CN103178319A

CN103178319A - Interdigital coupling duplexer

Info

Publication number: CN103178319A
Application number: CN2013100996874A
Authority: CN
Inventors: 王世伟; 刘晓晗; 陈瑞森; 汪凯; 郑丽昇; 褚庆昕
Original assignee: South China University of Technology SCUT
Current assignee: South China University of Technology SCUT
Priority date: 2013-03-26
Filing date: 2013-03-26
Publication date: 2013-06-26

Abstract

The invention discloses an interdigital coupling duplexer which comprises a substrate, wherein a metal ground layer covers the bottom of the substrate; the front surface of the substrate comprises an upper pair of coupling wires and a lower pair of coupling wires which have the same structures and matching wires with the flush end parts respectively arranged in the centers of two ends of the two pairs of coupling wires; each pair of coupling wires have centrosymmetric short-circuit branch structures; short-circuit branches are connected with the metal ground layer at the bottom of the substrate; and the lengths of the matching wires at the two ends of each pair of coupling wires are equal to the coupling lengths of the coupling wires. Due to the short-circuit branches, transmission zero points are produced; the bandwidth of the duplexer is adjusted by changing the positions of the short-circuit branches, so that a requirement of a communication system on a specific bandwidth can be met; and the lengths of the matching wires at the two ends of each pair of coupling wires are equal to the coupling lengths of the coupling wires, so that an interdigital coupling structure is formed, the out-of-band attenuation is improved, and a relatively good filtration characteristic is achieved. The technical measure is simple, convenient and feasible, small in size, low in cost, good in characteristic and suitable for multiple communication systems.

Description

A kind of interdigital coupling duplexer

Technical field

The present invention relates to microstrip line form duplexer, relate in particular to a kind of interdigital coupling duplexer.

Background technology

Along with the fast development of radio communication, the frequency resource growing tension, as the important part of wireless communication system, the performance quality of duplexer directly has influence on the quality of communication system.

Duplexer commonly used in the communications field has:

1, waveguide duplexer: the time that this duplexer is used is also the most ripe at most, and its loss is low, and operating frequency is high, but volume is large, cost is high, tuning difficulty;

2, coaxial duplexer: as medium and the silver-plated coaxial duplexer of internal and external conductor, its dielectric loss and ohmic loss are all very little with air, and stability is high, shielding good, but in the mobile communication frequency domain, it is too large that its volume still seems;

3, dielectric duplexer: it has realized the miniaturization of duplexer, but because cost is too high, so be not widely used in the communications field;

4, SAW duplexer: this duplexer is due to the frequency characteristic that can realize arbitrary accuracy, and volume is little, design flexibility is good, high reliability, be widely used in the communications field, its weak point is that cost is high, and insertion loss is large, and it is low that high frequency bears power, so be suitable for the exigent mobile communication terminal of miniaturization.

Summary of the invention

The object of the invention is to overcome the shortcoming and defect of above-mentioned prior art, a kind of interdigital coupling duplexer is provided, overcome the relatively poor difficulty of existing micro-strip duplexer filtering characteristic, and solved the problem that passband can't independently be controlled.

The present invention is achieved through the following technical solutions:

A kind of interdigital coupling duplexer comprises substrate, and the bottom surface of substrate is covered by the metal stratum, and substrate front side comprises the two pairs of coupling lines that structure is identical and the end flushes in up and down, and the matched line that is separately positioned on coupling line two ends, two pairs of up and down central authorities; Every a pair of coupling line all has centrosymmetric short branch, and the metal stratum of short branch and substrate bottom surface is connected; The matched line at every a pair of coupling line two ends equates with this coupling length to coupling line.

The length of the two pairs of coupling lines in up and down can be different, perhaps go up the length of coupling line greater than the length of lower coupling line.

The coupling length of upper coupling line two ends matched line is greater than the coupling length of lower coupling line two ends matched line.

The matched line of the two pairs of mutually same ends of coupling line in up and down shares connectivity port one, and the matched line of the two pairs of coupling line other ends in up and down is connectivity port two and port three respectively.

In the central authorities of port one matching connection line one end, also have additional rectangle coupling detail.

The present invention has following advantage and effect with respect to prior art:

By increasing short branch (virtual earth), produce transmission zero, can adjust by the position that changes short branch the bandwidth of duplexer, to satisfy in communication system the needs to specific bandwidth.

The matched line at every a pair of coupling line two ends equates with this coupling length to coupling line, and this coupling has formed interdigital coupled structure, has improved attenuation outside a channel, has better filtering characteristic.

The technology of the present invention means are simple and easy to do, and volume is little, and cost is low, and characteristic is good, is applicable to plurality of communication systems.

Description of drawings

Fig. 1 is the interdigital coupling diplexer structure of the present invention schematic diagram.

