CN203883094U - A Microstrip Duplexer Based on Electromagnetic Hybrid Coupling - Google Patents

Abstract

The utility model discloses a microstrip duplexer based on electromagnetism hybrid coupling, including two-sided copper-clad microstrip board, two filters with controllable passband frequency and bandwidth, a first port feeder, a second port feeder, a T-shaped joint, a first port, a second port and a third port are respectively manufactured on the same side of the two-sided copper-clad microstrip board, and the other side of the two-sided copper-clad microstrip board is a copper-clad ground plate; the two filters are both mainly composed of three mutually coupled micro-strip resonators with quarter wavelength, a grounding through hole is arranged at the connecting position of one end of each micro-strip resonator, and electric coupling exists between two adjacent micro-strip resonators in each filter. The utility model discloses on original magnetic coupling basis, the electric coupling has been introduced for intensity through adjusting magnetic coupling and electric coupling can change the bandwidth of duplexer in a flexible way, and near cutoff frequency can produce several transmission zero point about the wave filter after the improvement, makes the mutual influence of the reducible two wave filters in position of adjusting these zero points.

Description

A Microstrip Duplexer Based on Electromagnetic Hybrid Coupling

technical field

The utility model relates to the technical field of frequency division duplexing, in particular to a microstrip duplexer based on electromagnetic hybrid coupling.

Background technique

Due to the rapid development of wireless communication in recent years, whether it is the popularization of 3G technology, the popularity of the Internet of Things or the arrival of 4G, it marks that wireless technology will usher in a peak period of vigorous development. Today's wireless communication systems are basically duplex systems. For time-division duplex, the problem can be solved by arranging reception and transmission in different time slices. For frequency-division duplex, in order to reduce the number of antennas, it is necessary A special device is designed to make electromagnetic waves of different frequencies share an antenna without causing mutual interference. Such a device is a duplexer. The miniaturized, low-cost, low-loss, high-isolation duplexer has also become one of the research hotspots in recent years.

Currently, commonly used types of duplexers include: waveguide duplexers, coaxial duplexers, dielectric duplexers, and SAW duplexers. These duplexers have their own advantages and disadvantages. For example, the waveguide duplexer has been used for the longest time and is the most mature. It has low loss and high operating frequency, but it is large in size, high in cost, and difficult to tune; The loss is very small, and the stability is high, and the shielding is good, but in the mobile communication frequency domain, its volume is still too large; although the dielectric duplexer realizes the miniaturization of the duplexer, the cost is too high; SAW duplexer The device can achieve frequency characteristics with arbitrary precision, and is small in size, good in design flexibility, and high in reliability, but its disadvantages are high cost, large loss, and low high-frequency withstand power.

Nowadays, with the continuous development of mobile communication technology, spectrum resources are becoming increasingly scarce. With the crazy growth of portable wireless electronic products, miniaturization, low cost, and high frequency have become the research direction of duplexers, and microstrip duplexers can meet these requirements, and duplexers with good structure can also meet Lower loss and higher isolation requirements.

At present, the commonly used and convenient design method of microstrip duplexer is to design two bandpass filters located in the low frequency band and high frequency band, and then connect the two bandpass filters with different center frequencies with T-shaped connectors. Then, by adjusting the matching of each port and correcting the influence of mutual coupling caused by the connection between the two filters and the T-shaped connector, the performance of the microstrip duplexer can reach the expected index. By far the most common type of coupling in microstrip duplexers is electrical coupling.

Contents of the invention

The purpose of the utility model is to overcome the deficiencies of the prior art and provide a microstrip duplexer based on electromagnetic hybrid coupling with better comprehensive performance, which has more flexible selectivity and can meet the requirements of miniaturization, low cost, and good filtering characteristics. , high isolation, and a duplexer with a wide range of controllable performance in the passband.

