CN203644912U - Narrowband difference band-pass filter based on terminal-short-circuit self-coupling annular resonator - Google Patents

Abstract

The utility model discloses a narrowband difference band-pass filter based on a terminal-short-circuit self-coupling annular resonator, and the filter comprises the terminal-short-circuit self-coupling annular resonator, and two coupling micro-strip lines. The filter provided by the utility model employs the design of micro-strip lines. The filter provided by the utility model is light in weight, is high in reliability, is excellent in performance, is good in temperature stability, is low in cost of batch production, is especially suitable for the corresponding microwave communication, a digital radar, military and civil multi-mode and multipath communication system terminals, and corresponding systems which have strict requirements for the weight, performance and reliability.

Description

Arrowband differential bandpass filter based on terminal short circuit from coupling loop shape resonator

Technical field

The utility model belongs to microwave and millimeter wave technical field, particularly a kind of based on terminal short circuit the arrowband differential bandpass filter from coupling loop shape resonator.

Background technology

Along with the fast development of modern wireless communication systems, the demand of balancing circuitry and application seem more and more important.Difference filter, with its good anti-noise jamming and dynamic range characteristics, seems and is even more important in balancing circuitry structure.For a good difference filter structure, only have required difference mode signal by filter structure, common-mode signal is inhibited simultaneously.In addition, difference filter must have good edge selectivity characteristic and harmonic responses.In recent years, people have proposed many different types of difference filter structures, to meet the demand of arrowband, double frequency-band or broadband and high common mode inhibition.In recent years, have scholar first to propose a kind of broadband coupled differential bandpass filter structures based on multistage, but this structure is due to the inhibition lacking common-mode signal, thereby is difficult to be applied in balancing circuitry and go as real difference filter.In order to overcome this shortcoming, a kind of super wide band microstrip differential bandpass filter with good common mode inhibition characteristic be designed application, but in order to meet the requirement of ultra broadband frequency range, but due to it multistage be connected, increased whole circuit volume; And the inhibition of the outer common-mode signal of band is also undesirable.In order to reduce volume, have scholar to use coupled resonators and coupling line to improve common mode inhibition and the upper limit stopband of expanding differential mode, but its differential loss is larger again.Based on above analysis, we have proposed the arrowband differential bandpass filter from coupling loop shape resonator based on terminal short circuit, and not yet find its correlative study and report.

Utility model content

The purpose of this utility model is to provide a kind of very high differential mode passband selectivity, precipitous sideband, high common mode inhibition, volume is little, lightweight, reliability is high, be easy to processing and the low arrowband differential bandpass filter from coupling loop shape resonator based on terminal short circuit of cost.

The technical scheme that realizes the utility model object is: a kind of based on terminal short circuit the arrowband differential bandpass filter from coupling loop shape resonator, comprise that terminal short circuit is from coupling loop shape resonator, this terminal short circuit is respectively the first microstrip line in the direction of the clock from four microstrip lines of coupling loop shape resonator, the second microstrip line, the 3rd microstrip line, the 4th microstrip line, the first microstrip line is rectangular top, wherein the first microstrip line and the 3rd microstrip line are symmetrical up and down, the second microstrip line and the 4th microstrip line are symmetrical, the second microstrip line right-hand member arranges the first plated-through hole, the first microstrip line and the coupling of the 5th microstrip line, the 3rd microstrip line and the coupling of the 6th microstrip line, the 6th microstrip line one port is first input end, an other port is the first output, the 5th microstrip line one port is the second input, another port is the second output, the 5th microstrip line and the 6th microstrip line are symmetrical up and down along TT ', wherein TT ' is the center line of rectangle terminal short circuit from coupling loop shape resonator.

Compared with prior art, its remarkable advantage is the utility model: 1) the utility model can have less differential mode in-band insertion loss, larger return loss, smooth group delay, higher common mode inhibition; (2) circuit structure is simple, only needs a plated-through hole and several microstrip lines; (3) in technique, be easy to realize; (4) utilize micro-band high-temperature stability and reliability, make element there is high-temperature stability and high reliability.

Below in conjunction with specific embodiment, the utility model is done to comparatively detailed description.

