JPH045577A - Method and instrument for measuring resonance frequency and load q of resonator - Google Patents

Abstract

PURPOSE:To measure the resonance frequency, etc., with simple constitution by oscillating the resonator in fundamental mode and connecting it to two oscillation loop circuits which differ in electric length alternately, measuring the oscillation frequencies of the loop circuits, and calculating the resonance frequency and load Q. CONSTITUTION:The dielectric resonator 1 is oscillated in the fundamental mode through a high frequency signal generator 1. Then a switch SW1 is turned off to select microstrip lines 31 and 32 which differ in electric length with associated switches SW2 and SW3, and the frequencies f1 and f2 of signals which are generated in the loop circuits differing in electric length and passed through a directional coupler 34 are measured. Then a microprocessor 40 performs arithmetic to measure the resonance frequency f0 and load Qu of the resonator 11 with the simple constitution wherein a spectrum analyzer, etc., is not necessary.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application 1] The present invention relates to a method and apparatus for measuring the resonant frequency and load Q of a resonator such as a dielectric resonator.

[Prior art] FIG. 5 shows the resonant frequency and load Q of the dielectric resonator 111.
The conventional measurement method is shown below.

In FIG. 5, a cylindrical dielectric resonator 111 is placed in the center of a shield case 110, and L-turn coils 121. 122 is provided. A frequency sweep signal including the resonant frequency of this dielectric resonator 111 is sent from the sweep signal generator 101 to the coil 121.
On the other hand, the frequency spectrum characteristics of the signal output from the coil 122 are input to the spectrum analyzer 10.
2.

The resonance frequency f in the frequency spectrum characteristics of the measured signal. located on both sides of and 3 from the maximum level point.
The frequency fl+fz (f, <fz) at the point where the frequency has decreased by dB (hereinafter referred to as the 3dB decrease point) is measured, and the measured frequency f1. Substitute fz into the following equation to find the resonant frequency f. , and further, the resonance frequency f calculated above. and the above measured frequency f1. The load Q (QL) of the dielectric resonator 111 is calculated by substituting fz into the following equation.

Furthermore, in place of the sweep signal generator 101 and the spectrum analyzer 102, a network analyzer is used to similarly calculate the resonant frequency f0 of the dielectric resonator 111.
and the load Q can be measured.

[Problems to be Solved by the Invention] However, the conventional method has a problem in that it requires an expensive measuring device such as the spectrum analyzer 102 or a network analyzer.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and provide a measuring method and a measuring device that can measure the resonant frequency and load Q of a resonator using a measuring device that is cheaper than conventional ones.

[Means for Solving the Problems] A method for measuring the resonant frequency of a resonator according to claim 1 of the present invention includes measuring two oscillation loop circuits each including an amplification means for amplifying an oscillation signal and having different electrical lengths. The oscillation frequency of each oscillation signal generated in each of the two oscillation loop circuits is measured by alternately switching and electrically connecting the resonators to each resonator, causing each of the resonators to oscillate in a predetermined fundamental mode, and measuring the oscillation frequency of each oscillation signal generated in the two oscillation loop circuits. The method is characterized in that the resonant frequency of the resonator is calculated and measured based on each measured oscillation frequency.

Further, in the method for measuring the load Q of a resonator according to claim 2 of the present invention, two oscillation loop circuits each having an amplifying means for amplifying an oscillation signal and having different electrical lengths are alternately connected to the resonator to be measured. The resonators are switched and electrically connected to oscillate each resonator in a predetermined fundamental mode, and the oscillation frequency of each oscillation signal generated in the two oscillation loop circuits is measured, and the oscillation frequency is adjusted to each of the measured oscillation frequencies. It is characterized in that the load Q of the resonator is calculated and measured based on the above.

Furthermore, the resonant frequency measuring device of a resonator according to claim 3 of the present invention includes two oscillation loop circuits that are equipped with amplifying means for amplifying an oscillation signal and have different electrical lengths, and that measures the two oscillation loop circuits. a switching means that alternately switches and electrically connects the resonators to each resonator to oscillate each resonator in a predetermined fundamental mode; and a switching means that measures the oscillation frequency of each oscillation signal generated in each of the two oscillation loop circuits. The present invention is characterized by comprising: a frequency measuring means; and a calculating means for calculating the resonant frequency of the resonator based on each oscillation frequency measured by the frequency measuring means.

