JP2967214B2 - Method and apparatus for measuring resonance frequency and load Q of resonator - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and a device for measuring a resonance frequency and a load Q of a resonator such as a dielectric resonator.

[Prior Art] FIG. 10 shows the resonance frequency and load Q of a dielectric resonator 111.
2 shows a conventional measurement method.

In FIG. 10, a cylindrical dielectric resonator 111 is placed in the center of the shield case 110, and one-turn coils 121 and 122 are provided on the inner surfaces of the shield cases 110 on both sides of the dielectric resonator 111, respectively. Is provided. A frequency sweep signal including the resonance frequency of the dielectric resonator 111 is input from the sweep signal generator 101 to the coil 121, while the frequency spectrum characteristic of the signal output from the coil 122 is measured by the spectrum analyzer 102.

It is located on both sides of the resonance frequency f ₀ in the frequency spectrum characteristic of the measured signal and 3d from the maximum level point.
Frequency at the point where B is reduced (hereinafter referred to as 3dB or less)
Measure f ₁ and f ₂ (f ₁ <f ₂ ). The measured frequencies f ₁ and f ₂
Into the following equation to calculate and obtain the resonance frequency f ₀ , Further, the load Q (Q _L ) of the dielectric resonator 111 is calculated by substituting the calculated resonance frequency f ₀ and the measured frequencies f ₁ and f ₂ into the following equation.

In addition, the resonance frequency f ₀ and the load Q of the dielectric resonator 111 can be similarly measured using a network analyzer instead of the sweep signal generator 101 and the spectrum analyzer 102.

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

An object of the present invention is to provide a measuring method and a measuring apparatus which can solve the above problems and can measure the resonance frequency and the load Q of a resonator with a measuring apparatus which is inexpensive as compared with the related art.

[Means for Solving the Problems] According to a method for measuring a resonance frequency of a resonator according to claim 1 of the present invention, a resonator to be measured, amplifying means for amplifying an oscillation signal, and a method for converting the oscillation signal into a predetermined signal. A predetermined phase shift means for shifting the phase of the resonator by an amount of phase shift, and a phase modulation means for phase-modulating the oscillation signal with a predetermined transmission phase shift amount by an AC signal. Oscillates in the basic mode, the oscillation signal generated in the oscillation loop circuit is phase-modulated by the phase modulation means, the phase-modulated oscillation signal is detected, and the phase shift amount of the phase shift means is changed to perform the detection. Detecting the minimum value of the level of the AC signal, and measuring the oscillation frequency of the unmodulated oscillation signal when detecting the minimum value of the level of the AC signal, as the resonance frequency of the resonator. You You.

Further, the method of measuring the load Q of the resonator according to claim 2 of the present invention is further the method of measuring the resonance frequency of the resonator according to claim 1. The measured resonance frequency,
A load Q of the dielectric resonator is calculated based on a shift amount of a transmission phase of the oscillation signal in the phase modulation unit and a minimum value of the level of the detected AC signal.

Further, according to a third aspect of the present invention, there is provided an apparatus for measuring a resonance frequency of a resonator, wherein the resonator to be measured, amplifying means for amplifying an oscillation signal, and shifting the oscillation signal by a predetermined phase shift amount. An oscillation loop circuit comprising: a phase shifter; and a phase modulator for phase-modulating the oscillation signal with a predetermined transmission phase shift amount by an AC signal, and generating a phase-modulated oscillation signal in a predetermined fundamental mode. Detecting means for detecting the phase-modulated oscillating signal; detecting means for detecting the level of the AC signal detected by the detecting means; frequency measuring means for measuring the oscillating frequency of the oscillating signal; and Control means for changing the amount of phase shift and detecting a minimum value of the level of the AC signal detected by the detection means, wherein the frequency is detected when the level of the detected AC signal becomes a minimum value. The oscillation frequency of the unmodulated of said oscillation signal measured by the measuring means and measuring the resonance frequency of the resonator.

Further, according to a fourth aspect of the present invention, there is provided an apparatus for measuring a load Q of a resonator according to the third aspect of the present invention, further comprising a resonance frequency measured by the frequency measuring means. Calculating means for calculating a load Q of the dielectric resonator based on a shift amount of a transmission phase of the oscillation signal in the phase modulation means and a minimum value of a level of the AC signal detected by the control means. It is characterized by having.

