KR20080088120A - Tunable rf using slot and rf filter tuning device - Google Patents

Abstract

A tunable RF(Radio Frequency) filter using a slot and an RF filter tuning device are provided to implement individual tuning for a plurality of tuning bars and effective broadband-tuning with one motor. A tunable RF filter includes a motor, a tuning slide, a plurality of tuning bars(500,512), and a resonator. The tuning slide is slid by driving the motor. The tuning bars move vertically by interlocking with sliding of the tuning slide. The resonator is provided in each cavity by being connected to the tuning bars. The tuning slide includes a plurality of slots(510,502) and a hole. The slots suspend the tuning bars. The hole through which the tuning bars pass prevents the tuning bar from being moved in a sliding direction.

Description

Tunable RF Using Slot and RF Filter Tuning Device

1 is a view showing the appearance of a cavity filter of a conventional RF filter.

2 is a cross-sectional view of one of the plurality of cavities provided in the conventional RF cavity filter.

3 is a circuit diagram of an RF filter;

Figure 4 is a perspective view showing the configuration of a tunable filter using a slot according to an embodiment of the present invention.

5 illustrates a cross-sectional view of a tunable RF filter according to an embodiment of the present invention.

6 illustrates a housing structure of a tunable RF filter according to an embodiment of the present invention.

7 illustrates an equivalent circuit configuration of a tunable RF filter according to an embodiment of the present invention.

The present invention relates to an RF filter, and more particularly, to an RF filter suitable for wideband tuning.

The RF filter is a device for passing only a signal of a specific frequency band among input frequency signals, and has been implemented in various formats. The band pass frequency of the RF filter is determined by the inductance component and the capacitance component of the filter, and the operation of adjusting the band pass frequency of the filter is called tuning.

1 is a view showing the appearance of the cavity filter of the conventional RF filter.

Referring to FIG. 1, a housing of a conventional RF cavity filter is provided with an input connector 100 and an output connector 102, and the housing of the RF cavity filter is generally rectangular parallelepiped.

An RF signal is input to the input connector 100, and only a signal of a frequency band preset by the filter among the input RF signals is output through the output connector.

A plurality of cavities are provided inside the RF cavity filter, and each cavity is provided with a resonator. Typically, in the case of TE mode resonance, a dielectric material resonator is provided, and in the case of TM mode resonance, a metal material resonator is provided.

The upper housing of the RF cavity filter is provided with a plurality of tuning screws 104. The tuning screw is used to adjust the band pass frequency of the filter. The tuning screw is inserted into the RF filter, and the depth of the tuning screw can be adjusted by rotating the screw.

The band pass frequency of the RF filter depends on the depth into which the tuning screw is inserted.

Referring to FIGS. 2 and 3, the principle of band pass frequency tuning in the RF cavity filter by the tuning screw will be described.

FIG. 2 is a cross-sectional view of one cavity among a plurality of cavities included in a conventional RF cavity filter, and FIG. 3 is a circuit diagram of an RF filter.

Referring to FIG. 2, a tuning screw 200 is inserted into each cavity, and a resonator 202 is coupled to a lower portion of the cavity. As shown in FIG. 2, a capacitance 204 is formed between the tuning screw 200 and the resonator 202 inserted into the cavity, and the capacitance 204 is a distance between the tuning screw 200 and the resonator 202. It depends on.

Typically, the capacitance is defined as Equation 1 below, and as the distance between the tuning screw and the resonator decreases, the capacitance value increases.

Is the permittivity, A is the cross-sectional area, and d is the distance.

Referring to FIG. 3, the band pass frequency of the filter is determined by the values of the inductors L1, L2, L3 and capacitors C1, C2, C3 connected in parallel, and the resonance frequency of the filter is represented by Equation 2 below. Is determined.

The RF cavity filter can adjust the capacitance value by adjusting the distance between the tuning screw 200 and the resonator 202, and it can be seen that the resonance frequency of the filter is adjusted when the capacitance value is changed by Equation 2 below. have.