Furthermore, the device for measuring the load Q of a resonator according to claim 4 of the present invention includes: two oscillation loop circuits each having an amplification means for amplifying an oscillation signal and having different electrical lengths; A switching means that alternately switches and electrically connects the resonators to be measured to cause each of the resonators to oscillate in a predetermined fundamental mode, and measures the oscillation frequency of each oscillation signal generated in each of the two oscillation loop circuits. and calculating means for calculating the load Q of the resonator based on each oscillation frequency measured by the frequency measuring means.

[Function] With the above configuration, two oscillation loop circuits each having an amplifying means for amplifying an oscillation signal and having different electrical lengths are alternately switched and electrically connected to the resonator to be measured. By causing each of the resonators to oscillate in a predetermined fundamental mode and measuring the oscillation frequency of each oscillation signal generated in the two oscillation loop circuits,
The resonance frequency and load Q of the resonator can be calculated and measured based on each of the measured oscillation frequencies.

In the present invention, instead of measuring based on the frequency spectrum characteristics of the resonator measured by a frequency sweep signal as in the conventional example, the resonator to be measured is electrically connected to two oscillation loops having different electrical lengths. The oscillation frequency of each oscillation signal generated in the circuit is measured, and the resonant frequency and load Q of the resonator are calculated and measured based on the measured oscillation frequencies, so the device is less expensive than conventional methods. automatically calculates the resonant frequency and load Q of the resonator using
can be measured.

[Example] Hereinafter, an apparatus for measuring the resonant frequency and load Q of a dielectric resonator according to an example of the present invention will be described in the order of the following items with reference to the drawings.

(1) Configuration of the device for measuring the resonant frequency of the dielectric resonator and the load Q (2) Principle of measuring the resonant frequency of the dielectric resonator and the load Q (3) Measurement flow of the measuring device (4) Other examples The measuring device of the embodiment includes switches SW2. 2 which is configured by switching SW3 in conjunction and has mutually different electrical lengths.
dielectric resonator 1 in each of the two oscillation loop circuits.
1 is the basic mode, TE. 1. Different oscillation frequencies f1. oscillate at f2, each oscillation frequency f,,
f, and the above measured two oscillation frequencies f, ,
The resonant frequency f of the dielectric resonator 11 is based on f2. It is characterized by calculating the load Q.

(1) Configuration of an apparatus for measuring the resonant frequency and load Q of a dielectric resonator FIG. 1 is a block diagram of an apparatus for measuring the resonant frequency and load Q of a dielectric resonator 11, which is an embodiment of the present invention. FIG. 2 is a longitudinal sectional view of the dielectric resonator 11 of FIG. 1 and the shield case 10 housing it.

This measurement device has two operation modes: a filter operation mode in which the dielectric resonator 11 operates as a bandpass filter, and a measurement operation mode in which the resonant frequency f0 and load Q of the dielectric resonator 11 are measured. have

As shown in FIGS. 1 and 2, the cylindrical dielectric resonator 11 to be measured has the same coefficient of linear expansion as the dielectric resonator 11 at the center of the cylindrical shield case 10. It is placed on a support stand 14. This dielectric resonator 11 has, for example, T]0□ as its main component and MgO1
It is a ceramic dielectric resonator made of a mixture of oxides such as Ba○ and ZrO2, and the dielectric resonator 11 of this embodiment has a power of about 800 MH in the fundamental mode TEor-mode.
Resonant frequency f of z. has. Further, a cylindrical dielectric 12 is provided inside the cylinder of the dielectric resonator 11 and supported by a shaft 15, and by moving the shaft 15 in the direction of arrow A1, the dielectric 12 is caused to resonate. By moving the dielectric resonator 11 within the gradient of the electric field, the resonant frequency f0 of the dielectric resonator 11 can be finely adjusted.

The shield case IO is constructed by baking a silver electrode onto the outer surface of a cylindrical casing made of ceramic having the same coefficient of linear expansion as the dielectric resonator 11 for electromagnetic shielding. As shown in FIG. 2, the magnetic field H of the dielectric resonator 11 is coupled to four positions on the inner surface of the shield case IO, which are spaced apart by an angle of 90 degrees from each other around the center of the cylinder. For example, an L-turn coil 21, 22, 23° 24 for signal input/output.
is provided. Here, coils 21 and 22 used in the filter operation mode are provided facing each other with the dielectric resonator 11 in between, and coils 23 and 24 used in the measurement operation mode are provided with the dielectric resonator 11 in between. They are placed opposite each other.

