JPH0818307A - Dielectric filter - Google Patents

Abstract

PURPOSE:To satisfy requested characteristics in the temperature range and/or the humidity range where a filter is used. CONSTITUTION:Element values are so reset that operation parameters at the use upper limit temperature and/or the use upper limit humidity of the dielectric filter are uniform. Thus, characteristics of the dielectric filter are optimized in the use temperature range and the use humidity range.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microwave band mainly used for mobile communication equipment, etc.
The present invention relates to a dielectric filter in the high frequency band of Hz.

[0002]

2. Description of the Related Art As an example of a conventional dielectric filter, the structure of a bandpass filter using two coaxial resonators is shown in FIG.
Shown in The coaxial resonator 31 is grounded on a ground conductor 32, and a terminal 34 is connected to the internal conductor 33.
The electrical coupling elements 37, 38, 39 for coupling the plurality of coaxial resonators 31 are electrically connected to the conductor pattern 36 formed on the wiring board 35 by means such as soldering.

Further, the input / output terminal 40 is connected to the conductor pattern 3
A filter is formed between the input / output terminals 40 by connecting to the input / output terminal 6. In addition, in FIG.
Although capacitors 8 and 39 are shown to use capacitors, other coupling elements such as coils may be used. In addition to the bandpass filter, a band elimination filter may be used. FIG. 3 shows the circuit configuration.

In such a dielectric filter, the circuit configuration is selected from the required characteristics of the dielectric filter such as the center frequency, insertion loss and band attenuation, and the number of 31 stages, the resonance frequency, the coupling capacitance value, etc. are calculated. To do. The operation transfer coefficient (hereinafter referred to as S parameter) is calculated based on these element values, and the frequency characteristic of the dielectric filter is simulated from the operation function.

In the conventional design of the dielectric filter, since the temperature characteristics of each coaxial resonator 31, the electric element, the wiring board 35, etc. are not taken into consideration, the element values obtained by the design are normal temperature and normal humidity. Optimal filter characteristics (minimum insertion loss)
Was chosen to be.

FIG. 4 shows frequency characteristics of a dielectric filter manufactured by a conventional design method. The center frequency of the dielectric filter is 1575 MHz, the pass band width is 20 MHz, and the insertion loss is 2.0 dB.

FIG. 5 shows the dependency of the insertion loss (dB) on the temperature (° C.). In the temperature range from −20 ° C. to 80 ° C., the temperature loss deteriorates by about 0.5 dB as the temperature rises.

Mobile communication equipment and the like in which the dielectric filter is used are often used in a temperature range from a low temperature of -20 ° C. to 80 ° C. to a high temperature, or in a high humidity environment of 90% RH. The dielectric filter needs to satisfy the required characteristics in a wide temperature range and humidity range.

[0009]

However, since the conventional dielectric filter is designed so that the frequency characteristic of the filter is optimized at room temperature and normal humidity, the coaxial type resonance filter is particularly effective under high temperature and high humidity. There is a problem that the insertion loss of the dielectric filter increases due to changes in the characteristics of the electrical device such as the container 31, the capacitor and the coil, and the wiring board 35, and it is difficult to satisfy the required characteristics.

Further, when a dielectric filter is designed in consideration of temperature characteristics and humidity characteristics of element values of each electric element, the parameters become complicated and it is difficult to match the behavior of the actual dielectric filter. There is.

Therefore, an object of the present invention is to provide a dielectric filter which satisfies the required characteristics in the temperature range and humidity range in which the dielectric filter is used.

[0012]

According to the present invention, the element value of the electric element constituting the dielectric filter is selected so that the frequency characteristic is optimized at the upper limit temperature of use of the dielectric filter. A dielectric filter is obtained.

According to the present invention, there is provided a dielectric filter characterized in that the element value of an electric element constituting the dielectric filter is selected so that the frequency characteristic is optimized at the upper limit humidity of use of the dielectric filter. can get.

According to the present invention, the element value of the electric element forming the dielectric filter is selected so that the frequency characteristic is optimized depending on the use upper temperature limit and the use upper limit humidity of the dielectric filter. A dielectric filter is obtained.