In the conventional case, frequency tuning has generally been achieved by manually rotating the tuning screw or by using a tuning device using a motor. When the tuning screw was rotated manually or by using a motor, tuning was performed while checking the waveform through a waveform analyzer. When tuning by a motor, all tuning screws were tuned in a batch.

Therefore, the conventional frequency tuning not only requires considerable time and manpower consumption, but also individual tuning is difficult because all tuning skews are collectively tuned, which also makes broadband tuning difficult.

In the present invention, to solve the problems of the prior art as described above is to propose an RF filter that can be tuned with easier operation.

Another object of the present invention is to propose an RF filter that can be individually tuned for each resonator.

Another object of the present invention is to propose an RF filter suitable for wideband tuning.

Other objects of the present invention will be understood by those skilled in the art through the following examples.

In order to achieve the object as described above, according to a preferred embodiment of the present invention, a plurality of tuning bar and the plurality of tuning bar that moves up and down in conjunction with the sliding of the tuning slide sliding by the drive of the motor motor A tunable RF filter using a slot is provided that includes a resonator provided in each cavity in association with a tuning bar.

The tuning slide includes a plurality of slots for engaging the tuning bar and holes for preventing the tuning bar from penetrating and moving in the sliding direction, and the tuning bar is formed with at least one protrusion for engaging the slot.

Each of the plurality of slots is preferably formed in an inclined shape,

The inclination of each of the plurality of slots is preferably formed differently.

The inclination of each of the plurality of slots may be set by an initial length between the tuning bar and the resonator.

The RF filter may further include a main housing through which the tuning bar penetrates, a main housing for closing the resonator and the cavity, and a sub housing including the tuning slide and the motor.

On the other hand, according to another aspect of the present invention, the motor includes a tuning slide sliding by the drive of the motor and a plurality of tuning bars moving up and down in conjunction with the sliding of the tuning slide, the tuning slide is a plurality of the plurality of tuning bars for the tuning bar; And a hole for preventing the slot and the tuning bar from penetrating and moving in the sliding direction, wherein the tuning bar is provided with an RF filter tuning device in which at least one protrusion is formed to span the slot.

Hereinafter, exemplary embodiments of a tunable RF filter using a slot according to the present invention will be described in detail with reference to the accompanying drawings.

4 is a perspective view showing the configuration of a tunable filter using a slot according to an embodiment of the present invention.

4, a tunable filter using a slot according to an embodiment of the present invention is a motor 400, a shaft 402, a tuning slide 404, a plurality of tuning bars 406, a resonator 408, The cavity 410 and the input / output ports 412 and 414 may be included.

Referring to FIG. 4, the configuration and operation of a tunable filter according to an embodiment of the present invention are as follows.

The motor 400 functions to provide a driving force for the mechanical tuning of the RF filter. The motor 400 performs a rotational movement, and the rotational movement of the motor acts as a driving force for the tuning slide 404 to move. According to one embodiment of the present invention, a step motor whose rotation degree is determined according to a pulse may be used.

The shaft 402 is coupled to the motor 400 and the tuning slide 404, and coupled to the tuning slide 404 in the form of a screw engagement such that the rotational movement of the motor 400 acts as a linear movement of the tuning slide 404. The driving force of the motor 400 is provided to the tuning slide 404.

The tuning slide 404 performs a sliding movement left and right by a driving force transmitted by the shaft 402. The sliding direction of the tuning slide 404 is determined by the rotation direction of the motor, and the degree of sliding is determined by the rotation angle of the motor.

The tuning slide 404 is formed with a plurality of holes 420 corresponding to the number of tuning bars 406 and resonators 408. In addition, the tuning slide 404 is formed with a plurality of slots 422 corresponding to the number of the tuning bar 406 and the resonator 408 so that the tuning bar 406 can span the tuning slide.