In the filter operation mode, the switch SWI is turned on and the switch SW4 is turned off, and a signal in the approximately 800 MHz band output from the high frequency signal generator l is transmitted to the switch SWl.
After being input to the coil 21 via the dielectric resonator 11, the input signal is filtered. The filtered signal is output from the coil 22 to the load 2.

On the other hand, in the oscillation operation mode, switch/7 switch SWI is turned off and switch SW4 is turned on.

At this time, in one of the two oscillation loop circuits connected between the coils 23 and 24 and configured to satisfy the oscillation conditions described in detail later, the basics of the dielectric resonator 11 are mode TEo+a
An oscillation signal is generated that oscillates in the mode.

Switch SW2. When SW3 is interlocked and switched to the a side, the first oscillation loop circuit is connected between the coils 23 and 24, and the oscillation signal output from the coil 24 is connected to the a side of the switch SW2, with a predetermined characteristic impedance z0. and a microstrip line 31 having a predetermined electrical length λg1
．． The signal is then inputted to the input terminal of the amplifier 33 with the amplification degree A via the a side of the switch SW3. On the other hand, switch SW2. S
When W3 is interlocked and switched to side b, a second oscillation loop circuit is connected between coils 23 and 24, and coil 2
The oscillation signal output from 4 is the b side of switch SW2,
The signal is inputted to the input end of the amplifier 33 via the microstrip line 32 having a predetermined characteristic impedance Z0 and an electrical length λg2 different from that of the microstrip line 32, and the b side of the switch SW3.

The oscillation signal output from the output end of the amplifier 33 is output to the coil 23 via the transmission line connected between the ports 34a and 34b of the directional coupler 34 and the switch SW4. Note that the above-mentioned switches SWl, SW2 . SW3. S
As will be described in detail later, W4 is switched and controlled by a microprocessor unit (hereinafter referred to as MPU) 40 which is a control device of the measuring device.

A port 34d of the directional coupler 34 that detects an oscillation signal that is a traveling wave passing through the transmission line between the ports 34a and 34b is connected to the frequency counter 35, and a port that detects the reflected wave passing through the transmission line. 34c is terminated by a negative W34e of a predetermined characteristic impedance. This frequency counter 35 measures the frequency of the oscillation signal detected at the port 34d, and outputs data fm of the measured frequency to the MPU 40.

The MPU 40 controls the measurement device and controls the dielectric resonator 11.
A CPU (not shown) that measures the resonant frequency f0 and load Q of the measuring device, a control program for controlling the measuring device, and a ROM (not shown) that stores the data necessary to execute the control program. ), a RAM (not shown) used as a working memory of the CPU, and switches SWI, SW2 . SW3. It includes an input/output port circuit (not shown) connected to the SW 4, the frequency counter 35, and the CRT display 41 and operating as an interface circuit. This MPU 40 includes the above-mentioned switch SWI, as will be described in detail later.

SW2. SW3. SW4 is switched and controlled, and the measured frequency data fm is received from the frequency counter 35, thereby calculating the resonant frequency f0 and load Q (Q, ) of the dielectric resonator 11, and calculating these values. The data is displayed on the CRT display 41.

(2) Measuring principle of resonant frequency and load Q of dielectric resonator The oscillation conditions in the first and second oscillation loop circuits shown in FIG. 1 are expressed by the following equation.

Re(A・β,)=1−(2a)Im(A
・βυ=O-(2b) Re(A・β2)=1-(3a)Im(A
・β, ) =O・(3b) Here, A is the amplification degree of the amplifier 33, β1 is the feedback amount in the first oscillation loop circuit, and β is the feedback amount in the second oscillation loop circuit. It's the amount. As described above, the electrical lengths λg + + 3g2 of the microstrip line 31 and the microstrip line 32 are different from each other, and the respective feedback amounts β1 . Since β2 is different from each other, the above equations (2b) and (3b) are used in the first and second oscillation loop circuits, respectively.
), the different oscillation frequencies f1. It can be seen that an oscillation signal having fx is generated.

