JPS6143287Y2 - - Google Patents

Description

[Detailed description of the invention] Conventionally, filters used in the VHF band or UHF band include filters that use LC resonators and filters that use cavity resonators. However, the former does not provide sufficient selectivity characteristics, and the latter
The drawback was the large shape.

In recent years, in the communication equipment field, there has been a strong desire to make systems smaller and lighter.While other components are being made smaller and lighter, filters are still being used in large numbers due to their importance. However, it has been difficult to make the system smaller and lighter, which has delayed efforts to make the system smaller and lighter. Therefore, the size and weight of the filter can be reduced.
This was a supreme command for engineers in this field. This is solved by providing a compact and high performance resonator. Moreover, if such a small and high-performance resonator is provided, it can be said to be very preferable for devices other than filters using the resonator.

Some prior inventions have been made to overcome the above-mentioned drawbacks.

The present invention can be implemented mainly based on this prior invention, and prior to explaining the present invention, the prior invention will be explained first.

The main objective of this prior invention is to provide a coaxial TEM resonator with a compact shape.

Another object of this prior invention is to provide a highly productive coaxial
The purpose is to provide a TEM resonator.

Another object of this prior invention is to provide a coaxial TEM resonator that is simple in structure and highly reliable.

Another object of this prior invention is to provide a coaxial TEM resonator with excellent temperature characteristics.

Another object of this prior invention is to
The goal is to obtain the highest Q in the TEM resonator.

Examples of this prior invention will be described below with reference to the drawings.

In FIG. 1, 1 is a cylindrical ceramic dielectric. The total length L is set to be 1/2 wavelength or 1/4 wavelength at the resonant frequency. As shown in FIG. 2, silver pastes 4 and 5, which are to become the outer conductor and inner conductive shaft, respectively, are applied to the outer circumferential surface 2 and inner circumferential surface 3 of the dielectric body 1 which has been fired in advance in this way, and is re-baked. . Repeat this until the required film thickness is achieved. Of course, any known conductive material other than silver that has excellent high frequency conductivity and excellent adhesion to the dielectric 1 may be used. In addition to coating and baking such a material, plating, vapor deposition, sputtering, printing, and even pressing a sheet made of such a material may be considered. As shown in FIG. 3, a rod-shaped dielectric 6 may be placed in the hole surrounded by the inner guide shaft to improve the strength. Alternatively, the entire rod including the inner guide shaft may be a metal rod.

The dielectric does not need to be a single piece, and a plurality of pieces may be combined depending on manufacturing issues.

In each of these embodiments, Q reaches its maximum value when (inner diameter of outer conductor portion of resonator)/(outer diameter of inner guiding shaft of resonator) is approximately 3.6. In addition, if the temperature coefficient of the dielectric material is appropriately selected, the effect of the linear expansion coefficient of the metal conductor can be canceled out, so coaxial cables with excellent temperature characteristics can be used.
TEM resonator can be provided.

As is clear from the above embodiments, the coaxial TEM resonator of this prior invention includes a dielectric material having an inner circumferential surface and an outer circumferential surface, at least a film-like inner guide shaft provided on the inner circumferential surface, and It has a film-like outer conductor provided on the outer peripheral surface. In this way, since the dielectric is interposed between the inner guide shaft and the outer conductor, the shape is smaller than that of a conventional cavity resonator even at the same resonant frequency. In addition, there is no need to manage the dimensions of both the inner guide shaft and the outer conductor, and only the dimensions of the dielectric are required, resulting in excellent productivity. Furthermore, since there is no need for a structure to maintain the positional relationship between the inner guide shaft and the outer conductor, the structure is simplified and reliability is improved. In addition, by selecting the temperature coefficient of the dielectric material, it is possible to cancel the influence of the coefficient of linear expansion of the inner conductor and outer conductor, and to adjust the dimensional ratio of the inner diameter of the outer conductor to the outer diameter of the inner guide shaft. The highest Q can be obtained by selecting approximately 3.6.

Incidentally, in such a coaxial TEM resonator, the resonant frequency is almost determined by the total length L as described above, but due to problems such as dimensional accuracy, the desired resonant frequency may not be obtained. To correct the resonant frequency to a higher value, as shown in FIG. 4, the entire end face is usually shaved to shorten the overall length L to, for example, L'. However, this process is troublesome, and it has been desired to easily modify the resonant frequency to a higher value.

Therefore, the main purpose of this invention is to provide a coaxial TEM resonator with a frequency adjustment structure that allows the resonant frequency to be easily modified higher.

In summary, this invention is a frequency adjustment structure in which grooves are provided in the end face of the dielectric material corresponding to the open end to adjust the resonant frequency to a desired value.

The above objects and other objects and features of the present invention will become more apparent from the following detailed description with reference to the drawings.

FIG. 5 is a perspective view of an embodiment of this invention. This FIG. 5 is the same as FIG. 2 except for the following points. The present invention is applied when the resonant frequency of the resonator at hand is lower than the desired value. In other words,
A groove 7 is provided by hollowing out a portion of the open end surface of the dielectric 1. Such a simple structure increases the resonance frequency. The shape, depth, number, position, etc. of the grooves 7 are determined appropriately so that the resonance frequency becomes a desired value.

As described above, according to this invention, the resonant frequency can be easily modified by forming grooves on the dielectric surface located at the open end face without shortening the overall axial dimension of the resonator. Can be done. This can improve the rate of non-defective products and lead to cost reductions.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing a dielectric 1 of the prior invention, FIG. 2 is a perspective view of an embodiment of the prior invention, FIG. 3 is a sectional view of another embodiment of the prior invention, and FIG. 4 is a dielectric 1 of the prior invention. Frequency Adjustment Method FIG. 5 is a perspective view of an embodiment of the present invention. 1 is a ceramic dielectric, 2 is an outer peripheral surface, 3 is an inner peripheral surface, 4 and 5 are silver pastes, and 7 is a groove.

Claims (1)

[Scope of utility model registration request] In the frequency adjustment structure of a coaxial TEM resonator, which has a dielectric body having an inner peripheral surface and an outer peripheral surface, an inner guide shaft provided on the inner peripheral surface, and an outer conductor provided on the outer peripheral surface, the resonator corresponds to the open end. A coaxial TEM resonator frequency adjustment structure with grooves partially formed on the end face of the dielectric.