[Operation] With the configuration described above, the resonator oscillates in a predetermined fundamental mode using the oscillation loop circuit,
The oscillation signal generated in the oscillation loop circuit is phase-modulated by the phase modulation means, the phase-modulated oscillation signal is detected, and the phase shift amount of the phase shift means is changed to change the level of the detected AC signal. And the oscillation frequency of the non-modulated oscillation signal when the minimum value of the level of the AC signal is detected. It can be measured as the resonance frequency of the resonator.

Further, based on the measured resonance frequency, the shift amount of the transmission phase of the oscillation signal in the phase modulation unit, and the minimum value of the level of the detected AC signal, the load of the dielectric resonator is determined. Q can be calculated.

In the present invention, the level of the detected AC signal is minimized by changing the amount of phase shift of the phase shift means of the oscillation loop circuit based on the frequency spectrum characteristic of the resonator measured by the frequency sweep signal as in the conventional example. Detecting the value, measuring the oscillation frequency of the unmodulated oscillation signal when the minimum value of the level of the AC signal is detected as the resonance frequency of the resonator, and further measuring the resonance frequency based on the measured resonance frequency. Since the load Q of the resonator is measured, the resonance frequency and the load Q of the resonator can be automatically measured by using an inexpensive device as compared with the conventional example.

[Embodiment] Hereinafter, with reference to the drawings, an apparatus for measuring a resonance frequency and a load Q of a dielectric resonator according to an embodiment of the invention will be described.
The description will be made in the following order.

(1) Configuration of measurement device for resonance frequency and load Q of dielectric resonator (2) Measurement principle of resonance frequency and load Q of dielectric resonator (3) Measurement flow of measurement device (4) Other embodiments The measuring apparatus of the embodiment oscillates the dielectric resonator 11 in a _TE01δ mode that is a fundamental mode, phase-modulates the oscillation signal of the dielectric resonator 11 with a low-frequency signal, and converts the phase-modulated oscillation signal. Detecting and measuring the non-modulated oscillation frequency of the oscillation signal at which the detected signal level is minimized to determine the resonance frequency f ₀ of the dielectric resonator 11 and the measured resonance frequency f ₀ The load Q of the dielectric resonator 11 is calculated based on ₀ , the shift amount of the transmission phase of the oscillation signal at the time of the phase modulation, and the minimum value of the detected signal level.

(1) Configuration of Measurement Apparatus for Resonant Frequency and Load Q of Dielectric Resonator FIG. 1 is a block diagram of a measurement apparatus for resonance frequency and load Q of dielectric resonator 11 according to one 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 accommodating the same.

This measuring device includes a filtering operation mode in which the dielectric resonator 11 operates as a band-pass filter,
It has two operation modes of 11 measurement modes for measuring the resonance frequency f ₀ and the load Q.

As shown in FIGS. 1 and 2, a cylindrical dielectric resonator 11 to be measured has the same linear expansion coefficient as the dielectric resonator 11 at a central portion in a cylindrical shield case 10. It is placed on a support 14. This dielectric resonator 11
For example, it is a ceramic dielectric resonator in which an oxide such as MgO, BaO, or ZrO ₂ is mixed with TiO ₂ as a main component, and the dielectric resonator 11 of the present embodiment has about a TE _01δ mode as a fundamental mode. having a resonant frequency f ₀ of 800MHz. Further, inside the cylinder of the dielectric resonator 11, a cylindrical dielectric 12 is provided.
Is supported by the shaft 15 and provided.
The move in the arrow A ₁ direction, the dielectric 12 by moving in a gradient of the electric field of the dielectric resonator 11, it is possible to finely adjust the resonant frequency f ₀ of the dielectric resonator 11 .

The shield case 10 is configured by baking silver electrodes on the outer surface of a cylindrical housing made of ceramics having the same linear expansion coefficient as the dielectric resonator 11 for electromagnetic shielding. As shown in FIG. 2, the inner surface of the shield case 10 is coupled to the magnetic field H of the dielectric resonator 11 at four positions separated from each other by 90 degrees with respect to the center of the cylinder. Thus, for example, one-turn coils 21, 22, 23, 24 for inputting / outputting signals are provided. Here, the coil used in the filtering operation mode
21 and 22 are provided to face each other with the dielectric resonator 11 therebetween, and coils 23 and 24 used in the measurement operation mode are provided to face each other with the dielectric resonator 11 therebetween.

