CN201298583Y - Cavity filter for mobile communication network - Google Patents

Abstract

The utility model relates to a cavity filter for mobile communication network. The utility model provides the cavity filter for mobile communication network for settling the technical problems of inconsistent structural dimensions, complex structure, etc. in the cavity filter which is manufactured with Chebyshev Mathematical Response Model. According to the cavity filter for mobile communication network, the mathematical response model adopts identical-element low-pass prototype as the mathematical response model for designing the structure of cavity filter, so the structure of filter cavity obtained according to the mathematical response model of the utility model has united and consistent structural dimension on the resonant cavity, resonant lever, coupling adjusting lever and resonant cavity baffle. Thus the technique for manufacturing the cavity filter product is greatly simplified. Simultaneously the debugging of assembled cavity filter is simpler and the bulk production is facilitated. The technical plan of the utility has another advantage that the central attrition of reference passband is reduced to minimum at the condition that the attenuation of attenuation band is satisfied. Furthermore the non-load Q value can be guaranteed to maximum. The insertion loss of cavity filter is minimum.

Description

The mobile communication network cavity body filter

Technical field

The utility model relates to the components and parts of microwave communication system---band pass filter, in particular the mobile communication network cavity body filter.

Background technology

In mobile communication network, in the especially present 3G mobile communication network, filter has crucial effect, requires it to possess the little and high characteristic of selectivity of the loss of insertion.With the TD-SCDMA base station construction is example, because TD-SCDMA adopts the comparatively complicated smart antenna of structure, non-linear will be above other common antenna for base station, thereby TD-SCDMA is subjected to the low noise recruitment of electromagnetic effect can be higher than the low noise recruitment of ordinary base station, so just need a large amount of band pass filters that the insertion loss is little, selectivity is high in the uplink and downlink link of base station.In order to satisfy mobile communication network to the high request of band pass filter at aspects such as weight, volume, stability, reliability and economy, what multiselect was used is cavity body filter.These cavity body filters are many to be that mathematical response model manufactures and designs with Chebyshev, because the nonloaded Q of the actual cavity body filter that makes is limited, all want pre-abnormal design method to design so use Chebyshev's mathematical response model, so just make the passband center insert loss and increase, thereby be difficult to satisfy the user demand that base station uplink and downlink link desired signal is transmitted and suppressed to disturb in the TD-SCDMA network.Especially some technical problems of the cavity body filter of Chebyshev's mathematical response model manufacturing existence are fatal: the coupling capacitance of its resonant tank is unequal, the inductance of resonant tank is unequal, each loop coupling amount disunity, the equal disunity of the size of designed resonant cavity and adjustment component, complex structure, the complexity and the difficulty that have increased processing greatly and debugged.

Summary of the invention

Goal of the invention of the present utility model is to utilize first method characteristic such as grade of LC filter chart designing institute foundation and designs unified, the consistent mobile communication network cavity body filter of a kind of physical dimension.

The mobile communication network that the utility model provides cavity body filter technical scheme, its technical scheme is to the effect that: a kind of mobile communication network cavity body filter, lontitudinal series is shaped on the chamber, resonant cavity side of a plurality of size dimension unanimities in its cavity, the resonant cavity wall symmetry connection at cavity two ends is provided with input, output electromagnetic coupled line link, central authorities are provided with the interior screwed pipe that unified size cooperates with the resonance screw rod in each resonant cavity, form the resonant cavity group by the cavity input side in twos to the resonant cavity of outlet side, two resonant cavity adjacent window apertures places of each resonant cavity group, pass the coupling adjusting lever that cover plate is provided with unified size.

The technical scheme that the utility model application provides, first low-pass prototypes such as employing have made full use of the characteristic of its method mathematical response model such as unit such as grade as cavity body filter structural design mathematical response model, and these characteristics comprise:

(1), all loop inductances are identical, i.e. L ₁=L ₂=L3=L4=......Ln=L=Z _C/ 2 π f ₀, Z wherein _CBe cavity characteristic impedance, f ₀Centre frequency for passband.

