JPH06268445A - Frequency modulator - Google Patents

Abstract

PURPOSE:To obtain a milliwave band frequency modulator which can be mounted on an automobile by providing a dielectric resonator so as to be adjacent to a varactor diode, and a modulation circuit which impresses a modulation signal to the electrode of the varactor diode. CONSTITUTION:The arbitrary oscillation frequency of 50-70GHz can be obtained by a Gunn diode 3 and a metallic strip resonator 5, and the output of an oscillator 22 is transmitted to a non-radiative dielectric line 7. This device is equipped with a modulation circuit 20, and a variable capacity diode 1 which is mounted on the dielectric line 7 and arranged along the dielectric line 7 in a non-contact state while a dielectric resonator 9 is made adjacent to it. The variable capacity diode 1 is an element whose electrostatic capacity is changed according to a voltage, and the resonance frequency of the resonator influence. Thus, the milliwave band frequency modulator frequency being the output of the oscillator 22 transmitted to the dielectric line 7 is changed and modulated under the influence. Thus, the milliwave band frequency modulator which can be mounted on the automobile can be obtained with a simple constitution.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention is used to generate a frequency modulation signal in the millimeter wave region. The present invention was developed for use in a proximity warning device, a collision prevention device, and other radars that use electromagnetic waves, which are installed in automobiles, but can also be used in other devices.

[0002]

2. Description of the Related Art It has been attempted to equip a vehicle with a proximity warning device for a preceding vehicle, a collision prevention device for warning an approaching object, and the like by a radar device utilizing an electromagnetic wave having an extremely high frequency. In recent years, it has been planned to allocate radio waves in the 60 GHz band to radar devices for automobiles.

A technique for an oscillator or an integrated circuit in this frequency band is disclosed by, for example, one of the inventors of the present application, "Yoneyama: Millimeter wave integrated circuit using non-radiative dielectric line,
IEICE Transactions CI, Vol J73-CI No3 pp87
-94 March 1990 ". In this document, 35G
There is a description about a Hz band oscillator, a power distributor, an antenna, and the like.

[0004]

Electromagnetic waves in the 60 GHz band have a wavelength of about 5 mm, and practical oscillators and modulators cannot be realized by simply downsizing conventional three-dimensional circuits and semiconductor integrated circuits.

The present invention has been made against such a background, and an object thereof is to realize an effective frequency modulator in the millimeter wave band with a simple structure. An object of the present invention is to realize a millimeter waveband frequency modulator that can be used by being mounted on an automobile.

[0006]

SUMMARY OF THE INVENTION The present invention is a frequency modulator, which is characterized in that a non-radiative dielectric line into which a carrier wave is introduced, and a non-radiative dielectric line in the propagation direction thereof. A non-contact variable capacitance diode, a dielectric resonator provided between the variable capacitance diode and the non-radiative dielectric line in proximity to the variable capacitance diode, and an electrode of the variable capacitance diode. And a modulation circuit for applying a modulation signal.

In this frequency modulation circuit, the carrier frequency can be selected to be 50 to 70 GHz.

The carrier wave is transmitted from an oscillator including a Gunn diode oscillation circuit and a resonator connected to an electrode of the Gunn diode and resonating at an oscillation frequency, and the variable capacitance diode is preferably a varactor diode.

It is desirable that a mode suppressor for suppressing a mode other than a mode propagating through the non-radiative dielectric line be inserted in a connection circuit between the resonator and the non-radiative dielectric line.