In the filtering operation mode, the switch SW1 is turned on and the switch SW2 is turned off, and a signal of about 800 MHz band output from the high-frequency signal generator 1 is input to the coil 21 via the switch SW1, and then input. The resulting signal is filtered by the dielectric resonator 11. The filtered signal is coil 22
Is output to the load 2.

On the other hand, in the oscillation operation mode, the switch SW1 is turned off and the switch SW2 is turned on. At this time, in the oscillation loop circuit connected between the coils 23 and 24 and configured to satisfy the oscillation conditions described later in detail, an oscillation signal oscillating in the TE _01δ mode, which is the basic mode of the dielectric resonator 11, is generated. I do.

In the oscillation loop circuit, an oscillation signal output from the coil 24 includes a phase modulator 31, a phase shifter 32 having a transmission phase θs, an amplifier 33 having an amplification degree A, and ports 34a and 34b of a directional coupler 34. A transmission line connected between the directional coupler 35
A transmission line connected between the ports 35a and 35b of the
Output to the coil 23 via W2.

Here, as the modulation signal of the phase modulator 31, when the switch SW3 is switched to the a side, the low frequency signal Vs sinωst output from the low frequency signal generator 30 is switched.
The input to the phase modulator 31 via SW3, while the switch S
When W3 is switched to the b side, the ground potential is input to the phase modulator 31 via the switch SW3. The switching of the switches SW1, SW2, and SW3 is controlled by a microprocessor unit (hereinafter, referred to as an MPU) 50, which is a control device of the measurement device, as described later in detail. The transmission phase θs of the phase shifter 32 is set by the MPU 50.

A port 34d for detecting an oscillation signal which is a traveling wave passing through a transmission line between the ports 34a and 34b of the directional coupler 34
Is connected to a frequency counter 40, and a port 34c for detecting a reflected wave passing through the transmission line is terminated by a load 34e having a predetermined characteristic impedance. The frequency counter 40 measures the frequency of the oscillation signal detected at the port 34d, and outputs data fm of the measured frequency.
Output to MPU50.

Further, a port for detecting an oscillation signal which is a traveling wave passing through a transmission line between the ports 35a and 35b of the directional coupler 35.
35d is connected to the mixer 41, and a port 35c for detecting a reflected wave passing through the transmission line is terminated by a load 35e having a predetermined characteristic impedance. The oscillating signal detected at the port 35 is mixed with a local oscillating signal output from a local oscillator 42 in a mixer 41, and then the mixed signal is filtered by an intermediate frequency bandpass filter 34 to a predetermined frequency. Only the intermediate frequency signal is extracted, and the filtered intermediate frequency signal is subjected to FM detection by the FM detector 44. FM
The detector 44 outputs the signal after the FM detection to the AC voltage detector 45, and after the AC voltage detector 45 detects the AC voltage of the input signal, the peak value of the detected AC voltage, that is, 0
-Output the peak value data Va to the MPU 50.

The MPU 50 controls the measuring device to measure the resonance frequency f ₀ and the load Q of the dielectric band resonator 11, and a CPU (not shown).
A control program for controlling the measuring device and data necessary for executing the control program are stored.
ROM (not shown), RAM (not shown) used as a working memory of the CPU, and switches SW1, SW2, S
It includes an input / output port circuit (not shown) connected to W3, frequency counter 40, AC voltage detector 45, and CRT display 51 and operating as an interface circuit. this
The MPU 50 has the switches SW1, SW2, S
W3 is switched and controlled, and the transmission phase θs of the phase shifter 32 is set, the data fm of the frequency measured from the frequency counter 40 is received, and the AC voltage detected by the AC voltage detector 45 is further changed. Upon receiving the data Va, the resonance frequency f ₀ and the load Q (Q _L ) of the dielectric resonator 11 are calculated, and these data are displayed on the CRT display 51.

(2) Principle of Measuring Resonant Frequency and Load Q of Dielectric Resonator The oscillation condition in the oscillation loop circuit shown in FIG. 1 is expressed by the following equation.

Re (A · β) = 1 (2) Im (A · β) = 0 (3) where A is the amplification degree of the amplifier 33 and β is the feedback amount in the oscillation loop circuit. The above oscillation condition (2)
When (3) is satisfied, an oscillation signal is generated in the oscillation loop circuit.