(2), all loop resonance frequencys are all identical, i.e. f ₀₁=f ₀₂=f ₀₃=f ₀₄=... fn=f ₀

(3), all tank capacitances are identical, promptly $C1=\mathrm{<figure-callout\; id="2"\; label="C"\; filenames="Y200820219820E00083.png"\; state="\{\{state\}\}">C</figure-callout>}2=\mathrm{<figure-callout\; id="3"\; label="C"\; filenames="Y200820219820E00083.png"\; state="\{\{state\}\}">C</figure-callout>}3=\mathrm{<figure-callout\; id="4"\; label="C"\; filenames="Y200820219820E00083.png"\; state="\{\{state\}\}">C</figure-callout>}4=......\mathrm{Cn}=C=\frac{25330}{f_0^{2}L}$

(4), all identical C of all loop coupling capacitances ₁₂=C ₂₃=C ₃₄=... C _{N, n+1}=C _MSo in=KC cavity body filter the structure disclosed in the utility model, resonant cavity, resonant cavity dividing plate, resonant rod, coupling adjusting lever all have unified, consistent physical dimension, cavity body filter product manufacturing processing technic is oversimplified greatly, the cavity body filter debugging that assembles simultaneously is also more simple, is suitable for producing in batches.The big advantage of another of the technical program is: the utility model with etc. first method serve as the design mathematical response model, the band pass filter of this mathematical response model is that the loss band pass filter is inserted at minimum band center, make and satisfying under the stopband attenuation condition, it is minimum that the center loss of benchmark passband reduces to, and under the certain condition of cavity volume, by selecting the size of suitable resonant rod external diameter, can guarantee the nonloaded Q maximum of cavity, thereby guarantee the insertion loss minimum of cavity body filter.

From following chart as can be known: the mobile communication network cavity body filter that the utility model provides, its index of inserting loss and the outer inhibition of band is better than the index of domestic like product, and near U.S. K﹠amp; The technical target of the product of L.

Business Name	IL(fo)Db	Stopband?1	Stopband?2
				Dandong Hua Xun	1.0	1860≥38dB	1960≥38dB
U.S. K﹠L	1.0	1854≥30dB	1966≥30dB
				Logical sequence is won in Anhui	1.2	1860≥35dB	1960≥35dB

Description of drawings

Fig. 1 is the cavity body filter cavity resonator structure schematic diagram with the design of Chebyshev's mathematical response model

Fig. 2 is this mobile communication network cavity body filter cavity resonator structure schematic diagram

Fig. 3 shows the resonant cavity general assembly structural representation of this mobile communication network with cavity body filter

Fig. 4 is the structure chart of cover plate 8.

Embodiment

The disclosed mobile communication network cavity body filter of the utility model, its structure as shown in Figures 2 and 3, it such as is based at first method cavity body filter structural design mathematical response model.The content of this mathematical response model is: the main electric parameters before implementing the design derivation below at first definite cavity body filter: centre frequency f ₀, bandwidth is inserted loss, the outer As that suppresses of band, input, output impedance R ₀, determine the cavity body filter physical dimension by step again:

1., determine the cavity body filter joint number $n=\frac{6+\mathrm{As}}{8.68};$

2., the chamber, the resonant cavity side of being of cavity body filter, its side chamber side length b and resonant rod outside diameter d ratio, cavity nonloaded Q the best when promptly b/d is between 3-4 is determined a numerical value between 3-4, being tabled look-up by " microwave transmission line design manual " obtains characteristic impedance Z _CAccording to formula $L=\frac{\mathrm{<figure-callout\; id="2"\; label="Zc"\; filenames="Y200820219820E00083.png"\; state="\{\{state\}\}">Zc</figure-callout>}}{{2\mathrm{\&pi;f}}_0}$ Calculate resonant rod equivalent inductance value L, again according to formula $C=\frac{25330}{f_0^{2}L}$ Carry out the calculating of resonant rod equivalent capacitance value C; Determine the resonant rod size by the C value again, promptly according to formula $C=\frac{{2\mathrm{\&pi;h}}_1{\mathrm{\&xi;}}_0}{\lg \frac{\mathrm{rb}}{\mathrm{ra}}},$ And machining requires to determine circular diameter, resonant rod outside diameter d in the resonant rod, r wherein _aBe radius of circle in the resonant rod, r _bBe to adjust the screw rod radius, at last according to etc. first method b/d optimum range and resonant rod outside diameter d determine the resonant cavity side length b; Determine resonant rod length x according to the cavity centre frequency ₀, this length is got 1/8 of centre frequency wavelength, $x_0=\frac{1}{8}\mathrm{\&lambda;},$ $\mathrm{\&lambda;}=\frac{c}{f_0},$ Wherein c is the light velocity;