Fig. 2 is port one and the transmission coefficient of port two and the reflection coefficient of port two (unit: decibel).

Fig. 3 be port one to port three transmission coefficient and the reflection coefficient (unit: decibel) of port three.

Fig. 4 be port three with port two isolation and the reflection coefficient (unit: decibel) of port one.

In Fig. 2～Fig. 4, solid line represents Simulation, and dotted line represents Measurement.

Embodiment

Below in conjunction with specific embodiment, the present invention is done further concrete detailed description the in detail.

Embodiment

As shown in Figure 1, the interdigital coupling duplexer of the present invention, comprise substrate 9, the bottom surface of substrate 9 is by metal stratum covering (not shown), substrate 9 fronts comprise two pairs of the up and down coupling line that structure is identical and the

end flushes

4,5, and the matched line 6 that is separately positioned on two pairs of up and down

coupling line

4,5 two ends central authorities; Every a pair of coupling line all has centrosymmetric short branch 7, and the metal stratum of short branch structure 7 and substrate 9 bottom surfaces is connected; The matched line 6 at every a pair of coupling line two ends equates with this coupling length to coupling line, but the coupling length of upper coupling line 4 two ends matched lines 6 is greater than the coupling length of lower coupling line 5 two ends matched lines 6.

In practical application, the two pairs of coupling lines 4 in up and down, 5 length can be different, and the length of the upper coupling line that this implementation column provides is greater than the length of lower coupling line.

The matched line 6 of two pairs of up and down

coupling line

4,5 mutually same ends shares connectivity port 1, and the matched line 6 of two pairs of up and down

coupling line

4,5 other ends is connectivity port 22 and port 33 respectively.

In the central authorities of port one 1 matching connection line 6 one ends, also have additional rectangle coupling detail 8.

In fact the two pairs of

coupling lines

4,5 that structure is identical in up and down have consisted of two rotational symmetric band pass filters, and every pair of coupling line all has centrosymmetric short branch structure 7(and is equivalent to virtual earth) be used for producing transmission zero, adjust bandwidth;

And the matched line 6 at every a pair of

coupling line

4,5 two ends forms interdigital coupling, is used for improving attenuation outside a channel, improves filtering characteristic; Port 1, port 22 and port 33 adopt 50 ohm microstrip to be used for doing feeder line.

By adjusting two pairs of up and down

coupling line

4,5 length, width, spacing, and adjust matched line 6 and the coupling length between the two pairs of

coupling lines

4,5 up and down etc. in practical application, the passband of higher (perhaps lower) frequency is moved.

The present invention's structure as shown in Figure 1 have good attenuation outside a channel characteristic, and insertion loss is little, and volume is little, in actual applications, uses convenient.

Fig. 2 shows port 1 and the transmission coefficient of port 22 and the reflection coefficient of port 22 (unit: decibel) curve chart.

Fig. 3 show port 1 to port 33 transmission coefficient and the reflection coefficient (unit: decibel) curve chart of port 33.

Fig. 4 show port 33 and port 22 isolation and the reflection coefficient (unit: decibel) curve chart of port 1.

As mentioned above, just can realize preferably the present invention.

Embodiments of the present invention are not restricted to the described embodiments; other are any does not deviate from change, the modification done under Spirit Essence of the present invention and principle, substitute, combination, simplify; all should be the substitute mode of equivalence, within being included in protection scope of the present invention.

Claims

1. interdigital coupling duplexer, comprise substrate, the bottom surface of substrate is covered by the metal stratum, it is characterized in that: substrate front side comprises the two pairs of coupling lines that structure is identical and the end flushes in up and down, and the matched line that is separately positioned on coupling line two ends, two pairs of up and down central authorities; Every a pair of coupling line all has centrosymmetric short branch, and the metal stratum of short branch and substrate bottom surface is connected; The matched line at every a pair of coupling line two ends equates with this coupling length to coupling line.

2. interdigital coupling duplexer according to claim 1, is characterized in that: the length difference of the two pairs of coupling lines in up and down.

3. interdigital coupling duplexer according to claim 1, is characterized in that: go up the length of coupling line greater than the length of lower coupling line.

4. the described interdigital coupling duplexer of any one according to claim 1～3 is characterized in that: the coupling length of upper coupling line two ends matched line is greater than the coupling length of lower coupling line two ends matched line.

5. interdigital coupling duplexer according to claim 4 is characterized in that: the matched line of the two pairs of mutually same ends of coupling line in up and down shares connectivity port one, and the matched line of the two pairs of coupling line other ends in up and down is connectivity port two and port three respectively.

6. interdigital coupling duplexer according to claim 5, is characterized in that: in the central authorities of port one matching connection line one end, also have additional rectangle coupling detail.