In order to achieve the above purpose, the technical solution provided by the utility model is: a microstrip duplexer based on electromagnetic hybrid coupling, including a double-sided copper-clad microstrip board, and the same surface of the double-sided copper-clad microstrip board There are two passband frequency and bandwidth controllable filters, the first port feeder, the second port feeder, T-shaped joints, the first port for transmitting mixed frequency electromagnetic wave signals, and the first port for transmitting high frequency band electromagnetic wave signals. The second port, the third port for transmitting low-frequency electromagnetic wave signals, the other side of the double-sided copper-clad microstrip board is a copper-clad grounding plate; wherein, the T-shaped joint is adjacently arranged between the two filters, The longitudinal feeder of the T-joint is connected to the first port; the first port feeder is adjacent to the other side of one of the filters relative to the T-joint, and one end of the first port feeder is connected to the T-joint. There is a coupling gap between the ends of a horizontal feeder, which can introduce source-load coupling, and its other end is connected to the third port; the feeder at the second port is adjacently arranged on the other side of the other filter relative to the T-shaped joint, the There is a coupling gap between one end of the second port feeder and the other transverse feeder end of the T-joint, which can introduce source-load coupling, and its other end is connected to the second port; the two filters are mainly composed of three One end of the three microstrip resonators is connected to each other, and there is a ground via at the connection, and the three microstrip resonators in each filter spaced side by side, and there is electrical coupling between two adjacent microstrip resonators; the grounding vias of the two filters can be connected with solder and the copper-clad grounding plate, and after connection, they become short-circuit ends, and are the respective microstrip Magnetic coupling is introduced between the resonators.

The first port, the second port, and the third port all have a matching impedance of 50 ohms.

In each filter, the microstrip resonator in the middle is parallel to the longitudinal feeder of the T-joint, and the microstrip resonators on both sides are composed of four microstrips, two of which are parallel to the longitudinal feeder of the T-joint, Two other longitudinal feeders perpendicular to the T-joint, one end of the microstrip parallel to the T-joint longitudinal feeder is connected by one of the microstrips perpendicular to the T-joint longitudinal feeder; the parallel to the T-joint Among the two microstrips of the longitudinal feeder, the shorter one is close to the microstrip resonator in the middle, and the other end of the longer one is connected to another microstrip perpendicular to the T-joint longitudinal feeder, and the microstrip The strip is connected with a microstrip resonator located in the middle.

There is a reserved space between the first port feeder, the T-shaped connector, and the grounding hole of one of the filters, and there is a reserved space between the second port feeder, the T-shaped connector, and the grounding hole of the other filter. Reserved space.

Compared with the prior art, the utility model has the following advantages and beneficial effects:

1. By introducing source-load coupling and electromagnetic hybrid coupling, the filter generates multiple transmission zeros, and reasonably adjusting the frequency positions of these transmission zeros can enable the entire duplexer to obtain a high degree of isolation;

2. The electromagnetic hybrid coupling method is adopted between the resonators so that the bandwidth of the duplexer can be controlled in a large range, and the center frequency of the two bandpass filters can be changed by adjusting the length of the resonators. Therefore, the utility model Microstrip duplexers can be very flexibly adapted to a variety of communication systems;

3. The duplexer with this structure has the characteristics of low insertion loss, good out-of-band selectivity, and good filtering characteristics;

4. Since the duplexer has a microstrip structure, it is light in weight, low in cost, and suitable for industrial mass production, so the duplexer has the advantages of simple structure, easy design, and low manufacturing cost.

Description of drawings

FIG. 1 is a schematic diagram of a microstrip duplexer of the present invention.

FIG. 2 is a simulation result diagram of scattering parameters of the microstrip duplexer of the present invention.

Detailed ways

Below in conjunction with specific embodiment the utility model is further described.

Referring to Fig. 1, the microstrip duplexer based on electromagnetic hybrid coupling described in this embodiment includes a double-sided copper-clad microstrip board 1, and the same surface of the double-sided copper-clad microstrip board 1 is respectively made with Two filters with controllable passband frequency and bandwidth, first port feeder 12, second port feeder 4, T-shaped connector 8, first port Port1 for transmitting mixed frequency electromagnetic wave signals, and for transmitting high frequency band electromagnetic wave signals The second port Port2, the third port Port3 for transmitting low-frequency electromagnetic wave signals, the other side of the double-sided copper-clad microstrip board 1 is a copper-clad grounding board; wherein, the T-shaped connector 8 is adjacently arranged on two Between the filters, the longitudinal feeder of the T-shaped joint 8 is connected to the first port Port1; the first port feeder 12 is adjacently arranged on the other side of one of the filters relative to the T-shaped joint 8, and the first port feeder There is a coupling gap 9 between one end of 12 and a transverse feeder end of the T-shaped joint 8, which can introduce source-load coupling to obtain better out-of-band selectivity. The other end of the first port feeder 12 is connected to the first port The three-port Port3 is connected; the second port feeder 4 is adjacent to the opposite side of the other filter relative to the T-shaped joint 8, and one end of the second port feeder 4 is connected to the other transverse feeder of the T-shaped joint 8 There is a coupling gap 7 between the ends, which can introduce source-load coupling to obtain better out-of-band selectivity. The other end of the second port feeder 4 is connected to the second port Port2; the first port Port1, the second port Both the port Port2 and the third port Port3 have a matching impedance of 50 ohms.