3., calculate coupling dividing plate height: by formula $Q_0=\frac{b}{\mathrm{\&delta;}}*\frac{\mathrm{lh}\frac{b}{d}}{1+\frac{b}{d}+\frac{b}{x_0}\mathrm{lh}\frac{b}{d}}$ Calculate the nonloaded Q of cavity, δ wherein is a skin depth, by＜＜the microwave transmission line design manual the skin effect curve chart check in the δ value; By formula Q _CP=f ₀/ BW _-3dBCalculate cavity loaded quality factor Q _CpAccording to formula $K=\frac{1}{Q_{\mathrm{cp}}}-\frac{1}{Q_0}$ Calculate coupling factor K; By formula C _m=KC calculates the equivalent coupled capacitor C _mBy formula C _M=C _mX ₀Determine the coupling capacitance when cavity does not have dividing plate, and according to formula $R=\frac{C_m}{C_M}$ Determine the correction factor of cavity dividing plate; Determine the dividing plate height by formula c=b-Rb at last, c is the dividing plate height in the formula;

4., calculate the input/output terminal coupling inductance, determine the size of coupling line: the loaded quality factor of each resonant cavity is: Q _b=0.435Q _CpThe resonance impedance of each resonant cavity is: R _b=Q _b* Z _cInput and output insert coefficient: $P=\sqrt{R_0/R_b},$ R in the formula ₀Be input, output impedance; Input and output coupling inductance are: L _i=L ₀=PL, L in the formula _iAnd L ₀Be respectively input, output coupling inductance; According to formula L _i=0.21[ln (2l/r)-1.0] (μ H) and the diameter of wire selected calculate the length of input, output lead-in wire.

Just be based on the mobile communication network cavity body filter that each structural parameters that first method mathematical response model such as above-mentioned grade calculates are made, it is that lontitudinal series is shaped on a plurality of size dimensions unanimity side cavate resonant cavity 2 in the aluminum shielding cavity 1 that its structure constitutes, in the present embodiment, lontitudinal series is shaped on four size dimension unanimity side cavate resonant cavitys 2 in its shielding cavity 1, the resonant cavity wall 10 at cavity two ends, the connection of 11 outsides is provided with input, output electromagnetic coupled wiring connector, what adopt in the present embodiment is SMA base connector 5, its inboard is symmetrically welded and is fixed with input, export silver-plated coupling lead-in wire 4 and carry out electromagnetic coupled, the introducing end line part of its coupling lead-in wire 4 be arranged in parallel with resonant rod.Central authorities are provided with the interior screwed pipe 3 of unified size in each resonant cavity 2, and each copper resonant rod 7 passes cavity and the coupling of interior screwed pipe 3 threaded engagement implementation spaces.Form the resonant cavity group in twos by shielding cavity 1 input side to the resonant cavity of outlet side, in the structure of Fig. 3, from left to right, first resonant cavity and second resonant cavity, the 3rd resonant cavity and the 4th resonant cavity are formed two resonant cavity groups, adjacent window apertures place between adjacent window apertures place, the 3rd resonant cavity and the 4th resonant cavity between first resonant cavity and second resonant cavity, penetrate the copper coupling adjusting lever 6 that is provided with unified size by shielding cavity 1 screw, last securing cover plate 8 constitutes.Its shielding cavity 1, resonant rod 7, coupling adjusting lever 6 and all silver-plated processing of lid surface, for guaranteeing resonance frequency, its silver-plated thickness is 5 μ m.

Claims (1)

1, a kind of mobile communication network cavity body filter, it is characterized in that the interior lontitudinal series of cavity is shaped on the chamber, resonant cavity side of a plurality of size dimension unanimities, the resonant cavity wall symmetry connection at cavity two ends is provided with input, output electromagnetic coupled line link, central authorities are provided with the interior screwed pipe that unified size cooperates with the resonance screw rod in each resonant cavity, form the resonant cavity group by the cavity input side in twos to the resonant cavity of outlet side, two resonant cavity adjacent window apertures places of each resonant cavity group, pass the coupling adjusting lever that cover plate is provided with unified size.

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