference to the drawings.

In Figure 3, a3, 1 is an alumina Q9 dielectric substrate,
On the - side, there is a line electrode 2, a resonance electrode 3.3 protruding from both ends of the line electrode 2 at an arbitrary angle with respect to the line electrode, for example, white, and a resonant electrode 3.3 protruding in the opposite direction to the resonance electrode 3.3.
．． 4 are integrated.

One end of each of a human power lead 5 and an output lead 6 is connected to both ends of the line electrode 2. Line lightning (pulling 2, manual lead 5, and output lead 0 utilize their respective inductance components.Resonant electrodes 3, 3 are each
The resonator of the band-pass filter combined with this low-pass filter has a t-tree resonance frequency of 3 (8) frequency components.
The length of the resonant electrode 4.4 is set so that 1/4λ resonance occurs at 4 times the frequency component, unlike the resonant electrode 3.3. The inductance value is set to a predetermined value (111) by the width and length of the line electrode 2, the impedance is set to a predetermined value by the width of the resonant electrodes 3, 3, 4. It is covered so that the true band can be obtained and impedance matching can be achieved in the pass band of the band pass filter to be combined with the low pass filter.The equivalent circuit of the structure shown in FIG. 3 is as shown in FIG.

FIG. 5 is an example in which the J+, vibration electrodes 3, 3, 4.4 are observed in the good direction \1 method, and the external shape of the dielectric plate 1 is reduced.

Figure 6 shows an electrode 7 replacing the input lead 5 and the output lead.
．． This is an example in which 8 is provided.

In the above example, it is optional whether or not to provide a ground electrode on the back surface of the dielectric substrate @1. Further, the number of resonant electrodes having the same resonant frequency is also arbitrary.

FIG. 7 shows the characteristics of a low-pass filter that is designed to match a band-pass filter with a center frequency of 880 MHz.

From the above embodiments, it is clear that according to this invention, A31=jrul can be used in the high frequency region with a small and simple structure.
- Pass filters can be provided at low prices.

[Brief explanation of drawings]

Fig. 1 is a 10) inscription, Fig. 2 is a plan view of a subordinate) 141+-pass filter, Fig. 3 is a plan view of an embodiment of the present invention, and Fig. 4 is a plan view of an embodiment of the present invention.
The figures are equivalent circuit diagrams, Figures 1) and 6 are plan views of modified examples, and Figure 7 is a special f1 diagram. 1 is a dielectric substrate, 2 is a line electrode, and 3.4 is a J (vibration current).

Claims (1)

[Claims] A line electrode that functions as an inductance in the frequency range used is provided on one surface of the dielectric substrate, and a resonant electrode with a nil-shaped tip that protrudes from this line electrode and resonates at a specific frequency is integrally provided, and the width and length of the line electrode are The inductance value is set to a predetermined value, and the characteristic impedance is set to a predetermined value by the width of the resonant electrode. I use 4 bonsai tans.
-Bass filter.