Accompanying drawing explanation

Fig. 1 be the utility model based on terminal short circuit from the arrowband differential bandpass filter of coupling loop shape resonator from coupling loop shape resonator schematic diagram.

Fig. 2 be the utility model based on terminal short circuit from the arrowband differential bandpass filter of coupling loop shape resonator from coupling loop shape resonator common mode, differential mode equivalent circuit figure.

Fig. 3 be the utility model based on terminal short circuit from the arrowband differential bandpass filter of coupling loop shape resonator from coupling loop shape resonator common mode, differential mode resonance frequency comparison diagram.

Fig. 4 be the utility model based on terminal short circuit from the arrowband differential bandpass filter of coupling loop shape resonator from coupling loop shape resonator resonance frequency and length l ₁between graph of a relation.

Fig. 5 be the utility model based on terminal short circuit from the arrowband differential bandpass filter of coupling loop shape resonator from coupling loop shape resonator parity mode parameter with from coupling coefficient k graph of a relation.

Fig. 6 be the utility model based on terminal short circuit from the common mode from coupling loop shape resonator of the arrowband differential bandpass filter of coupling loop shape resonator, differential mode zero point with from coupling coefficient k graph of a relation

Fig. 7 frequency response chart from coupling loop shape resonator that is the utility model based on terminal short circuit from the terminal short circuit of the arrowband differential bandpass filter of coupling loop shape resonator.

Fig. 8 be the utility model based on terminal short circuit the balance filter applying frequency response diagram from the arrowband differential bandpass filter of coupling loop shape resonator.

Embodiment

The utility model discloses a kind of based on terminal short circuit the arrowband differential bandpass filter from coupling loop shape resonator, comprise that terminal short circuit is from coupling loop shape resonator, this terminal short circuit is rectangle from coupling loop shape resonator, these four microstrip lines are respectively the first microstrip line 1 in the direction of the clock, the second microstrip line 2, the 3rd microstrip line 3, the 4th microstrip line 4, the first microstrip line 1 is rectangular top, wherein the first microstrip line 1 and the 3rd microstrip line are symmetrical Shang Xia 3, the second microstrip line 2 and the 4th microstrip line 4 are symmetrical, the second microstrip line 2 right-hand members arrange the first plated-through hole V ₁the first microstrip line 1 and the 5th microstrip line 5 are coupled, the 3rd microstrip line 3 and the 6th microstrip line 6 are coupled, the 6th microstrip line 6 one ports are first input end 7, an other port is that the first output 8, the five microstrip line 5 one ports are the second input 7 ', and another port is the second output 8 ', the 5th microstrip line 5 and the 6th microstrip line 6 are symmetrical up and down along TT ', and wherein TT ' is the center line of rectangle terminal short circuit from coupling loop shape resonator.

The first plated-through hole V of described the second microstrip line 2 right-hand members ₁be connected to the ground.

Described adjustable from coupling loop shape resonator dimensions, dimension of microstrip line, plated-through hole.

Described the 5th microstrip line 5 equates with the width of the 6th microstrip line 6, and is greater than the width of formation rectangle terminal short circuit from four microstrip lines of coupling loop shape resonator.

The common and different mode input impedance of this filter meets following formula:

$\begin{array}{c}{Z}_{\mathrm{inC}}=\frac{2Z_{\mathrm{oe}}{Z}_{\mathrm{oo}}\cos \mathrm{\&theta;}}{{[-{(Z_{\mathrm{oe}}-Z_{\mathrm{oo}})}^2+{(Z_{\mathrm{oe}}+Z_{\mathrm{oo}})}^2{\mathrm{<figure-callout\; id="2"\; label="cso"\; filenames="HDA0000420352810000021.png,HDA0000420352810000023.png"\; state="\{\{state\}\}">cso</figure-callout>}}^2\mathrm{\&theta;}]}^{1/2}}\\ Z_{\mathrm{inD}}=\frac{2Z_{\mathrm{oe}}{Z}_{\mathrm{oo}}}{Z_{\mathrm{oe}}+Z_{\mathrm{oo}}}\end{array}$

In formula, meaning of parameters is: Z _oethe characteristic impedance of even mould, Z _oobe the characteristic impedance of strange mould, θ is the electrical length of the 5th microstrip line 5 or the 6th microstrip line 6.