[0010]

The oscillation output generated from the Gunn diode resonates with the metal strip resonator and has an arbitrary oscillation frequency within 50 to 70 GHz. The oscillator output propagates in the non-radiative dielectric line. The modulator is one in which a dielectric resonator is placed close to a variable capacitance diode mounted on a non-radiative dielectric, and the dielectric resonator is installed along the non-radiative dielectric line in a non-contact manner. The variable capacitance diode is an element whose capacitance changes with voltage. The resonance frequency of the dielectric resonator changes due to the change. An electric field is generated around the dielectric resonator at this resonance frequency. This changes the propagation characteristics of the non-radiative dielectric waveguide. The frequency of the oscillator output propagating through the non-radiative dielectric line is affected by the resonance frequency change of the dielectric resonator, and the signal returned to the oscillator side due to the reflection of the dielectric resonator changes with the capacitance of the variable capacitance diode. As a result, the oscillation frequency of the output of the oscillator changes and is modulated. With this device, an effective frequency modulator in the millimeter wave band can be realized with a simple configuration.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure of an embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a block diagram of an apparatus according to an embodiment of the present invention. FIG. 2 is a perspective view of the device of the present invention. FIG. 3 is a configuration diagram of a varactor diode mount.

The present invention is a frequency modulator. The feature of the present invention resides in that, as a non-radiative dielectric line into which a carrier wave is introduced, a tetrafluoroethylene resin piece 7 and the tetrafluoroethylene resin piece 7 are provided. Varactor diode 1 as a variable capacitance diode provided in a non-contact manner along the propagation direction
And a dielectric resonator 9 provided between the varactor diode 1 and the tetrafluoroethylene resin piece 7 and adjacent to the varactor diode 1, and the varactor diode 1
And a modulation circuit 20 for applying a modulation signal to the electrodes of the. This frequency modulation circuit has a carrier frequency of 5
It is 0 to 70 GHz.

The carrier wave is transmitted from an oscillator 22 including a Gunn diode mount 4 as a Gunn diode oscillation circuit and a metal strip resonator 5 as a resonator which is connected to an electrode of the Gunn diode 3 and resonates at an oscillation frequency.

In the connection circuit between the metal strip resonator 5 and the tetrafluoroethylene resin piece 7, the tetrafluoroethylene resin piece 7 is provided.
A mode suppressor 6 that suppresses a mode other than the mode that propagates is transmitted.

Next, the operation of the apparatus of the present invention will be described with reference to FIG. Figure 3 shows the varactor diode mount 2
FIG. As shown in FIG. 3, the varactor diode 1 is mounted on the tetrafluoroethylene resin plate 14 with the copper foil 13. By applying a modulation signal to the electrodes of the varactor diode mount 2 by the modulation circuit 20, the dielectric resonance close to the varactor diode mount 2 via the high dielectric constant plate 8 as shown in FIGS. 1 and 2. The resonance frequency of the container 9 changes. The oscillation frequency propagating through the tetrafluoroethylene resin piece 7 is affected by the resonance of the dielectric resonator 9, and the oscillator 2 is reflected by the dielectric resonator 9.
The signal returning to the 2 side changes with the capacitance of the variable capacitance diode. As a result, the oscillation frequency of the output of the oscillator 22 is changed and modulated.

The high dielectric constant plate 8 is inserted to improve impedance matching with the varactor diode mount 2.

Next, the configuration for measuring the operating characteristics of the embodiment of the present invention will be described with reference to FIG. FIG. 4 is a diagram showing a configuration for measuring operating characteristics. By inserting the tetrafluoroethylene resin piece 7 of the device of the embodiment of the present invention into the conversion horn 11, the conversion horn 11 operates as an antenna. The signal under measurement input to the directional coupler 32 via the attenuator 30 is branched and output to the spectrum analyzer. Other measured signals are further input to the EH tuner 34 and the power meter 36.

Next, the frequency characteristics of the apparatus of the present invention will be described using the configuration for measuring the operation characteristics shown in FIG.
FIG. 5 is a diagram showing frequency characteristics of the device of the present invention.
The horizontal axis represents the varactor diode bias voltage, and the vertical axis represents the frequency modulation width. Using the apparatus of the present invention, it is almost linear over about 0 to 80 MHz, and the output is 100
A frequency modulated signal of mW was obtained.

