CN2428925Y

CN2428925Y - Strip-line structure meter-wave trap

Info

Publication number: CN2428925Y
Application number: CN 00238623
Authority: CN
Inventors: 陈兆武
Original assignee: BEIJING JIZHAO ELECTRONICS Co Ltd
Current assignee: BEIJING JIZHAO ELECTRONICS Co Ltd
Priority date: 2000-06-23
Filing date: 2000-06-23
Publication date: 2001-05-02
Anticipated expiration: 2010-06-23

Abstract

The utility model provides a strip-line structure meter-wave trap, belonging to the structural design field of the radio-frequency wave trap. The utility model is composed of a main transmission line part, a resonant cavity part and a coupling mechanism part which is used for connecting the main transmission line and the resonant cavity, wherein, the main transmission line is composed of a strip-line inner conductor and a strip-line outer conductor; the resonant cavity is composed of a spiral line inner conductor, a spiral line outer conductor and an adjustable screw rod; the coupling mechanism is composed of a main transmission line coupling piece and a metal rod which is used for connecting the coupling piece and the spiral line inner conductor. The utility model has the advantages of small size, simple structure, convenient fabrication, stability, reliability and low cost, and the utility model is particularly suitable for a transmitter system of a television with large power.

Description

Strip line structured meter wave trap

The utility model belongs to the trapper structural design field of radio frequency channel.

Traps are widely used in the field of radio transmission. The wave trap in various forms is composed of three parts of a main transmission line, resonant cavities and a coupling mechanism between the main transmission line and the resonant cavities, and the number of the resonant cavities can be one or more according to actual needs.

Conventional radio frequency traps typically employ a coaxial line structure. The single resonant cavity structure of the trap is shown in fig. 1a and 1b, and the main transmission line 11 and the resonant cavity 12 both adopt coaxial structures, that is, the inner conductors 111 and 121 of the main transmission line 11 and the resonant cavity 12 are cylinders, and the outer conductors 112 and 122 are round metal cylinders coaxial with the inner conductors. The frequency adjusting mechanism 13 of the wave trap adopts a piston drawing type structure, the length of the resonant cavity 12 changes along with the drawing of the piston 13, and the resonant frequency of the resonant cavity 12 changes along with the change. The intracavity conductor 121 is pulled to change the gap between the end surface and the main transmission line inner conductor 111, so as to adjust the degree of coupling between the main transmission line 11 and the cavity 12. The structure requires good electric contact among the relative movement structural members, and is easy to fix and lock, the fixed connection part among the structural members adopts a silver soldering process, the sliding connection part adopts an electric brush structure, the process difficulty is large, the processing precision requirement is high, the fixing and locking structure is complex, and the stability is poor. Moreover, such traps are bulky. For example, the physical dimensions of a typical embodiment of a trap of this type of structure are: 870mm by 510mm by 103 mm.

The equivalent circuit of this coaxial single-resonator trap is shown in fig. 1 c: the gap between the end face of the conductor 121 in the resonant cavity and the inner conductor 111 of the main transmission line is equivalent to a variable capacitor C1, and the resonant cavity is equivalent to a variable inductor L1; the C1 and the L1 form a series resonant circuit to form a resonant point. The radio frequency signal RF travels along the main transmission line and a frequency component equal to the resonance point is trapped.

The traditional trap has a large adjusting range, but has the disadvantages of complex structure, various manufacturing procedures, high precision requirement, poor stability, larger volume and high price.

An object of the utility model is to overcome prior art's weak point, provide a radio frequency trapper of stripline structure, make it not only the electrical property is good, have simple structure moreover, processing is convenient, and is with low costs, small, advantage such as cost-performance ratio.

The utility model provides a radio frequency wave trap with a strip line structure, which consists of a main transmission line, a resonant cavity and a coupling mechanism connecting the main transmission line and the resonant cavity; the main transmission line is characterized by consisting of a strip line inner conductor and a strip line outer conductor; the resonant cavity consists of a spiral line inner conductor, an outer conductor and an adjustable screw rod with one end inserted into the resonant cavity; the coupling mechanism consists of a main transmission line coupling piece and a metal rod connecting the coupling piece and the helical line inner conductor.

The main transmission line and the outer conductor of the resonant cavity can be rectangular or circular cylinders. The coupling sheet may be a thin metal sheet.

The utility model has the advantages of that: 1. the inner conductor and the outer conductor of the resonant cavity do not need to be adjusted, the resonant frequency can be changed only by changing the depth of the adjusting screw rod, and the coupling degree is determined by designing and selecting coupling pieces with proper sizes and gaps between the coupling pieces and the inner conductor; 2. the structure is simple, the processing is easy, and the manufacturing cost is low; 3. compact structure, small size and easy installation.

