CN202977672U - Strong coupling wideband cavity filter - Google Patents

Abstract

The utility model discloses a strong coupling wideband cavity filter, relates to the field of electronic communication, and aims to solve the technical problems that the existing wideband filter can only use a Chebyshev method and is only used under the condition of a low out-of-band restraining demand and the like. According to the utility model, a number of parallel circuits are arranged between a first port (1) and a second port (2) of the cavity filter, wherein each parallel circuit is composed of an inductor (L), a capacitor (C) and an inner impedance (R); and one end of each parallel circuit is connected between the first port (1) and the second port (2), and the other end is grounded.

Description

Close coupling wideband cavity filter

Technical field

The utility model relates to electronic communication field, particularly a kind of close coupling wideband cavity filter for mobile communication base station, repeater or trunk amplifier etc.

Background technology

Along with the development of mobile communication, requiring for communication channel capacity is also day by day to increase severely, so needs to improve with the broadband filter of the Wideband Signal Processing the channel capacity of whole system in system equipment.

Bandwidth (band width) be again frequency range, refers to the data quantity that can transmit in the fixing time, that is can transmit the ability of data in transmission pipeline.In digital device, frequency range represents with bps usually, i.e. the figure place that can transmit of per second.In the communication radio frequency analog machine, frequency range usually transmits the cycle with per second or hertz (Hz) represents.

Can be divided into the arrowband from the band wide angle, middle band, the types such as broadband, wherein relative bandwidth is less than 20% the narrow band filter that belongs to, and the broadband filter that belongs to greater than 40% belongs to middle band filter between 20% and 40%.The relative bandwidth of narrow band filter: BW=(f2-f1)/f0.F1, f2 are respectively the start-stop frequencies of passband, and f0 is passband central frequency.

Also diversified filter on Vehicles Collected from Market, but the bandwidth requirement of general so conventional filter is all the filter of arrowband or middle bandwidth, and the filter in broadband generally is difficult to realize with cavity.Usually the filter of realizing the broadband is all to adopt pectination or interdigitated structure to realize, but the filter of this class formation is only suitable for for Chebyshev's mode filter, and just can not realize elliptic function mode filter.More existing conventional filters mainly contain following characteristics:

1. coaxial cavity filter, its main feature is that insertion loss is little, and squareness factor is good, and the volume of cavity is moderate for general power, and the systematicness that cavity is arranged requires high, but this cavity is only suitable for for relative bandwidth less than 20% arrowband;

2. pectination, interdigital filter, its main feature insertion loss is little, volume is little, this class filter is only suitable for for Chebyshev's mode filter and the less demanding situation of Out-of-band rejection, contour structures is all generally microscler cavity, and relative bandwidth can realize with this type of filter at the filter of 40%～60% filter and profile comparison rule.

Summary of the invention

The utility model is intended to solve existing broadband filter can only be adopted Chebyshev's mode and the technical problem such as be only applicable to use in the less demanding situation of Out-of-band rejection, adopts elliptic function mode or Chebyshev's mode to provide a kind of, applicable to the close coupling wideband cavity filter that uses in the demanding situation of Out-of-band rejection.

The purpose of this utility model is achieved through the following technical solutions.

Close coupling wideband cavity filter of the present utility model, be provided with the parallel circuits that several are made of inductance L, capacitor C and internal impedance R between the port 1 of cavity body filter and port 22, one of parallel circuits is terminated between port 1 and port 22, other end ground connection.

Close coupling wideband cavity filter of the present utility model, wherein said cavity body filter are Chebyshev's cavity body filter or elliptic function cavity body filter.

Close coupling wideband cavity filter of the present utility model, wherein said parallel circuits is 5.

The beneficial effect of the utility model close coupling wideband cavity filter:

1. relative bandwidth is wide;

2. insertion loss is low;

3. volume is little;

4. bear power large.