Next, other characteristics of the apparatus according to the present invention will be described with reference to FIGS. FIG. 6 shows the distance L between the mode suppressor 6 and the dielectric resonator 9 and VSWR (Voltage
It is a figure which shows the relationship between a Standing Wave Ratio) and a resonance frequency. FIG. 7 is a diagram showing the distance L between the mode suppressor 6 and the dielectric resonator 9 and the probe position used for measurement. The horizontal axis represents the distance L, and the vertical axis represents VSWR and the resonance frequency. The solid line is the value measured by inserting the tip of the tetrafluoroethylene resin piece 7 into the conversion horn 11, and the alternate long and short dash line is the value measured by the probe provided at the position shown in FIG. It can be seen that the distance L is preferably about 0.4 mm when measured with the conversion horn 11, and the distance L is preferably about 0.8 mm when measured at the probe position.

FIG. 8 is a diagram showing the relationship between the distance g1 between the dielectric resonator 9 and the mode suppressor 6 and the frequency modulation width. The horizontal axis shows the distance g1 and the vertical axis shows the frequency modulation width. It can be seen that the distance g1 is preferably about 0.5 mm.

FIG. 9 shows the dielectric resonator 9 described in the explanation of FIG.
FIG. 11 is a diagram showing a distance g1 between the mode suppressor 6 and and a distance g2 between the high dielectric constant plate 8 and the dielectric resonator 9 described in FIG.

FIG. 10 is a diagram showing the relationship between the distance g2 between the high dielectric constant plate 8 and the dielectric resonator 9 and the frequency modulation width. The horizontal axis represents the distance g2, and the vertical axis represents the frequency modulation width. The shorter the distance g2, the larger the frequency modulation width.

FIG. 11 is a diagram showing the relationship between the thickness t of the high dielectric constant plate 8 and the frequency modulation width. The horizontal axis represents the thickness t, and the vertical axis represents the frequency modulation width. The high dielectric constant plate 8 has a thickness of 0.0
It turns out that about 5 mm is preferable.

[0024]

As described above, according to the present invention, an effective frequency modulator in the millimeter wave band can be realized with a simple structure. It is possible to realize a millimeter-wave frequency modulator that can be mounted on a vehicle and used.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an apparatus according to an embodiment of the present invention.

FIG. 2 is a perspective view of an apparatus according to an embodiment of the present invention.

FIG. 3 is a diagram showing a varactor diode mount.

FIG. 4 is a diagram showing a configuration for measuring operating characteristics.

FIG. 5 is a diagram showing frequency characteristics of the device according to the embodiment of the present invention.

FIG. 6 is the distance between the mode suppressor and the dielectric resonator and V
The figure which shows the relationship with SWR and a resonance frequency.

FIG. 7 is a diagram showing a distance between a mode suppressor and a dielectric resonator and a probe position used for measurement.

FIG. 8 is a diagram showing a relationship between a distance between a mode suppressor and a dielectric resonator and a frequency modulation width.

FIG. 9 is a diagram showing a distance between a mode suppressor and a dielectric resonator and a distance between a high dielectric constant plate and a mode suppressor.

FIG. 10 is a diagram showing the relationship between the distance between the high dielectric constant plate and the mode suppressor and the frequency modulation width.

FIG. 11 is a diagram showing the relationship between the thickness of the high dielectric constant plate and the frequency modulation width.

[Explanation of symbols]

 1 Varactor diode 2 Dullactor diode mount 3 Gunn diode 4 Gunn diode mount 5 Metal strip resonator 6 Mode suppressor 7 Tetrafluoroethylene resin piece 8 High dielectric constant plate 9 Dielectric resonator 10 Aluminum plate 11 Conversion horn 13 Copper foil 14 Polytetrafluoroethylene resin plate 20 Modulation circuit 22 Oscillator 30 Attenuator 32 Directional coupler 34 EH tuner 36 Power meter

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location // G01S 7/282 Z 8940-5J

Claims (1)

[Claims] 1. A non-radiative dielectric line into which a carrier wave is introduced, a variable capacitance diode provided in the non-radiative dielectric line in a non-contact manner along the propagation direction thereof, the variable capacitance diode and the non-radiative dielectric line. A frequency modulator comprising: a dielectric resonator provided between the variable capacitance diode and adjacent to the body line; and a modulation circuit for applying a modulation signal to an electrode of the variable capacitance diode.