Brief description of the drawings:

FIG. 1 is a structure and equivalent circuit diagram of a conventional coaxial line RF trap; wherein,

fig. 1a is a front view, fig. 1b is a side view, and fig. 1c is an equivalent circuit diagram.

Fig. 2 is a structural and equivalent circuit diagram of a meter wave trap with a strip line structure according to the present invention; wherein,

fig. 3a is a front view, fig. 3b is a side view, and fig. 3c is an equivalent circuit diagram.

Fig. 3 is a schematic structural diagram of an embodiment of a meter wave trap of the present invention.

The structure, equivalent circuit, and embodiments of the present invention will be described in detail with reference to the accompanying drawings.

The structure and equivalent circuit of the meter wave trap of the utility model are shown in figure 3, wherein,

fig. 2a is a front view, fig. 2b is a side view, and fig. 2c is an equivalent circuit diagram.

In fig. 2a and 2b, the main transmission line 21 is composed of a stripline inner conductor 211 and a rectangular outer conductor 212; the resonant cavity 22 is composed of a spiral line inner conductor 221, a rectangular outer conductor 222, two

end plates

241 and 242 and a screw 223, and the resonant frequency can be adjusted by changing the depth of the screw 223; the coupling mechanism 23 is composed of a main transmission line coupling piece 231 and a metal rod 232 connecting the coupling piece 231 and the helical line inner conductor 221, and a proper coupling degree between the main transmission line and the resonant cavity is obtained by selecting a proper size of the coupling piece 231 and a gap between the piece and the main transmission line inner conductor 211.

The equivalent circuit of the single resonant cavity trap is shown in fig. 2C, the gap between the spiral line inner conductor 221 and the screw 223 of the resonant cavity 22 is equivalent to a capacitor C2, and a section of transmission line formed by the spiral line inner conductor 221 and the rectangular outer conductor 212 is equivalent to an inductor L2; the gap between the coupling tab 231 of the coupling mechanism 23 and the main transmission line inner conductor 211 is equivalent to a capacitance C3. C2, L2 and C3 together form a resonant tank. The radio frequency signal RF travels along the main transmission line and forms a trap at the resonant frequency as it passes through the resonant cavity.

An embodiment of the trap of this configuration is shown in figure 3 and is applied to a radio frequency VHF band 6CH television transmitter. The main transmission line forms a radio frequency signal transmission channel, and the six resonant cavities trap five frequency points respectively (one frequency point is used as two resonant cavities). The two ends of the main transmission line inner conductor 32 are welded with the radio frequency connector 31, supported by the insulating support 34 and symmetrically suspended in the main transmission line rectangular outer conductor 33. The resonator inner conductor 37 is mounted on the resonator end wall 39, and the tuning screw 38 is mounted on the other resonator end wall 310, coaxially with the inner conductor 37; the turning in and out of the tuning screw 38 changes the gap with the inner conductor 37. The main transmission line is coupled to the resonant cavity by a coupling mechanism 36.

The structural dimensions of the present embodiment are as follows: (unit: mm)

The external dimension is as follows: 432X 135X 90

Main transmission line: 386X 23.5X 2 strip line, 384X 60X 26 rectangular outer conductor

A resonant cavity: helix (wire diameter phi 4, helix radius phi 30, thread pitch 7.9), rectangular cavity 54X 86

A coupling mechanism: coupling sheet phi 22 multiplied by 2 and connecting rod phi 3 multiplied by 36

The technical indexes of the embodiment are as follows:

center frequency: 175MHz for VHF 6CH

Image carrier frequency: FV = 168.25 MHz

Each frequency point and trap amount: FV-13= 155.25 MHz, -12dB

FV-11=157．25MHz，-12dB

FV-6．5=161．75MHz，-16dB

FV+11=179．25MHz，-12dB

FV+13=181．25MHz，-12dB

Within the 6CH passband: insertion loss is less than 0.1 dB;

the return loss is > 24 dB.

Claims

1. A radio frequency wave trap with a strip line structure consists of three parts, namely a main transmission line, a resonant cavity and a coupling mechanism for connecting the main transmission line and the resonant cavity; the main transmission line is characterized by consisting of a strip line inner conductor and a strip line outer conductor; the resonant cavity consists of a spiral line inner conductor, an outer conductor and an adjustable screw rod with one end inserted into the resonant cavity; the coupling mechanism consists of a main transmission line coupling piece and a metal rod connecting the coupling piece and the helical line inner conductor.

2. The radio frequency trap of claim 1 or 2, wherein the main transmission line and the outer conductor of the resonant cavity are rectangular or circular cylinders.

3. A radio frequency trap as claimed in claim 1 or 2, characterized in that said coupling strip is a thin metal strip.