JPH0460362B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a strip line resonator using a dielectric and used as a resonant element in filters, oscillators, etc. in the VHF to SHF band.

Conventional Structures and Problems Today's stripline resonators have simple structures and are extremely easy to design, so they are often used as resonant elements in VHF to SHF filters and oscillators. In order to reduce the loss of this resonator and eliminate the need for adjustment, a half-wavelength resonator with both ends open is used, and in order to achieve miniaturization, a U-shaped resonator is folded into a hairpin shape. is often used.

FIG. 1 shows a conventional U-shaped strip line half-wavelength resonator with both ends open.

In FIG. 1, reference numeral 11 denotes a dielectric substrate, on one surface of which a ground conductor 13 is provided, and on the other surface a strip conductor 12. Although this example uses an unbalanced micro-strip line, a balanced type structure may also be used in which a dielectric substrate is also used above the strip center conductor. Such a resonator has a high no-load Q and good reproducibility of characteristics such as resonance frequency, but in order to create the strip conductor, high-precision printing or etching technology is required, and the positioning of the substrate is difficult. There are manufacturing problems such as difficulty in achieving high accuracy.Furthermore, the phase difference between the two open ends is 180°, which causes large coupling at both ends, increasing dielectric loss and causing stray coupling. There were also problems in terms of electrical performance, such as .

Purpose of the Invention In view of the above-mentioned drawbacks, the present invention facilitates the manufacture of a U-shaped strip or micro-strip line resonator with both open ends, reduces the cost, and weakens the coupling between the open ends to reduce the electrical resistance. It is an object of the present invention to provide a strip line resonator that can improve performance, reduce spurious signals, and simplify frequency adjustment.

Structure of the Invention The present invention provides a rectangular (but thick) dielectric substrate with a slit extending from approximately the center of the short side of the rectangle, parallel to the long side (longitudinal direction), and penetrating in the thickness direction. In addition, a conductor film is provided on both sides of the rectangular dielectric substrate, and one surface with the conductor film is used as a ground conductor, and the other surface with the conductor film is used as a strip conductor, thereby achieving the above purpose. The goal is to achieve the following.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 2 shows each cross section of a strip line resonator in an embodiment of the present invention. In FIG. 2, a slit groove 24 is provided in the length direction of the substrate from one end surface of the dielectric substrate 21 to form a U-shape, and conductor patterns are created on the two surfaces with the slit, one of which is used as a ground conductor. The other is used as the center conductor of the micro-strip resonator. This slit groove 2
Step 4 may be performed when processing the substrate, or the slit grooves 24 may be provided after providing conductors on both surfaces.
In either case, the metal conductor can be easily produced by printing, sputtering, or the like without using a mask, making it possible to significantly reduce costs.

FIG. 3 shows an example of a balanced strip resonator, in which conductors are provided on the upper and lower surfaces of U-shaped dielectrics 31 and 32 similar to those in FIG. The structure includes ground conductors 34 and 35 and a center conductor 33. In this case as well, the formation of the metal conductor can be realized much more easily than in the past.

In addition, in the resonators shown in Figures 2 and 3, since there is an air gap between the two open ends, the coupling between the open ends can be significantly reduced, which also contributes to reducing dielectric loss and improving the unburdened Q. do. Furthermore, regarding no-load Q,
Since the line width is wide at the portion where the current is maximum, the conductor resistance is low, and the conductor loss can be reduced, the no-load Q can be improved in this respect as well.