Below in conjunction with accompanying drawing, the utility model is described in further detail.

In conjunction with Fig. 1, Fig. 2, the utility model is the arrowband differential bandpass filter from coupling loop shape resonator based on terminal short circuit, comprise that terminal short circuit is from coupling loop shape resonator, this terminal short circuit is respectively the first microstrip line 1, the second microstrip line 2, the 3rd microstrip line 3, the 4th microstrip line 4 in the direction of the clock from four articles of microstrip lines of coupling loop shape resonator, the first microstrip line 1 is rectangular top, wherein the first microstrip line 1 and the 3rd microstrip line are symmetrical Shang Xia 3, the second microstrip line 2 and the 4th microstrip line 4 are symmetrical, and the second microstrip line 2 right-hand members arrange the first plated-through hole V ₁the first microstrip line 1 and the 5th microstrip line 5 are coupled, the 3rd microstrip line 3 and the 6th microstrip line 6 are coupled, the 6th microstrip line 6 one ports are first input end 7, an other port is that the first output 8, the five microstrip line 5 one ports are the second input 7 ', and another port is the second output 8 ', the 5th microstrip line 5 and the 6th microstrip line 6 are symmetrical up and down along TT ', and wherein TT ' is the center line of rectangle terminal short circuit from coupling loop shape resonator.

The size of described dimension of microstrip line, plated-through hole and the size of coupling space are adjustable, are to determine according to the operating frequency of the dielectric-slab of different materials and setting.

The utility model is the arrowband differential bandpass filter from coupling loop shape resonator based on terminal short circuit, and its operation principle is summarized as follows: Fig. 1 has provided the schematic diagram from coupling loop shape resonator of terminal short circuit, and Fig. 2 has provided his differential mode, common mode equivalent circuit figure, Z _oe, Z _oo, θ _eand θ _orespectively even mould, the strange characteristic impedance of mould and the electrical length of parallel coupled line.Suppose θ _e=θ _o=θ, can obtain the input impedance of common and different mode

$\begin{array}{c}{Z}_{\mathrm{inC}}=\frac{2Z_{\mathrm{oe}}{Z}_{\mathrm{oo}}\cos \mathrm{\&theta;}}{{[-{(Z_{\mathrm{oe}}-Z_{\mathrm{oo}})}^2+{(Z_{\mathrm{oe}}+Z_{\mathrm{oo}})}^2{\mathrm{<figure-callout\; id="2"\; label="cso"\; filenames="HDA0000420352810000021.png,HDA0000420352810000023.png"\; state="\{\{state\}\}">cso</figure-callout>}}^2\mathrm{\&theta;}]}^{1/2}}\\ Z_{\mathrm{inD}}=\frac{2Z_{\mathrm{oe}}{Z}_{\mathrm{oo}}}{Z_{\mathrm{oe}}+Z_{\mathrm{oo}}}\end{array}$

As shown in Figure 3, for common mode, there is a transmission zero at θ=pi/2, for differential mode, there is all-pass characteristic.But, work as θ _e≠ θ _otime, zero point f _ccan move a little, for differential mode, now at 2f _calso having there is a zero point in frequency place, does not wish to produce but be us this zero point, and this phenomenon is relevant with the microstrip line of non-uniform dielectric.

In order to verify the impact on balancing band bandpass filter application from coupling loop shape resonator, will further discuss two zero point f _cand f _dand the relation between the parameter of coupling loop shape resonator.First, we consider from coupling loop shape resonator length l ₁impact.Fig. 4 has described different length l ₁corresponding different common mode resonance frequency f _cwith differential mode resonance frequency f _d.F as seen from Figure 4 _cand f _dall be subject to l ₁effect length, and f _dstill equal 2f _c.Secondly, we consider the impact from coupling coefficient k from coupling loop shape resonator again.Fig. 5 has described from coupling coefficient k and characteristic impedance (Z from the even mould of coupling loop shape resonator and Qi Mo _oeand Z _oo), dielectric constant (ε _eand ε _o) between variation tendency.Obviously easily see, different from coupling coefficient k, can make characteristic impedance and electrical length size variation.In the time of k=0, when coupling effect can be ignored, even mould and strange mould parameter equate.F _cand f _dand the corresponding relation between k as shown in Figure 6.Obviously, f _cincrease f along with the increase of k value _dreduce along with the increase of k value; Resonance frequency f _din close coupling situation away from 2f _c.Generally speaking, in order to obtain wider differential mode passband, select a less value k, make resonance frequency f _dwith f _cfrom farther.