Now, assuming that the transmission phase of the dielectric resonator 11 is θd and the transmission phase of the phase modulator 31 when the switch SW3 is switched to the b side is θp, the oscillation phase obtained from the equation (3) of the above oscillation condition is It is assumed that an oscillation signal is generated at the oscillation frequency fa when the following condition is satisfied: θd + θp + θst + θc = 2nπ (4) Here, the unit on both sides of the above equation (4) is radian, n is an integer, and θc is the device and transmission except the dielectric resonator 11, the phase modulator 31, and the phase shifter 32 in the oscillation loop circuit. This is the transmission phase of the line.

Next, when the switch SW3 is switched to the a side, a low frequency signal of Vs sinωst is input from the low frequency signal generator 30 to the phase modulator 31 as a modulation signal, and the oscillation signal is transmitted at the transmission phase θp ′ of the following equation. Is phase modulated.

.theta.p '=. theta.p + .DELTA..theta.p sin.omega.st (5) Hereinafter, for the sake of simplicity, when the low frequency signal has the maximum amplitude, that is, when .theta.p' =. theta.p + .DELTA..theta.p (6) Under the phase condition, θd ′ + θp ′ + θs ′ + θc ′ = 2nπ (7) It is assumed that the dielectric resonator 11 oscillates at the oscillation frequency fa ′. The terms on the left side of the above equation (7) are respectively represented by the above (4)
This is the transmission phase at the time of oscillation that satisfies Expression (6) in each device and transmission line corresponding to each term on the left side of the expression.

 Generally, the transmission phase θd of the resonator is expressed by the following equation.

Here, Q _L is the loaded Q of the resonator, f ₀ is the resonance frequency of the resonator. From the above equation (8), the following equation is obtained.

Therefore, from the equation (9), the transmission phase θd ′ of the dielectric resonator 11 at the time of oscillation when the low frequency signal has the maximum amplitude is obtained.
Is represented by the following equation.

In the above formula (10), the oscillation frequency fa is a dielectric resonator
Assuming that the resonance frequency is approximately equal to 11 resonance frequencies f ₀ , the following equation is obtained.

The transmission phase θc ′ at the time of oscillation when the low frequency signal has the maximum amplitude is expressed by the following equation.

here, far. Furthermore, in approximately 300MHz or more in the UHF band and a microwave band, the load Q _L of the dielectric resonator 11 is 50 to 100,00
0 and the transmission phase of the resonator during oscillation is approximately in the range of | cos θd |> 0.3, so that Δθd≫Δθs (15a) Δθd≫Δθc (15a)

The following equation is obtained by rewriting the above equation (7) using the amount of shift of the transmission phase of the oscillation signal in the case where the low-frequency signal has the maximum amplitude.

 (Θd + Δθd) + (θp + Δθp) + (θs + Δθs) + (θc + Δθc) = 2nπ (16) On the other hand, the following equation is obtained from the above equations (4) and (16).

Δθd + Δθp + Δθs + Δθc = 0 (17) Further. In the above equation (17), the above equation (15a), (15
b) Applying the condition of the formula, the following formula is obtained.

Δθd + Δθp ≒ 0 (18) From the above equation (18), a dielectric resonator satisfying the oscillation condition
It can be seen that the shift amount Δθd of the transmission phase 11 has substantially the same absolute value as the shift amount Δθp of the transmission phase of the phase shifter 32 and a sign different from the sign.

Further, the frequency deviation amount Δf of the oscillation signal can be expressed by the following equation.

Δf = fa′−fa (19) Further, as described above, the oscillation frequency fa becomes the resonance frequency f ₀
Assuming that it is approximately equal to: fa ′ = f ₀ + Δf (20)

Further, since the transmission phase θd of the dielectric resonator 11 becomes 0 at the time of resonance, the load Q (Q _L ) of the dielectric resonator 11 is obtained from the above equations (8), (18) and (20). Is represented by the following equation.

In addition, the oscillation signal has the predetermined transmission phase shift amount Δθp.
When the signal is modulated by the phase modulator 31, the oscillation signal in the oscillation loop circuit is FM-modulated by the frequency deviation Δf. Therefore, the frequency deviation Δ
f is expressed by the following equation using the peak value data Va of the AC voltage output from the FM detector 44.

Δf = αVa (22) where α is a device constant of the FM detector 44 that can be measured in advance.