Description of drawings

The circuit theory diagrams of Fig. 1 close coupling wideband cavity of the present utility model filter

Fig. 2 close coupling principle schematic of the present utility model

The conventional coupling principle schematic diagram of Fig. 3

The number in the figure explanation:

1 port one, 2 ports two, 3 resonance points one, 4 resonance points two, 5 resonance points three, 6 resonance points four, 11 coupling one, 12 coupling two, 13 coupling three, 14 coupling four, 15 coupling five, 16 couplings six

Embodiment

The utility model detailed construction, application principle, effect and effect with reference to accompanying drawing 1-3, are explained by following execution mode.

Consult shown in Figure 1ly, be provided with the parallel circuits that several are made of inductance L, capacitor C and internal impedance R between the port 1 of cavity body filter and port 22, one of parallel circuits is terminated between port 1 and port 22, other end ground connection.

Referring to accompanying drawing 3, the coupling of general cavity body filter is all to carry out Energy Transfer by the Space Coupling between resonance 1 and resonance 2, the coupling energy of this form a little less than, relative bandwidth can only be in 20%;

referring to accompanying drawing 2, close coupling wideband cavity filter of the present utility model adopts cavity body structure to realize, coupling is Space Coupling between resonance 1 and resonance 2, increase by a coupling block between resonance 1 and resonance 2 in order to strengthen being coupling between them, the coupling of this structure is very strong can realize that relative bandwidth is more than 60%, and can realize with the elliptic function form of high squareness factor, the cavity volume of this close coupling filter is little, and can come according to actual conditions the layout in arbitrary arrangement chamber, relative bandwidth can not realize just can coming fine realization with the method with conventional method at the filter more than 40%.

Close coupling wideband cavity filter of the present utility model mainly contains following index:

Band bandwidth: be namely the frequency range that need to satisfy the specification requirement of product standard electrical property.

Relative bandwidth: cut-off frequency f2 deducts the difference of cut-off frequency f1 divided by the centre frequency between them.

Insertion loss: the ratio of power output and input power is caused loss when weighing by filter.

Passband fluctuation: the degree that signal amplitude rises and falls in filter passband, poor between the value of signal fluctuation maximum in passband and minimum value.

Voltage standing wave ratio: the ratio that refers to incoming level power and output level power.It is mainly to weigh the signal important indicator whether matched well is transmitted in filter passband.

Out-of-band rejection: refer to the inhibition ability to the passband external signal, get the pad value of the outer a certain frequency of passband as this index.

Referring to accompanying drawing 1, be artificial circuit schematic diagram of the present utility model, this type of filter can adopt the filter of Chebyshev or elliptic function type.Can select according to the requirement of actual index, if require the high optional Chebyshev's type of inband flatness; Relative bandwidth requires the high elliptic function the selected type of Out-of-band rejection, even also can be selected this high elliptic function structure that suppresses at 〉=60% filter.

Close coupling wideband cavity filter of the present utility model, the internal impedance R on inductance L, capacitor C and the left side in the middle of in circuit are connected in parallel and produce frequency F0, and the scope of its medium frequency just depends on inductance L and capacitor C, be worths larger frequency just lower, otherwise with regard to height.In-band insertion loss just depends on single chamber internal resistance R, and the Q value of single chamber internal resistance R is higher just shows that the insertion loss in passband is just little, otherwise bigger than normal.Shunt inductance L, capacitor C and internal resistance R are resonance points to the part on ground, have 5 parallel circuitss in Fig. 1, i.e. 5 resonance points, two adjacent Frequency points transmit the increase bandwidth of operation by the capacitive coupling form, the coupling one of Fig. 1-coupling six totally 6 be coupled as the electric capacity normalized value.

Therefore close coupling wideband cavity filter of the present utility model has that relative bandwidth is wide, insertion loss is low, volume is little, bears many technological merits such as power is large.

Claims (3)

1. close coupling wideband cavity filter, it is characterized in that: be provided with the parallel circuits that several are made of inductance (L), electric capacity (C) and internal impedance (R) between the port one (1) of cavity body filter and port two (2), one of parallel circuits is terminated between port one (1) and port two (2), other end ground connection.

2. close coupling wideband cavity filter according to claim 1, it is characterized in that: described cavity body filter is Chebyshev's cavity body filter or elliptic function cavity body filter.

3. close coupling wideband cavity filter according to claim 1, it is characterized in that: described parallel circuits is 5.

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