The two filters are mainly composed of three mutually coupled quarter-wavelength microstrip resonators, as shown in Figure 1, one of the filters includes microstrip resonators 13, 14, 15, and Another filter includes microstrip resonators 2, 3, 16, one end of the three microstrip resonators 13, 14, 15 are connected to each other, and there is a ground via hole 11 at the connection, the three microstrips One end of the resonators 2, 3, and 16 is connected to each other, and there is a grounding hole 5 at the connection, and the three microstrip resonators in each filter are spaced and arranged side by side, and there is an electric current between two adjacent microstrip resonators. Coupling, in each filter, the microstrip resonator in the middle is parallel to the longitudinal feeder of the T-joint 8, and the microstrip resonators on both sides are composed of four microstrips, two of which are parallel to the T-joint 8 The longitudinal feeder, the other two longitudinal feeders perpendicular to the T-joint 8, one end of the two microstrips parallel to the T-joint 8 longitudinal feeder is connected by one of the microstrips perpendicular to the T-joint 8 longitudinal feeder; Among the two microstrips parallel to the longitudinal feeder of the T-joint 8, the shorter microstrip is close to the microstrip resonator in the middle, and the other end of the longer microstrip is connected to another one perpendicular to the T-joint 8 The microstrip of the vertical feed line is connected to the microstrip resonator located in the middle. By adjusting the electrical coupling and magnetic coupling between the microstrip resonators, the bandwidth of each filter can be adjusted in a wide range; by introducing source-side coupling, two The transmission zero greatly improves the out-of-band rejection of the duplexer.

The ground vias 11 and the ground vias 5 can be connected to the copper-clad ground plate with solder, and become short-circuit terminals after connection. The two filters described in this embodiment are connected to the copper-clad ground plate through the corresponding ground vias. connected to introduce magnetic coupling between the respective microstrip resonators.

In addition, in order to facilitate the welding of through holes and prevent the short circuit between the microstrip resonator and the feeder, there is a reserved space between the first port feeder 12, the T-shaped joint 8, and the grounding through hole 11 of one of the filters described in this embodiment. Space 10 , a reserved space 6 is reserved among the second port feeder 4 , the T-joint 8 , and the grounding hole 5 of another filter.

Referring to Fig. 2, it shows the simulation results of the scattering parameters of the microstrip duplexer, and its center frequencies are 1.8Ghz and 2.4Ghz respectively. The horizontal axis represents the signal frequency of the microstrip duplexer, and the vertical axis represents the amplitude, including the amplitude of insertion loss (S ₁₂ , S ₁₃ ), the amplitude of return loss (S ₁₁ , S ₂₂ , S ₃₃ ) and the isolation ( S ₂₃ ), where S ₁₁ represents the return loss of port1, S ₂₂ represents the return loss of port2, S ₃₃ represents the return loss of port3, S ₁₂ represents the insertion loss of port1 and port3, S ₁₃ represents the port1 and port3 insertion loss. Insertion loss represents the relationship between the input power of a signal and the output power of another port signal, and its corresponding mathematical function is: output power/input power (dB)=20*log|S ₂₁ |. Return loss represents the relationship between the input power of the port signal and the reflected power of the signal, and the corresponding mathematical function is as follows: reflected power/incident power==20*log|S ₁₁ |.

It can be seen from the figure that in the 1.8Ghz passband, the absolute value of the return loss |S ₁₁ | and S ₃₃ is greater than 20DB, and the absolute value of the insertion loss S ₁₃ is less than 1.5DB. The absolute value of loss _S11 and _S22 is greater than 20DB, and the absolute value of insertion loss _S12 is less than 1.5DB. Seen from the frequency range of 0-4Ghz, the absolute value of the isolation S ₂₃ of the microstrip duplexer is greater than 40DB. In addition, several transmission zero points can be generated on both sides of each passband of the microstrip duplexer, which greatly improves the out-of-band suppression.