Further, since the frequency deviation Δf of the oscillation signal is sufficiently smaller than the resonance frequency f ₀ , the load Q (Q _L ) of the dielectric resonator 11 can be expressed by the following equation from the above equation (21). .

The following equation is obtained by substituting the above equation (22) into the above equation (23).

Here, Δθp is the amount of shift of the transmission phase when a low-frequency signal is input to the phase modulator 31, and is a device constant that can be measured in advance by the phase modulator 31. Therefore, the above (2
In equation (4), only the resonance frequency f ₀ of the dielectric resonator 11 is unknown, but can be measured by the following procedure.

FIG. 3 is a graph showing the frequency characteristic of the transmission phase of the dielectric resonator 11. As apparent from Figure 3, the variation of the transmission phase of the dielectric resonator 11 to the oscillation frequency is found to be the maximum at the resonance frequency f _0. Therefore, in other words, in a case where the oscillation signal is phase-modulated with the predetermined transmission phase shift Δθp, when the oscillation frequency fa is equal to the resonance frequency f ₀ , the frequency shift Δf of the phase-modulated oscillation signal becomes the fourth shift. Minimum as shown in the figure, and
When the oscillation frequency fa is higher or lower than the resonance frequency f ₀ , the frequency deviation Δf of the oscillation signal becomes larger than that at the resonance frequency f ₀ as shown in FIGS. 5 and 6, respectively. That is, the frequency shift amount Δ of the oscillation signal
f has a minimum value at the resonance frequency f ₀ as shown in FIG.

Accordingly, since the frequency deviation Δf of the oscillation signal is proportional to the peak value Va of the AC voltage after FM detection as shown in the above equation (22), the oscillation signal is phase-shifted by a predetermined transmission phase deviation Δp. The transmission phase θ of the phase shifter 32 is modulated so as to minimize the output Va while measuring the output Va of the AC voltage detector 45.
Change s. After setting the transmission phase shift amount θs when the output Va of the AC voltage detector 45 becomes minimum to the phase shifter 32, the switch SW3 is switched to the b side, and the oscillation signal is phase-shifted by the phase modulator 31. the frequency of the oscillation signal when no modulation measured at a frequency counter 40 and the measured frequency and the resonance frequency f ₀ of the dielectric resonator 11.

The measured resonance frequency f ₀ and the AC voltage detector
The minimum value of the output Va of 45, by substituting in (24), it is possible to calculate the load Q of the dielectric resonator 11 (Q _L).

(3) Measurement Flow of Measurement Apparatus FIG. 8 is a flowchart showing a main routine of a measurement flow in the measurement operation mode of the measurement apparatus of FIG. 1. The measurement flow of the measurement apparatus will be described with reference to FIG. .

First, in step # 1, the switch SW1 is turned off, the switch SW2 is turned on, and the switch SW3 is turned on.
Is switched to the b side, and the measuring apparatus is set to the non-modulation measuring operation mode. In step # 2, the transmission phase shift θs of the phase shifter 32 is set to a predetermined initial value θs at which oscillation can be performed in the oscillation loop circuit. In the oscillation loop circuit, the dielectric resonator 11 is set to TE in the fundamental mode.
Oscillate in _01δ mode to generate an oscillation signal.

Next, in step # 3, the switch SW3 is switched to the a side, the low-frequency signal output from the low-frequency signal generator 30 is input to the phase modulator 31, and the oscillation signal is converted into a predetermined transmission phase shift amount. Phase modulation is performed by Δθp.

Further, in step # 4, a process of detecting the transmission phase θs of the phase shifter 32 at which the AC voltage Va output from the AC voltage detector 45 becomes minimum and the minimum value of the AC voltage Va at that time is performed. That is, as described above, the AC voltage detector
While measuring the output Va of the AC voltage detector 45, the transmission phase θs of the phase shifter 32 is changed so that the output Va is minimized. The phase θs is set as the transmission phase of the phase shifter 32, and the minimum value of the AC voltage Va is stored in the RAM in the MPU 50.

Next, in step # 5, the switch SW3 is switched to the b side to put the oscillation signal in a non-modulated state.
The frequency fm of the oscillator signal is measured by the frequency counter 40 at 6, to the measured oscillation frequency fm and a resonance frequency f ₀ of the dielectric resonator 11. Further, Step # 7
In the above, by substituting the minimum value of the AC voltage Va obtained in step # 4 and the resonance frequency f ₀ measured in step # 6 into the above equation (24),
Calculate the eleven load Q (Q _L ).