Furthermore, by changing the length of the strip grooves, the frequency tuning range can be made approximately one octave. That is, in the resonator of Fig. 2 or 3, the impedance of the line on both sides of the slit groove is Z ₂ , the electrical length of the line is θ ₂ , the impedance of the line without the slit groove is Z ₁ , and the electrical length of the line is If 2θ ₁ , then Z ₂ > Z ₁ and the resonance path is valence-4th.
It can be reached by three routes 41, 42, and 43 as shown in the figure. The resonance condition at this time can be expressed as tanθ ₁ · tanθ ₂ = Z ₂ /Z ₁ , where the total length of the resonator is l ₀ , the length of the slit groove is ₀ , and the phase constant of the line is β,
When the wavelength at the resonance frequency is λ _g , θ ₁ =β( ₀ −)/2=π( ₀ −)λ _g θ ₂ =β ₀ =2π ₀ /λ _g . Now, if the length of the slit groove is O, this resonator becomes a uniform line resonator, and the resonant frequency at this time is 2f ₀ , and as the length of the slit groove is increased, the resonant frequency becomes As shown in Figure 5, it gradually decreases and approaches 2f ₀ /2=f ₀ as it approaches ₀ . This is because the route length is almost twice as long.
This is because the resonance frequency is also halved. In this way, even if the total length of the resonator is kept constant, the resonant frequency can be varied over approximately one octave from f ₀ to 2f ₀ by providing the slit grooves. Therefore, the frequency can be finely tuned by adjusting the length of the slit groove.

Note that when a slit groove is present, the resonator becomes a composite line resonator as shown in FIG. 4, and as is well known, the spurious frequency deviates from an integral multiple of the fundamental wave. This means that when a signal containing harmonic components is passed through a filter using this resonator, it is possible to achieve a characteristic in which only the fundamental wave propagates and does not pass harmonics that are integral multiples of the fundamental wave. do. This is a feature not found in ordinary uniform line resonators, and is extremely useful as an output filter containing many harmonic components such as booster amplifiers.

Effects of the Invention As described above, the present invention has a simple configuration and is easy to manufacture, making it possible to realize a low-cost resonator, and having a slit at the open end reduces deterioration of characteristics due to coupling, resulting in a high Q. By changing the length of the slit, a variable range of almost one octave can be realized with a resonator of the same size.Furthermore, by adjusting the length of the slit, fine tuning of the frequency is possible, which eliminates spurious resonance. It is possible to shift the frequency from an integer multiple of the fundamental wave. This stripline resonator is especially
It is extremely useful as a resonant element for filters and oscillators in the VHF to UHF band, and has great industrial value.

[Brief explanation of the drawing]

Figures 1 a and b are cross-sectional views of a conventional strip line open-ended 1/2 wavelength resonator, and Figures 2 a and b, respectively.
3A and 3B are sectional views of a stripline resonator according to another embodiment of the present invention, respectively, and FIG. 4 is a sectional view of a stripline resonator according to another embodiment of the present invention. FIG. 3 is an equivalent circuit diagram of the strip line resonator, and FIG. 5 is a characteristic diagram showing changes in the resonant frequency when the length of the slit is changed. 21, 31, 32...dielectric substrate, 22, 33
... Strip conductor, 23, 34, 35 ... Ground conductor, 24, 36 ... Slit.

Claims (1)

[Claims] 1. A rectangular (but thick) dielectric substrate having a slit extending from approximately the center of the short side of the rectangle in parallel to the long side (longitudinal direction) and penetrating in the thickness direction. and a conductor film is provided on both sides of the rectangular dielectric substrate, one surface with the conductor film is used as a ground conductor, and the other surface with the conductor film is used as a strip conductor. strip line resonator. 2. Claim 1, characterized in that the frequency is adjusted by changing the length of the slit.
The stripline resonator described in Section 1. 3. A rectangular (but thick) dielectric substrate is provided with a slit extending from approximately the center of the short side of the rectangle, parallel to the long side (longitudinal direction), and penetrating in the thickness direction. , the first and second strip lines of the same shape with conductor films provided on both sides of the rectangular dielectric substrate are superimposed and fixed in the same direction, and the outer two conductor surfaces are connected to the ground plane and the center A balanced strip line resonator with the conductor plane as the center conductor. 4 Claim 3, characterized in that the frequency is adjusted by changing the length of the slit.
The stripline resonator described in Section 1.