After adopting the above scheme, the utility model introduces electric coupling between the microstrip resonators on the basis of the original magnetic coupling, so that the bandwidth of the duplexer can be changed very flexibly by adjusting the strength of the magnetic coupling and electric coupling, Moreover, the improved filter will generate several transmission zeros near the upper and lower cutoff frequencies, so that the mutual influence of the two filters can be reduced by adjusting the positions of these zeros, thereby improving the isolation of the entire duplexer. Compared with the prior art, the utility model is a microstrip duplexer with better overall performance, which can effectively overcome the poor filtering characteristics of the existing microstrip duplexer, has more flexible selectivity, and can It meets the design requirements of miniaturization, low cost, good filtering characteristics, high isolation, and wide-range controllable passband, and is worthy of promotion.

The implementation examples described above are only preferred embodiments of the present utility model, and are not intended to limit the scope of implementation of the present utility model, so all changes made according to the shape and principle of the present utility model should be covered by the scope of the present utility model. within the scope of protection.

Claims (4)

1. A microstrip duplexer based on electromagnetic hybrid coupling, comprising a double-sided copper-clad microstrip board (1), characterized in that: the same surface of the double-sided copper-clad microstrip board (1) is respectively made with Two filters with controllable passband frequency and bandwidth, first port feeder (12), second port feeder (4), T-shaped connector (8), first port (Port1) for transmitting mixed frequency electromagnetic wave signals , the second port (Port2) for transmitting high-frequency electromagnetic wave signals, the third port (Port3) for transmitting low-frequency electromagnetic wave signals, the other side of the double-sided copper-clad microstrip board (1) is a copper-clad grounding board ; Wherein, the T-shaped joint (8) is adjacently arranged between two filters, and the longitudinal feeder of the T-shaped joint (8) is connected to the first port (Port1); the first port feeder (12) is adjacent to It is arranged on the other side of one of the filters opposite to the T-shaped joint (8), and there is a coupling gap between one end of the first port feeder (12) and a transverse feeder end of the T-shaped joint (8) ( 9), the source-load coupling can be introduced, the other end of which is connected to the third port (Port3); the feeder line (4) of the second port is adjacent to the other side of the other filter relative to the T-shaped connector (8), There is a coupling gap (7) between one end of the second port feeder (4) and the other transverse feeder end of the T-joint (8), which can introduce source-load coupling, and its other end is connected to the second port (Port2 ) connection; the two filters are mainly composed of three quarter-wavelength microstrip resonators coupled to each other, one end of the three microstrip resonators is connected to each other, and there is a ground via at the connection , the three microstrip resonators in each filter are spaced side by side, and there is electrical coupling between two adjacent microstrip resonators; the grounding vias of the two filters can be connected to the copper-clad grounding plate with solder , and become a short-circuit terminal after connection, and introduce magnetic coupling between the respective microstrip resonators. 2. A microstrip duplexer based on electromagnetic hybrid coupling according to claim 1, characterized in that: the first port (Port1), the second port (Port2), and the third port (Port3) are all 50 ohm matching impedance. 3. A microstrip duplexer based on electromagnetic hybrid coupling according to claim 1, characterized in that: in each filter, the microstrip resonator located in the middle is parallel to the longitudinal direction of the T-shaped joint (8) Feedlines, the microstrip resonators on both sides are composed of four microstrips, two of which are parallel to the longitudinal feedlines of the T-joint (8), and the other two are perpendicular to the longitudinal feedlines of the T-joint (8), the two One end of the microstrip parallel to the longitudinal feeder of the T-joint (8) is connected by one of the microstrips perpendicular to the longitudinal feeder of the T-joint (8); the two microstrips parallel to the longitudinal feeder of the T-joint (8) In the strip, the shorter microstrip is close to the microstrip resonator located in the middle, and the other end of the longer microstrip is connected to another microstrip perpendicular to the longitudinal feeder line of the T-joint (8), and the microstrip is located at The middle microstrip resonator is connected. 4. A microstrip duplexer based on electromagnetic hybrid coupling according to claim 1, characterized in that: the first port feeder (12), the T-shaped connector (8), and the ground connection of one of the filters A reserved space (10) is reserved between the holes (11), and a reserved space is reserved between the second port feeder (4), the T-shaped joint (8), and the grounding hole (5) of another filter (6).