Finally, in step # 8, the switch SW2 is turned off and the switch SW1 is turned on, so that the measuring device is set to the filtering operation mode, and the measuring process is completed.

FIG. 9 is a flowchart showing a subroutine of a phase shift amount detection process of the phase shifter in which the AC voltage Va in FIG. 8 is minimized. Hereinafter, the operation of this subroutine will be described with reference to FIG.

First, in step # 101, it sets the change amount .DELTA..theta.s the transmission phase of the phase shifter 32 to a predetermined initial value .DELTA..theta.s _0. Further, in the measuring apparatus of the present embodiment, the following step # 10
When the difference between the measured values of the two AC voltages Va measured continuously in step 5 becomes smaller than a predetermined voltage difference threshold ΔVa, it is determined that the AC voltage Va has become the minimum value. In step # 101, for example, the threshold value ΔVa of the difference is preferably set to a predetermined value that is preferably the minimum resolution that can be measured by the AC voltage detector 45.

Then, at step # 102, the AC voltage Va after the FM detection of the oscillation signal from the AC voltage detector 45 captures the data, stored as alternating voltages V ₁ in the RAM in the MPU 50. Further, in step # 103, the sum of the transmission phase θs of the phase shifter 32 set in step # 2 of the main routine of FIG. 8 and the variation Δθs set in step # 101 is calculated. The obtained sum is set as a new transmission phase θs in the phase shifter 32.

Then, at step # 104, captures data similarly alternating voltage Va to step # 102, stored in the RAM in the MPU data as the AC voltage V _2, at step # 105, the AC voltage V ₂ and V ₁ It is determined whether or not the difference is smaller than the threshold value ΔVa of the voltage difference set in step # 101. When the absolute value | V ₂ −V ₁ | is smaller than the threshold value ΔVa, the AC voltage V ₂ is substantially equal to the minimum value of the AC voltage value, that is, in the oscillation loop circuit, the oscillation signal causes the resonance of the dielectric resonator 11. it is determined that oscillates at substantially equal oscillation frequency to the frequency f _0, the flow returns to the main routine.
In the main routine of this embodiment, as the AC voltage V ₂ is the minimum value of the AC voltage, it is used in the calculation of the load Q (Q _L) in step # 7.

On the other hand, in step # 105, when the absolute value | V ₂ −V ₁ | is equal to or greater than the threshold value ΔVa, step #
AC voltage V ₂ to determine whether less than AC voltages V ₁ at 106. Here, when the AC voltage V ₂ is small AC voltage V _1, shift amount Δf of the frequency of the oscillation signal in the direction of arrow A ₁₁ or A ₁₂ in Figure 7 is changed, i.e. the oscillation of the oscillation signal by the change It is determined that the frequency has changed in the direction toward the resonance frequency f ₀ , and in step # 107, the set change amount Δθs of the transmission phase is divided by 2 and the quotient is set as a new change amount Δθs. move on. On the other hand, when the AC voltage V ₂ is the or greater equal AC voltages V _1, shift amount Δf of the frequency of the direction to the oscillation signal of the arrow A ₂₁ or A ₂₂ in Figure 7 is changed, i.e. the oscillation signal by the change Is determined to have changed in a direction away from the resonance frequency f _0, the sign of the set change amount Δθs of the transmission phase is inverted in step # 108, and the change amount is set as a new change amount Δθs. Go to 109.

In step # 109, and updates the alternating voltages V ₁ as an alternating voltage V ₂ and the amount of change in the set transmission phase θs and step # 107 or set in # 108 permeate phase Δ
The phase shifter 32 updates the sum with θs as a new transmission phase θs.
Set to. Further, returning to step # 104, steps # 104 to # 1 are performed until the absolute value | V ₂ −V ₁ | becomes smaller than the predetermined threshold value ΔVa, that is, until the minimum value of the AC voltage Va is detected.
The processing up to 09 is repeated.

(4) Other Embodiments In the above embodiments, the measurement method and the measurement device for measuring the resonance frequency and the load Q of the dielectric resonator 11 have been described. However, the present invention is not limited to this, and the cavity resonator is not limited thereto. , And other types of resonators such as a semi-coaxial resonator.

Although the phase modulator 31 is used in the above embodiments, the present invention is not limited to this, and a frequency modulator may be used.