The slot 422 is formed to be inclined at an angle, and the side of the tuning bar 406 is inserted into the slot to form a protrusion for the tuning bar 406 to engage the slot.

Since the slot 422 is formed in an inclined shape, when the tuning slide 404 is slid left and right, the tuning bar 406 across the slot 422 is raised in accordance with the sliding operation of the tuning slide 404. Perform the motion of moving up and down.

5 is a cross-sectional view of a tunable RF filter according to an embodiment of the present invention.

Referring to FIG. 5, an operation of moving the tuning bar up and down according to the slide lamp operation of the tuning slide will be described in more detail.

Referring to FIG. 5, a first tuning bar 500 is spanned by a first slot 510 and a second tuning bar 512 is spanned by a second slot 502.

In FIG. 5, when the tuning slide is slid, since the slot is formed in an inclined shape, the position at which the tuning bar spans the slot is changed according to the sliding of the tuning slide, thereby changing the height of the tuning bar.

In FIG. 5, the first tuning bar 500 spans the first slot 502 at position B. FIG. At this time, when the tuning slide is slid to the left, the first tuning bar 500 will be changed to a shape that spans the slot at the position C. When the first tuning bar 500 spans the first slot 502 at position C, the first tuning bar 500 is lowered as a result of the movement of the tuning slide.

On the contrary, when the tuning slide is slid to the right, the first tuning bar 500 is changed to a shape that spans the slot at position A, and thus the first tuning bar is raised.

That is, the horizontal motion of the tuning slide can be converted into the vertical motion of the tuning bar by inclining the slots to which the tuning bars are coupled.

In this case, the hole 420 formed in the tuning slide 404 serves to fix the position on the horizontal surface of the tuning bar when the tuning slide 404 slides.

Although not shown in FIG. 4, each cavity provided with a resonator and a tuning bar should be closed at the top. Therefore, an upper cover is formed in the lower part of the tuning slide to seal the upper part of the RF filter, and in this case, a hole into which the tuning bar is inserted is formed in the upper cover so that the tuning bar can be freely moved up and down as the tuning slide slides. do.

6 is a diagram illustrating a housing structure of a tunable RF filter according to an embodiment of the present invention.

Referring to FIG. 6, a housing of a tunable RF filter according to an embodiment of the present invention includes a main housing 600 into which a part of a tuning bar is inserted and a tuning device such as a tuning slide and a motor, including a resonator. Housing 602. An upper cover 604 is formed at the boundary between the main housing 600 and the sub housing 602, and as described above, the upper cover 604 functions to seal the upper surface of each cavity in which the resonator is provided.

According to a preferred embodiment of the present invention, it is preferable that the inclination angle of the slot of the tuning slide is differently formed so that the height of the tuning bar whose height is adjusted according to the movement of the tuning slide is adjusted differently.

In the conventional RF filter tuning using a motor, the height that each tuning screw is adjusted at the time of tuning was the same because it uses a single motor instead of tuning using an independent motor for each tuning screw.

Such equal height adjustment of all tuning screws caused many problems when the frequency width to be tuned was large. For example, even if the center frequency is shifted to a desired degree, the skirt characteristic of the filter, etc. does not maintain the characteristics before tuning, so there is a problem in that it is practically impossible to use by tuning.

Therefore, according to a preferred embodiment of the present invention, by varying the inclination angle of the slot that each tuning bar is put, so that individual tuning is made, not collective tuning.

According to the present inventors, it has been found that the characteristics of the filter are not distorted even when tuning with a relatively large frequency width when the capacitance change rate in each resonator is equalized during the filter tuning.

For example, the rate of change of the first capacitance that occurs between the first tuning bar and the first resonator due to the height adjustment of the first tuning bar and between the second tuning bar and the second resonator due to the height adjustment of the second tuning bar When the rate of change of the second capacitance is the same, tuning for wideband is possible without distorting the characteristic.

