KR100943678B1 - Multi-frequency dielectric resonator oscillator - Google Patents

Abstract

The present invention provides a dielectric resonator oscillator (DR), in particular a transmission device, which may have multiple oscillation frequencies. The oscillator may use two interfering conductors 30, 31 that are switched to or may not form a metal plane close to the dielectric resonator DR, so that the frequency of the oscillator may be varied even with a single resonator. The interference conductors 30, 31 are located in the cavity CAV close to the resonator DR, and switching means may electrically connect or open the interference conductors 30, 31.

Description

MULTI-FREQUENCY DIELECTRIC RESONATOR OSCILLATOR}

1A and 1B are circuit block diagrams of a dielectric resonator oscillator.

2 is a resonator assembly according to the prior art.

3 to 5 are detailed views of the dielectric resonator assembly according to the present invention, viewed in different directions and phases.

6 shows an improvement of the assembly of FIGS. 3 to 5;

7 illustrates a variant of the present invention.

<Explanation of symbols for the main parts of the drawings>

10, 20: substrate 30, 31, 41, 42: interference conductor

40, 50: screw

FIELD OF THE INVENTION The present invention relates to multi-frequency dielectric resonator oscillators, and more particularly to oscillators operating at microwave frequencies.

Microwave oscillators are used in close proximity to transmission systems, in particular antennas, to perform frequency transposition between the intermediate frequency band and the transmission frequency band. Frequency crossing uses two units, one generally located inside the building, while the other outside is located adjacent to the antenna. Internal and external units are linked using, for example, electrical conductors such as coaxial gables, which result in a large loss when a transmission frequency greater than 10 GHz is used, for example.

Communications systems use increasing high transmission frequencies and increasing wide frequency bands. Single frequency crossing involves the use of a wider band for intermediate frequencies by the transmission frequency. However, the use of intermediate frequency bandwidths greater than GHz has implementation issues. This is because the losses in the coaxial cable connecting the internal and external units vary considerably for the intermediate frequency bandwidth. In addition, it is expensive to build a frequency synthesizer that can provide agility in terms of the frequencies needed to scan very wide intermediate frequency bands.

In order to obtain an intermediate frequency band narrower than the transmission band, it is possible to segment the transmission band before crossing. This division can be done by using several switched oscillators in the external unit. Depending on the oscillator selected, the intermediate frequency band receives only a portion of the transmission band, which portion corresponds to the selected frequency.

Dielectric resonator oscillators are commonly used in external transmission system units. Dielectric resonators are commonly used in feedback loops, for example, as shown in either FIG. 1A or 1B. Coupling between the dielectric resonator DR and the electrical circuit is produced by bringing the dielectric resonator DR and the conductor CL of the electrical circuit close to each other, the conductor being for example a microstrip line. to be. The position of the dielectric resonator directly affects the degree of coupling, the output power of the oscillator, the frequency stability and the oscillator frequency.

The oscillation frequency of the dielectric resonator oscillator depends on the size of the oscillator and the electromagnetic characteristics around it. To control this element, the resonator is located in a screened cavity through which the conductor passes. 2 shows an embodiment of this kind, in which the microstrip line CL passes through a screened cavity CAV with a dielectric resonator DR therein. The resonator DR is held in the cavity CAV by a spacer (not shown). For further details of fabricating dielectric resonator oscillators, those skilled in the art can refer to the "Dielectric Resonator" (second edition), published by Darko Kajfez and Pierre Guillon and published in 1998 by Noble Publishing Corporation. will be.

A known solution for obtaining multiple frequencies from a dielectric resonator oscillator is to use multiple oscillators and switch their outputs. Increasing the number of oscillators, however, increases the size of the circuit located in the external unit.

It is an object of the present invention to reduce the size of the external unit using several crossover frequencies. To this end, the present invention provides a dielectric resonator oscillator in which the oscillation frequency can take several values. In order to change the frequency of the oscillator while using a single resonator, the device of the present invention uses an interfering conductor which is located in close proximity to the dielectric resonator and is switched, wherein the interfering conductor is formed of two separate conductors or metal planes. Play a role.

The present invention is an oscillator circuit comprising a dielectric resonator located proximate to a coupling conductor providing coupling with the rest of the oscillator circuit, wherein the resonator and the coupling conductor are located in a cavity. The oscillating circuit includes at least a pair of interfering conductors located inside the resonance, close to the resonator. The switching means may or may not establish an electrical connection between the interfering conductors.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention will be better understood upon reading the following description with reference to the accompanying drawings, where other specific features and advantages will become apparent.

As noted above, FIGS. 1A and 1B show a dielectric resonator oscillator circuit. Such an oscillator circuit may be used with the present invention, or may be used with other known circuits in which the frequency of the oscillator is determined only by the resonator DR and its surroundings.

3 shows a perspective view of an assembly of a dielectric resonator DR proximate the conducting line CL of one of the oscillator circuits of either FIG. 1A or 1B. 4 is a side view of the assembly.