Below in conjunction with embodiment, the utility model is done to further detailed description:

Embodiment is the arrowband differential bandpass filter of terminal short circuit from coupling loop shape resonator.Referring to Fig. 1, introduce the final circuit size parameter of this filter: the first microstrip line 1 and the 3rd microstrip line 3 length and width are respectively l ₁=20mm, w ₁=0.4mm; The second microstrip line 2 and the 4th microstrip line 4 length and width are respectively s=0.8mm, w ₁=0.4mm; The first microstrip line 1 and the 5th microstrip line 5 coupling spaces are g ₁=0.3mm; The 3rd microstrip line 3 and the 6th microstrip line 6 coupling spaces are g ₁=0.3mm; The 5th microstrip line 5 and the 6th microstrip line 6 are all 50 Ω microstrip lines.The frequency response of differential bandpass filter as shown in Figure 7.As can be seen from the figure, from 0 to 4.8GHz, differential signal does not have change substantially, and common-mode signal has a very narrow stopband near 2.4GHz frequency.In the broadband of 0-4.8GHz, the return loss of differential mode is greater than 10dB, and insertion loss is less than 3dB; Inhibition in common mode center frequency point exceedes 25dB.These characteristics, in the case of the differential mode frequency response of balance filter is constant, have great role to improving common mode inhibition.We have been applied to the utility model in balance filter, find, in common mode passband, to suppress to exceed 20dB; In differential mode passband, suppress to have exceeded especially 60dB, as shown in Figure 8, excellent performance.

The foregoing is only two embodiment of the present utility model, not in order to limit the utility model, all within the utility model spirit and principle, any modification of making, be equal to replacement, improvement etc., within all should being included in the utility model protection range.

Claims (4)

1. One kind based on terminal short circuit the arrowband differential bandpass filter from coupling loop shape resonator, it is characterized in that, comprise that terminal short circuit is from coupling loop shape resonator, this terminal short circuit is rectangle from coupling loop shape resonator, article four, microstrip line is respectively the first microstrip line (1) in the direction of the clock, the second microstrip line (2), the 3rd microstrip line (3), the 4th microstrip line (4), the first microstrip line (1) is rectangular top, wherein the first microstrip line (1) is symmetrical up and down with the 3rd microstrip line (3), the second microstrip line (2) is symmetrical with the 4th microstrip line (4), the second microstrip line (2) right-hand member arranges the first plated-through hole V ₁the first microstrip line (1) and the 5th microstrip line (5) coupling, the 3rd microstrip line (3) and the 6th microstrip line (6) coupling, the 6th microstrip line (6) one ports are first input end (7), an other port is the first output (8), the 5th microstrip line (5) one ports are the second input (7 '), another port is the second output (8 '), the 5th microstrip line (5) is symmetrical up and down along TT ' with the 6th microstrip line (6), and wherein TT ' is the center line of rectangle terminal short circuit from coupling loop shape resonator.
2. According to claim 1 based on terminal short circuit the arrowband differential bandpass filter from coupling loop shape resonator, it is characterized in that the first plated-through hole V of the second microstrip line (2) right-hand member ₁be connected to the ground.
3. According to claim 1 based on terminal short circuit the arrowband differential bandpass filter from coupling loop shape resonator, it is characterized in that, adjustable from coupling loop shape resonator dimensions, dimension of microstrip line, plated-through hole.
4. According to claim 1 based on terminal short circuit the arrowband differential bandpass filter from coupling loop shape resonator, it is characterized in that, the 5th microstrip line (5) equates with the width of the 6th microstrip line (6), and is greater than the width of formation rectangle terminal short circuit from four microstrip lines of coupling loop shape resonator.

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