[0015]

According to the dielectric filter of the present invention, by resetting the element values so that the S parameters measured at the upper limit temperature of use and / or the upper limit humidity of use of the dielectric filter become equal, the dielectric filter is used within the use temperature range and used. Optimize dielectric filter characteristics in the humidity range. This maximizes the insertion loss at the maximum temperature and / or the maximum humidity.

[0016]

EXAMPLE A first example of the dielectric filter of the present invention will be described below. The S parameter calculated based on the element value obtained by the conventional design method (the optimum value of the dielectric filter characteristic at room temperature and normal humidity) is defined as SD, and the dielectric filter prototyped from the element value is used as the upper limit. The S-parameter SHT is measured at temperature.

Here, by resetting each element value forming the dielectric filter so that S parameter SD = S parameter SHT, optimized frequency characteristics at room temperature can be obtained at the upper limit temperature. Become.

As described in the prior art, the insertion loss of the dielectric filter increases as the temperature rises. Therefore, by optimizing the insertion loss at the upper limit temperature, the insertion loss is required characteristics within the operating temperature range of the dielectric filter. Never exceeds.

Further, since the optimization is carried out on the basis of the actual measurement data of the dielectric filter, the characteristics that are more in agreement with the substance can be obtained.

FIG. 1 shows the temperature (° C.) dependency of the insertion loss (dB) of a prototype dielectric filter based on the element values obtained by the dielectric filter according to the present invention. Referring to FIG. 1, it can be seen that the filter characteristics are optimized at the upper limit temperature and the insertion loss is maximized at the upper limit of use. The circuit configuration is the same as that of the equivalent circuit shown in FIG. 3 as a conventional technique.

As a second embodiment, each element value constituting the dielectric filter is reset so that the S parameter SHH measured at the upper limit humidity of use of the dielectric filter becomes equal to the S parameter SD.

As a result, within the operating humidity range,
Since the dielectric filter characteristics are optimized and the insertion loss becomes maximum at the upper limit humidity, the required characteristics can be satisfied within the humidity range in which the dielectric filter is used.

Further, as a third embodiment, the S parameter SHTH measured at the upper limit temperature and the upper limit humidity of the dielectric filter is made equal to the S parameter SD.
By resetting each element value, the dielectric filter characteristics are optimized within the operating temperature range and operating humidity range,
Since the insertion loss becomes maximum at the upper limit temperature and the upper limit humidity, a dielectric filter satisfying the required characteristics can be realized within the temperature range and humidity range of the dielectric filter.

[0024]

As described above with reference to the embodiments, according to the dielectric filter of the present invention, the S parameter measured at the upper limit temperature and / or the upper limit humidity of the dielectric filter is measured at room temperature and normal humidity. By resetting each element value so as to be equal to the S parameter calculated based on the design value, required characteristics can be satisfied in the temperature range and / or humidity range in which the dielectric filter is used.

[Brief description of drawings]

FIG. 1 is a graph showing the temperature dependence of a dielectric filter according to the present invention.

FIG. 2 is an exploded perspective view showing a conventional dielectric filter.

FIG. 3 is an equivalent circuit diagram illustrating a circuit of the dielectric filter of FIG.

FIG. 4 is a graph showing frequency characteristics of a dielectric filter designed by a conventional design method.

FIG. 5 is a graph showing the temperature dependence of a conventional dielectric filter.

[Explanation of symbols]

 31 coaxial resonator 32 grounding conductor 33 inner conductor 35 wiring board 36 conductor pattern 37, 38, 39 electrical coupling element 40 input / output terminal

Claims (3)

[Claims] 1. A dielectric filter, wherein an element value of an electric element forming the dielectric filter is selected so that a frequency characteristic is optimized at a use upper limit temperature of the dielectric filter. 2. The dielectric filter, wherein the element value of an electric element constituting the dielectric filter is selected so that the frequency characteristic is optimized at the upper limit humidity of use of the dielectric filter. 3. A dielectric filter, wherein element values of electric elements constituting the dielectric filter are selected so that frequency characteristics are optimized depending on the use upper limit temperature and use upper limit humidity of the dielectric filter.