A screened cavity (CAV) surrounds the resonator DR to insulate the resonator from external electromagnetic interference. The cavity CAV consists of, for example, a metal cover connected to ground. Substrate 10 closes the screened cavity CAV. The substrate 10 includes a conductor CL formed on a surface located inside the cavity CAV, for example, using a microstrip line. In the face of the substrate 10 located outside of the cavity, an earth plane provides electromagnetic sealing. Holes 15 located on either side of the cavity CAV allow the conductor CL to pass through. The substrate 10 extends beyond the cavity and supports the rest of the oscillator circuit.

The second substrate 20 is held inside the cavity CAV, for example, by adhesion bonding. The resonator DR is attached and bonded to one surface of the second substrate 20. In order to ensure coupling between the resonator DR and the conductor CL in accordance with known techniques, the resonator DR is positioned on the second substrate 20, which is in the cavity CAV. Located.

The second substrate 20 includes two interfering conductors 30, 31 on opposite sides of the resonator. The interfering conductors 30, 31 can be made, for example, of printed lines. In order to prevent parasitic coupling between the interference conductors 30 and 31 and the conductors CL, the interference conductors 30 and 31 are preferably oriented along the plane, perpendicular to the conductors CL. . The magnetic field lines of the resonator DR are preferably perpendicular to the substrate in the second substrate 20.

5 shows an operational aspect of the present invention. The interference conductors 30, 31 are located symmetrically over the resonator DR. The length of the interference conductor is substantially equal to half of the wavelength of the lowest frequency desired to be obtained, which wavelength depends on the medium through which the wave propagates, i. E. The substrate described. The resonator DR should be centered with respect to the interference conductors 30 and 31. The interference conductors 30 and 31 are located on either side of the resonator DR so as not to cover most of the area of the resonator DR. In addition, the coupling of the interference conductors 30, 31 defines an area that is larger in size than that of the resonator DR.

The interference conductor 30 is connected to ground through the matching impedance Z1. The interference conductor 31 is connected to the control line through the matching impedance Z2. Matched impedances Z1 and Z2 serve as lowpass filters that short circuit the circuit at low frequencies and open the circuit at the frequency range generated by the oscillator. The interference conductors 30, 31 are preferably connected to one another in the middle, for example by means of a diode 33 of the PIN type. The control line may take two states depending on the first and second control states. Impedances Z1, Z2, diode 33 and control lines form a switching circuit located on second substrate 20.

In the first control state the control line is in a potential state in which the diode 33 is switched off. In the first control state the interference conductors 30, 31 are electrically independent. The magnetic field propagates through the second substrate to the upper surface of the cavity. Thus, the coupling of the magnetic field generated by the resonator DR is maximum between the interference conductors 30 and 31. The oscillation frequency corresponds to a low operating frequency whose value varies with the length and width of the interference conductor, the space between the interference conductor and the size of the cavity.

In the second control state the control line is in a voltage state sufficient for the diode 33 to energize. The diode 33 is switched on and the interference conductors 30, 31 are electrically connected. Thus, the two interfering conductors 30, 31 serve as interfering metal planes of width L. The interfering metal plane switches off the magnetic field of the resonator DR at a distance of substantially zero, corresponding to the thickness of the substrate. The oscillation frequency corresponds to the maximum frequency of the resonator DR. The potential between the interference conductors 30, 31 corresponds to the threshold voltage of the diode 33, but the change in potential at the oscillation frequency is the same at both interference conductors.

For example, a low frequency of 9 GHz and a high frequency of 10.9 GHz are achieved by coupling a dielectric resonator with a nominal frequency of 9.9 GHz and a microstrip line of 9.1 mm in length and 3.5 mm in width. You can get it.

In order to obtain different frequencies by the same resonator, it is possible to reduce the upper frequency by moving the plane in which the interference conductor is located. It is also possible to vary the size of the interference conductor to change the low frequency.

In order to reduce the design and dimensioning constraints of the device of the invention, it is possible to use adjusting screws. Figure 6 shows one possible way of positioning a screw that allows the upper and lower frequencies to be adjusted. The first screw 40 passes through the upper cavity CAV along the magnetic axis of the resonator DR. The second screw 50 passes through a cavity in the side wall perpendicular to the magnetic axis of the resonator DR, which is along the axis of the screw. The first and second screws provide independent adjustment of high and low frequencies.

In the second control state, the interference conductors 30, 31 form a metal plane above the resonator DR. The first screw 40 has no effect. The high frequency can be adjusted using the second screw 50.

In the first controlled state, the interfering conductors 30, 31 allow the magnetic field to pass through the top of the cavity forming a visible metal plane. The magnetic field is disturbed depending on the degree of insertion of the first screw, so that adjustment of the low frequency is possible.