The rate of change of capacitance is then related to the rate of change of length between the tuning bar and the resonator. Also, the rate of change of length is affected by the length between the initial resonator and the tuning bar.

For example, even if the tuning bar moves about 5 mm, the change rate of the length is different in the case of 5 mm movement at the initial distance of 5 cm and 5 mm movement at the initial distance of 2 cm.

Therefore, according to a preferred embodiment of the present invention, the inclination angle of each slot is set differently so that the rate of change of the length is constant in consideration of the initial distance between each tuning bar and the resonator. In more detail, when the distance between the tuning bar and the resonator is short, the inclination angle is formed small so that the change in height due to sliding is relatively small. When the distance between the tuning bar and the resonator is long, the inclination angle is increased so that the change in height due to sliding is relatively large Make the angle large.

When the inclination angle is formed as described above, it is possible to individually tune a plurality of tuning bars using one motor and to enable efficient broadband tuning.

7 illustrates an equivalent circuit configuration of a tunable RF filter according to an exemplary embodiment of the present invention.

Referring to FIG. 7, a tunable RF filter according to an embodiment of the present invention may be represented by a parallel combination of a plurality of capacitors C1, C2, C3, and C4 and inductors L1, L2, L3, and L4. have.

7 shows a parallel combination of four capacitors and an inductor, each parallel combination of an inductance formed by a resonator and a tuning bar provided in each cavity and cavity in an RF filter according to an embodiment of the present invention. Implemented by capacitance.

In the RF filter according to an embodiment of the present invention, the inductance is fixed, and the capacitance is varied by adjusting the height of the tuning bar.

At this time, the inclination angle of the slot is adjusted based on the initial length between the tuning bar and the resonator. Therefore, preferably, DELTA C1, DELTA C2, DELTA C3, DELTA C4, which is the change rate of capacitance, are set the same.

Preferred embodiments of the present invention described above are disclosed for purposes of illustration, and those skilled in the art will be able to make various modifications, changes, and additions within the spirit and scope of the present invention. Additions should be considered to be within the scope of the following claims.

As described above, according to one embodiment of the present invention, tuning can be performed by easier operation, and there is an advantage that individual tuning is possible for each resonator.

In addition, according to an embodiment of the present invention, it is suitable for wideband tuning, can be applied to all the various filter structures can contribute to the miniaturization of the product and there is an advantage that can be manufactured at a low cost.

Claims (9)

motor Tuning slide slid by the drive of the motor A plurality of tuning bars moving up and down in association with sliding of the tuning slide; And a resonator provided in each cavity in association with the plurality of tuning bars. The method of claim 1, The tuning slide includes a plurality of slots for fastening the tuning bar and holes for preventing the tuning bar from penetrating and moving in the sliding direction, The tuning bar is a tunable RF filter using a slot, characterized in that at least one protrusion is formed to span the slot. The method of claim 1, Tunable RF filter using a slot, characterized in that each of the plurality of slots is formed in an inclined form. The method of claim 3, Tunable RF filter using a slot, characterized in that the inclination of each of the plurality of slots are formed differently. The method of claim 4, wherein The slope of each of the plurality of slots is set by the initial length between the tuning bar and the resonator tunable RF filter using a slot. The method of claim 1, And a sub housing including a main housing for sealing the resonator and the cavity, and a sub housing including the tuning slide and the motor. motor A tuning slide that is slid by the drive of the motor and Including a plurality of tuning bars moving up and down in conjunction with the sliding of the tuning slide, The tuning slide includes a plurality of slots for engaging the tuning bar and holes for preventing the tuning bar from penetrating and moving in the sliding direction, wherein the tuning bar is formed with at least one protrusion for engaging the slot. RF filter tuning device. The method of claim 7, wherein RF filter tuning apparatus, characterized in that each of the plurality of slots is formed in an inclined form. The method of claim 8, And the slope of each of the plurality of slots is set by an initial length between the tuning bar and the resonator of the RF filter.

Images