In the first oscillation loop circuit, the resonant frequency f of the dielectric resonator 11. Letting el be the transmission phase of devices and lines other than the dielectric resonator 11 at an arbitrary frequency fa close to , the transmission phase θ1 of the dielectric resonator 11 is expressed by the following equation.

Here, n is an integer.

On the other hand, in the second oscillation loop circuit, the dielectric resonator 11
The resonant frequency f. The transmission phase of devices and lines other than the dielectric resonator 11 at an arbitrary frequency fa close to 82
Then, the transmission phase θ of the dielectric resonator 11 is expressed by the following equation.

2, where n is an integer and the above transmission phase cB.

θ2 is an equipment constant that can be measured in advance. Therefore, the oscillation frequency f□ in each oscillation loop circuit.

By measuring β2, the transmission phase θ1. of the dielectric resonator 11 in each oscillation loop circuit is determined. θ2 can be obtained.

The resonant frequency of the resonator is r. Then, in general, the following relationship holds between the transmission phase θ of a resonator and its load Q (QL).

Therefore, by applying the first and second oscillation loop circuits to the above equation (6), the following equation is obtained.

The load Q (Qt) is eliminated using the above equations (7) and (8), and the resonant frequency f is determined. By solving, we obtain the following equation.

(9) Furthermore, by substituting the above equation (9) into equation (7), the following equation is obtained.

Here, F r= f 1tanθ+−β2tanθ2 −(
Ila) F2=f2tanθ, -f, tanθx
-(llb).

Therefore, after measuring the oscillation frequency f1 of the oscillation signal generated in the first oscillation loop circuit and also measuring the oscillation frequency f2 of the oscillation signal generated in the second oscillation loop circuit, the measured oscillation frequency fr , f2 into the above equations (4) and (5), respectively,
The transmission phase θ1 of the dielectric resonator 11. θ2 can be calculated. Furthermore, the above calculated transmission phase θ1. θ2
By substituting the measured oscillation frequencies f+ and fz into the equations (9), (lO), (lla), and (llb), respectively, the resonant frequency f of the dielectric resonator 11 is obtained. and load Q (QL) can be calculated and measured.

(3) Measurement flow of the measuring device FIG. 3 is a flowchart showing the measurement flow of the measuring device of FIG. 1 in the measurement operation mode, and the measurement flow of the measuring device will be explained with reference to FIG.

First, in step #l, the switch SWI is turned off and the switch SW4 is turned on to set this measuring device in the measurement operation mode, and then in step #2, the switch SW2. Switch SW3 to the a side in conjunction with the first
An oscillation loop circuit is connected between the coils 23 and 24.

Next, in step #3, the oscillation frequency f of the oscillation signal generated in this first oscillation loop circuit is measured by the frequency counter 35, and the data fm is
It is stored in the RAM in U40 as the oscillation frequency f. Furthermore, in step #4, the transmission phase θ1 of the dielectric resonator 11 is calculated by substituting the measured oscillation frequency f1 into the above equation (4), and the calculated result is stored in the RAM.

Next, in step #5, switches SW2, SW
3 to the b side and connect the second oscillation loop circuit between the coils 23 and 24. In step #6, the oscillation frequency f2 of the oscillation signal generated in this second oscillation loop circuit is set to It is measured by the counter 35, and the data fm is stored in the RAM in the MPU 40 as the oscillation frequency f2. Furthermore, in step #7, the transmission phase θ2 of the dielectric resonator 11 is calculated by substituting the measured oscillation frequency f2 into the above equation (5), and the calculated result is stored in the RAM.

Next, in step #8, the calculated transmission phase θ1. θ2 and the above-measured oscillation frequencies f, , f are expressed by the above equations (9), (10), (lla) and (llb
), respectively, dielectric resonator 1
1 resonant frequency f. After calculating the load Q (QL) and displaying the calculated results on the CRT display 41, in step #9, switch SW4 is turned off and switch SWI is turned on to put the measuring device into the filtering operation mode. Set this to end this measurement process.

(4) Other Embodiments In the above embodiments, the two microstrip lines 31, 32 are connected to switches SW2. Although the first and second oscillation loop circuits are configured by switching by SW3, the present invention is not limited to this. Two coils are provided, which are independent from each other and have different electrical lengths.
Two oscillation loop circuits may be configured. In this case, when in the filter operation mode, both oscillation loop circuits are turned off, and when in the measurement operation mode, one oscillation loop circuit is turned on and the other oscillation loop circuit is turned off. Then, one oscillation loop circuit may be turned off and the other oscillation loop circuit is turned on, and the measurement operation may be performed in the same manner as in the above embodiment.