[Effects of the Invention] As described above in detail, according to the present invention, the phase shift amount of the phase shift means of the oscillation loop circuit is not based on the frequency spectrum characteristic of the resonator measured by the frequency sweep signal as in the conventional example. Is changed to detect the minimum value of the detected AC signal level, and measure the oscillation frequency of the unmodulated oscillation signal when the minimum value of the AC signal level is detected as the resonance frequency of the resonator. Further, since the load Q of the resonator is measured based on the measured resonance frequency, the resonance frequency and the load Q of the resonator can be automatically measured using an inexpensive device as compared with the conventional example. There is an advantage that can be.

[Brief description of the drawings]

FIG. 1 is a block diagram of an apparatus for measuring the resonance frequency and load Q of a dielectric resonator according to one embodiment of the present invention. FIG. 2 is a longitudinal section of the dielectric resonator of FIG. 1 and a shield case accommodating the same. FIG. 3, FIG. 4, FIG. 5, FIG. 6, and FIG. 6 are graphs showing the frequency characteristics of the transmission phase of the dielectric resonator, and FIG. 8 is a graph showing a frequency shift amount of an oscillation signal with respect to an oscillation frequency when phase modulation is performed with a phase shift amount Δθp; FIG. 8 is a flowchart showing a main routine of a measurement flow in a measurement operation mode of the measurement apparatus in FIG. 1; FIG. 9 is a flowchart showing a subroutine for detecting a transmission phase of the phase shifter in which the AC voltage is minimized in FIG. 8, and FIG. 10 is a block showing a conventional method of measuring the resonance frequency and load Q of the dielectric resonator. It is a figure . 11: Dielectric resonator, 23, 24: Coil, 30: Low frequency signal generator, 31: Phase modulator, 32: Phase shifter, 33: Amplifier, 34, 35: Directivity Coupler, 40: Frequency counter, 44: FM detector, 45: AC voltage detector, 50: Microprocessor unit (MPU), SW2, SW3: Switch.

Claims (4)

(57) [Claims] 1. A resonator to be measured, amplifying means for amplifying an oscillation signal, phase shifting means for shifting the oscillation signal by a predetermined phase shift amount, and a predetermined transmission phase for the oscillation signal by an AC signal. The resonator is oscillated in a predetermined fundamental mode using an oscillation loop circuit having phase modulation means for performing phase modulation with a deviation amount of the phase shift means, and an oscillation signal generated in the oscillation loop circuit is phase-modulated by the phase modulation means. Detecting the phase-modulated oscillation signal, detecting the minimum value of the level of the detected AC signal by changing the phase shift amount of the phase shifting means, and detecting the minimum value of the level of the AC signal. Measuring the oscillation frequency of the unmodulated oscillation signal at the time as the resonance frequency of the resonator. 2. The method for measuring the number of resonance fields of a resonator according to claim 1, further comprising the steps of:
A resonance Q is calculated based on a shift amount of a transmission phase of the oscillation signal in the phase modulation means and a minimum value of a level of the detected AC signal. How to measure the load Q of the vessel. 3. A resonator to be measured, amplifying means for amplifying an oscillation signal, phase shifting means for shifting the oscillation signal by a predetermined amount of phase shift, and a predetermined transmission phase of the oscillation signal by an AC signal. An oscillation loop circuit that includes a phase modulation unit that performs phase modulation with a deviation amount of the oscillation loop circuit that generates a phase-modulated oscillation signal in a predetermined basic mode; a detection unit that detects the phase-modulated oscillation signal; and the detection unit. Detecting means for detecting the level of the AC signal detected by the detecting means, frequency measuring means for measuring the oscillation frequency of the oscillation signal, and changing the phase shift amount of the phase shifting means and detecting the AC signal detected by the detecting means. Control means for detecting the minimum value of the level, wherein the oscillation of the unmodulated oscillation signal measured by the frequency measurement means when the level of the detected AC signal becomes the minimum value Measuring device resonant frequency of the resonator, characterized in that to measure the wave number as the resonant frequency of the resonator. 4. The apparatus for measuring a resonance frequency of a resonator according to claim 3, further comprising: a resonance frequency measured by said frequency measurement means; and a shift amount of a transmission phase of said oscillation signal in said phase modulation means. And a calculating means for calculating the load Q of the dielectric resonator based on the minimum value of the level of the AC signal detected by the control means.