The present invention also enables the manufacture of switched oscillators that can provide more than one frequency. 7 shows an embodiment in which a third substrate 39 is positioned over the second substrate 20. The third substrate 39 includes two interfering conductors 41 and 42 and a switching circuit similar to that shown in FIG. The interference conductors 41, 42 are parallel to the interference conductors 30, 31. The conductor 41 located above the interference conductor 30 is connected to ground. There are three operational possibilities depending on the various control states of the switching circuit.

According to the first state, the interference conductors 30 and 31 form a first metal plane corresponding to the high operating frequency. This state is independent of the conductors 41 and 42.

According to the second state, the conductors 30 and 31 are not electrically connected, and the conductors 41 and 42 form a metal plane at different distances from the resonator DR. This state corresponds to the intermediate operating frequency.

According to the third state, the conductors 30, 31, 41, 42 are independent of each other. This state corresponds to a low operating frequency.

By adding another substrate that supports other interfering conductors, different operating frequencies can be obtained. n + 1 operating frequencies can be obtained for n substrates.                     

Other embodiments are also possible.

This embodiment describes a substrate 20 which, on the one hand, supports the resonator DR, and on the other hand, the conductors 30, 31 which are produced using lines printed with copper. This is a simple and efficient solution. However, it is possible to fix the resonator by using a spacer different from the substrate. It is also possible to use a conductor other than the printed line, which is held in the cavity by any means. Similarly, conductors 30 and 31 need not be located in a plane perpendicular to the magnetic field coming from resonator DR. It is possible to obtain two different operating frequencies by switching two linear conductors, which may or may not produce a metal plane. It can be seen that the proposed embodiment is the simplest solution to implement.

Similarly, Figure 5 shows an interference conductor with a switching circuit. This circuit is matched according to the diode and the control voltage to be used. The low frequency characteristic of the impedance may be equivalent to a bias resistor that limits the current. In addition, connecting Z1 to ground as one option allows the diode to be switched off to a control voltage near zero volts. It goes without saying that other choices are possible. More generally, other types of switching circuits can be used if it is possible for the two interfering conductors to be electrically connected at least for high frequencies.

In the described embodiment, the cavity CAV is covered by the ground plane and closed by the substrate 10 supporting the conductor CL. As a variant, a closed metal cavity through which the conducting wire simply passes may be used.

In this specification the cavity is in the shape of a rectangle. However, other cavity shapes may be used, in particular, such as cylindrical cavities.

The present invention provides a dielectric resonator oscillator (DR), in particular a transmission device, which may have multiple oscillation frequencies. The oscillator may use two interfering conductors 30, 31 that are switched to or may not form a metal plane close to the dielectric resonator DR, so that the frequency of the oscillator may be varied even with a single resonator. By such a configuration, the present invention has the effect of obtaining a plurality of crossover frequencies without increasing the size of a circuit located in an external unit by increasing the number of oscillators.

Claims (8)

An oscillator circuit comprising a dielectric resonator DR positioned proximate to a coupling conductor CL, the coupling conductor CL providing coupling with the dielectric resonator DR, and coupled with the resonator DR. In the oscillator circuit, the coupling conductor CL is located inside the cavity CAV. At least a pair of interfering conductors 30, 31, 41, 42 located inside a cavity (CAV), in proximity to the resonator; A switching means 33, Z1, Z2, controller, which may or may not establish an electrical connection between the interference conductors 30, 31, The length of the interference conductors 30, 31, 41, 42 is equal to half the wavelength of the lowest frequency that the oscillator circuit can provide. An oscillator circuit, characterized in that. 2. An oscillator circuit according to claim 1, characterized in that the switching means (33, Z1, Z2, controller) comprise a diode (33) located between the interference conductors (30, 31). 3. A connection point according to claim 2, characterized in that the connection point between the diode (33) and each of the interference conductors (30, 31, 41, 42) is located at the center of each of the interference conductors (30, 31, 41, 42). Oscillator circuit. delete 4. The oscillator circuit according to any one of the preceding claims, wherein the oscillator circuit comprises a substrate (20) having surfaces facing each other, wherein the resonator (DR) is attached and bonded onto one of the facing surfaces, and the interference An oscillator circuit, characterized in that the conductors (30, 31, 41, 42) are fabricated on the other side of the opposing face using printed lines. 4. The coupling conductor (CL) and the interference conductors 30, 31, 41 and 42 are orthogonal and the interference conductors 30, 31, Oscillator circuit, characterized in that perpendicular to the coupling conductor (CL). 4. The oscillator circuit according to claim 1, wherein the oscillator circuit comprises a second pair of interference conductors 41, 42 located inside the cavity CAV, and a pair of second interference conductors 41, 42. And second switching means capable of switching the circuit. 4. The oscillator circuit according to claim 1, wherein each pair of the interference conductors 30, 31, 41, 42 is located in a plane perpendicular to the magnetic field emerging from the dielectric resonator. 5. .

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