In the above embodiment, the two microstrip lines 31, 32 are connected to the switches SW2. Although the first and second oscillation loop circuits are configured by switching by SW3, the present invention is not limited to this, and as shown in FIG. 4, microstrip lines 31, 32 and switches SW2, . Instead of SW3, a phase shifter 50 whose transmission phase θS can be set by the MPU 40 may be connected between the coil 24 and the amplifier 33.

In this case, in order to configure two oscillation loop circuits, two different and predetermined transmission phases θSl+θs2 that can oscillate in the oscillation loop circuits are M
Set by PU40. At this time, similarly to the above-described embodiment, the transmission phase θ1. θ2 can be measured in advance.

In the above embodiment, the microstrip line 31.
Although the present invention is not limited to this, transmission lines such as coplanar lines and slot lines having mutually different electrical lengths may be used.

In the above embodiments, a measuring method and a measuring device for measuring the resonant frequency and load Q of the dielectric resonator 11 have been described, but the present invention is not limited to this, and the present invention is not limited to this, and the present invention is not limited to this. Can be applied to other types of resonators.

[Effects of the Invention] As detailed above, according to the present invention, the resonator to be measured is electrically Measure the oscillation frequency of each oscillation signal generated in two oscillation loop circuits with different electrical lengths connected to each other, and calculate the resonant frequency and load Q of the resonator based on each of the measured oscillation frequencies. This method has the advantage that the resonant frequency and load Q of the resonator can be automatically measured using a device that is cheaper than the conventional example.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a device for measuring the resonant frequency and load Q of a dielectric resonator, which is an embodiment of the present invention, and FIG.
3 is a flowchart showing the measurement flow in the measurement operation mode of the measuring device shown in FIG. 1, and FIG. 4 is a longitudinal cross-sectional view of the dielectric resonator shown in FIG. Block Diagram Showing Modification Example FIG. 5 is a block diagram showing a conventional method for measuring the resonant frequency and load Q of a dielectric resonator. 11... Dielectric resonator, 23.24... Coil, 31.32... Microstrip line, 33...
Amplifier, 34... Directional coupler, 35... Frequency counter, 40... Microprocessor unit (MPU), 5
0...phase shifter, SW2. SW3...Switch. Patent applicant: Murata Manufacturing Co., Ltd. (Fig. 2)-A1 Agent: Patent attorney: 1 person

Claims (4)

[Claims] (1) Two oscillation loop circuits equipped with amplification means for amplifying oscillation signals and having different electrical lengths are alternately switched and electrically connected to the resonator to be measured, and each resonator is set to a predetermined fundamental mode. The oscillation frequency of each oscillation signal generated in each of the two oscillation loop circuits is measured, and the resonant frequency of the resonator is calculated and measured based on each of the measured oscillation frequencies. How to measure the resonant frequency of a resonator. (2) Two oscillation loop circuits equipped with amplification means for amplifying oscillation signals and having different electrical lengths are alternately switched and electrically connected to the resonator to be measured, and each resonator is set to a predetermined basic mode. oscillation, the oscillation frequency of each oscillation signal generated in the two oscillation loop circuits is measured, and the load Q of the resonator is calculated and measured based on each of the measured oscillation frequencies. How to measure the load Q of a resonator. (3) Two oscillation loop circuits equipped with amplification means for amplifying oscillation signals and having different electrical lengths, and the two oscillation loop circuits are alternately switched and electrically connected to the resonator to be measured to generate the above-mentioned resonance, respectively. a switching means for causing the device to oscillate in a predetermined basic mode; a frequency measuring means for measuring the oscillation frequency of each oscillation signal generated in the two oscillation loop circuits; and calculation means for calculating the resonant frequency of the resonator. (4) Two oscillation loop circuits equipped with amplification means for amplifying the oscillation signal and having different electrical lengths, and the two oscillation loop circuits are alternately switched and electrically connected to the resonator to be measured to generate the above-mentioned resonance. a switching means for causing the device to oscillate in a predetermined basic mode; a frequency measuring means for measuring the oscillation frequency of each oscillation signal generated in the two oscillation loop circuits; and calculation means for calculating the load Q of the resonator.